JP2015199173A - Grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinder which can perform an efficient grinding of a work-piece having a high hardness while reducing a wear amount of a grinding stone.SOLUTION: A grinder 1 is equipped with a chuck table 31 which holds a disk-shaped work-piece W, and a grinding unit 5 onto which a grinding wheel 51, in which grinding stones 52 that contact and grind the disk-shaped work-piece held by the chuck table are annularly disposed, is rotatably mounted. The grinder is so configured that during grinding of the disk-shaped work-piece, a grinding surface of a squeeze-out part of the grinding stone is irradiated with a laser beam from a laser radiation mechanism 6, while a surface to be ground of the disk-shaped work-piece, which is ground by the grinding stone, is irradiated with a laser beam.

Description

  The present invention relates to a grinding apparatus, and more particularly, to a grinding apparatus that performs grinding with a grinding wheel on a work surface of a disk-shaped workpiece as a work piece.

  2. Description of the Related Art Conventionally, as a grinding apparatus that grinds a workpiece, one in which a part of a grinding wheel arranged in a ring on a grinding wheel is brought into contact with the workpiece is known (for example, see Patent Document 1). In this grinding apparatus, in order to avoid the phenomenon that grinding debris generated in the grinding process is clogged in the grinding wheel, cleaning water is supplied to the grinding wheel in a portion not in contact with the workpiece to perform grinding. The grinding stone is cooled and cleaned.

  In addition, in order to ensure grinding accuracy for workpieces with high hardness, such as sapphire, silicon carbide (SiC), gallium nitride (GaN), etc., grinding is performed while performing dressing to sharpen the blade of the grinding wheel A grinding apparatus has also been proposed (see, for example, Patent Document 2). In this grinding apparatus, dressing is performed by bringing a dressing grindstone into contact with a portion of the grindstone that is not in contact with the workpiece.

JP 2010-149222 A JP 2012-135851 A

  However, when the dressing process is performed in parallel with the grinding process as in the above-described grinding apparatus of Patent Document 2, the dressing amount of the grinding wheel may be excessive. In such a case, the amount of wear of the grinding wheel may increase due to wear associated with the dressing process and the grinding process, and the life of the grinding wheel may be shortened. On the other hand, when grinding is performed on a workpiece having high hardness, if the dressing process for the grinding wheel is insufficient, the grinding process takes time, and the processing efficiency may be significantly reduced.

  The present invention has been made in view of such circumstances, and provides a grinding apparatus capable of performing an efficient grinding process on a workpiece having high hardness while extending the life of a grinding wheel. With the goal.

  The grinding apparatus according to the present invention is a grinding in which a chuck table for holding a disk-shaped workpiece and a grinding wheel in which a grinding wheel for grinding in contact with the disk-shaped workpiece held by the chuck table is annularly mounted are rotatably mounted. The grinding wheel is disposed in an annular shape with an inner diameter having a diameter larger than the radius of the disk-shaped workpiece, passing through the center of the disk-shaped workpiece, and the grinding wheel is centered on the center of the disk-shaped workpiece. By positioning so as to pass through, a protruding portion that protrudes outside the disk-shaped workpiece is formed during grinding, and the first and second irradiation means for irradiating the grinding surface with a laser beam on the protruding portion of the grinding wheel A second irradiating means for irradiating the surface to be ground of the disk-shaped workpiece to be ground with laser light, and the first irradiating means during the grinding of the disk-shaped workpiece on the protruding portion of the grinding wheel. While irradiating the laser beam on the grinding surface that, and then irradiating a laser beam to be ground surface of the disk-shaped workpiece by the second irradiating means.

  According to the grinding apparatus, it is possible to easily grind the disk-shaped workpiece through the formation of the modified layer or the groove on the surface to be ground by the laser beam from the second irradiation unit. On the other hand, the grinding performance of the grinding wheel can be enhanced through dressing of the grinding surface of the grinding wheel with the laser beam from the first irradiation means. For this reason, the disk-shaped workpiece can be easily ground and the disk-shaped workpiece can be ground while improving the grinding performance of the grinding wheel. Thereby, it becomes possible to perform an efficient grinding process with respect to a workpiece with high hardness. Further, since the grinding work is performed while making the disk-shaped workpiece easy to grind, it is possible to reduce the wear of the grinding wheel and reduce the amount of dressing processing required when worn. As a result, it is possible to efficiently grind the workpiece having high hardness while extending the life of the grinding wheel.

  For example, in the grinding apparatus, the third irradiating means that enables the first irradiating means and the second irradiating means with one laser light emitting part includes a laser light emitting part that emits laser light, and a laser light emitting part. A splitter that divides the emitted laser light into two directions, a direction that goes straight and a direction that is perpendicular to the direction, and a laser beam that is unidirectionally divided by the splitter is reflected by a mirror and condensed on the ground surface of the protruding portion. And a second condensing lens that reflects laser light in the other direction with a mirror, irradiates the disc-shaped workpiece from above, and collects it on the surface to be ground of the disc-shaped workpiece. According to this configuration, the laser light emitted from the single laser emitting unit is divided by the splitter, and the grinding surface of the grinding wheel and the workpiece to be ground of the disk-shaped workpiece are respectively divided by the first and second condenser lenses. It can be focused on the surface. This makes it possible to improve the grinding performance of the grinding wheel while making it easy to grind the disk-shaped workpiece using laser light from a single laser emitting section.

  Further, in the grinding apparatus, the first moving means for raising and lowering the first condensing lens according to the height of the grinding surface, and the second condensing lens at the height of the ground surface. And a second moving means that moves up and down accordingly. According to this configuration, the first and second condensing lenses can be moved to the desired positions by the first and second moving means, respectively, so that the laser light from the single laser emitting unit can be condensed at the desired position. It is possible to improve the grinding performance of the grinding wheel while effectively making the disk-shaped workpiece easy to grind.

  Further, in the above grinding apparatus, the chuck table is formed of a material capable of transmitting a laser beam having a wavelength that is transmissive to the disc-shaped workpiece, and the first irradiation unit and the second irradiation unit are set to 1. The fourth irradiating means enabled by one laser emitting unit is a laser emitting unit that emits laser light having a wavelength that is transmissive to the disc-shaped workpiece, and the laser beam emitted from the laser emitting unit goes straight. A splitter that divides the laser beam in two directions, a direction orthogonal to the direction, a first condenser lens that reflects the laser light in one direction divided by the splitter by a mirror and collects it on the ground surface of the protruding portion, A first moving means for moving one condenser lens according to the height of the grinding surface, and a laser beam in the other direction is reflected by a mirror so that the chuck table and the disc-shaped workpiece are transmitted from under the chuck table to make a circle. Board A second focusing lens for focusing light at the ground surface of the workpiece, and a second moving means for moving in response to the second condenser lens to the height of the ground surface, may be provided with a. According to this configuration, the laser light emitted from the single laser emitting unit is divided by the splitter, and the grinding surface of the grinding wheel and the workpiece to be ground of the disk-shaped workpiece are respectively divided by the first and second condenser lenses. It can be focused on the surface. This makes it possible to improve the grinding performance of the grinding wheel while making it easy to grind the disk-shaped workpiece using laser light from a single laser emitting section. In addition, the chuck table and the disk-shaped workpiece are transmitted from below the chuck table and focused on the surface to be ground of the disk-shaped workpiece, so compared with the case of irradiating laser light on the disk-shaped workpiece. The optical path length of laser light can be shortened. Further, since the first and second condenser lenses can be moved to the desired positions by the first and second moving means, respectively, the laser light from the single laser light emitting unit can be condensed at the desired position, effectively. It is possible to improve the grinding performance of the grinding wheel while making it easy to grind the disk-shaped workpiece.

  In the said grinding apparatus, it is preferable to provide a lambda / 2 wavelength plate between a laser light emission part and a splitter. According to this configuration, since the laser light from the laser emission unit can be incident on the λ / 2 wavelength plate before being divided by the splitter, the polarization state (polarization plane) of the laser light is changed without changing the light amount. be able to. Thereby, it can be set as the polarization state suitable for the division | segmentation aspect by a splitter, and it becomes possible to divide | segment the laser beam from a laser light emission part efficiently (with a required dividing ratio). In particular, it is possible to adjust the amount of reflected light and adjust the light amount ratio between transmitted light and reflected light by configuring the splitter with a beam splitter and using a λ / 2 wavelength plate. In the case where the λ / 2 wavelength plate is not used, it is possible to divide by using a splitter (beam splitter, half mirror) that divides the light amount ratio between the transmitted light and the reflected light at a predetermined ratio.

  For example, in the above grinding apparatus, the first condenser lens is composed of a first cylindrical lens having a width corresponding to the width of the grinding wheel, and the second condenser lens is a second condenser having a width corresponding to the radius of the chuck table. It consists of a cylindrical lens. According to this configuration, it is possible to focus the laser light from the laser light emitting unit in a linear shape so as to correspond to the radii of the grinding wheel and the chuck table. This makes it possible to dress the grinding surface of the grinding wheel in the width direction at once by using laser light from a single laser emitting section, and to easily grind the disk-shaped workpiece in the radial direction at once. It becomes.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to perform an efficient grinding process with respect to a workpiece with high hardness, reducing the abrasion amount of a grinding wheel.

It is a perspective view which shows the external appearance of the grinding device which concerns on 1st Embodiment. It is a schematic diagram for demonstrating the positional relationship of the grinding wheel and disk-shaped workpiece | work at the time of the grinding process of the grinding device which concerns on 1st Embodiment. It is a schematic diagram for demonstrating the structure of the laser irradiation mechanism which the grinding apparatus which concerns on 1st Embodiment has, and the optical path of a laser beam. It is a schematic diagram for demonstrating the structure of the laser irradiation mechanism which the grinding apparatus which concerns on the modification of 1st Embodiment has, and the optical path of a laser beam. It is a schematic diagram for demonstrating the structure of the laser irradiation mechanism which the grinding apparatus which concerns on 2nd Embodiment has, and the optical path of a laser beam. It is a schematic diagram for demonstrating the modified layer formed in a disk shaped workpiece | work with the grinding device which concerns on 1st, 2nd embodiment.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The grinding apparatus according to the present embodiment includes a disk-shaped workpiece that is a workpiece, and a single or a plurality of irradiation means that irradiate laser light to a grinding wheel that grinds the disk-shaped workpiece. While making it easy to grind disc-shaped workpieces with light, dressing a grinding wheel reduces the amount of wear of the grinding wheel and efficiently grinds workpieces with high hardness. .

  In the following, a grinding apparatus that grinds a disk-shaped workpiece (semiconductor wafer) as a high-hardness workpiece such as sapphire, silicon carbide (SiC), or gallium nitride (GaN) to a predetermined thickness will be described. To do. However, the material of the disk-shaped workpiece as the workpiece in the grinding apparatus according to the present invention is not limited to these and can be appropriately changed.

(First embodiment)
FIG. 1 is a perspective view showing an external appearance of a grinding apparatus 1 according to the first embodiment. In the following, for convenience of explanation, the lower left side shown in FIG. 1 is called the front side of the grinding apparatus 1, and the upper right side shown in FIG. 1 is called the rear side of the grinding apparatus 1. In the following, for convenience of explanation, the vertical direction shown in FIG. FIG. 1 shows a state in which a grinding wheel 51 described later is disposed at a position for grinding a disk-shaped workpiece W held on the chuck table 31.

  As shown in FIG. 1, the grinding apparatus 1 has a base 2 having a generally rectangular parallelepiped shape. A table support 3 for supporting the chuck table 31 is provided on the upper surface of the base 2. A column portion 4 is provided on the rear side of the table support 3. A grinding unit 5 is supported on the front surface of the support column 4 so as to be movable in the vertical direction. In the base 2 and in the vicinity of the grinding unit 5, components of the laser irradiation mechanism 6 that irradiates the disc-shaped workpiece W held by the grinding wheel 52 and the chuck table 31 of the grinding unit 5 with laser light are arranged. Has been.

  In the grinding apparatus 1 according to the present embodiment having such a configuration, the grinding wheel 51 of the grinding unit 5 and the chuck table 31 holding the disk-like workpiece W are relatively rotated so as to rotate the disc-like workpiece. W is configured to be ground. Further, in the grinding apparatus 1 according to the present embodiment, the laser beam is irradiated from the laser irradiation mechanism 6 to the grinding wheel 52 included in the grinding unit 5 and the disk-shaped workpiece W held on the chuck table 31 during the grinding process. It is configured as follows.

  The table support 3 is provided in a square shape when viewed from above, and supports the chuck table 31 rotatably. The table support 3 is connected to a drive mechanism (not shown), and slides in the front-rear direction in the opening 2 a formed on the upper surface of the base 2 by a drive force supplied from the drive mechanism. As a result, the chuck table 31 is separated from the grinding position where the part of the disk-shaped workpiece W is opposed to the grinding unit 5 to the front side, and is supplied with the disk-shaped workpiece W before processing. Then, the disk-shaped workpiece W after the processing is slid and moved to the replacement position where the workpiece is collected.

  Before and after the table support 3, a dustproof cover 7 is provided to prevent the grinding grindstone 51 generated during grinding of the disk-shaped workpiece W from entering the base 2. The dust cover 7 is attached to the front surface and the rear surface of the table support 3, and is provided so as to be extendable / contractible according to the movement position, and is configured to cover the opening 2 a of the base 2.

  The chuck table 31 is formed in a disk shape, and a holding surface 31a for holding the disk-shaped workpiece W is formed on the upper surface thereof (see FIG. 3). An adsorption surface is formed of a porous ceramic material at the central portion of the holding surface 31a. The chuck table 31 is connected to a suction source (not shown) disposed in the base 2 and sucks and holds the disk-shaped workpiece W by the suction surface of the holding surface 31a. Further, the chuck table 31 is connected to a rotation drive mechanism (not shown), and is rotated in a state where the disk-like workpiece W is held on the holding surface 31a by the rotation drive mechanism.

  The support column 4 is provided in a rectangular parallelepiped shape, and a grinding unit moving mechanism 41 that moves the grinding unit 5 above the chuck table 31 is provided on the front surface thereof. The grinding unit moving mechanism 41 has a Z-axis table 42 that moves up and down with respect to the support column 4 by a ball screw type moving mechanism. The grinding unit 5 is supported on the Z-axis table 42 via a support portion 43 attached to the front side thereof.

  The grinding unit 5 constitutes a grinding means, and has a grinding wheel 51 rotatably attached to a lower end of a spindle (not shown). A plurality of grinding wheels 52 are provided on the lower surface of the grinding wheel 51. These grinding wheels 52 are annularly arranged on the lower surface of the grinding wheel 51. Each grinding wheel 52 is composed of, for example, a diamond grindstone in which diamond abrasive grains are hardened with a binder such as metal bond or resin bond. At the time of grinding, these grinding wheels 52 come into contact with each other to grind the disk-shaped workpiece W.

  Here, the positional relationship between the grinding wheel 51 and the disk-shaped workpiece W during grinding will be described with reference to FIG. FIG. 2 is a schematic diagram for explaining the positional relationship between the grinding wheel 51 and the disk-shaped workpiece W during the grinding process of the grinding apparatus 1 according to the present embodiment. In FIG. 2, the grinding wheel 51 and the disk-shaped workpiece W at the time of grinding are shown from the upper side. In FIG. 2, for convenience of explanation, the grinding wheel 52 arranged on the lower surface of the grinding wheel 51 is shown and hatched.

  As shown in FIG. 2, the diameter of the grinding wheel 51 is configured with substantially the same dimensions as the diameter of the disk-shaped workpiece W. A plurality of grinding wheels 52 are annularly arranged on the outer peripheral edge of the lower surface of the grinding wheel 51. At the time of grinding, the grinding wheel 51 is disposed at a position where the grinding wheel 52 always passes through the center of the disk-shaped workpiece W. For this reason, some of the grinding wheels 52 of the plurality of grinding wheels 52 are not arranged to face the disk-shaped workpiece W and protrude beyond the disk-shaped workpiece W.

  Here, the case where the diameter of the grinding wheel 51 is configured to be approximately the same as the diameter of the disk-shaped workpiece W is shown. However, the configuration of the grinding wheel 51 can be appropriately changed on the condition that the plurality of grinding wheels 52 are not arranged to face the disk-shaped workpiece W and have a portion protruding outside the disk-shaped workpiece W. It is. For example, the portion that protrudes outward from the disk-shaped workpiece W is formed by arranging a plurality of grinding wheels 52 in an annular shape with an inner diameter that is larger than the radius of the disk-shaped workpiece W.

  Returning to FIG. 1, the description of the components of the grinding apparatus 1 according to the present embodiment will be continued. The laser irradiation mechanism 6 constitutes the third irradiation means in the claims, and includes a laser light emitting unit 601, a λ / 2 wavelength plate 602, a splitter 603, a plurality of mirrors 604a to 604c, A first condenser lens 605 and a second condenser lens 606 are included. For example, the laser light emitting unit 601, the λ / 2 wavelength plate 602, the divider 603, the plurality of mirrors 604 a, and the first condenser lens 605 are arranged in the base 2. The mirror 604 b is accommodated in the accommodating portion 21 provided so as to protrude from the upper surface of the base 2. The mirror 604 c and the second condenser lens 606 are supported by a support arm provided on the upper surface of the base 2.

  Here, the configuration of the laser irradiation mechanism 6 and the optical path of the laser light included in the grinding apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 3 is a schematic diagram for explaining the configuration of the laser irradiation mechanism 6 and the optical path of the laser light included in the grinding apparatus 1 according to the present embodiment. In FIG. 3, only the laser irradiation mechanism 6, the chuck table 31 including the laser irradiation target, and the grinding wheel 51 are shown. Further, FIG. 3 shows a state in which the grinding wheel 51 is arranged at a position for grinding the disk-shaped workpiece W held on the chuck table 31.

  In the laser irradiation mechanism 6 shown in FIG. 3, the laser light emitting unit 601 emits laser light toward the upper side of the grinding apparatus 1. The laser light emitting unit 601 can emit first and second laser beams having different wavelengths. For example, the first laser beam has a wavelength of 515 nm, a power of about 20 W, a pulse width of about 8 ps, and a repetition frequency of 200 kHz. On the other hand, the second laser beam has a wavelength of 1030 nm, a power of about 20 W, a pulse width of about 8 ps, and a repetition frequency of 200 kHz. Further, the wavelength of the first laser beam and the wavelength of the second laser beam can be set to 257 nm and 515 nm, respectively. The first laser beam is used when a groove is formed on the surface to be ground Wa of the disk-shaped workpiece W, and the second laser beam is a modified layer on the surface to be ground Wa of the disk-shaped workpiece W. It is used when forming.

  The divider 603 is disposed above the laser light emitting unit 601. The divider 603 divides the laser light emitted from the laser light emitting unit 601 into two directions, ie, a direction that goes straight and a direction perpendicular to the direction. For example, the splitter 603 can be composed of a beam splitter, a half mirror, and a dichroic mirror. Here, it is assumed that the splitter 603 includes a beam splitter. The beam splitter reflects a part of the incident laser light and transmits a part thereof. The splitter 603 reflects the incident laser light in the orthogonal direction.

  Note that the divider 603 can also be formed of a half mirror. The half mirror is a kind of beam splitter and is an optical device that equalizes the intensity of reflected light and the intensity of transmitted light. Further, the divider 603 can also be constituted by a dichroic mirror. The dichroic mirror is a kind of mirror made using a special optical material, and is an optical device that reflects light of a specific wavelength and transmits light of other wavelengths. Therefore, it can be used when laser light having a different wavelength is emitted from the laser light emitting unit 601. Here, the laser beams having different wavelengths indicate laser beams including two wavelengths on the same optical path. For example, a laser beam having different wavelengths includes two wavelengths, such as 515 um and 1030 um or 257 um and 515 um. By making such a laser beam incident on the dichroic mirror, it can be divided according to the wavelength.

  The λ / 2 wavelength plate 602 is disposed on the optical path between the laser light emitting unit 601 and the splitter 603. The λ / 2 wavelength plate 602 changes its polarization state (polarization plane) without changing the amount of laser light emitted from the laser light emitting unit 601. For example, the λ / 2 wavelength plate 602 is configured to be able to change the polarization direction of the linearly polarized laser light according to the type and state of the splitter 603 employed in the grinding apparatus 1. Further, by using a combination of the λ / 2 wavelength plate 602 and the beam splitter, the transmitted light amount and the reflected light amount can be adjusted, and the light amount ratio between the transmitted light and the reflected light can be adjusted.

  The mirror 604 a is disposed on the side of the divider 603 and on the lower side of the grinding wheel 51. The mirror 604 a is disposed on the optical path of the laser light divided in the orthogonal direction by the splitter 603, and reflects this laser light to the upper side of the grinding device 1. For example, the mirror 604a is composed of a galvanometer mirror, a polygon mirror, or a PZT mirror, and is configured so that the reflection angle can be adjusted. For example, the mirror 604a adjusts the reflection angle of the laser beam so that the laser beam condensed by the first condenser lens 605 can scan the dimension (L1 shown in FIG. 2) of the grinding wheel 52 in the thickness direction.

  The first condenser lens 605 is disposed above the mirror 604a and between the mirror 604a and the grinding wheel 51. The first condenser lens 605 is disposed on the optical path of the laser light reflected by the mirror 604 a and condenses the laser light on the grinding surface 52 a of the grinding wheel 52. More specifically, the first condenser lens 605 has a grinding surface 52 a of the grinding wheel 52 that is not opposed to the disk-shaped workpiece W among the plurality of grinding wheels 52 provided on the lower surface of the grinding wheel 51. To focus the laser light. The laser light condensed by the first condenser lens 605 is irradiated onto the grinding surface 52 a of the grinding wheel 52 through the opening 23 formed in the base 2.

  For example, the first condenser lens 605 is configured by a cylindrical lens (first cylindrical lens) having a width corresponding to the dimension in the width direction of the grinding wheel 52 (L2 shown in FIG. 2). By configuring the first condensing lens 605 with such a cylindrical lens, the laser light from the laser light emitting unit 601 can be condensed linearly so as to correspond to the width of the grinding wheel 52. As a result, the grinding surface 52a of the grinding wheel 52 can be collectively dressed in the width direction using the laser light from the laser emitting section 601.

  The mirror 604b is disposed above the splitter 603 and on the optical path of the laser light divided in the straight direction by the splitter 603, and this laser light is disposed on the side of the grinding apparatus 1 (on the grinding wheel 51 side). To reflect. The laser light divided in the straight direction from the splitter 603 is incident on the mirror 604b through the opening 24 formed in the base 2. Unlike the above-described mirror 604a, the reflection angle of the mirror 604b is fixed. For example, the mirror 604b is configured by a surface mirror in which a metal film or a dielectric multilayer film having high reflection characteristics is deposited on the surface of a substrate (glass or metal).

  The mirror 604c is disposed on the upper side of the chuck table 31 disposed at the grinding position on the optical path of the laser light reflected by the mirror 604b. The mirror 604c reflects the laser beam condensed by the second condenser lens 606 to the chuck table 31 side. For example, the mirror 604c is composed of a galvanometer mirror, a polygon mirror, or a PZT mirror, and is configured so that the reflection angle can be adjusted. For example, the mirror 604 c adjusts the reflection angle of the laser light so that the laser light condensed by the second condenser lens 606 can scan the width corresponding to the radius of the chuck table 31.

  The second condenser lens 606 is disposed on the side of the mirror 604b and between the mirror 604b and the mirror 604c. The second condenser lens 606 is disposed on the optical path of the laser light reflected by the mirror 604b, and condenses the laser light reflected by the mirror 604c on the surface Wa to be ground of the disk-shaped workpiece W. More specifically, the second condensing lens 606 condenses the laser beam on the surface Wa to be ground of the disk-shaped workpiece W that is being ground by the grinding wheel 52 of the grinding wheel 51.

  For example, the second condensing lens 606 can be configured by a cylindrical lens (second cylindrical lens) having a width corresponding to the radius of the chuck table 31. By configuring the second condensing lens 606 with such a cylindrical lens, the laser light from the laser light emitting unit 601 can be condensed linearly so as to correspond to the radius of the chuck table. Thereby, it is possible to easily grind the disk-shaped workpiece collectively in the radial direction using the laser light from the laser light emitting unit 601.

  Hereinafter, the operation | movement at the time of the grinding process in the grinding device 1 which concerns on this Embodiment is demonstrated. At the time of grinding, first, the chuck table 31 holding the disk-shaped workpiece W is transported to the grinding position, and the grinding wheel 52 contacts the surface to be ground Wa of the disk-shaped workpiece W by the grinding unit moving mechanism 41. The grinding unit 5 is moved downward to the contact position. At that time, a driving force is supplied from the rotational drive mechanism to the chuck table 31 and the grinding wheel 5, and the chuck table 31 and the grinding wheel 51 are rotationally driven in the same direction. As a result, the grinding surface 52a of the grinding wheel 52 rotates while contacting the surface to be ground Wa of the disk-shaped workpiece W to perform grinding.

  During grinding of the disk-shaped workpiece W by the grinding wheel 52, a laser beam is emitted from the laser emission unit 601 of the laser irradiation mechanism 6. The laser light emitted from the laser emitting unit 601 passes through the λ / 2 wavelength plate 602 and enters the splitter 603. When passing through the λ / 2 wavelength plate 602, the laser light is adjusted to a polarization state suitable for the splitter 603 without changing its light quantity. The laser light incident on the splitter 603 is split in the orthogonal direction as reflected light, and is split in the straight direction as transmitted light. The laser light divided in the orthogonal direction is reflected by the mirror 604 a and enters the first condenser lens 605, and is condensed on the grinding surface 52 a of the grinding wheel 52. The ground surface 52a of the grinding wheel 52 is dressed by the laser light thus condensed. By this dressing, the blade in the grinding wheel 52 is sharpened, and the grinding performance of the grinding wheel 52 is enhanced.

  On the other hand, the laser light divided in the straight traveling direction is reflected by the mirror 604b, enters the second condenser lens 606, is reflected by the mirror 604c, and is collected on the surface to be ground Wa of the disk-like workpiece W. . A modified layer or a groove is formed on the ground surface Wa of the disk-shaped workpiece W by the laser light thus condensed. For example, when the first laser beam is emitted from the laser light emitting unit 601, a part of the surface Wa is volatilized to form a groove. On the other hand, when the second laser light is emitted from the laser light emitting unit 601, a modified layer is formed on a part of the ground surface Wa. When the groove or the modified layer is formed on the surface to be ground Wa, the blade in the grinding wheel 52 is easily caught on the surface to be ground Wa, and the disk-shaped workpiece W is easily ground.

  When the disc-like workpiece W reaches a predetermined thickness by such grinding, the grinding is stopped. Then, after the grinding wheel 51 is separated from the chuck table 31 by the grinding unit moving mechanism 41, the chuck table 31 is transported to the replacement position. When the disk-shaped workpiece W is carried out of the chuck table 31 at the replacement position, a series of operations during a series of grinding processes is completed.

  As described above, according to the grinding apparatus 1 according to the present embodiment, a circle is formed by forming a modified layer or a groove on the surface Wa to be ground of the disk-shaped workpiece W by the laser light from the laser light emitting unit 601 of the laser irradiation mechanism 6. The plate-like workpiece W can be easily ground. On the other hand, the grinding performance of the grinding wheel 52 can be enhanced through the dressing of the grinding surface 52a of the grinding wheel 52 by the laser beam from the laser emitting unit 601. For this reason, the disk-shaped workpiece W can be easily ground and the disk-shaped workpiece W can be ground while improving the grinding performance of the grinding wheel 52. Thereby, it becomes possible to perform an efficient grinding process with respect to a workpiece with high hardness. Further, since the grinding work is performed while making the disk-shaped workpiece W easy to grind, it is possible to reduce the wear of the grinding wheel 52 and reduce the amount of dressing required when worn. As a result, it is possible to efficiently grind the workpiece having high hardness while extending the life of the grinding wheel 52.

  In particular, in the grinding apparatus 1 according to the present embodiment, the laser light emitted from the single laser emission unit 601 provided in the laser irradiation mechanism 6 is divided by the divider 603, and the first condenser lens 605 and The second condenser lens 606 can condense on the grinding surface 52a of the grinding wheel 52 and the grinding surface Wa of the disk-shaped workpiece W, respectively. Thereby, it is possible to improve the grinding performance of the grinding wheel 52 while making it easy to grind the disk-shaped workpiece W using the laser light from the single laser light emitting unit 601.

  In the grinding apparatus 1 according to the present embodiment, a λ / 2 wavelength plate 602 is disposed between the laser light emitting unit 601 and the divider 603 in the laser irradiation mechanism 6. Accordingly, since the laser light from the laser light emitting unit 601 can be incident on the λ / 2 wavelength plate 602 before being divided by the divider 603, the polarization state of the laser light can be changed without changing the light amount. As a result, the polarization state suitable for the division mode by the divider 603 can be achieved, and the laser light from the laser light emitting unit 601 can be efficiently divided. In particular, by configuring the splitter 603 with a beam splitter, the transmitted light amount and the reflected light amount can be adjusted, and the light amount ratio between the transmitted light and the reflected light can be adjusted.

  In the above embodiment, as the grinding process is performed, the positions (grinding surfaces 52a of the grinding wheel 52 and the ground surface Wa of the disk-like workpiece W) of the laser light irradiation target by the laser irradiation mechanism 6 (grinding). The height position in the vertical direction of the device 1 changes. In order to cope with such a change in the position of the laser light irradiation target, it is preferable as an embodiment to adjust the condensing position of the laser light by the first and second condensing lenses 605 and 606.

  The adjustment of the laser beam condensing position by the first and second condensing lenses 605 and 606 is performed by moving the first condensing lens 605 according to the height of the grinding surface 52a of the grinding wheel 52, for example. This can be realized by the first moving means to be moved and the second moving means for moving the second condenser lens 606 in accordance with the height of the surface Wa of the disc-like workpiece W.

  Further, the first and second condenser lenses 605, 606 are provided with moving means for moving the positions of the mirrors 604a and 604b arranged on the optical path of the laser light up to the first and second condenser lenses 605 and 606. By adjusting the optical path length of the laser light after passing through 606, the condensing position of the laser light by the first and second condenser lenses 605 and 606 can be adjusted.

  Furthermore, a concave lens or a convex lens is disposed on the optical path from the divider 603 to the first and second condenser lenses 605 and 606, and the curvatures of these concave and convex lenses are changed to change the first and second condensers. It is also possible to adjust the condensing position of the laser beam by the lenses 605 and 606.

  By adjusting the condensing position of the laser light by the first and second condensing lenses 605 and 606 as described above, the disk follows the irradiation target position of the laser light that changes with the execution of the grinding process. It is possible to grind the disk-shaped workpiece W while improving the grinding performance of the grinding wheel 52 by making the workpiece W easy to grind. Thereby, for example, even when the grinding process is performed for a long time, it is possible to continuously perform the efficient grinding process on the workpiece having high hardness.

  Moreover, in the above description, the case where the laser light emission part 601, (lambda) / 2 wavelength plate 602, the splitter 603, etc. are arrange | positioned in the base 2 is demonstrated regarding the component of the laser irradiation mechanism 6. FIG. However, the arrangement of the components of the laser irradiation mechanism 6 is not limited to this, and can be changed as appropriate. These components can be arranged at arbitrary positions according to the optical path length from the laser light emitting unit 601 to the irradiation target, the interference state with other components in the grinding apparatus 1, and the like. In addition, the quantity and type of the mirror 604 can be changed as appropriate in order to realize the arrangement of these components.

  For example, as shown in FIG. 4, the laser emission unit 601, the λ / 2 wavelength plate 602 and the divider 603 are arranged on the upper side of the chuck table 31, while the mirror 604 b is arranged in the base 2. Good. In the laser irradiation mechanism 6 shown in FIG. 4, a divider 603 is disposed on the side of the second condenser lens 606, and a λ / 2 wavelength plate 602 and a laser light emitting unit 601 are disposed on the side of the divider 603. Is arranged.

  In the laser irradiation mechanism 6 shown in FIG. 4, the laser light emitted from the laser emission unit 601 passes through the λ / 2 wavelength plate 602 and is incident on the splitter 603. In the splitter 603, the laser light split in the straight direction as transmitted light is incident on the second condenser lens 606, reflected by the mirror 604 c, and condensed on the surface Wa to be ground of the disk-like workpiece W. . On the other hand, the laser light divided in the orthogonal direction as reflected light is reflected by the mirror 604b and the mirror 604a, enters the first condenser lens 605, and is condensed on the grinding surface 52a of the grinding wheel 52.

  In the case where the components of the laser irradiation mechanism 6 shown in FIG. 4 are arranged in this way, similarly to the above embodiment, grinding is performed by the laser light condensed by the first and second condenser lenses 605 and 606. The ground surface 52a of the grindstone 52 is dressed, and a modified layer or groove is formed on the ground surface Wa of the disk-shaped workpiece W. As a result, the disk-shaped workpiece W is easily ground, and grinding is performed while improving the grinding performance of the grinding wheel 52. As a result, it is possible to efficiently grind the workpiece having high hardness while extending the life of the grinding wheel 52.

(Second Embodiment)
In the first embodiment, the laser beam is irradiated from above the chuck table 31 to the ground surface Wa of the disk-shaped workpiece W. On the other hand, the second embodiment is different from the first embodiment in that laser light is irradiated from the lower side of the chuck table 31 to the surface Wa to be ground of the disk-shaped workpiece W. Hereinafter, the configuration of the grinding apparatus according to the second embodiment will be described focusing on differences from the grinding apparatus 1 according to the first embodiment.

  The grinding apparatus according to the second embodiment is different from the grinding apparatus 1 according to the first embodiment in the configuration of the chuck table 31 and the laser irradiation mechanism 6. Since the components other than the chuck table 31 and the laser irradiation mechanism 6 are the same as those of the grinding apparatus 1 according to the first embodiment, the description thereof is omitted.

  FIG. 5 is a schematic diagram for explaining the configuration of the laser irradiation mechanism and the optical path of the laser light included in the grinding apparatus according to the second embodiment. In FIG. 5, the same reference numerals are given to the same components as those of the grinding apparatus 1 shown in FIG. 3, and the description thereof is omitted as appropriate.

  The chuck table 131 according to the second embodiment is formed of a material capable of transmitting laser light having a wavelength that is transmissive to the disk-shaped workpiece W. 31. For example, the chuck table 131 is made of a transparent material such as glass. Except for the constituent materials, the chuck table 131 has the same function as the chuck table 31 according to the first embodiment.

  In the laser irradiation mechanism 16 according to the second embodiment, all the constituent elements are accommodated in the base 2 and the laser light emitting unit 1601 has a wavelength that is transmissive to the disk-shaped workpiece W. It differs from the laser irradiation mechanism 6 according to the first embodiment in that it emits laser light. In addition, this laser irradiation mechanism 16 comprises the 4th irradiation means in a claim.

  As shown in FIG. 5, the laser irradiation mechanism 16 includes a laser light emitting unit 1601, a λ / 2 wavelength plate 1602, a splitter 1603, a plurality of mirrors 1604 a to 1604 c, a first condenser lens 1605, a second one. The condenser lens 1606, the first moving unit 1607, and the second moving unit 1608 are configured. The λ / 2 wavelength plate 1602, the divider 1603, the mirror 1604c, the first condenser lens 1605, and the second condenser lens 1606 have the same functions as those in the first embodiment.

  The first moving unit 1607 is connected to the first condenser lens 1605 and plays a role of moving the first condenser lens 1605 in accordance with the height of the grinding surface 52 a of the grinding wheel 52. The second moving means 1608 is connected to the second condenser lens 1606 and plays a role of moving the second condenser lens 1606 in accordance with the height of the surface to be ground Wa of the disk-shaped workpiece W.

  In the laser irradiation mechanism 16, a λ / 2 wavelength plate 1602, a divider 1603, and a mirror 1604 a are disposed above the laser light emitting unit 1601. The mirror 1604b is disposed on the optical path of the laser light divided in the orthogonal direction by the splitter 1603, and reflects the laser light upward (on the grinding wheel 51 side). For example, the mirror 1604b is composed of a galvanometer mirror, a polygon mirror, or a PZT mirror, and is configured so that the reflection angle can be adjusted. The first condenser lens 1605 is disposed above the mirror 1604 b and at a position between the mirror 1604 b and the grinding wheel 51. The first condenser lens 1605 is disposed on the optical path of the laser light reflected by the mirror 1604 b and condenses the laser light on the grinding surface 52 a of the grinding wheel 52.

  The mirror 1604a is disposed on the optical path of the laser light divided in the straight direction by the splitter 1603, and reflects the laser light to the side. For example, the mirror 1604a is a surface mirror in which a metal film or a dielectric multilayer film having high reflection characteristics is deposited on the surface of a substrate (glass or metal). The mirror 1604c is disposed on the optical path of the laser beam reflected by the mirror 1604a and below the chuck table 131 disposed at the grinding position. The mirror 1604c reflects the laser beam condensed by the second condenser lens 1606 to the chuck table 31 side. For example, the mirror 1604c is composed of a galvanometer mirror, a polygon mirror, or a PZT mirror, and is configured so that the reflection angle can be adjusted. For example, the mirror 1604 c adjusts the reflection angle of the laser light so that the laser light condensed by the second condenser lens 1606 can scan the width corresponding to the radius of the chuck table 131.

  The second condenser lens 1606 is disposed on the side of the mirror 1604a and between the mirror 1604a and the mirror 1604c. The second condenser lens 1606 is disposed on the optical path of the laser light reflected by the mirror 1604a, and condenses the laser light reflected by the mirror 1604c on the surface to be ground Wa of the disk-shaped workpiece W. More specifically, the second condensing lens 1606 condenses the laser beam on the surface Wa to be ground of the disk-shaped workpiece W that is being ground by the grinding wheel 52 of the grinding wheel 51. For example, the second condenser lens 1606 can be configured by a cylindrical lens having a width corresponding to the radius of the chuck table 31.

  Also in the second embodiment, a laser beam is emitted from the laser light emitting unit 1601 of the laser irradiation mechanism 16 during grinding of the disk-shaped workpiece W by the grinding wheel 52. Laser light emitted from the laser light emitting unit 1601 passes through the λ / 2 wavelength plate 1602 and enters the splitter 1603. The laser light incident on the splitter 1603 is split in the orthogonal direction as reflected light, and is split in the straight direction as transmitted light. The laser beam divided in the orthogonal direction is reflected by the mirror 1604b, enters the first condenser lens 1605, and is condensed on the grinding surface 52a of the grinding wheel 52. The ground surface 52a of the grinding wheel 52 is dressed by the laser light thus condensed. By this dressing, the blade in the grinding wheel 52 is sharpened, and the grinding performance of the grinding wheel 52 is enhanced.

  On the other hand, the laser light divided in the straight traveling direction is reflected by the mirror 1604a, enters the second condenser lens 1606, is reflected by the mirror 1604c, and is collected on the surface Wa to be ground of the disk-like workpiece W. . The modified layer is formed on the surface Wa to be ground of the disk-shaped workpiece W by the laser light thus condensed. By forming the modified layer on the surface to be ground Wa as described above, the blade in the grinding wheel 52 is easily caught on the surface to be ground Wa, and the disk-shaped workpiece W is easily ground.

  As described above, according to the grinding apparatus according to the present embodiment, the disk-shaped workpiece is formed through the formation of the modified layer on the surface to be ground Wa of the disk-shaped workpiece W by the laser light from the laser emitting unit 1601 of the laser irradiation mechanism 16. W can be easily ground. On the other hand, the grinding performance of the grinding wheel 52 can be enhanced through the dressing of the grinding surface 52a of the grinding wheel 52 by the laser beam from the laser emitting section 1601. For this reason, the disk-shaped workpiece W can be easily ground and the disk-shaped workpiece W can be ground while improving the grinding performance of the grinding wheel 52. Further, since the grinding work is performed while making the disk-shaped workpiece W easy to grind, it is possible to reduce the wear of the grinding wheel 52 and reduce the amount of dressing required when worn. As a result, it is possible to efficiently grind the workpiece having high hardness while extending the life of the grinding wheel 52.

  In particular, in the grinding apparatus according to the present embodiment, the first and second condenser lenses 1605 and 1606 can be moved to desired height positions by the first and second moving means 1607 and 1608, respectively. . As a result, the laser beam from the laser emitting section 1601 can be properly condensed according to the height of the grinding surface 52a of the grinding wheel 52 and the surface to be ground Wa of the disk-shaped workpiece W, and the disk-shaped workpiece W can be effectively collected. It is possible to improve the grinding performance of the grinding wheel 52 while making it easy to grind. That is, the height of the to-be-ground surface Wa of the disk-shaped workpiece W ground by the grinding wheel 52 decreases as it is ground. The second moving means 1608 moves the second condensing lens 1606 according to the height of the ground surface Wa to be lowered, and adjusts the height of the condensing point. Further, the height of the grinding surface 52a of the grinding wheel 52 to be ground also decreases as grinding is performed. The first moving means 1607 moves the first condensing lens 1605 in accordance with the height of the grinding surface 52a coming down to adjust the height of the condensing point. Thereby, the height of the condensing point by the 1st, 2nd condensing lenses 1605 and 1606 can always be adjusted to an appropriate position, and the grinding performance of the grinding wheel 52 can be improved while making the disk-shaped workpiece W easy to grind. Can be increased.

  Further, in the grinding apparatus according to the present embodiment, the chuck table 131 and the disk-shaped workpiece W are transmitted from below the chuck table 131 and are condensed on the surface Wa to be ground of the disk-shaped workpiece W. The optical path length of the laser beam can be shortened as compared with the case where the laser beam is irradiated from above the disk-shaped workpiece W (see FIGS. 3 and 5). Thereby, it is possible to improve the grinding performance of the grinding wheel 52 while making it easy to grind the disk-like workpiece W in a short time from the start of laser light emission by the laser emitting unit 1601.

  Furthermore, in the grinding apparatus according to the present embodiment, the chuck table 131 and the disk-shaped workpiece W are transmitted from below the chuck table 131 and are condensed on the surface Wa to be ground of the disk-shaped workpiece W. Compared with the case where the laser beam is irradiated from above the disk-shaped workpiece W, a region of the modified layer formed on the ground surface Wa can be ensured.

  Hereinafter, the region of the modified layer formed on the surface Wa to be ground of the disk-like workpiece W by the grinding apparatus according to the first and second embodiments will be described. 6A and 6B are schematic views for explaining a modified layer formed on a surface to be ground Wa of a disk-like workpiece W by the grinding apparatuses according to the first and second embodiments, respectively. In FIG. 6, the region of the modified layer (modified layer region) formed on the surface to be ground Wa of the disk-shaped workpiece W is indicated as ML (ML1, ML2).

  As shown in FIG. 6A, in the grinding apparatus 1 according to the first embodiment, the laser beam is disposed on the upper side of the chuck table 31 in order to irradiate the laser beam on the upper side of the chuck table 31. Interfere with 51. For this reason, the modified layer region ML1 is formed on the surface Wa to be ground of the disk-shaped workpiece W disposed outside the grinding wheel 51. At the time of grinding, the grinding wheel 51 is arranged so that the grinding wheel 52 always passes through the center of the disk-shaped workpiece W. For this reason, the modified layer region ML1 is not formed at the center position of the disk-shaped workpiece W.

  On the other hand, in the grinding apparatus according to the second embodiment, the laser beam is irradiated from the upper side of the chuck table 131, and thus there is no restriction as in the first embodiment. Therefore, the modified layer region ML2 is formed including the center of the disk-shaped workpiece W. Since the modified layer region ML2 is thus formed on the surface to be ground Wa of the disk-shaped workpiece W, the surface to be ground Wa of the disk-shaped workpiece W can be easily ground without unevenness.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above-described embodiment, the single laser irradiation mechanism 6 (16) is provided, the laser light from the single laser light emitting unit 601 (1601) is divided by the divider 603 (1603), and the grinding wheel 52 is divided. The case of irradiating the ground surface 52a and the ground surface Wa of the disk-shaped workpiece W is described. However, the configuration in which the laser beam is irradiated onto the grinding surface 52a of the grinding wheel 52 and the surface Wa to be ground of the disk-shaped workpiece W is not limited to this, and can be appropriately changed. For example, it is good also as a structure provided with the 1st, 2nd irradiation means which each irradiates a laser beam to the grinding surface 52a of the grinding wheel 52, and the to-be-ground surface Wa of the disk-shaped workpiece W, respectively. As described above, in the case of irradiating laser light from the first and second irradiation means to the grinding surface 52a of the grinding wheel 52 and the ground surface Wa of the disc-shaped workpiece W, respectively, as in the above embodiment, the grinding wheel It is possible to efficiently grind a workpiece with high hardness while reducing the amount of wear of the workpiece.

  In the laser irradiation mechanism 6 (16) according to the above-described embodiment, the λ / 2 wavelength plate 602 (1602) is disposed in the optical path between the laser emission unit 601 (1601) and the splitter 603 (1603). Shows when to do. However, the configuration of the laser irradiation mechanism 6 (16) is not limited to this and can be changed as appropriate. For example, the λ / 2 wavelength plate 602 (1602) may be omitted, and the laser light emitted from the laser light emitting unit 601 (1601) may be directly incident on the splitter 603 (1603).

  As described above, according to the present invention, there is an effect that it is possible to perform an efficient grinding process on a workpiece having a high hardness while extending the life of the grinding wheel. This is useful for a grinding apparatus that grinds a plate-like workpiece made of silicon (SiC) or the like.

DESCRIPTION OF SYMBOLS 1 Grinding device 2 Base 31, 131 Chuck table 31a, 131a Holding surface 5 Grinding unit 51 Grinding wheel 52 Grinding wheel 52a Grinding surface 6, 16 Laser irradiation mechanism 601, 1601 Laser emission part 602, 1602 λ / 2 wavelength plate 603, 1603 Dividers 604a to 604c, 1604a to 1604c Mirrors 605 and 1605 First condenser lenses 606 and 1606 Second condenser lenses 1607 First moving means 1608 Second moving means W Disk-shaped workpiece Wa Surface to be ground

Claims (6)

A grinding table comprising: a chuck table for holding a disk-shaped workpiece; and a grinding means for rotatably mounting a grinding wheel in which a grinding wheel that is in contact with and grinds against the disk-shaped workpiece held by the chuck table is annularly arranged. In the device
The grinding wheel is annularly arranged with an inner diameter having a diameter larger than the radius of the disk-shaped workpiece passing through the center of the disk-shaped workpiece, and grinding is performed by positioning the center of the disk-shaped workpiece so that the grinding wheel passes. A protruding part that protrudes outside from the disk-shaped work is formed inside,
A first irradiating means for irradiating the ground surface of the grinding wheel with a laser beam on the protruding portion; a second irradiating means for irradiating the surface to be ground of a disk-shaped workpiece ground with the grinding wheel with a laser beam; With
During grinding of a disk-shaped workpiece, the first irradiation means irradiates the ground surface of the grinding wheel at the protruding portion with laser light, while the second irradiation means applies laser to the surface to be ground of the disk-shaped workpiece. A grinding device that emits light. The third irradiation means that enables the first irradiation means and the second irradiation means with one laser light emitting unit,
A laser light-emitting unit that emits laser light, a splitter that divides the laser light emitted from the laser light-emitting unit into two directions, a direction orthogonal to a straight line direction, and a unidirectional laser that is divided by the splitter A first condensing lens that reflects light by a mirror and condenses on the ground surface of the protruding portion, and a laser beam in the other direction is reflected by the mirror and irradiated from above the disc-shaped workpiece to be covered with the disc-shaped workpiece. The grinding apparatus according to claim 1, further comprising a second condenser lens that collects light on the grinding surface.   First moving means for raising and lowering the first condenser lens according to the height of the grinding surface, and second movement for raising and lowering the second condenser lens according to the height of the grinding surface And a grinding device according to claim 2. The chuck table is formed of a material that can transmit laser light having a wavelength that is transmissive to a disk-shaped workpiece,
The fourth irradiation means that enables the first irradiation means and the second irradiation means with one laser light emitting unit,
A splitter that divides a laser light emitting portion that emits laser light having a wavelength having transparency with respect to a disk-shaped workpiece, and a laser light emitted from the laser light emitting portion into two directions, a direction orthogonal to a straight direction. A first condensing lens that reflects the laser light in one direction divided by the divider by a mirror and collects the light on the ground surface of the protruding portion, and the first condensing lens on the ground surface. A first moving means that moves according to height, a laser beam in another direction is reflected by a mirror, and the chuck table and the disk-shaped workpiece are transmitted from under the chuck table to be ground on the disk-shaped workpiece. The grinding apparatus according to claim 1, further comprising: a second condenser lens that collects the light with a second moving means that moves the second condenser lens according to the height of the surface to be ground.   The grinding apparatus according to any one of claims 2 to 4, further comprising a λ / 2 wavelength plate between the laser light emitting unit and the divider.   The first condenser lens is composed of a first cylindrical lens having a width corresponding to the width of the grinding wheel, and the second condenser lens is composed of a second cylindrical lens having a width corresponding to the radius of the chuck table. The grinding apparatus according to any one of claims 2 to 4, which is performed.

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