JP2013039639A - Plate-like body polishing device and polishing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform normal polishing by securing a polishing amount and reducing back pressure near a center without reducing a slurry flow rate, and to suppress the reattachment of abraded substrate components to a polished substrate surface by improving the circulation of slurry, especially when polishing a large-sized substrate.SOLUTION: A plate-like body polishing device includes: a plate-like body holding means for holding a plate-like body having a side length of 1,000 mm or longer; and a polishing pad placed facing the plate-like body held by the plate-like body holding means. The polishing pad is provided with: a plurality of slurry feed holes formed at a surface thereof facing the plate-like body for feeding slurry into a contact portion between the polishing pad and the plate-like body; and suction holes formed only at a central portion of the surface facing the plate-like body, and slurry feed holes for sucking the slurry fed into the contact portion.

Description

  The present invention relates to a plate-like body polishing apparatus and a polishing system.

  A glass substrate for an FPD (Flat Panel Display) used for a liquid crystal display or the like is formed by forming a molten glass into a plate shape by a glass manufacturing method called a float method, and this is a continuous type disclosed in Patent Document 1 and the like. By polishing and removing fine irregularities and undulations on the surface with a polishing apparatus, a thin plate satisfying the flatness required for a glass substrate for FPD is manufactured.

  A polishing apparatus such as Patent Document 1 polishes the surface of a glass substrate (hereinafter referred to as a surface to be polished) using a slurry in which an abrasive is dispersed with a dispersant. The slurry is supplied between the polishing surface of the polishing pad and the surface to be polished of the glass substrate from a slurry supply hole provided in the center of the polishing pad. When the amount of slurry supplied between the polishing surface of the polishing pad and the surface to be polished of the glass substrate becomes nonuniform on the polishing surface, the flatness of the surface to be polished of the polished glass substrate deteriorates. Therefore, the supplied slurry needs to be uniformly distributed on the polishing surface.

  In order to distribute the supplied slurry uniformly on the surface to be polished of the glass substrate, the applicant has a slurry supply hole in the center of the polishing surface, and the polishing surface is formed by a plurality of grooves formed from the center toward the outside. Japanese Patent Application No. 2010-11111 proposes a polishing pad that is radially divided.

  Further, for example, in the polishing apparatus described in Patent Document 2, the polishing pad has a highly flat polishing surface on the surface facing the substrate, and the polishing surface has many grooves formed at substantially equal intervals in the front-rear direction. In the polishing process, the diffusion of the polishing agent is promoted, and the polishing agent supply hole and the polishing agent discharge hole that penetrate vertically through the polishing pad and face the substrate are alternately arranged on almost the entire polishing surface. A plurality are formed side by side.

JP 2004-122351 A JP 2009-125873 A

  However, in the conventional method in which the slurry supplied to the central portion of the polishing pad is discharged to the outside of the polishing pad by a groove formed on the polishing surface of the polishing pad, there is a limit to increasing the flow rate of the slurry. In addition, it was difficult to secure the polishing amount near the center by controlling the flow rate of the slurry.

  For example, in a polishing apparatus such as Patent Document 1, a surface to be polished of a glass substrate is polished using a slurry in which an abrasive is dispersed with a dispersant as described above. At this time, when a glass substrate having a side of 1000 mm or more is polished, it is necessary to increase the amount of slurry supplied in order to spread the slurry over the entire surface to be polished of the glass substrate. However, the amount of slurry supplied from the supply hole of the polishing pad is larger than the amount of slurry supplied from the central portion of the glass substrate to the peripheral portion by the grooves formed on the polishing surface of the polishing pad. That is, as shown in FIG. 10, the polishing pad of the glass substrate G adhered to the carrier film 310 is supplied to the polishing pad while supplying the slurry S from the slurry supply hole 330 provided in the center of the polishing pad 320. When polishing is performed at 320, the slurry S is accumulated in the central portion Z of the glass substrate G. As a result, the central portion Z of the glass substrate G is separated from the polishing pad 320, and the central portion Z of the glass substrate G becomes difficult to be polished, resulting in insufficient polishing.

  Moreover, in the thing of the said patent document 2, at the time of grinding | polishing, although slurry is attracted | sucked on the whole surface of a polishing pad and discharged | emitted out of a glass substrate, if a slurry suction hole is further provided, the peripheral part of the surface to be polished of a glass substrate The amount of slurry supplied to the surface is reduced, and polishing scratches and the like are likely to occur. Further, since the capacity of the suction pump for sucking the slurry is limited, it is necessary to increase the number of suction pumps. This complicates the slurry supply and suction piping paths, increasing costs and maintenance. Further, the control of slurry supply and suction becomes troublesome, and there is a problem that the adjustment becomes complicated as the glass substrate which is an object to be polished becomes larger.

  The present invention has been made in view of such circumstances, and particularly when polishing a large size substrate, without reducing the slurry flow rate, while ensuring a polishing amount near the center of the substrate while reducing the back thickness. An object of the present invention is to provide a plate-like body polishing apparatus and polishing system capable of suppressing polishing and re-deposition of the components of the substrate on the surface to be polished by improving the circulation of the slurry while performing polishing. And

  In order to achieve the object, the plate-like body polishing apparatus of the present invention comprises a plate-like body holding means for holding a plate-like body having a side length of 1000 mm or more and the plate-like body holding means held by the plate-like body holding means. A polishing pad disposed opposite the plate-like body, and the polishing pad is formed on the opposing surface of the plate-like body, and slurry is applied to a contact portion between the polishing pad and the plate-like body. A plurality of slurry supply holes to be supplied, and a slurry suction hole that is formed only in the central portion of the opposing surface of the plate-like body and sucks the slurry supplied to the contact portion are formed. And

  As a result, for example, even when polishing a plate-like substrate having a large size of 1000 mm square or more, the polishing margin near the center is ensured without reducing the slurry flow rate by sucking the slurry only from the center portion of the polishing pad. Normal polishing can be performed.

  Moreover, as one embodiment, the central part of the opposing surface of the plate-like body of the polishing pad in which the slurry suction hole is formed is within a range of 25% or less of the diameter from the center of the polishing pad. preferable.

  In this way, by sucking the slurry only from the central portion of the polishing pad, it is possible to ensure a polishing margin near the center and perform normal polishing without reducing the slurry flow rate.

  Moreover, as one embodiment, a plurality of grooves are linearly formed in an arbitrary direction on the opposing surface of the plate-like body of the polishing pad, and are formed in the central portion along a direction orthogonal to the direction. It is preferable that the width of the groove is formed wider than the width of the groove formed outside the central portion along the swing direction.

  In one embodiment, the polishing pad further includes means for swinging the polishing pad in a horizontal direction relative to the plate-like body holding means, and means for rotating and revolving the polishing pad. A plurality of grooves are formed linearly in the swing direction on the opposing surface of the plate-like body, and the width of the groove formed in the center along the direction orthogonal to the swing direction is the swing direction. It is preferable that the groove is formed wider than the width of the groove formed outside the central portion.

  Thereby, the slurry at the center of the polishing pad can be discharged well, and a polishing allowance near the center can be secured.

  In one embodiment, the central portion along the swing direction is preferably within a range of 25% or less of the diameter of the polishing pad from the center.

  Thereby, the slurry at the center of the polishing pad can be discharged well, and a polishing allowance near the center can be secured.

  Similarly, in order to achieve the object, the polishing system of the present invention is held by a plate-like body holding means for holding a plate-like body having a side length of 1000 mm or more, and the plate-like body holding means. A polishing pad installed opposite to the plate-like body, and the polishing pad is formed on a surface facing the plate-like body, and a slurry is formed at a contact portion between the polishing pad and the plate-like body. A plurality of slurry supply holes for supplying the slurry, and a slurry suction hole formed only in the central portion of the opposing surface of the plate-like body for sucking the slurry supplied to the contact portion, A slurry tank for storing a slurry containing abrasive grains, a slurry supply means for supplying the slurry from the slurry tank to a contact portion between the polishing pad and the plate-like body through the slurry supply hole, Through slurry suction hole A slurry recovery means for sucking the slurry supplied to the contact portion and returning the sucked slurry to the slurry tank; a concentration meter for detecting the concentration of the slurry provided in the slurry supply means; Based on the detection result of the densitometer, when the concentration of the slurry falls below a preset lower limit value, the slurry is controlled to add an abrasive and a predetermined additive to the slurry tank, and the concentration of the slurry And a controller that controls the densitometer to be washed when it exceeds a preset upper limit value.

  As a result, the slurry is circulated and the concentration of the slurry is detected by a densitometer. When the concentration value is lower than a predetermined lower limit value, cerium oxide or an additive is added to the slurry, or the concentration value exceeds a predetermined upper limit value. When the densitometer is cleaned, the polishing rate is kept constant to ensure a polishing allowance, and the slurry is reattached to the polished surface by increasing the slurry circulation rate. Can be suppressed.

  In one embodiment, the predetermined additive is preferably a dispersant that prevents aggregation of the abrasive.

  Thereby, aggregation of cerium oxide can be prevented and the polishing rate can be maintained.

  In one embodiment, the central portion of the opposing surface of the plate-like body of the polishing pad in which the slurry suction hole is formed is within a range of 25% of the diameter from the center of the polishing pad. preferable.

  Thereby, the slurry at the center of the polishing pad can be discharged well, and a polishing allowance near the center can be secured.

  In one embodiment, the concentration meter is preferably washed every 30 to 40 minutes in addition to or instead of when the concentration of the slurry exceeds a preset upper limit. .

  Thereby, the concentration value can always be detected correctly without the concentration meter clogging and detecting an abnormal value.

  As described above, according to the present invention, even when a large-sized plate-like substrate of, for example, 1000 mm square or more is polished, the polishing margin near the center is ensured and normal polishing is performed without reducing the slurry flow rate. be able to. Further, the slurry is circulated and the concentration of the slurry is detected by a densitometer. When the concentration value is lower than a predetermined lower limit value, cerium oxide or an additive is added to the slurry, or the concentration value exceeds a predetermined upper limit value. If the densitometer is cleaned in some cases, the polishing rate is kept constant, the polishing allowance is secured, and the adhesion of the polished glass component to the polished surface is suppressed by increasing the slurry circulation rate. can do.

The top view which shows the whole structure of the grinding | polishing apparatus as one Embodiment of the plate-shaped body grinding | polishing apparatus used for the grinding | polishing system of this invention. Assembly perspective view of membrane frame and carrier for attaching membrane frame Side view showing embodiments of polishing stage and polishing head FIG. 1 is a plan view of a polishing pad of the polishing apparatus shown in FIG. The top view which shows the formation range of the slurry suction hole 1 of the polishing pad surface Sectional view of the groove in the center of the polishing surface of the polishing pad Cross section of the groove on the outside of the polishing surface of the polishing pad Schematic showing the slurry circulation system Graph showing the change over time of the concentration detection value by the densitometer The top view which shows the grinding | polishing amount according to the position of the to-be-polished surface of a glass substrate when slurry suction is carried out The top view which shows the grinding | polishing amount according to the position of the to-be-polished surface of a glass substrate when slurry suction is not carried out Sectional drawing which shows the problem of the slurry supply in the conventional grinding | polishing apparatus

  Hereinafter, a plate-like body polishing apparatus and a polishing system according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view showing the entire structure of a polishing apparatus as an embodiment of a plate-like polishing apparatus used in the polishing system of the present invention.

  The polishing apparatus 10 shown in FIG. 1 is, for example, a large glass substrate G having a size of 1000 mm in length × 1000 mm in width or larger and a thickness of 0.7 mm or less (for example, a thickness of 0.2 mm to 0.7 mm). This is a polishing apparatus for polishing the surface to be polished of G to a flatness necessary for a glass substrate for a liquid crystal display.

  The polishing apparatus 10 includes a glass substrate carry-in conveyor 12 for carrying a glass substrate G before polishing, a glass substrate sticking stage 16 for sticking the glass substrate G to a film frame (plate-like body sticking member) 14, and a first one. Polishing stage 18, second polishing stage 20, glass substrate removal stage 22 for removing polished glass substrate G from film frame 14, glass substrate carry-out conveyor 24, film frame cleaning stage 26, film frame drying stage 28, and film A frame return conveyor 30 is mainly provided.

  Hereinafter, in order to simplify the description, the glass substrate adhering stage 16, the first polishing stage 18, the second polishing stage 20, the glass substrate removing stage 22, the film frame cleaning stage 26, and the film frame drying stage 28 will be described. Are simply described as stages 16, 18, 20, 22, 26, 28.

  The polishing apparatus 10 includes a transport device 150 that transports the film frame 14 from the stage 16 to the stage 18, a transport device 152 that transports the film frame 14 from the stage 18 to the stage 20, and transports the film frame 14 from the stage 20 to the stage 22. A conveying device 154 is provided. These transfer devices 150, 152, and 154 have the same configuration, and their operations are controlled by a control unit 200 that controls the polishing apparatus 10 in an integrated manner, and are reciprocated synchronously in the left-right direction in FIG.

  The unpolished glass substrate G carried in by the glass substrate carrying conveyor 12 is sucked and held by a suction pad 34 provided on the arm 33 of the robot 32. The arm 33 is moved from the glass substrate carry-in conveyor 12 to the conveyor 36 by the rotating operation of the arm 33, and is conveyed to the stage 16 by the conveyor 36.

  On the stage 16, the glass substrate G before polishing is stuck to the film frame 14.

  FIG. 2 shows an assembled perspective view of the membrane frame 14 and the carrier 52 to which the membrane frame 14 is attached.

  As shown in FIG. 2, the film frame 14 is formed by stretching a rectangular film body 38 to which the glass substrate G can be attached between a rectangular upper frame 40 and a lower frame 42. 40 and the lower frame 42 are fastened by bolts (not shown).

  The film frame 14 and the film body 38 are not limited to a rectangular shape, and may be a circular shape.

  The method of sticking the glass substrate G before polishing to the film frame 14 will be described. The film frame 14 is held by a lifting device (not shown) on the stage 16, and the glass substrate G is positioned below the film frame 14. By the way, the film frame 14 is moved downward by the elevating device, and the flexible and self-adsorbing film body 38 stretched on the film frame 14 shown in FIG. 2 is pressed against the surface to be polished of the glass substrate G. The surface to be polished of the glass substrate G is adhered to the film body 38 by this pressing force. Thereafter, the film frame 14 is held by the transfer device 150 of FIG. 1 and transferred to the stage 18, and is attached to a carrier (plate-shaped body holding portion) 52 of a polishing head (described later) on the stage 18. The film frame 14 described below refers to the whole of the film body 38 stretched.

  As shown in FIG. 2, a lifting frame 78 is fixed to the upper outer peripheral portion of the carrier 52 by a bolt (not shown). Through holes 80, 80,... Are opened at predetermined equal intervals in the flange portion of the lifting frame 78, and the upper surface of the slide frame 82 (slide-contact frame) is inserted into the through holes 80, 80,. A sliding frame hanger 84 projecting from is penetrated from below. The sliding frame suspension 84 is penetrated by the lifting spring 88 and is connected to a screw jack (not shown).

  Then, the sliding frame 82 is pulled up with respect to the carrier 52 by operating the screw jack and pulling up the sliding frame suspension 84 against the urging force of the lifting spring 88. Thereby, the membrane frame 14 detachably attached to the sliding frame 82 is pulled up, and a predetermined tension is applied to the membrane body 38.

  A spindle 56 is connected to the carrier 52.

  FIG. 3 is a side view showing an embodiment of a polishing stage and a polishing head.

  Next, the polishing head 50 shown in FIG. 3 will be described. Since the polishing head 50 of the stage 18 and the polishing head 50 of the stage 20 have the same structure, the same reference numerals are used for explanation.

  As shown in FIG. 3, the polishing head 50 includes a main body casing 51, and a revolving drive mechanism (not shown) is built in the main body casing 51. The revolution drive mechanism is composed of a planetary gear mechanism and a motor, and the output shaft of the planetary gear mechanism driven by the motor is connected to a spindle 56 that hangs down in the vertical direction. As described above, the carrier 52 is connected to the spindle 56. Thus, when the planetary gear mechanism is driven, the carrier 52 and the film frame 14 are revolved around a predetermined revolution center.

  Further, the main casing 51 shown in FIG. 3 is connected to the lifting mechanism 156 via the slider 158. When the main body casing 51 is moved up and down with respect to the slider 158 by the lifting mechanism 156, the carrier 52 is moved forward and backward with respect to the circular polishing pad 58 of the stage 18 and the circular polishing pad 60 of the stage 20, and the film frame. 14 is pressed against the polishing pads 58 and 60 by a predetermined polishing pressure.

  The slider 158 may be removed from the polishing apparatus 10 and the main body casing 51 may be directly connected to the lifting mechanism 156.

  The polishing pad 58 is attached to the upper surface of the polishing surface plate 62. The polishing surface plate 62 is rotatably supported by the polishing table 64 via a bearing (not shown), and the center of rotation is set coaxially with the center axis of the polishing pad 58. Then, by driving a motor (not shown), the polishing pad 58 is rotated (rotated) around its central axis. Further, the polishing pad 58 side may not be rotated, and a motor is not necessarily required. As described below, the polishing pad 58 side may be swung.

  The polishing table 64 is slidably supported by a pair of guide rails 69 and 69 arranged in parallel. By providing a drive unit (not shown) for reciprocating the polishing table 64 along the guide rails 69, 69, the polishing pad 58 is swung horizontally when necessary. The swinging direction of the polishing pad 58 may be a direction orthogonal to the transport direction by the transport device 150 of FIG. 1 or may be a direction parallel to the transport direction. That is, any direction that swings the polishing pad 58 in the horizontal direction may be used.

  The polishing surface plate 62 is connected to a number of hoses (not shown) for supplying slurry to the back side of the polishing pad 58. In order to prevent the hoses from being entangled, the rotation of the polishing pad 58 is regulated so as to turn within a predetermined angle range from a predetermined reference position. The slurry supplied from the hose to the back side of the polishing pad 58 is supplied to the polishing surface of the polishing pad 58 through a slurry supply hole passing through the inside of the polishing pad 58.

  Further, the range of the turning angle of the polishing pad 58, the turning operation such as the turning speed, and the revolution operation such as the revolution speed per unit time are independently controlled by the control unit 200 of FIG.

  Note that the configuration of each part of the polishing pad 60 is the same as the configuration of the polishing pad 58 described above, and therefore the description thereof is omitted here.

  Further, as shown in FIG. 3, linear motion guides 70 are attached to the slider 158 of the stage 18. The linear motion guides 70, 70 are fitted to the guide rails 72, 72. The guide rails 72 and 72 are disposed toward a maintenance stage 74 for maintaining the spindle 56 of the stage 18 and the carrier 52 as indicated by broken lines in FIG.

  Further, as shown in FIG. 3, linear motion guides 70, 70 are similarly attached to the slider 158 of the stage 20, and the linear motion guides 70, 70 are fitted to the guide rails 160, 160. The guide rails 160 and 160 are arranged toward a maintenance stage 76 for maintaining the spindle 56 and the carrier 52 of the stage 20 as indicated by broken lines in FIG.

  Note that the slider 158 may be removed from the polishing apparatus 10, and the linear motion guides 70 and 70 may be directly attached to the lifting device 156.

  The carrier 52 is provided with an air chamber (not shown) in FIG. 3 and communicates with the air supply path 102 indicated by a broken line in FIG. The air supply path 102 extends outside the polishing head 50 via a rotary joint (not shown) attached to the polishing head 50, and is connected to the air pump 106 via a valve 104. Thus, when the valve 104 is opened, the compressed air from the air pump 106 is supplied to the air chamber provided in the carrier 52 via the air supply path 102. The pressure of the compressed air supplied to the air chamber is transmitted to the glass substrate G through the film body 38, and the polished surface of the glass substrate G is pressed against the polishing pads 58 and 60 of FIG. The

  As for the polishing of the glass substrate G, the film frame 14 to which the glass substrate G is adhered is transferred from the stage 16 to the stage 18 by the transfer device 150 as shown in FIG. The film frame 14 to which the glass substrate G is attached by the transfer device 152 is sequentially transferred from the stage 18 to the stage 20, and the polished surface of the glass substrate G is polished by the stage 20 in two steps.

  In this embodiment, a slurry suction hole for sucking slurry is provided near the slurry supply hole near the center of the polishing surface of the polishing pad, and the slurry is circulated by sucking and returning the slurry from the slurry suction hole, thereby polishing the polishing pad. The back pressure generated at the center of the surface is reduced to ensure a desired polishing amount and perform normal polishing.

  FIG. 4 is a plan view of the polishing pad 58 of the polishing apparatus 10 shown in FIG. 1 (the polishing pad 60 has the same configuration as described above and will be described below as the polishing pad 58).

  In FIG. 4, the slurry supply hole 122 and the slurry suction hole 124 formed on the polishing surface of the polishing pad 58 and the groove 126 for flowing the slurry are displayed.

  As shown in FIG. 4, the polishing surface of the polishing pad 58 is provided with slurry supply holes 122 indicated by white circles and slurry suction holes 124 indicated by black circles. The number and arrangement of the slurry supply holes 122 and the slurry suction holes 124 and the number of the grooves 126 shown in FIG. 4 are merely examples, and the present invention is not limited to this. In reality, a larger number of grooves 126 and the like are formed. .

  Thus, a large number (for example, several tens) of slurry supply holes 122 for supplying slurry between the polishing pad 58 and the glass substrate G (not shown in FIG. 4) are provided on the substantially entire surface of the polishing pad 58. .

  On the other hand, the slurry suction hole 124 for sucking the slurry is formed only in the central portion of the polishing pad 58, and in particular, the slurry is sucked from the central portion.

  FIG. 5 is a plan view showing the formation range of the slurry suction holes on the polishing surface of the polishing pad 58.

  As indicated by a broken-line circle in FIG. 5, the area where the slurry suction hole 124 is formed on the polishing surface of the polishing pad 58 is preferably a region F inside a circle drawn with a radius C from the center of the polishing pad 58. Here, the radius C is 25% or less of the diameter H of the polishing surface of the polishing pad 58. When the radius C is within 25% of the diameter H, insufficient polishing at the center of the surface to be polished of the glass substrate G can be solved. When the radius C exceeds 25% of the diameter H, the slurry is formed on the peripheral edge of the polishing surface of the glass substrate G. Is difficult to get around.

  Further, as shown in FIG. 4, the slurry supplied to the central portion of the polishing surface of the polishing pad 58 from the slurry supply hole is applied to the polishing surface of the polishing pad 58 from the central portion of the polishing pad 58 to the outside of the polishing pad 58. A groove 126 is formed to spread the slurry over the entire polishing surface of the polishing pad 58 (so-called “dicing”).

  The groove 126 through which the slurry flows has a diameter H along one diameter H of the polishing surface of the polishing pad 58 substantially parallel to the swing direction of the polishing head 50 (see FIG. 3) that performs a linear swing operation. A straight line that is substantially perpendicular to the diameter H is formed over the whole D. That is, the groove 126 is formed in a direction orthogonal to the swinging direction of the polishing head 50.

  As shown in FIG. 4, the width of the groove 126 is different along the diameter H between the central portion E of the diameter H and the outside thereof. In other words, the central portion E having the diameter H is formed wider than the outside of the central portion E, and is narrower than the width of the central portion E outside the central portion E with respect to the entire diameter D along the diameter H. Is formed. In addition, the width | variety of the groove | channel 126 shall mean the distance between the angle | corners of the protruding item | line which forms the groove | channel 126 here, as shown by the code | symbol W1 in FIG. 6A and the code | symbol W2 in FIG. 6B.

  Thus, the width of the groove 126 is formed because the slurry accumulated in the central portion E of the polishing pad 58 passes through the groove 126 formed in the central portion E from both ends of the groove 126 to the outside of the groove 126. This is to prevent the slurry from staying in the center by facilitating the discharge. In addition, the depth of each groove | channel 126 of the center part E and the outer side of the center part E may be the same, and may differ.

  6A is a cross-sectional view of the groove in the central portion E along the diameter H of the polishing surface of the polishing pad 58 shown in FIG. 4, and FIG. 6B shows the central portion E along the diameter H of the polishing surface of the polishing pad 58. It is sectional drawing of the outside groove | channel. In the central portion E of the polishing pad 58, the lateral cross-sectional shape of the groove 126 is concave, and its width W1 is 3 mm. In addition, outside the central portion E along the diameter H of the polishing surface of the polishing pad 58, the lateral cross-sectional shape of the groove 126 is concave and its width W2 is 1.5 mm. However, the widths W1 and W2 are not limited to the above values, and are preferably 1.5 to 3.0 mm. In addition, although the space | interval L1, L2 of the groove | channel 126 is 3 mm, it is not limited to this, Preferably it is 3.0-9.0 mm. The depths T1 and T2 of the groove 126 are both 2.0 mm, but are not limited to this, as long as the depths T1 and T2 are the same.

  Therefore, as shown in FIG. 4, both the slurry supply hole 122 and the slurry suction hole 124 and the groove 126 through which the slurry flows are formed on the polishing surface of the polishing pad 58.

  In the present embodiment, the slurry is supplied to the contact portion between the polishing pad 58 and the glass substrate G, the slurry is sucked to return the slurry to a slurry tank (described later), and the returned slurry is returned to the polishing pad 58 and the glass substrate G again. And the slurry is circulated.

  FIG. 7 shows a schematic diagram of this slurry circulation system.

  As shown in FIG. 7, a rotary joint 128 is installed on the side of the polishing pad 58 facing the polishing surface 14 a, and through this, the slurry supply hole 122 formed in the entire polishing surface 58 a of the polishing pad 58. The slurry is supplied from the slurry, and the slurry is sucked from the slurry suction hole 124 formed in the central portion of the polishing surface 58a of the polishing pad 58.

  When supplying the slurry, the slurry is taken into the slurry supply line 123 from the slurry tank 130 by the pump 132, and the polishing surface 58a of the polishing pad 58 and the glass substrate G (FIG. 7) from the slurry supply hole 122 through the rotary joint 128. The slurry is supplied to the abutting portion with (not shown).

  Further, when the slurry is sucked, the slurry is sucked by the pump 134 from the slurry suction hole 124 formed only in the central portion of the polishing surface 58a of the polishing pad 58. The sucked slurry is taken into the slurry collection pipe 125 via the rotary joint 128 and returned to the slurry tank 130 via the punching metal filter 136. The cullet of the glass substrate G contained in the sucked slurry is removed by the punching metal filter 136. The slurry returned to the slurry tank 130 is again sucked by the pump 132 and supplied to the polishing surface 58 a of the polishing pad 58. In this way, the slurry is circulated.

  A flow meter 138 is installed in the slurry supply line 123 between the rotary joint 128 and the pump 132, and the flow rate of the supplied slurry is constantly monitored.

  A concentration meter 140 is installed in the pipeline 123a branched from the slurry supply pipeline 123. For example, the concentration of the slurry is monitored by flowing the flow rate of about 10 liters per minute through the pipeline 123a. Yes. The slurry that has passed through the densitometer 140 is returned to the slurry tank 130 again. The slurry concentration is the mass ratio (mass%) of the abrasive in the slurry.

  The detection results of the flow meter 138 and the concentration meter 140 are input to the control unit 142.

  The control unit 142 controls the pumps 132 and 134 according to the detection result of the flow meter 138 to control the supply amount of slurry during polishing.

  In addition, when the concentration of the slurry is lowered according to the detection result of the densitometer 140, the control unit 142 opens the electromagnetic valve 144 and removes the abrasive (abrasive grains) from the abrasive material storage container 146 in the slurry tank 130. In addition, the electromagnetic valve 148 is opened to inject the dispersant from the dispersant storage container 149 into the slurry tank 130.

  This is because the abrasive tends to agglomerate, and if the polishing is continued for a long time, the abrasive agglomerates and precipitates and the concentration of the slurry is lowered, thereby the polishing rate gradually worsens. A dispersant is added as an agent to prevent agglomeration of the abrasive and maintain the polishing rate.

  Examples of the abrasive include cerium oxide, zirconium oxide, iron oxide, and silicon dioxide, and these abrasives may be used alone or in combination of two or more.

  As the dispersant, for example, acrylic acid / maleic acid copolymer Na salt (Polyty A-550, manufactured by Lion Co., Ltd.) is conceivable. In addition, methanol, Na citrate, or the like may be added.

  Note that a minute voltage of 1 to 2.5 V may be applied to the slurry in order to prevent agglomeration of the abrasive.

  By adding these dispersants and applying a minute voltage, it is possible to prevent the agglomeration of the abrasives, prevent the polishing rate from decreasing, and improve the polishing rate.

  The slurry concentration management based on the detection result of the densitometer 140 will be described with reference to FIG.

  FIG. 8 is a graph showing the time change of the density detection value by the densitometer 140. The vertical axis represents slurry concentration, and the horizontal axis represents time. The upper limit value and the lower limit value on the vertical axis are the upper limit value and the lower limit value of the desired slurry concentration range.

At the initial stage of polishing, the slurry concentration of the slurry changes within a desired range, but after a certain time, the slurry concentration decreases. Therefore, at time t _L when the control unit 142 falls below the lower limit value of the slurry concentration set in advance, as described above, the control unit 142 opens the electromagnetic valves 144 and 148, and a predetermined amount of abrasive and dispersant. Is added to the slurry in the slurry tank 130.

Further, when the slurry is clogged inside the densitometer 140, the slurry concentration increases. Also at this time, the control unit 140 determines that the densitometer 140 is clogged at the time point t _U when the upper limit value of the slurry concentration preset in the control unit 142 is exceeded, and flushes (cleans) the densitometer 140.

  In addition to the pipe line 123a, a flushing pipe line (not shown) is connected to the densitometer 140. During normal operation, the flushing pipe line opening / closing valve is closed and the pipe line 123a is closed. The on-off valve is open. When flushing, in order to switch the connection to the densitometer 140 from the conduit 123a to the flushing conduit, the on / off valve of the flushing conduit is opened and the on / off valve of the conduit 123a is closed. Thereafter, a mixture of water and compressed air sent from the flushing conduit is introduced from the inlet of the concentration meter 140, and the slurry clogged inside the concentration meter 140 with the mixture is removed. The removed slurry is discharged from the outlet of the densitometer 140. After the flushing is completed, in order to switch the connection from the flushing pipeline to the pipeline 123a, the open / close valves of the respective pipelines are returned to their original positions.

  The flushing may be performed when the concentration value detected by the densitometer 140 exceeds the upper limit value as described above, but may be periodically performed so as to be performed once every 30 to 40 minutes. Thereby, the concentration value can always be detected correctly without the concentration meter clogging and detecting an abnormal value.

  8A and 8B show the effects of this embodiment. 8A and 8B are diagrams showing the polishing amount for each position of the surface to be polished of the glass substrate G, and the amount of polishing at the peripheral portion of the surface to be polished of the glass substrate G is normalized as 100. FIG. FIG. 8A shows a case where slurry is sucked, and FIG. 8B shows a case where slurry is not sucked.

  As shown in FIG. 8B, when slurry suction is not performed, the polishing amount of the central portion of the surface to be polished of the glass substrate G is 80, which is significantly lower than the polishing amount of the peripheral portion of the surface to be polished. On the other hand, as shown in FIG. 8A, when the slurry is sucked, the polishing amount at the central portion of the glass substrate G is 90, which is improved compared to the case where the slurry is not sucked.

  As described above, in the present embodiment, when polishing a glass substrate having a large size of at least 1000 mm square, the slurry being polished is forcibly sucked from the central portion of the polishing pad to stay in the central portion. By reducing the slurry, the back pressure of the slurry can be suppressed, and the polishing amount at the center can be ensured.

  In addition, the slurry is sucked from the holes formed in the polishing pad surface, and the sucked slurry is supplied again to the polishing surface of the polishing pad and circulated to increase the circulation amount of the slurry. Further, by sucking the slurry being polished and increasing the circulation amount of the slurry in this way, it is possible to reduce the retention of the polished glass component in the slurry. Thereby, it can suppress that the grind | polished glass component adheres to a grinding | polishing surface again.

  Further, by increasing the circulation amount of the slurry by suction, it is possible to suppress the temperature rise of the slurry and to suppress the adhesion of dirt to the glass substrate. Furthermore, by suppressing the temperature rise of the slurry, it is possible to suppress deterioration of the selective polishing property due to softening of the polishing pad.

  The plate-like body polishing apparatus and the polishing system according to the present invention have been described in detail above. However, the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course you can go.

  DESCRIPTION OF SYMBOLS 10 ... (Plate-shaped body) Polishing apparatus, 12 ... Glass substrate carrying conveyor, 14 ... Film frame (plate-shaped body sticking member), 16 ... Glass substrate sticking stage, 18 ... First polishing stage, 20 ... First 2 polishing stage, 22 ... glass substrate removal stage, 24 ... glass substrate carry-out conveyor, 26 ... film frame cleaning stage, 28 ... film frame drying stage, 30 ... film frame return conveyor, 32 ... robot, 33 ... arm, 34 DESCRIPTION OF SYMBOLS ... Adsorption pad, 36 ... Conveyor, 38 ... Film body, 51 ... Main body casing, 52 ... Carrier (plate body holding part), 56 ... Spindle, 58, 60 ... Polishing pad, 62 ... Polishing surface plate, 64 ... Polishing table , 122 ... Slurry supply hole, 124 ... Slurry suction hole, 126 ... Groove, 128 ... Rotary joint, 130 ... Slurry tank, 132, 134 ... Pump, 136 ... Pan Ring metal filter, 138 ... flow meter, 140 ... densitometer, 142 ... control unit, 144, 148 ... electromagnetic valve, 146 ... abrasive container, 149 ... dispersing agent container, 150 ... transporting apparatus, 200 ... control unit

Claims (9)

Plate-like body holding means for holding a plate-like body having a side length of 1000 mm or more;
A polishing pad installed opposite to the plate-like body held by the plate-like body holding means,
The polishing pad is
A plurality of slurry supply holes that are formed on the opposing surface of the plate-like body and supply slurry to the contact portion between the polishing pad and the plate-like body;
A slurry suction hole that is formed only in the central portion of the opposing surface of the plate-like body and sucks the slurry supplied to the contact portion;
Is formed. A plate-like body polishing apparatus.   2. The plate-like body polishing according to claim 1, wherein the central portion of the opposing surface of the plate-like body of the polishing pad in which the slurry suction hole is formed is within a range of 25% of the diameter from the center of the polishing pad. apparatus. The plate-like body polishing apparatus according to claim 1 or 2,
A plurality of grooves are formed linearly in an arbitrary direction on the opposing surface of the plate-like body of the polishing pad, and the width of the groove formed in the center portion along the direction orthogonal to the direction is the swing direction. A plate-like body polishing apparatus formed so as to be wider than the width of the groove formed on the outer side of the central portion along the line. The plate-like body polishing apparatus according to any one of claims 1 to 3, further comprising: a means for swinging the polishing pad in a horizontal direction relative to the plate-like body holding means; A means for rotating and revolving the polishing pad;
A plurality of grooves are formed linearly in the swing direction on the opposing surface of the plate-like body of the polishing pad, and the width of the groove formed in the central portion along the direction orthogonal to the swing direction is A plate-like body polishing apparatus formed wider than the width of a groove formed on the outer side of the central portion along the swinging direction.   5. The plate-like body polishing apparatus according to claim 3, wherein the central portion along the swing direction is a range within 25% of the diameter of the polishing pad from the center. Plate-like body holding means for holding a plate-like body having a side length of 1000 mm or more;
A polishing pad installed opposite to the plate-like body held by the plate-like body holding means,
The polishing pad includes a plurality of slurry supply holes that are formed on an opposing surface of the plate-like body and supply slurry to a contact portion between the polishing pad and the plate-like body, and a center of the opposing surface of the plate-like body. A slurry suction hole for sucking the slurry that is formed only in the portion and supplied to the contact portion,
A slurry tank for storing a slurry containing abrasive grains as an abrasive;
Slurry supply means for supplying the slurry from the slurry tank to the contact portion between the polishing pad and the plate-like body via the slurry supply hole;
Slurry collecting means for sucking the slurry supplied to the contact portion through the slurry suction hole and returning the sucked slurry to the slurry tank;
A concentration meter for detecting the concentration of the slurry provided in the slurry supply means;
Based on the detection result of the densitometer, when the concentration of the slurry falls below a preset lower limit value, the slurry is controlled to add an abrasive and a predetermined additive to the slurry tank, and the concentration of the slurry A control unit that controls to perform cleaning of the densitometer when a preset upper limit is exceeded,
A polishing system comprising:   The polishing system according to claim 6, wherein the predetermined additive is a dispersant that prevents aggregation of the abrasive.   The polishing system according to claim 6 or 7, wherein a center portion of the opposing surface of the plate-like body of the polishing pad in which the slurry suction hole is formed is within a range of 25% of the diameter from the center of the polishing pad. .   The concentration meter is washed every 30 to 40 minutes in addition to or instead of when the concentration of the slurry exceeds a preset upper limit value. The polishing system described.

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