JP2013202738A - Manufacturing method of disk-like substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control a polishing amount in polishing of a disk-like substrate, and suppress dispersion of quality of the disk-like substrate after being polished.SOLUTION: A doughnut-like glass block 40 is housed in a disk holder 11. A polishing liquid is supplied to at least an inner peripheral end face of the doughnut-like glass block 40. A polishing brush 13 is inserted into the hollow part of the doughnut-like glass block 40, and is rotated around a brush rotary shaft 12 to polish the inner peripheral end face. A control section 20 monitors data of an actual rotation speed for a prescribed time, calculates an average value of the actual rotation speed, and defines it as a representative value of the actual rotation speed. The control section 20 calculates a×[the representative value of the actual rotation speed]+b (a, b: coefficients calculated beforehand for each brush and for each set rotation speed) on the basis of the representative value of the actual rotation speed, and calculates the polishing work time from a start till end of an end face polishing process. In a polishing device 1, the end face polishing process is carried out for the calculated polishing work time.

Description

  The present invention relates to a method for manufacturing a disk-shaped substrate including an end surface polishing step for polishing an end surface of the disk-shaped substrate.

  In a glass substrate for a magnetic disk mounted in a hard disk drive storage device or the like, with the recent increase in recording density and rotation speed, not only the surface of the glass substrate is smoothed, but also the processing accuracy, mainly the inner and outer diameter accuracy, High precision is also required for the inner and outer peripheral end shapes.

  As such a glass substrate end surface polishing method, techniques described in Patent Documents 1 and 2 have been proposed. Patent Document 1 describes a method in which a polishing liquid containing loose abrasive grains is used to polish a laminated glass substrate by rotating a polishing brush against an inner peripheral end face or an outer peripheral end face. Patent Document 1 also discloses a method for finely managing the viscosity of the polishing liquid, that is, the concentration.

  In Patent Document 2, a polishing brush or a polishing pad is used to supply a polishing liquid to the inner hole portion of the laminated glass substrate, and the downward suction generated by rotating the spiral polishing brush or the polishing pad is disclosed. A method is disclosed in which polishing is performed by supplying a polishing liquid to the inner peripheral end surface portion using the above.

  In recent years, with the increase in recording density of magnetic disks, there has been a demand for higher accuracy in the inner and outer diameters and end shapes of glass substrates. However, with the above-described conventional technology, sufficient accuracy cannot be obtained, and it has been difficult to achieve the required quality at a low cost.

  Therefore, in Patent Document 3, a defective load rate is obtained by detecting a driving load of a polishing brush or a polishing pad that rotates in contact with a glass substrate and adjusting the contact position in a direction perpendicular to the rotation axis direction. A method for reducing the cost by reducing the cost is proposed.

JP 2007-234218 A JP 2000-185927 A JP 2004-174695 A

  However, in the method described in Patent Document 3, for example, when monitoring the load current output of the inverter connected to the motor for rotating the polishing brush, it is difficult to control the torque with low noise. Met. Therefore, there has been a problem that it is difficult to suppress variations in the quality of the glass substrate to be polished.

  The present invention has been made in view of the above, and an object of the present invention is to appropriately control the amount of polishing in end face polishing of a disk-shaped substrate such as a glass substrate. An object of the present invention is to provide a method for manufacturing a disk-shaped substrate that can suppress variations in quality.

  In order to solve the above-described problems and achieve the above object, a manufacturing method of a disk-shaped substrate according to the present invention supplies a polishing liquid to an end surface of a disk-shaped substrate and also uses a rotary polishing means as a disk-shaped substrate. In the manufacturing method of the disk-shaped substrate including the end surface polishing process in which the end surface is polished by rotating while being in contact with the end surface, the end surface polishing process is a load of contact rotation between the rotating polishing means and the end surface of the disk-shaped substrate. A measurement step for measuring the actual rotation speed of the rotary polishing means that varies according to the calculation, a calculation step for calculating the polishing time based on the actual rotation speed, and control so that the end face polishing process is executed in the polishing time. And a control step.

  In the method for manufacturing a disk-shaped substrate according to the present invention, in the above invention, the end surface polishing treatment is performed by simultaneously polishing the end surfaces of the plurality of disk-shaped substrates in a state where the plurality of disk-shaped substrates are stacked. It is characterized by.

  In the disc substrate manufacturing method according to the present invention, in the above invention, the calculation step is calculated based on a target polishing amount in the end surface polishing process and an estimated polishing rate set before starting the end surface polishing process. The polishing time is calculated on the basis of the average value of the actual rotation speed in the rotary polishing means or the total number of rotations in the predetermined time measured at a predetermined time less than the maximum polishing time.

  The method for manufacturing a disc-shaped substrate according to the present invention is characterized in that, in the above invention, the rotational speed set for the rotary polishing means is 600 rpm or more and 5500 rpm or less.

  The disk-shaped substrate manufacturing method according to the present invention is characterized in that, in the above invention, the disk-shaped substrate is a glass substrate, and the polishing liquid contains cerium oxide, colloidal silica, or zirconium oxide.

  According to the method for manufacturing a disk-shaped substrate according to the present invention, it is possible to appropriately control the polishing amount in the end surface polishing of the disk-shaped substrate, and to suppress variations in the quality of the disk-shaped substrate after polishing. It becomes possible.

FIG. 1 is a configuration diagram illustrating a glass substrate polishing apparatus for polishing a glass substrate according to an embodiment of the present invention. FIG. 2 is a perspective view showing a donut-shaped glass block according to an embodiment of the present invention. FIG. 3 is a graph showing the correlation between the polishing processing time and the representative value of the actual rotational speed for explaining the derivation of the time arithmetic expression calculated by the control unit according to the embodiment of the present invention. FIG. 4 is a flowchart illustrating a glass substrate polishing method according to an embodiment of the present invention. FIG. 5 is a chart showing an example according to one embodiment of the present invention. FIG. 6 is a chart showing a comparative example corresponding to an example according to an embodiment of the present invention.

  Hereinafter, a manufacturing method of a disk-shaped substrate concerning one embodiment of the present invention is explained, referring to drawings. In all the drawings of the following embodiment, the same or corresponding parts are denoted by the same reference numerals. Further, the present invention is not limited to the embodiment described below.

  In addition, this one Embodiment concerns on the method of manufacturing the disk-shaped glass substrate which has a circular hole in the center, ie, a donut-shaped glass substrate. This glass substrate has, for example, a thickness of 0.635 mm, an outer diameter of 65.00 mm, and an inner diameter of 20.01 mm, and is used for a magnetic disk of a hard disk device.

  First, a glass substrate polishing apparatus according to an embodiment of the present invention will be described. FIG. 1 shows a glass substrate polishing apparatus according to this embodiment, and FIG. 2 shows a donut-shaped glass block to be polished. This glass substrate polishing apparatus is used in an end surface polishing step for polishing an end surface in a manufacturing process of a donut-shaped glass substrate.

  As shown in FIG. 1, the glass substrate polishing apparatus 1 according to this embodiment includes a disk holder 11, a polishing brush 13, a rotary translation motor 14, a bearing 15, and a control unit 20.

  The disk holder 11 is configured to be able to store a donut-shaped glass block 40. As shown in FIG. 2, the donut-shaped glass block 40 is formed by laminating a plurality of hollow disk-shaped donut-shaped glass substrates 40a via spacers, for example. As shown in FIG. 1, the disk holder 11 is configured to be capable of rotating about the center of the hollow disk of the donut-shaped glass substrate 40a in a cross section perpendicular to the longitudinal direction.

  Further, the polishing brush 13 which is a rotary polishing means has a brush rotating shaft 12 and brush bristles provided in a cylindrical shape on the outer periphery of the brush rotating shaft 12. The brush rotating shaft 12 is configured in a rod shape that can penetrate the disk holder 11 along the longitudinal direction. An example of the dimensions of the polishing brush 13 is, for example, a diameter of 22.0 mm and a length of 300 mm. The brush hair is made of, for example, 6-6 nylon having a bristle length of about 10 mm.

  The disc holder 11 is configured so that a cylindrical polishing brush 13 can be inserted therein. Further, the polishing brush 13 can be inserted into the hollow portion of the donut-shaped glass block 40 in a state where the disk holder 11 houses the donut-shaped glass block 40.

  Further, one end of the brush rotating shaft 12 is connected to a rotary translation motor 14 as a rotation driving means, and the other end is supported by a bearing 15 on a bearing. The rotary translation motor 14 can rotate the polishing brush 13 around the brush rotation shaft 12. Therefore, the polishing brush 13 can polish the inner peripheral end surface of the doughnut-shaped glass block 40 by rotating while being inserted into the hollow portion of the donut-shaped glass block 40. Further, the rotary translation motor 14 can reciprocate the polishing brush 13 along the longitudinal direction thereof. Thereby, the rotary translation motor 14 can reciprocate the polishing brush 13 along the longitudinal direction while rotating the polishing brush 13 around the brush rotation shaft 12. The rotational translation motor 14 measures the actual rotational speed (actual rotational speed) of the polishing brush 13 during rotational driving, and supplies the actual rotational speed data to the control unit 20.

  The control unit 20 that is a control unit according to the embodiment includes an arithmetic processing unit 20a that performs various arithmetic processes and a storage unit 20b that stores various data. The control unit 20 is configured to be able to control the rotation movement of the disk holder 11 and to be able to control the rotation movement and the reciprocation movement of the rotary translation motor 14. Further, the control unit 20 stores data on the actual number of rotations of the polishing brush 13 supplied from the rotary translation motor 14 in the storage unit 20b.

  In the storage unit 20b of the control unit 20, based on the actual rotational speed data supplied from the rotary translation motor 14, the rotational drive time of the rotary translation motor 14, that is, the polishing time of the end face polishing process by the polishing brush 13 is performed. A table including a time calculation formula for calculating time and various data is stored. The arithmetic processing unit 20a of the control unit 20 uses the time arithmetic expression based on the data and table of the actual rotational speed supplied from the rotary translation motor 14 stored in the storage unit 20b, thereby polishing the polishing time by the polishing brush 13. Is calculated. Then, the control unit 20 controls the rotation time of the polishing brush 13 by controlling the drive of the rotary translation motor 14 based on the calculated polishing time.

  Here, a time arithmetic expression calculated by the arithmetic processing unit 20a of the control unit 20 when controlling the above-described polishing by the polishing brush 13 devised by the present inventor will be described.

  First, the present inventor conducted various experiments in order to solve the problems of the prior art regarding an end surface polishing process for polishing an end surface of a disk-shaped substrate such as a doughnut-shaped glass substrate 40a and a polishing apparatus used for the end surface polishing process. And examined. As a result, it has been found that the load (rotational contact load) on the disk-shaped substrate of the rotating polishing means that performs polishing while rotating, such as a polishing brush and a polishing pad, has a correlation with the polishing rate.

  Therefore, the present inventor further studied this correlation, and in the rotational driving means that drives the rotational polishing means while applying the contact rotational load, the actual rotational speed that is affected by the contact rotational load varies to the polishing rate. And found a new relationship. That is, it has been found that the rotational speed (circumferential speed) of the rotary polishing means varies depending on the contact rotational load, and the rotational speed varies, so that the actual rotational speed varies and the polishing rate varies. In the present specification, the actual rotational speed includes the actual rotational speed and the total number of actual rotations (total number of rotations) at a predetermined time. When the polishing rate is derived, the rotation time of the rotary polishing means, that is, the so-called polishing time can be calculated based on a target polishing amount (target polishing amount) set in advance.

  Therefore, in this embodiment, the correlation between the actual rotational speed of the polishing brush 13 and the polishing processing time is stored in advance in the storage unit 20b as a time arithmetic expression together with a data table used for the time arithmetic expression. Then, the control unit 20 calculates the polishing processing time using a time arithmetic expression while referring to the actual number of revolutions of the polishing brush 13 and the table, and performs control to drive the rotary translation motor 14 during the polishing processing time. .

  Note that the time arithmetic expression calculated by the arithmetic processing unit 20a with reference to the table is set when polishing the kind of material used for the polishing brush or polishing pad as the rotary polishing means, or when polishing the donut-shaped glass block 40. Various equations can be set according to characteristics such as the set rotation speed. In particular, when various types of polishing brushes and polishing pads that are exchanged and specified by the polishing apparatus 1 have the same specifications, the same time calculation formula can be adopted because the characteristics are approximate.

  Next, the derivation of the time arithmetic expression for the arithmetic processing unit 20a of the control unit 20 to calculate will be described. FIG. 3 is a graph for explaining the derivation of the time arithmetic expression for the arithmetic processing unit 20a according to this embodiment to calculate.

  That is, in the polishing apparatus 1 according to this embodiment, first, for each type of the polishing brush 13 and the number of rotations of the polishing brush 13 set at the start of polishing, here, for each set rotation speed, the donut-shaped glass block 40 The polishing process is performed a number of times that statistical reliability can be ensured. Specifically, for example, the polishing process is repeated by using the same polishing brush 13 about 20 to 40 times.

At this time, the rotary translation motor 14 measures the actual rotation speed of the polishing brush 13 and supplies it to the controller 20. The control unit 20 calculates a polishing rate in the end surface polishing process based on the supplied actual rotation speed. Then, the arithmetic processing unit 20a performs the calculation of the following expression (1) based on the measured polishing rate and a preset polishing amount.
Polishing time = polishing amount / polishing rate (1)
Thereby, the arithmetic processing unit 20a calculates the polishing time of the doughnut-shaped glass block 40.

  Thereafter, the control unit 20 sets the average value of the actual rotation speed output from the rotary translation motor 14 for a predetermined time, specifically, for example, the average value for 10 minutes as the representative value of the actual rotation speed. Then, the control unit 20 plots the correlation between the polishing time calculated by the equation (1) from the target polishing rate and the target polishing amount and the representative value of the actual rotation speed on a graph. Thereby, the graph shown in FIG. 3 is created.

Then, based on the measured value of the correlation between the representative value of the actual rotation speed plotted as shown in FIG. 3 and the polishing time, an approximate expression shown in the following expression (2) is derived as a time calculation expression.
Polishing time = a × representative value of actual rotational speed + b (2)
(A and b are coefficients)

  As described above, the polishing rate and the polishing time vary in accordance with the actual rotation speed of the polishing brush 13. Therefore, the dependence on the actual rotation speed with respect to the polishing time can be derived for each type of polishing brush 13 and for each set rotation speed of the polishing brush 13 at the start of polishing. Then, the actual rotational speed dependence of the derived polishing processing time is stored in the storage unit 20b as a time arithmetic expression, and the arithmetic processing unit 20a reads out and performs arithmetic processing as necessary.

  That is, the values of the coefficients a and b in the expression (2) are set for each characteristic of the polishing brush 13, specifically, for each type such as the bristle thickness of the polishing brush 13, or for each set rotation speed during polishing. Derived in advance and stored in the storage unit 20b as a table. The control unit 20 reads out the coefficients a and b in the equation (2) from the storage unit 20b every time the polishing brush 13 is changed to a brush with a different characteristic of the specification or the set rotation speed is changed, ( 2) Determine the formula and use it for the calculation of the polishing time. Here, as a specific example of the coefficients a and b, the coefficient a is, for example, −0.2, and the coefficient b is, for example, 37.50.

  Note that, in this embodiment, the representative value of the actual rotation speed is calculated as the actual rotation speed based on the actual rotation speed for 10 minutes, for example, in order to improve the calculation accuracy, depending on the polishing conditions, Instead of the representative value of the actual rotation speed in the equation (2), the total number of rotations during a predetermined time may be adopted. Further, as the predetermined time for measuring the actual rotation speed and the predetermined time for measuring the total number of rotations, a time longer than 10 minutes may be adopted as necessary. Further, the rotation speed may be measured continuously or intermittently during a predetermined time. In any case, the predetermined time is calculated based on the target polishing amount in the end surface polishing process and the estimated polishing rate set before starting the end surface polishing process, and is the maximum time until the end surface polishing process ends. The time is less than the polishing time. Here, the estimated polishing rate set before starting the end surface polishing process may be determined as an approximate guide, and the calculation method is not particularly limited. For example, it may be calculated from the end surface polishing process performed immediately before, the end surface polishing process in which the polishing solution concentration and the brush rotation side speed were similar conditions, or an average value of a plurality of end surface polishing processes may be adopted. Good.

(Glass substrate manufacturing method)
Next, the manufacturing method of the glass substrate by one Embodiment of this invention comprised as mentioned above is demonstrated. The manufacturing method of the glass substrate by this one Embodiment includes the end surface grinding | polishing process based on the control method of the grinding | polishing apparatus of a glass substrate. FIG. 4 is a flowchart for explaining a glass substrate polishing method according to this embodiment.

  In the method of manufacturing a glass substrate according to this embodiment, first, a plurality of, for example, about 50 to 300, thin glass sheets are laminated while being separated from each other through a soft material spacer by a conventionally known method. Form a block. Thereafter, the glass block is cut into a donut shape to form a donut-shaped glass block 40 shown in FIG.

Next, the inner peripheral end face of the donut-shaped glass block 40 is polished by a polishing method using the glass substrate polishing apparatus 1 shown in FIG. That is, first, the doughnut-shaped glass block 40 is stored in the disc holder 11 (step ST1). Next, the polishing liquid is supplied by, for example, spraying a polishing liquid mixed with an abrasive onto at least the inner peripheral end face of the donut-shaped glass block 40 housed in the disk holder 11 (step ST2). In this embodiment, for example, cerium oxide (Ce ₂ O ₃ , CeO ₂ ), colloidal silica (silicon dioxide: SiO ₂ ), or zirconium oxide (ZrO ₂ ) is used as the abrasive.

  Next, the control unit 20 controls the rotary translation motor 14 to insert the polishing brush 13 into the hollow portion of the donut-shaped glass block 40. Then, the control unit 20 rotates the polishing brush 13 around the brush rotation shaft 12 and rotates the donut-shaped glass block 40 in the direction opposite to the rotation direction of the polishing brush 13. Here, the rotation speed set when the control unit 20 rotates the polishing brush 13 is selected from the range of 600 rpm to 5500 rpm. Furthermore, the control unit 20 causes the polishing brush 13 to reciprocate in the glass substrate stacking direction. Thereby, the end surface grinding | polishing process of the inner peripheral end surface of the donut-shaped glass block 40 is started (step ST3).

  Next, the rotational translation motor 14 sequentially transmits the actual rotational speed data to the control unit 20 from the time when the polishing of the inner peripheral end face of the donut-shaped glass block 40 is started (step ST4).

  The control unit 20 is a representative of the actual rotation speed based on the input data of the actual rotation speed after a predetermined time less than the maximum polishing time until the end surface polishing process is completed, specifically, for example, 10 minutes elapses. Calculate the value. As a representative value of the actual rotation speed, an average value of the actual rotation speed in a predetermined time, for example, 10 minutes, or the total number of rotations in, for example, 10 minutes can be employed. Then, the arithmetic processing unit 20a of the control unit 20 calculates the polishing processing time by applying the representative value of the calculated actual rotational speed to the time arithmetic expression read from the storage unit 20b, thereby calculating the polishing time (step ST5). .

  Thereafter, the control unit 20 sets the rotation time of the polishing brush 13 by setting the driving time of the rotary translation motor 14 to the calculated polishing time. Then, while the elapsed time from the start time of the end surface polishing process does not reach the set polishing time (step ST6: No), step ST6 is repeated and the end surface polishing process by the polishing brush 13 is continued. On the other hand, when the elapsed time from the start time of the end face polishing process reaches the set polishing time (step ST6: Yes), the control unit 20 stops driving the rotary translation motor 14, and the brush rotating shaft 12 is stopped. And the polishing brush 13 is extracted from the hollow part of the donut-shaped glass block 40, and the end surface grinding | polishing process of an inner peripheral end surface is complete | finished.

  Further, also on the outer peripheral end face of the donut-shaped glass block 40, the end face polishing treatment is performed while applying a predetermined rotational contact load to the outer peripheral end face with a polishing brush (not shown) in the same manner as the inner peripheral end face.

  After the polishing of the inner peripheral end face and the outer peripheral end face of the doughnut-shaped glass block 40 is finished, the individual donut-shaped glass substrates 40a are separated from the donut-shaped glass block 40 and stored, and a cleaning process is performed. Subsequently, the doughnut-shaped glass substrate 40a separated into single sheets is cleaned by a conventionally known method such as ultrasonic cleaning. Thereafter, beveling of the outer peripheral edge portion and the inner peripheral edge portion of the doughnut-shaped glass substrate 40a, polishing of the outer peripheral end surface and the inner peripheral end surface, and polishing of the main surface are sequentially performed. Finally, the donut-shaped glass substrate 40a is cleaned by a conventionally known method. As described above, the doughnut-shaped glass substrate 40a in which the outer peripheral beveling portion and the inner peripheral beveling portion are formed and chipping is removed is manufactured.

  By the way, conventionally, there has been a problem that a sufficient allowance for adjusting the contact position cannot be secured in polishing the inner peripheral end face of the donut-shaped glass block 40. Further, in order to fit the motor with high accuracy when manufacturing the hard disk device, the inner diameter dimension of the donut-shaped glass substrate 40a is required to be higher than the outer dimension. Further, like the polishing brush 13 used in the polishing apparatus 1 described above, the outer diameter is slightly larger than the inner diameter of the doughnut-shaped glass block 40, and the rotation center is coaxial with the circle center of the donut-shaped glass block 40. When performing the above, it becomes more difficult to adjust the contact position. Therefore, by applying the polishing method according to one embodiment of the present invention to the polishing of the inner peripheral end face of the donut-shaped glass block 40, the amount of polishing can be reduced even when the adjustment margin for the contact position of the inner peripheral end face cannot be secured sufficiently. It can be appropriately controlled and is more effective than polishing of the outer peripheral end face.

(Examples and Comparative Examples)
Next, as a control method for the glass substrate polishing apparatus, an example based on a polishing method according to an embodiment of the present invention and a comparative example based on a conventional polishing method will be described. In these examples and comparative examples, description will be made based on measurement results of variations in the inner diameter of the donut-shaped glass substrate 40a, which requires particularly high accuracy. FIG. 5 is a table showing the results of Examples 1-6, and FIG. 6 is a table showing the results of Comparative Examples 1-3.

  As shown in FIG. 5, first, in Examples 1 and 2, the brush A having the same specifications as the brush used in the above-described embodiment was used as the polishing brush 13. The set rotational speed of the polishing brush 13 was set to 1500 rpm in the end face polishing processing of Samples A-1 to A-5 of Example 1. Moreover, it was set to 2700 rpm in the end surface grinding | polishing process of sample A-6 of Example 2, and A-7. Sample No. A-1 to A-7 means that the polishing process was performed on the different donut-shaped glass blocks 40 in the order of samples A-1 to A-7 using the brush A. The same applies to other examples and comparative examples. The concentration of the polishing liquid is 30% by weight for Samples A-1 to A-3 of Example 1, and 10% by weight for Samples A-4 and A-5 of Example 1 and Sample A-6 of Example 2. Sample A-7 in Example 2 was 20% by weight. The values of the coefficients a and b in the expression (2) in the first embodiment and the values of the coefficients a and b in the expression (2) in the second embodiment are calculated in advance for each set rotation speed and stored in the storage unit 20b. Adopted values were adopted. The values of the coefficients a and b in the equation (2) were reset by feeding back the results of end face polishing performed with the same specification brush and the same set rotational speed as needed. As a result, the polishing amount can be made closer to the target value.

  Subsequently, in Examples 3 and 4, the brush B exchanged from the brush A was used as the polishing brush 13. The set rotational speed of the polishing brush 13 is set to 1500 rpm, which is the same as that in the first embodiment, in the end surface polishing processing of the samples B-1 to B-5 in the third embodiment, and the samples B-6 and B-7 in the fourth embodiment. It was set to 600 rpm in the end surface polishing process. Further, the concentration of the polishing liquid is 20% by weight for Samples B-1 and B-2 of Example 3, 30% by weight for Samples B-3 to B-5 of Example 3, and then Sample B of Example 4 is used. -6, B-7 to 10 wt%. Note that the values of the coefficients a and b in the expression (2) in Example 3 are the same as those in Example 1 because the specifications of the polishing brush 13 and the set rotational speed (1500 rpm) are the same as those in Example 1. The same value as that of b is adopted. Further, as the values of the coefficients a and b in the expression (2) in the fourth embodiment, the values calculated in advance according to the set rotational speed (600 rpm) and stored in the storage unit 20b are employed.

  Subsequently, in Examples 5 and 6, the brush C replaced from the brush B was used as the polishing brush 13. The set rotational speed of the polishing brush 13 is set to 1500 rpm, which is the same as that in Examples 1 and 3, in the end surface polishing processing of Samples C-1 to C-5 in Example 5, and Samples C-6 and C- in Example 6 are used. In the end surface polishing treatment of No. 7, the speed was 5500 rpm. Further, the concentration of the polishing liquid is 10% by weight in the sample C-1 of Example 5, 20% by weight in the samples C-2 to C-4 of Example 5, and the subsequent examples are performed from the sample C-5 of Example 5. In Samples C-6 and C-7 of Example 6, the content was 30% by weight. The values of the coefficients a and b in the expression (2) in the fifth embodiment are the same as those in the first and third embodiments because the brush specifications and the set rotational speed (1500 rpm) are the same as those in the first and third embodiments. The same values as the values of the coefficients a and b were adopted. In addition, as the values of the coefficients a and b in the expression (2) in Example 6, the values calculated in advance according to the set rotation speed (5500 rpm) and stored in the storage unit 20b are employed.

  In addition, the end surface grinding | polishing process by the above Examples 1-6 is performed sequentially along an Example. Moreover, the control part 20 calculates and sets the grinding | polishing processing time in Examples 1-6 according to one Embodiment mentioned above. Further, all of the brushes A to C used in Examples 1 to 6 have the same specifications, and the cylindrical outer diameter along the cross section perpendicular to the rotation axis of the brushes is a donut shape. It is slightly larger than the inner diameter of the glass substrate 40a.

  On the other hand, as a comparative example, in the polishing apparatus 1 according to the above-described embodiment, a case will be described in which the control unit 20 performs end surface polishing processing by performing control according to the related art.

  That is, as shown in FIG. 6, in Comparative Example 1, first, the brush D having the same specifications as the brushes A to C was used as the polishing brush 13. The set rotational speed of the polishing brush 13 was set to 1500 rpm in the five end face polishing processes of Comparative Example 1. Moreover, the density | concentration of polishing liquid was 30 weight% in the samples D-1 to D-3 of the comparative example 1, and was 10 weight% in the samples D-4 and D-5. The conditions for the set rotation speed and the concentration of the polishing liquid are the same as those in the first embodiment. Therefore, with respect to the polishing time in each end face polishing process according to Comparative Example 1, Sample D-1 was calculated using the polishing rate of Example 1. The polishing times for Samples D-2, D-3, and D-5 were calculated by feeding back the polishing rate in the end face polishing process immediately before the set rotational speed and the polishing liquid concentration were equal. The polishing time of sample D-4 having different polishing liquid concentrations is compared with the polishing rate of samples D-4 and D-5 having the same set rotation speed and the same polishing liquid concentration, and immediately before using the same brush D. It calculated by feeding back the average value with the polishing rate in the end surface grinding | polishing process of the sample D-3 of Example 1. FIG.

  Subsequently, in Comparative Example 2, the brush E replaced from the brush D is used as the polishing brush 13. The set rotational speed of the polishing brush 13 was set to 1500 rpm similar to that in Comparative Example 1. Moreover, the density | concentration of polishing liquid shall be 20 weight% in the samples E-1 and E-2 of the comparative example 2, and is increased to 30 weight% in the subsequent samples E-3 to E-5. The conditions for the set rotational speed and the concentration of the polishing liquid are the same as in Example 3. Therefore, with respect to the polishing time in each end face polishing process according to Comparative Example 2, Sample E-1 is calculated by adopting the polishing rate of Example 3. The polishing times of samples E-2, E-4, and E-5 are calculated by feeding back the polishing rate in the end face polishing process immediately before the set rotational speed and the polishing liquid concentration are equal. The polishing time of sample E-3 in which the concentration of the polishing liquid changes from the previous processing is the same as the polishing rate of samples B-3 to 5 of Example 3 in which the set rotational speed and the concentration of the polishing liquid are equal. The average value of the polishing rate in the end face polishing process of the sample E-2 of Comparative Example 2 immediately before using E is fed back and calculated.

  Subsequently, in Comparative Example 3, the brush F replaced from the brush E is used as the polishing brush 13. The set rotational speed of the polishing brush 13 is set to 1500 rpm, which is the same as in Comparative Examples 1 and 2. Moreover, the density | concentration of polishing liquid was 10 weight% in the samples F-1 and F-2 of the comparative example 3, and was 20 weight% in the samples F-3 to F-5. The conditions of the set rotation speed and the concentration of the polishing liquid are the same as those of Samples C-1 to C-4 of Example 5. Therefore, with respect to the polishing time in each end face polishing process according to Comparative Example 3, Sample F-1 employs the polishing rate of Sample C-1 of Example 5. The polishing times of samples F-2, F-4, and F-5 are calculated by feedback based on the polishing rate in the end face polishing process immediately before the set rotational speed and the polishing liquid concentration are equal. The polishing time of Sample F-3 in which the concentration of the polishing liquid changes from the previous processing is the same as the polishing rate of Samples C-2 to C-4 of Example 5 in which the set rotational speed and the concentration of the polishing liquid are equal. The average value of the polishing rate in the end surface polishing process of the sample F-2 of Comparative Example 3 immediately before using the brush F is calculated by feeding back.

  In addition, the end surface grinding | polishing process by the above comparative examples 1-3 is performed sequentially along a comparative example. The brushes D to F used in these comparative examples 1 to 3 are all brushes having the same specifications as the brushes A to C, and the cylindrical outer diameter along the cross section perpendicular to the rotation axis is It is slightly larger than the inner diameter of the doughnut-shaped glass substrate 40a.

  And in the above Examples 1-6 and Comparative Examples 1-3, the deviation | shift amount of the actual grinding | polishing amount with respect to the target grinding | polishing amount was measured. Further, the ratio of the number of doughnut-shaped glass substrates 40a in which the inner diameter dimension of the doughnut-shaped glass block 40 is defective, which is generated in accordance with the amount of deviation, was examined.

  From FIG. 6, it can be seen that in the comparative example, the deviation from the target polishing amount increases each time the polishing liquid concentration changes and the polishing brush 13 is changed, and the defect rate of the inner diameter increases. That is, it can be seen that if the individual difference of the polishing brush 13 or the concentration of the polishing liquid changes, the polishing apparatus controlled by the conventional control method cannot cope with the change and deteriorates the manufacturing yield of the doughnut-shaped glass substrate 40a. .

  On the other hand, in the embodiment shown in FIG. 5, even when the polishing brush 13 is changed or the concentration of the polishing liquid is changed, the deviation from the target polishing amount and the defect rate of the inner diameter are not greatly deteriorated. I understand that. As a result, the manufacturing yield such as the yield of the inner diameter of the doughnut-shaped glass substrate 40a can be improved as compared with the prior art. Moreover, even if the set rotational speed is changed by setting the coefficients a and b in the equation (2) in advance for each set rotational speed when the polishing brush 13 rotates, the control unit 20 The polishing apparatus 1 can be appropriately controlled in response to the change. Therefore, the manufacturing yield of the donut-shaped glass substrate 40a can be maintained satisfactorily.

  Furthermore, from FIG. 6, also in Comparative Example 1, in the end face polishing processes of Samples D-2 and D-3, the polishing time in the immediately preceding end face polishing process is fed back and the polishing time is calculated and set. It can be seen that the amount of deviation improves each time the end face polishing process is repeated. And it turns out that the defect rate of an internal diameter dimension is also improved with the improvement of the deviation | shift amount from target grinding | polishing amount. However, as shown in FIG. 5, when compared with the end surface polishing process according to Example 1 in which the set brush rotation speed and the polishing liquid concentration are equal, the overall manufacturing yield is poor through the samples D-1 to D-3 in Comparative Example 1. I understand that. In Comparative Example 1, when the concentration of the polishing liquid is changed from 30% by weight to 10% by weight when moving from sample F-3 to sample F-4, the deviation from the target polishing amount is 4% to 15%. It can be seen that the defect rate of the inner diameter dimension is greatly increased from 0% to 13%, both of which are extremely deteriorated. In contrast, in Example 1, even when the concentration of the polishing liquid was changed from 30 wt% to 10 wt%, the deviation from the target polishing amount slightly increased from 3% to 5%. In addition, the defect rate of the inner diameter dimension is only slightly increased from 0% to 1%. Thus, by adopting the polishing apparatus control method according to one embodiment of the present invention, even when the concentration of the polishing liquid is changed, the end surface polishing is not affected by the change in the concentration of the polishing liquid. The processing can be executed with an appropriate polishing amount.

  Such an effect can be confirmed in the same manner when Comparative Example 2 and Example 3 are compared and when Comparative Example 3 and Example 5 are compared. That is, in Examples 3 and 5, even when the concentration of the polishing liquid is changed, the end surface polishing process by the polishing apparatus 1 is executed with an appropriate polishing amount without being affected by the change in the concentration of the polishing liquid. be able to.

  Further, as shown in FIG. 6, when the polishing brush 13 is changed from the brush D to the brush E when moving from the comparative example 1 to the comparative example 2, the deviation amount of the target polishing amount is greatly deteriorated from 10% to 33%. In addition, it can be seen that the defect rate of the inner diameter dimension is greatly deteriorated from 11% to 55%. On the other hand, as shown in FIG. 5, even when the polishing brush 13 is changed from the brush A to the brush B when moving from the second embodiment to the third embodiment, the deviation amount from the target polishing amount is 0% and the inner diameter. It can be seen that the dimensional defect rate is also 0%. That is, even when the polishing brush 13 is changed from the brush A to another brush B, the end surface polishing process can be performed with an appropriate polishing amount without being affected by individual differences in the polishing brush.

  Such an effect can be confirmed in the same manner even when comparing the case of moving from the comparative example 2 shown in FIG. 6 to the comparative example 3 and the case of moving from the fourth embodiment shown in FIG. 5 to the fifth embodiment. That is, even when the polishing brush 13 is changed from the brush B to the brush C when moving from the fourth embodiment to the fifth embodiment, the end surface polishing process is performed with an appropriate polishing amount without being affected by individual differences of the polishing brush 13. Can be done with.

  Further, from FIG. 5, even when the setting brush rotation speed is changed from 1500 rpm to 2700 rpm when moving from Example 1 to Example 2, the deviation from the target polishing amount is slightly from 2% to 7%. It can only be seen that the defect rate of the inner diameter dimension is only slightly increased from 0% to 4%. Thus, even when the set rotation speed of the polishing brush 13 is changed, the values of the coefficients a and b in the equation (2) are set to appropriate values according to the set rotation speed, and the polishing time is calculated. Therefore, it was confirmed that the end surface polishing treatment can be executed with an appropriate polishing amount.

  Such an effect can be obtained even when the setting rotational speed is decreased as in the case of moving from the third embodiment to the fourth embodiment, as in the case of moving from the fifth embodiment to the sixth embodiment. The same can be confirmed when there is a change that greatly increases the speed.

  In addition, as a long run test, the present inventor controls the polishing apparatus 1 based on each of the control method according to the present invention and the control method according to the prior art for 10,000 donut-shaped glass substrates to perform an end face polishing process. Went. As a result, in the polishing apparatus controlled by the prior art, the defect rate was about 2.0%, whereas in the polishing apparatus 1 controlled by the present invention, the defect rate was 0.5%. It was confirmed that That is, even when the end surface polishing process is performed on a large number of doughnut-shaped glass substrates 40a (10,000 sheets), the defect rate of the donut-shaped glass substrate 40a is greatly increased by controlling the polishing apparatus 1 by the control according to the present invention. It was confirmed that it can be reduced.

  According to the embodiment of the present invention described above, the polishing time is calculated according to the actual rotation speed in polishing the donut-shaped glass block 40, and the end face polishing process is performed in this polishing time, whereby the donut The end surface of the glass block 40 can be polished to an appropriate polishing amount sequentially, and in particular, the inner diameter dimension yield can be improved. Therefore, since the material cost of glass can be reduced and the number of rework can be reduced, the cost required for polishing the doughnut-shaped glass substrate 40a can be reduced. In addition, according to one embodiment of the present invention, the inspection of the inner and outer diameters of the doughnut-shaped glass substrate before and after the end surface polishing treatment of each donut-shaped glass block, which is conventionally performed for stabilizing the polishing rate. Therefore, workability can be improved, and the number of workers can be reduced while improving productivity.

  Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

  In the above-described embodiment, the donut-shaped glass substrate 40a is configured by indirectly laminating a plurality of donut-shaped glass substrates 40a via spacers, for example, to form the donut-shaped glass block 40. The donut-shaped glass block 40 can also be configured by directly laminating without intervention.

  In the above-described embodiment, the polishing brush 13 is a polishing brush whose circular cross section has a diameter slightly larger than the diameter of the hollow portion of the donut-shaped glass block 40, but is not necessarily limited to this polishing brush. Absent. Specifically, as the polishing brush 13, it is possible to use the polishing brush 13 whose circular cross-sectional diameter is smaller than the diameter of the hollow portion of the donut-shaped glass block 40. A polishing pad may be employed instead of the polishing brush 13.

  In the above-described embodiment, the manufacturing method and the control method according to the present invention are used when the inner peripheral end surface of the donut-shaped glass block 40, that is, the inner peripheral end surface of the donut-shaped glass substrate 40a is polished by the polishing brush 13. Although applied, it is not necessarily limited to polishing of the inner peripheral end face. Specifically, even when the outer peripheral end surface of the donut-shaped glass block 40 is polished, a predetermined magnitude of torque acts on the polishing brush 13, so that the manufacturing method and the control method according to the present invention can be applied. It is.

  In the above-described embodiment, the end surface of the donut-shaped glass block 40 in which a plurality of donut-shaped glass substrates 40a are stacked is polished. However, the present invention is not necessarily limited to a state in which a plurality of sheets are stacked. Instead, the end surfaces of the doughnut-shaped glass substrates 40a may be polished one by one.

  In the above-described embodiment, the polishing liquid is supplied to the inner peripheral end face of the donut-shaped glass block 40 by spraying the polishing liquid. However, the donut-shaped glass block 40 is immersed in the polishing liquid. It is also possible.

  Further, in the above-described embodiment, in the calculation of the polishing process time, the average value of the actual rotation speed in 10 minutes is set as the representative value of the actual rotation speed, and the subsequent polishing process time is determined and set. However, it is not necessarily limited to this method. For example, at an arbitrary time point during the end face polishing process, the actual rotational speed is constantly monitored for a predetermined time, for example, 10 minutes before that point, and the average value of the actual rotational speeds for 10 minutes is constantly calculated to end face face During the polishing process, the polishing time may always be calculated. Also in this case, instead of the average value of the actual rotational speed, the total number of rotations from a certain time before a predetermined time, for example, 10 minutes before, is always measured, and the polishing time is always calculated from the total number of rotations. It may be. When the polishing processing time is constantly calculated at an arbitrary time as described above, the control unit 20 subtracts the time from the polishing start time to the calculation time from the calculated polishing time, and polishing is performed from that time. The remaining time until the end is calculated continuously, and the brush rotating shaft 12 and the polishing brush 13 are controlled.

  Further, the present invention is not limited to a magnetic disk for a hard disk device, but a glass substrate for other recording media such as an optical disk and a magneto-optical disk, a disk-shaped glass substrate having no circular hole in the center, and a semiconductor device manufacturing The present invention can be applied to end face polishing of single crystal or compound semiconductor semiconductor wafers for use, ferroelectric wafers for producing piezoelectric elements, and the like.

DESCRIPTION OF SYMBOLS 1 Polishing apparatus 11 Disc holder 12 Brush rotating shaft 13 Polishing brush 14 Rotation translation motor 15 Bearing 20 Control part 20a Arithmetic processing part 20b Storage part 40 Donut glass block 40a Donut glass substrate

Claims (5)

In a manufacturing method of a disk-shaped substrate including an end surface polishing process of supplying a polishing liquid to an end surface of a disk-shaped substrate and rotating the rotating polishing means while contacting the end surface of the disk-shaped substrate to polish the end surface ,
The end surface polishing treatment is
A measurement step of measuring the actual number of revolutions of the rotary polishing means that varies according to the load of contact rotation between the rotary polishing means and the end face of the disk-shaped substrate;
A calculation step of calculating a polishing time based on the actual rotational speed;
A control step for controlling the end face polishing process to be executed in the polishing time;
The manufacturing method of the disk-shaped board | substrate characterized by including.   2. The disk-shaped substrate according to claim 1, wherein the end surface polishing treatment is performed by simultaneously polishing end surfaces of the plurality of disk-shaped substrates in a state where a plurality of the disk-shaped substrates are stacked. Production method.   The rotational polishing measured in a predetermined time less than a maximum polishing time calculated based on a target polishing amount in the end surface polishing process and an estimated polishing rate set before starting the end surface polishing process in the calculation step. 3. The method for manufacturing a disk-shaped substrate according to claim 1, wherein the polishing processing time is calculated based on an average value of an actual rotation speed in the means or a total number of rotations in the predetermined time. .   The method for manufacturing a disc-shaped substrate according to any one of claims 1 to 3, wherein a rotation speed set for the rotary polishing means is 600 rpm or more and 5500 rpm or less.   The disk-shaped substrate according to any one of claims 1 to 4, wherein the disk-shaped substrate is a glass substrate, and the polishing liquid contains cerium oxide, colloidal silica, or zirconium oxide. Manufacturing method.

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