JPH10217076A - Work method of disk substrate, work device and outer peripheral blade grinding wheel used in this work method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of microscopic waviness by performing grinding work by moving either one of a disk substrate or a peripheral cutting edge grinding wheel so that side cut work and spark out work are successively and continuously performed on the disk substrate while rotating the peripheral cutting edge grinding wheel and the disk substrate. SOLUTION: In work, first of all, a side cut work part A performs depth directional grinding of a disk substrate 12 for the purpose of rough grinding, and about 80% of the whole work quantity is removed here. Next, a dimension producing work part B is the so-called plane grinding part, but dispersion of a thickness is controlled to about 1μm by grinding in this part B, and lastly, the work is finished by performing spark out work (leveling work) to remove a locus (microscopic waviness) of a grinding wheel caused by the work by a spark out work part C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness grinding method for a disk substrate which requires strict processing accuracy such as a glass disk used for a hard disk used as a recording medium of a computer or the like. The present invention relates to a disk substrate processing method and processing apparatus for preventing variations in the thickness of a disk substrate, pits (digging) on a ground surface, and minute undulations on the ground surface, and an outer peripheral grindstone used in the processing method.

[0002]

2. Description of the Related Art In recent years, hard disks used as recording media for computers and the like have been reduced in size and capacity. The hard disk is generally made of a non-magnetic metal aluminum disk as a substrate and coated with a magnetic material, and is sealed with a head and a drive device for recording information on the hard disk and the like. Put in. The head does not directly contact the disk by utilizing the air flow caused by the high-speed rotation of the disk, but the distance between the head and the disk is very small. Therefore, in order to maintain the recording accuracy and the reliability of the apparatus, the aluminum disk substrate as the substrate of the hard disk is required to have strict thickness uniformity and smooth surface. For example, at present, small undulations
A substrate having a thickness of 0.05 μm and a surface roughness (Ra) of 0.0025 μm or less is used.

However, at present, the hard disk drive development side has requested an aluminum substrate having a surface roughness (Ra) of 0.001 μm or less, but from the viewpoint of the manufacturing side, the ductility, ductility, strength, It is very difficult to meet this demand due to properties such as hardness. Of course, if you use special equipment or take time to process, it is possible to achieve the desired characteristics,
It becomes impossible to cope in terms of cost.

Therefore, it has been proposed to use a vitreous substrate such as crystallized glass, chemically strengthened glass, or glassy carbon instead of the conventional aluminum substrate. When these substrates are manufactured, a process of generally performing surface grinding of an original plate manufactured by various methods and further performing polishing is adopted, but a polishing process that requires equipment cost and running cost is reduced. As much as possible, it is preferable to perform as smooth a processing as possible in the surface grinding step.

As a specific surface grinding method, for example, a substrate is sandwiched between cast iron platens from above and below, GC (green silicon carbide abrasive), WA (white alumina abrasive), composite abrasive (alundum and carbonized abrasive). Lapping method using loose abrasive grains such as silicon mixed powder), rotary surface grinding method in which a high-speed rotating cup grinding wheel is pressed from above onto a fixed substrate, or horizontal surface grinding method in which the workpiece and grinding wheel are always entangled Is used. Subsequently, the substrate ground by such a method is mirror-polished on a pad using cerium oxide abrasive grains, so that the final surface roughness (Ra) is reduced to about 0.0008 μm. .

[0006]

However, in the lapping method using loose abrasives, there is no problem in terms of the quality variation in the thickness variation of a workpiece, but a pit (excavation) is generated on a part of the ground surface. There is. In addition, there is a disadvantage that the lap surface plate is worn by use and warps. As a method for suppressing the uneven wear of the lap plate, a diamond pellet plate has been developed, but the problem of pit formation has not been solved.

[0007] Also, in rotary surface grinding using a cup grindstone, although a partial combination of side cut processing and spark-out processing is partially performed, the allowable range of inclination control of the grindstone axis is narrow, and the grindstone width is small. Because it is narrow,
It is not possible to set sufficient conditions for combining side cut processing and spark out processing. Further, since the workpiece is not continuously meshed with the grindstone, the load resistance applied to the grindstone varies, and as a result, there is a problem that minute undulation due to the locus of the grindstone occurs.

In any of the above cases, in the polishing step after the surface grinding, the pits generated on the substrate surface by the surface grinding or the variation in the thickness are corrected to obtain the surface roughness (Ra).
About 30 μm to reduce to about 0.001 μm.
４０40 μm must be polished. Therefore, there is a disadvantage that the cost increases due to an increase in the polishing amount and a prolonged processing time.

On the other hand, the horizontal surface grinding method is superior to the above-described lap grinding method and rotary surface grinding method in terms of both the thickness processing accuracy and the occurrence of pits and the like, and the polishing depth in the polishing step is small. Although it can be suppressed to about 10 to 15 μm, there is a problem that clogging of the grindstone occurs or workability and productivity are poor due to in-field grinding. In general, pits are unavoidable in processing methods that use brittle fracture, such as the lap method and diamond pellet lap method, and in processing that uses plastic deformation such as the rotary surface grinding method and the horizontal surface grinding method, pits are generated. However, there is a problem that clogging of the grindstone and minute waviness due to the locus of the grindstone occur.

[0010]

Means for Solving the Problems The present invention has been made in view of the above problems, and realizes brittle fracture processing on an outer peripheral grinding wheel and plastic deformation processing on an object to be ground. In order to achieve this, a surface grinding method has been developed that simultaneously performs high-speed rotation of the workpiece, side-cut processing using a wide outer peripheral grinding wheel, and spark-out processing. That is,
According to the present invention, after the outer peripheral grindstone and the disk substrate as a workpiece are three-dimensionally positioned by a three-axis moving mechanism of X axis, Y axis, and Z axis orthogonal to each other, the outer peripheral grindstone and While rotating the disk substrate, either one of the disk substrate or the outer peripheral grindstone is moved in at least one axial direction so that side cut processing and spark-out processing are sequentially and continuously performed on the disk substrate. And a disk substrate processing method, characterized in that the disk substrate is processed by grinding.

Here, in the disk substrate processing method of the present invention, a diamond grindstone is suitably used as an outer peripheral grindstone, and the outer peripheral grindstone has a grindstone width of 5 mm or more and 70 mm or more.
mm or less. Examples of the substrate suitable for the processing method of the present invention include a blue glass disk and a crystallized glass disk.

According to the present invention, in order to carry out the above-described processing method, the X-axis, the Y-axis, and the Z-axis, which are orthogonal to each other, can three-dimensionally position the outer peripheral grindstone and the disk substrate as the workpiece. An apparatus for processing a disk substrate, comprising: a mechanism for moving a shaft in three axial directions; a mechanism for rotating the outer peripheral grindstone; and a mechanism for rotating the disk substrate. Side cutting section for grinding in the direction, a dimensioning section for performing surface grinding of the surface of the disk substrate formed by the side cutting section, and a spark-out section for removing a locus generated by the dimensioning section By moving one of the rotating disk substrate and the rotating outer peripheral grindstone in at least one axial direction, the disk The disk substrate is provided with a disk substrate processing apparatus, wherein the disk substrate is continuously processed in the order of the side cut processing section, the dimensioning processing section, and then the spark-out processing section.

[0013] A diamond grindstone is preferably used as the outer peripheral grindstone used in the disk substrate processing apparatus, and the outer peripheral grindstone has a grindstone width of 5 mm or more and 70 m or more.
m or less is preferable. Further, a blue glass disk and a crystallized glass disk are mentioned as disk substrates suitable for the processing of the present invention.

Further, in the present invention, as the outer peripheral grindstone mainly used for processing the disk substrate described above,
A side cut processing section for grinding the workpiece in the depth direction, a dimensioning processing section for performing surface grinding of the surface of the workpiece formed by the side cut processing section, and a locus generated by the dimensioning processing section. And a spark-out processing part to be removed.

[0015] The outer peripheral grindstone is preferably a diamond grindstone, and the width of the outer peripheral grindstone is preferably 5 mm or more and 70 mm or less.

[0016]

As described above, according to the processing method of the present invention, the thickness variation of the disk substrate after surface grinding can be suppressed to about 1 μm or less, so that the polishing step is reduced and the abrasive grains used Can be reduced and polishing can be performed in a short time. Therefore, there is an advantage that a disk substrate of the same quality can be provided at a lower cost than before. Hereinafter, embodiments of the present invention will be described in detail,
The present invention is not limited to these embodiments.

FIG. 1 shows the structure of a processing apparatus used in the processing method of the present invention. The outer peripheral grindstone 1 is attached to the end of the spindle 3 attached to the column 2, and the outer peripheral grindstone 1 can move in the Y-axis direction, which is the axial direction of the spindle 3, while rotating. Processing is possible.

The workpiece 4 is often a disk-shaped substrate in the present invention, and is attached to the upper surface of the rotating plate 5 attached on the sample table 6 by a method such as wax fixation or vacuum suction. Can be
The sample table 6 can be moved in the Z-axis direction, which is the height direction of the column 2, so that the grinding thickness can be controlled. Further, the sample table 6 can be moved in the X-axis direction which is a horizontal direction, and thereby, it is possible to perform feed processing in the X-axis direction with the outer peripheral grindstone 1 fixed.

The setting of the moving mechanism in each of the X-axis, Y-axis, and Z-axis directions is not limited to the above-described setting. axis,
A three-axis Z-axis moving mechanism may be provided. In FIG. 1, the outer peripheral grindstone 1 is held at one end. However, when the one end is held when the width of the grindstone is wide, the deviation of the outer peripheral grindstone 1 may increase. Further, although not shown in FIG. 1, usually, since the grinding process is performed by a wet process, equipment such as a pipe for supplying water to the grinding portion and a circulation pump is attached.

FIG. 2 is a view for explaining the grinding mechanism of the present invention. In FIG. 2, the outer peripheral grinding wheel 11 rotates from the outer peripheral portion of the disk substrate 12 as a workpiece while rotating in the direction of arrow E. It is sent in the direction of arrow G toward the center. On the other hand, the disk substrate 12 is rotating in the direction of arrow F, but its position is fixed. Here, the outer peripheral portion P of the disk substrate 12 is an area during or after the grinding by the outer peripheral grindstone 11, and as the outer peripheral grindstone 11 moves to the center, the unprocessed area Q is ground and the outer peripheral grindstone 11 is ground. When the grindstone 11 reaches the center of the disk substrate 12, it disappears, and the processing ends.

FIG. 3 is a diagram for explaining the mechanism of the processing shown in FIG. 2, and is an enlarged view of a contact portion between the outer peripheral grindstone 11 and the disk substrate 12. The grinding surface of the outer peripheral grindstone 11 is not flat, and a side cut portion A for grinding the disk substrate 12 in the depth direction, and dimensioning for performing surface grinding of the surface of the disk substrate 12 formed by the side cut portion A. Processing part B and dimensioning processing part B
Is formed from three regions of the spark-out processing portion C for removing the locus of the outer peripheral grindstone 11 formed by the process.

In the processing, first, the side cut processing part A performs grinding in the depth direction of the disk substrate 12 for the purpose of rough grinding, and about 80% of the entire processing amount is removed. Next, the dimensioning processing part B is a so-called surface grinding part, and the thickness variation is controlled to about 1 μm by grinding in this part, and finally, the trajectory of the grinding wheel generated by the processing by the spark-out processing part C. By performing spark-out processing (leveling processing) for removing (small undulations), the processing ends.

[0023] By the above-mentioned processing method, fine undulation due to the trajectory of the grinding wheel which occurs when using the conventional rotary surface grinding method is not generated, the thickness variation is suppressed to 1 μm or less, and free abrasive grains are used. No pits occur.

Here, a diamond grindstone is most preferably used as the outer peripheral grindstone used in the processing method of the present invention. However, depending on the material of the object to be ground, silicon carbide, silicon nitride, silicon carbide, High hardness ceramics such as boron can also be used.

Further, the width of the grindstone used in the processing of the present invention is preferably 5 mm or more and 70 mm or less. This is because, when the grindstone width is less than 5 mm, the width of each of the side cut processing portions A, the dimensioning processing portions B, and the spark-out processing portions C, which are set on the grindstone, is reduced, and the width of each processing portion is reduced. Due to insufficient processing. On the other hand, if the grindstone width is larger than 70 mm, it is difficult to secure linearity in the width direction of the grindstone on the contact surface of the dimensioning processing section B with the work piece, and there is a problem in grinding the work piece. This is not preferable because a problem arises in that it is necessary to precisely align the dimensioned portion B of the grindstone blade with the surface to be formed.

The processing apparatus and the processing method of the present invention are intended to grind a substrate that can reduce a polishing step, and its use is not limited to the processing of a glassy substrate for a hard disk described at the beginning of this specification. It should be understood that. For example, as another application field of the present invention, it is used for manufacturing a glass substrate for applying a resist used in a manufacturing process of a stamper manufactured for manufacturing an optical disk such as a compact disk, and for manufacturing a liquid crystal display. The present invention can be applied to the production of substrates and devices having various smoothness such as a glass substrate, an optical waveguide device, and a surface acoustic wave device.

[0027]

EXAMPLES The above embodiment of the present invention will be described with reference to examples. Table 1 shows a comparison between the grinding method according to the present invention and the conventional rotary surface grinding method.
The processing was performed under the processing conditions shown in (1), the surface appearance was inspected, and the thickness variation (surface roughness (Ra)) was measured. In addition,
The crystallized glass substrate, which is the object to be ground, is not crystallized at the time of the main grinding, and is subjected to the crystallization after the grinding.

[0028]

[Table 1]

The processing results are as shown in Table 1,
When the processing according to the present invention was performed, the trajectory of the grindstone could not be confirmed in the external appearance, whereas in the rotary surface grinding method, many trajectories of the striped grindstone were observed. FIG. 4 is a contour diagram showing the results of measuring the state of the ground surface of the glass disk as the object to be ground when the grinding method according to the present invention is used, on the front surface and the back surface. In FIG. 4, the front surface has a substantially concentric concave shape with the bottom at the center of the glass disk having a height difference of about 2.46 μm, while the back surface has the apex at the center of the glass disk having a height difference of about 3.51 μm. It has a substantially concentric convex shape, and the glass disk is processed into a bow shape as a whole, and the difference is 1.05 μm.
m is almost a thickness variation. It should be noted that this bow-shaped warpage does not pose a problem in product quality because it is corrected by crystallization processing after grinding.

On the other hand, FIG. 5 is a contour diagram showing the results of measuring the state of the ground surface of the glass disk as the object to be ground when the rotary surface grinding method is used, on the front surface and the back surface. According to FIG. 5, the surface has a height difference of about 5.61 μm.
The center of the glass disk is a bottom, but the grinding depth of the outer periphery is uneven and concave. On the other hand, the center of the glass disk whose height difference is about 8.89 μm is the top, but the back is the top. It had a non-uniform convex shape with different grinding depths, and was processed into a substantially bow shape as a whole. Therefore, the difference of 3.28 μm is a thickness variation, which is about three times or more that of the grinding method according to the present invention. As compared with the grinding method according to the invention, the size is increased, and the productivity is reduced.

[0031]

As described above, according to the processing method and the processing apparatus of the present invention, when the disk substrate is subjected to surface grinding, fine waviness due to the locus of the grindstone does not occur on the ground surface, and Since the thickness variation is suppressed to about 1 μm or less, it is possible to reduce the polishing depth in the polishing step which is the next step of the present step, thereby shortening the polishing time and reducing the amount of abrasive particles used. Can be. Furthermore, the processing method of the present invention has an advantage that the grinding speed is about 10 times or more faster than the conventional rotary surface grinding method, so that it is possible to provide a disk substrate of the same quality at a lower cost than before. It has a remarkable effect.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a disk substrate processing apparatus according to the present invention.

FIG. 2 is an explanatory view showing a grinding state of the disk substrate of the present invention.

FIG. 3 is an explanatory view showing a disk substrate grinding mechanism of the present invention.

FIG. 4 is a contour diagram showing a processed state of a front surface and a back surface of a glass substrate before crystallization according to the present invention.

FIG. 5 is a contour diagram showing a processing state of a front surface and a back surface of a glass substrate before crystallization by a rotary surface grinding method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Peripheral blade grindstone, 2 ... Column, 3 ... Spindle, 4 ... Workpiece, 5 ... Rotating plate, 6 ... Sample table, 11 ... Peripheral blade grindstone, 12 ... Disk substrate, A ... Side cut processing part, B ... Dimensioning part, C ... Spark out part,
E: rotating direction of outer peripheral blade, F: rotating direction of disk substrate 12, G: moving direction of outer peripheral grinding wheel, P: processed area, Q: unprocessed area, X: moving direction of sample table 6, Y: outer peripheral blade The moving direction of the grindstone, Z: the moving direction of the sample table 6.

Claims (11)

[Claims] After the outer peripheral grindstone and the disk substrate as a workpiece are three-dimensionally positioned by a three-axis moving mechanism of X axis, Y axis, and Z axis orthogonal to each other, the outer peripheral grindstone and the disk substrate are processed. While rotating the disk substrate, grinding is performed by moving either the disk substrate or the outer peripheral grindstone in one axis direction so that the side cut processing and the spark-out processing are sequentially and continuously performed on the disk substrate. A method of processing a disk substrate, characterized by processing. 2. The method for processing a disk substrate according to claim 1, wherein said outer peripheral grindstone is a diamond grindstone. 3. The grinding wheel width of the outer peripheral grinding wheel is 5 mm or more and 70 mm or more.
3. The method for processing a disk substrate according to claim 1, wherein the diameter is not more than mm. 4. The method for processing a disk substrate according to claim 1, wherein said disk substrate is made of blue glass or crystallized glass. 5. An X-axis, Y-axis, and Z-axis orthogonal moving mechanism that can three-dimensionally position an outer peripheral grindstone and a disk substrate as a workpiece, and the outer peripheral grindstone. A disk substrate processing apparatus having a mechanism for rotating the disk substrate and a mechanism for rotating the disk substrate, wherein the outer peripheral grinding wheel grinds the disk substrate in a depth direction, and the side cut processing section A dimensionalizing section for performing surface grinding of the surface of the disk substrate formed by the above, and a spark-out processing section for removing a trajectory generated by the dimensionalizing section, wherein the rotating disk substrate or the rotating By moving at least one of the outer peripheral grindstones in at least one axial direction, the disk substrate is dimensioned from the side cut portion. Coated portion, followed by the processing device of the disc substrate, characterized in that it is processed in succession in the order of the spark-out processing unit. 6. The disk substrate processing apparatus according to claim 5, wherein the outer peripheral grindstone is a diamond grindstone. 7. The grinding wheel width of the outer peripheral grinding wheel is 5 mm or more and 70 mm or more.
7. The disk substrate processing apparatus according to claim 5, wherein the diameter is equal to or less than mm. 8. The disk substrate processing apparatus according to claim 5, wherein said disk substrate is made of blue glass or crystallized glass. 9. A side cut processing part for grinding a workpiece in a depth direction, a dimension processing part for performing surface grinding of a surface of the workpiece formed by the side cut processing part, and the dimension processing part And a spark-out processing part for removing a trajectory generated by the step. 10. The outer peripheral grinding wheel according to claim 9, wherein the outer peripheral grinding wheel is a diamond grinding wheel. 11. The grinding wheel width of the outer peripheral grinding wheel is 5 mm or more.
11. The structure according to claim 9, wherein the distance is 0 mm or less.
The outer peripheral grinding wheel described.