Chuck table and laser processing device

Abstract

To provide a chuck table capable of easily and inexpensively replacing a holding surface that holds a workpiece.SOLUTION: The chuck table that sucks and holds a workpiece includes: a base table that has a suction path connected to a suction source; a support member mounted on the base table to support the workpiece; and a protective plate that is arranged to cover the upper surface of the support member to protect the support member. The protective plate has a plurality of through-holes for transmitting a suction force from the suction source to the workpiece.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a chuck table that suction-holds a workpiece, and a laser processing device equipped with the chuck table. [Background technology]

[0002] In the device chip manufacturing process, a wafer is used in which devices are formed in multiple areas defined by multiple planned division lines (streets) arranged in a grid pattern. By dividing this wafer along the planned division lines, multiple device chips, each equipped with a device, are obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] A cutting device is used to divide the wafer. The cutting device is equipped with a chuck table having a holding surface for holding the workpiece, and a cutting unit to which an annular cutting blade for cutting the workpiece is attached. The wafer is held on the holding surface of the chuck table, and the cutting blade is rotated to cut into the wafer, thereby cutting and dividing the wafer.

[0004] In recent years, attention has also been focused on techniques for dividing wafers by laser processing. For example, a method has been proposed in which grooves are formed in a wafer along the intended dividing lines by irradiating the wafer with a laser beam (see Patent Document 1). When an external force is applied to a wafer in which grooves have been formed along the intended dividing lines, the grooves function as dividing starting points, and the wafer is divided along the intended dividing lines.

[0005] A laser processing device is used for laser processing of a wafer. The laser processing device includes a chuck table having a holding surface for holding a workpiece, and a laser beam irradiation unit for irradiating a laser beam onto the workpiece. The wafer is held on the holding surface of the chuck table, and a laser beam is irradiated from the laser beam irradiation unit onto the wafer, whereby the wafer is subjected to a predetermined laser processing.

[0006] The chuck table mounted on the cutting device or laser processing device is made of a porous material such as porous ceramics. The surface of the porous material forms the holding surface of the chuck table, and the holding surface is connected to a suction source via holes inside the porous material. When a wafer is placed on the holding surface of the chuck table and negative pressure from the suction source is applied to the holding surface, the wafer is sucked and held by the chuck table.

[0007] However, the surface of the porous member has random irregularities. In addition, in some parts of the surface of the porous member, adjacent recesses may be connected to form large grooves. Therefore, when a porous member is used for the chuck table, it is difficult to form a uniform and flat holding surface. Furthermore, when a wafer is held by a chuck table having random irregularities on its holding surface, the wafer is held in an irregularly deformed state along the irregularities of the holding surface. If the wafer is processed in this state, various processing defects may occur due to the deformation of the wafer and the irregularities of the holding surface.

[0008] For example, when processing a wafer with a laser processing device, if the wafer is not held flat, it becomes difficult to scan the laser beam while keeping the focal point of the laser beam positioned at the intended depth inside the wafer, which results in variations in the depth position of the region inside the wafer that is laser processed.

[0009] In addition, when a wafer is processed by a cutting device, if the wafer is held by a chuck table with large grooves formed in its holding surface and the cutting blade cuts into the wafer, the area of ​​the wafer that overlaps with the groove comes into contact with the cutting blade while floating above the holding surface, which makes the wafer prone to processing defects such as chipping.

[0010] Therefore, a material other than a porous material may be used as a support member for supporting a wafer in a chuck table. For example, Patent Document 2 discloses a chuck table using a support member (holding portion) having regularly formed convex portions and concave portions and a suction path connected to the concave portions. Patent Document 3 discloses a chuck table using a support member (holding pad) having a plurality of regularly formed pores and a suction path connected to the pores.

[0011] The above-mentioned chuck table supports the wafer with a support member whose upper surface is at a uniform height position, thereby preventing the wafer from being held in an irregularly deformed state. Also, since the recesses and pores of the support member are formed with predetermined dimensions and intervals, the recesses and pores are not unintentionally connected to each other to form large grooves, and it is possible to prevent such grooves from interfering with proper holding of the wafer. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 10-305420 [Patent Document 2] JP 2006-263795 A [Patent Document 3] JP 2010-87141 A Summary of the Invention [Problem to be solved by the invention]

[0013] As described above, when a support member having recesses or pores is used for the chuck table, the surface of the support member forms the holding surface of the chuck table. When a wafer is processed by a processing device, foreign matter such as chips (processing chips) generated by processing the wafer may adhere to the holding surface of the chuck table. In addition, the holding surface of the chuck table may be unintentionally damaged by repeatedly transporting the workpiece to the chuck table.

[0014] If such an abnormality occurs on the holding surface of the chuck table, the workpiece may not be properly held on the holding surface, which may result in processing defects. Therefore, the support member of the chuck table is periodically replaced depending on the operating status of the processing device. In addition, the support member may need to be replaced if the shape or size of the wafer to be processed by the processing device is changed.

[0015] However, manufacturing the support member requires time and cost. Specifically, in order to hold the workpiece in a flat state, it is necessary to use a support member having a certain level of rigidity so that the support member does not easily deform when the workpiece is placed on the support member. Therefore, it is necessary to prepare a member having a certain thickness as the support member, and the material cost of the support member is high. In addition, if the support member is thick, the time and cost required for processing to form recesses and fine holes in the support member increases. Therefore, if the support member is replaced frequently, the burden of the work of replenishing replacement support members increases.

[0016] The present invention has been made in consideration of the above problems, and has an object to provide a chuck table in which the holding surface for holding a workpiece can be easily and inexpensively replaced, and a laser processing apparatus equipped with such a chuck table. [Means for solving the problem]

[0017] According to one aspect of the present invention, there is provided a chuck table for suction-holding a workpiece, comprising: a base table having a suction path connected to a suction source; a support member attached to the base table and supporting the workpiece; and a protective plate arranged to cover the upper surface of the support member and protect the support member, the protective plate having a plurality of through holes for transmitting suction force from the suction source to the workpiece.

[0018] Preferably, the porosity of the protective plate is 5% or more and 35% or less. Preferably, the base table has a support member suction path for suction-holding the support member, a protective plate suction path formed on the outer periphery side of the support member suction path for suction-holding the outer periphery of the protective plate, and a workpiece suction path for suction-holding the workpiece. Preferably, the protective plate is made of a transparent body. Preferably, the support member is made of a transparent body.

[0019] Also, preferably, the outer periphery of the protection plate is thicker than the central portion of the protection plate, and the density of the through holes formed on the outer periphery of the protection plate is preferably greater than the density of the through holes formed on the central portion of the protection plate.

[0020] According to another aspect of the present invention, there is provided a laser processing apparatus comprising: the above-mentioned chuck table; a laser beam application unit which irradiates a laser beam onto the workpiece held by the chuck table to process the workpiece; and a moving unit which moves the chuck table and the laser beam application unit relatively. Effect of the Invention

[0021] In a chuck table according to one aspect of the present invention, a support member for supporting a workpiece and a protective plate for covering and protecting the support member are attached to a base table. Then, the suction force of a suction source connected to the base table is transmitted to the workpiece via the support member and the protective plate. In other words, a member for transmitting the suction force acting on the base table to the workpiece is separated into the support member and the protective plate.

[0022] In the above-described chuck table, when an abnormality occurs in the holding surface of the chuck table, only the protective plate needs to be replaced, and there is no need to replace the support member. In addition, since the protective plate is supported by the support member, even if the rigidity of the protective plate itself is low, the protective plate can hold the workpiece in a flat state. This makes it possible to make the protective plate thinner, thereby reducing the material cost of the protective plate and the labor and cost required to process the protective plate. As a result, it becomes possible to easily and inexpensively replace the holding surface of the chuck table. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a perspective view showing a first laser processing device. [Diagram 2] FIG. [Diagram 3] FIG. 2 is an exploded perspective view showing a chuck table of the first laser processing apparatus. [Figure 4] FIG. 4(A) is a cross-sectional view showing a protective plate, FIG. 4(B) is an enlarged cross-sectional view showing a portion of the protective plate in which a shield tunnel is formed, and FIG. 4(C) is a perspective view showing the shield tunnel. [Diagram 5] FIG. 2 is a cross-sectional view showing a chuck table for holding a workpiece. [Figure 6] FIG. 13 is a cross-sectional view showing a chuck table including a protective plate having a recess formed therein. [Figure 7] FIG. 2 is a cross-sectional view showing a chuck table equipped with a plurality of frame holding mechanisms. [Figure 8] FIG. 4 is a perspective view showing a second laser processing device. [Figure 9] FIG. [Figure 10] FIG. 10(A) is a cross-sectional view showing the chuck table of the second laser processing device, and FIG. 10(B) is a plan view showing the chuck table of the second laser processing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment according to one aspect of the present invention will be described below with reference to the accompanying drawings. First, a configuration example of a processing device capable of mounting a chuck table according to this embodiment will be described. FIG. 1 is a perspective view showing a laser processing device (first laser processing device) 2. In FIG. 1, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0025] The laser processing apparatus 2 includes a base 4 that supports each of the components that make up the laser processing apparatus 2. The upper surface of the base 4 is formed along the horizontal direction (XY plane direction), and a moving unit (moving mechanism) 6 is provided on the upper surface of the base 4. The moving unit 6 includes a Y-axis moving unit (Y-axis moving mechanism) 8, an X-axis moving unit (X-axis moving mechanism) 18, and a Z-axis moving unit (Z-axis moving mechanism) 32.

[0026] The Y-axis movement unit 8 includes a pair of Y-axis guide rails 10 arranged along the Y-axis direction on the upper surface of the base 4. A flat Y-axis movement table 12 is attached to the pair of Y-axis guide rails 10 in a state in which it can slide along the Y-axis guide rails 10.

[0027] A nut portion (not shown) is provided on the back surface (lower surface) side of the Y-axis moving table 12, and a Y-axis ball screw 14 disposed along the Y-axis direction between a pair of Y-axis guide rails 10 is screwed into this nut portion. In addition, a Y-axis pulse motor 16 that rotates the Y-axis ball screw 14 is connected to an end portion of the Y-axis ball screw 14. When the Y-axis pulse motor 16 rotates the Y-axis ball screw 14, the Y-axis moving table 12 moves in the Y-axis direction along the pair of Y-axis guide rails 10.

[0028] The X-axis movement unit 18 includes a pair of X-axis guide rails 20 arranged along the X-axis direction on the front (upper) surface side of the Y-axis movement table 12. A plate-shaped X-axis movement table 22 is attached to the pair of X-axis guide rails 20 in a state where it can slide along the X-axis guide rails 20.

[0029] A nut portion (not shown) is provided on the back surface (lower surface) side of the X-axis moving table 22, and an X-axis ball screw 24 disposed along the X-axis direction between a pair of X-axis guide rails 20 is screwed into this nut portion. An X-axis pulse motor 26 that rotates the X-axis ball screw 24 is connected to an end of the X-axis ball screw 24. When the X-axis pulse motor 26 rotates the X-axis ball screw 24, the X-axis moving table 22 moves in the X-axis direction along the pair of X-axis guide rails 20.

[0030] A chuck table (holding table) 28 is provided on the surface (upper surface) of the X-axis moving table 22 to hold the workpiece 11 (see FIG. 2) to be processed by the laser processing device 2. The upper surface of the chuck table 28 is a flat surface formed along the horizontal direction (XY plane direction) and constitutes a holding surface 28a that holds the workpiece 11. The configuration of the chuck table 28 will be described in detail later (see FIGS. 3 to 7). In addition, a plurality of clamps 30 are provided around the periphery of the chuck table 28 to grip and fix the annular frame 19 (see FIG. 2) that supports the workpiece 11.

[0031] 2 is a perspective view showing a workpiece 11. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. The workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of planned division lines (streets) 13 that are arranged in a lattice pattern so as to intersect with each other.

[0032] Devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), MEMS (Micro Electro Mechanical Systems), etc. are formed on the front surface 11a side of the regions partitioned by the dividing lines 13. By dividing the workpiece 11 along the dividing lines 13, a plurality of device chips each including a device 15 are obtained.

[0033] There are no limitations on the type, material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer of any shape and size made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. In addition, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15, and the device 15 does not have to be formed on the workpiece 11.

[0034] A circular tape 17 having a diameter larger than that of the workpiece 11 is attached to the back surface 11b of the workpiece 11. The tape 17 is made of a sheet or the like having a circular film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-, acrylic-, or rubber-based adhesive. The adhesive layer may be made of an ultraviolet-curable resin that is cured by irradiation with ultraviolet light.

[0035] The outer periphery of the tape 17 is attached to an annular frame 19 made of metal such as SUS (stainless steel). A circular opening 19a having a diameter larger than that of the workpiece 11 is provided in the center of the frame 19. With the workpiece 11 placed inside the opening 19a of the frame 19, the center of the tape 17 is attached to the back surface 11b of the workpiece 11 and the outer periphery of the tape 17 is attached to the frame 19, whereby the workpiece 11 is supported by the frame 19 via the tape 17. When the workpiece 11 is processed, the workpiece 11 supported by the frame 19 is held by a chuck table 28 (see FIG. 1).

[0036] When the Y-axis moving table 12 is moved along the Y-axis direction, the chuck table 28 is moved along the Y-axis direction. When the X-axis moving table 22 is moved along the X-axis direction, the chuck table 28 is moved along the X-axis direction. Furthermore, a rotation drive source (not shown) such as a motor is connected to the chuck table 28, and the rotation drive source rotates the chuck table 28 around a rotation axis that is approximately parallel to the Z-axis direction.

[0037] A Z-axis moving unit 32 is provided at the rear end of the base 4 (rear of the Y-axis moving unit 8, the X-axis moving unit 18, and the chuck table 28). The Z-axis moving unit 32 has a support structure 34 arranged on the upper surface of the base 4. The support structure 34 includes a rectangular parallelepiped base 34a fixed to the base 4, and a columnar support 34b protruding upward from the end of the base 34a. The surface (side surface) of the support 34b is formed flat along the Z-axis direction.

[0038] A pair of Z-axis guide rails 36 are provided along the Z-axis direction on the surface of the support portion 34b. A flat Z-axis moving table 38 is attached to the pair of Z-axis guide rails 36 in a state where it can slide along the Z-axis guide rails 36.

[0039] A nut portion (not shown) is provided on the rear side of the Z-axis moving table 38, and a Z-axis ball screw (not shown) disposed along the Z-axis direction between a pair of Z-axis guide rails 36 is screwed into this nut portion. A Z-axis pulse motor 40 that rotates the Z-axis ball screw is connected to an end of the Z-axis ball screw. When the Z-axis pulse motor 40 rotates the Z-axis ball screw, the Z-axis moving table 38 moves in the Z-axis direction along the pair of Z-axis guide rails 36.

[0040] A support member 42 is fixed to the front surface side of the Z-axis moving table 38. The support member 42 supports some of the components of a laser beam irradiation unit 44. The laser beam irradiation unit 44 irradiates the workpiece 11 held by the chuck table 28 with a laser beam to perform laser processing on the workpiece 11. Specifically, the laser beam irradiation unit 44 includes a laser oscillator (not shown) such as a YAG laser or a YVO4 laser, and a condenser (not shown) that condenses the laser oscillated from the laser oscillator. For example, the laser oscillator is disposed on the base 4, and the condenser is supported by the support member 42.

[0041] An imaging unit 46 that images the workpiece 11 held by the chuck table 28 and the like is provided at the tip of the laser beam irradiation unit 44. For example, the imaging unit 46 is composed of a visible light camera equipped with an imaging element that receives visible light and converts it into an electric signal, an infrared camera equipped with an imaging element that receives infrared light and converts it into an electric signal, or the like, and is disposed adjacent to the tip of the laser beam irradiation unit 44 in the X-axis direction. Based on the image acquired by imaging the workpiece 11 with the imaging unit 46, the alignment of the chuck table 28 and the laser beam irradiation unit 44 and the like are performed.

[0042] When the Z-axis moving table 38 is moved along the Z-axis direction, the laser beam irradiation unit 44 and the imaging unit 46 move in the Z-axis direction. This allows adjustment of the height position of the focal point of the laser beam emitted from the laser beam irradiation unit 44, focus adjustment of the imaging unit 46, etc. The Y-axis moving unit 8, the X-axis moving unit 18, and the Z-axis moving unit 32 form a moving unit 6 that moves the chuck table 28, the laser beam irradiation unit 44, and the imaging unit 46 relatively.

[0043] Each component of the laser processing apparatus 2 (the moving unit 6, the chuck table 28, the clamp 30, the laser beam irradiation unit 44, the imaging unit 46, etc.) is connected to a control unit (control section) 48. The control unit 48 generates control signals that control the operation of the components of the laser processing apparatus 2, and controls the operation of the laser processing apparatus 2.

[0044] For example, the control unit 48 is configured by a computer, and includes a calculation section that performs various calculations necessary for the operation of the laser processing device 2, and a storage section that stores various information (data, programs, etc.). The calculation section is configured to include a processor such as a CPU (Central Processing Unit), and the storage section is configured to include various memories that constitute a main storage device, an auxiliary storage device, etc.

[0045] When the workpiece 11 (see FIG. 2) is processed by the laser processing device 2, first, the workpiece 11 is held by the chuck table 28. Specifically, the workpiece 11 is placed on the chuck table 28 so that the back surface 11b side (the tape 17 side) faces the holding surface 28a. In addition, the frame 19 is fixed by the clamp 30. In this state, when negative pressure is applied to the holding surface 28a, the workpiece 11 is sucked and held by the chuck table 28 via the tape 17.

[0046] Next, a laser beam is irradiated from the laser beam irradiation unit 44 toward the workpiece 11, and laser processing is performed on the workpiece 11. For example, the wavelength of the laser beam is set so that at least a part of the laser beam is absorbed by the workpiece 11. In addition, other irradiation conditions of the laser beam (power, spot diameter, repetition frequency, etc.) are appropriately set so that the area of ​​the workpiece 11 irradiated with the laser beam is processed by ablation processing.

[0047] When the chuck table 28 is moved along the X-axis direction with the focal point of the laser beam positioned on the surface 11a or inside the workpiece 11, the laser beam, which is absorbent for the workpiece 11, is irradiated along the intended division line 13. As a result, linear grooves (laser processed grooves) are formed in the workpiece 11 along the intended division line 13.

[0048] For example, grooves are formed from the front surface 11a to the back surface 11b of the workpiece 11 along all of the planned division lines 13, so that the workpiece 11 is divided along the planned division lines 13. Alternatively, grooves having a depth less than the thickness of the workpiece 11 are formed on the front surface 11a side of the workpiece 11 along all of the planned division lines 13, and then the back surface 11b side of the workpiece 11 is ground to expose the grooves on the back surface 11b of the workpiece 11, so that the workpiece 11 is divided along the planned division lines 13. In this way, a plurality of device chips each including a device 15 are manufactured.

[0049] As described above, when the laser beam irradiation unit 44 performs laser processing on the workpiece 11, the workpiece 11 is held by the chuck table 28. Fig. 3 is an exploded perspective view showing the chuck table 28 that holds the workpiece 11.

[0050] The chuck table 28 includes a cylindrical base table (base) 60 made of glass, ceramics, metal, resin, or the like. A cylindrical first groove (first recess) 62 is provided in the center of the upper surface 60a side of the base table 60. The first groove 62 includes a circular bottom surface 62a and an annular side surface (side wall) 62b. A cylindrical second groove (second recess) 64 having a smaller diameter than the first groove 62 is provided in the center of the bottom surface 62a side of the first groove 62. The second groove 64 includes a circular bottom surface 64a and an annular side surface (side wall) 64b.

[0051] A third groove (third recess) 66 is formed on the bottom surface 64a side of the second groove 64. For example, the third groove 66 includes a plurality of annular grooves 66a formed concentrically and a plurality of grooves 66b formed linearly along the radial direction of the base table 60. The plurality of grooves 66b are formed so as to intersect with each other from one end side to the other end side of the side surface 64b of the second groove 64, and are connected to each other at the center of the second groove 64. Moreover, the plurality of grooves 66b each intersect with the plurality of grooves 66a, and are connected to the grooves 66a at the intersection regions.

[0052] The base table 60 also has a plurality of suction paths connected to a suction source. Specifically, the base table 60 includes a plurality of suction paths (protective plate suction paths) 68 opening on the upper surface 60a of the base table 60, a plurality of suction paths (workpiece suction paths) 70 opening on the bottom surface 62a of the first groove 62, and a plurality of suction paths (support member suction paths) 72 opening on the bottom surface of the third groove 66.

[0053] The suction passage 68 is formed on the outer periphery side of the base table 60 relative to the suction passage 70. Moreover, the suction passage 70 is formed on the outer periphery side of the base table 60 relative to the suction passage 72. For example, the suction passages 68, 70, 72 are arranged at approximately equal intervals along the circumferential direction of the base table 60. Note that, although Fig. 3 shows the base table 60 having four suction passages 68, 70, 72, there is no limitation on the number and arrangement of the suction passages 68, 70, 72.

[0054] A support member 74 for supporting the workpiece 11 (see FIG. 2) is attached to the base table 60. For example, the support member 74 is formed in a disk shape with a thickness of about 7 mm. Furthermore, a groove (recess) 76 is formed on the upper surface 74a side of the support member 74. For example, the groove 76 includes a plurality of annular first grooves 76a formed concentrically and a plurality of second grooves 76b formed linearly along the radial direction of the support member 74.

[0055] The second grooves 76b are formed so as to intersect with one another from one end side to the other end side of the support member 74, and are connected to each other at the center of the support member 74. Both ends of the second grooves 76b are exposed at the side surface (outer peripheral surface) of the support member 74. The second grooves 76b each intersect with the first grooves 76a, and are connected to the first grooves 76a at the intersecting regions.

[0056] The support member 74 is formed so that its diameter is approximately equal to the diameter of the second groove 64 of the base table 60, and is fitted into the second groove 64. At this time, the bottom surface 64a of the second groove 64 functions as a support surface that supports the lower surface side of the support member 74. In addition, the thickness of the support member 74 is approximately equal to the difference in height between the upper surface 60a of the base table 60 and the bottom surface 64a of the second groove 64. Therefore, when the support member 74 is inserted into the second groove 64, the upper surface 60a of the base table 60 and the upper surface 74a of the support member 74 are arranged on approximately the same plane.

[0057] There is no limitation on the material of the support member 74. For example, the support member 74 is made of a transparent body such as glass (quartz glass, borosilicate glass, soda-lime glass, non-alkali glass, etc.), sapphire, calcium fluoride, lithium fluoride, magnesium fluoride, etc. Also, low-melting point glass having a melting point lower than that of soda-lime glass can be used as the support member 74. There is also no limitation on the shape, size, number, position, interval, etc. of the grooves 76.

[0058] A protective plate 78 for protecting the support member 74 is disposed on the support member 74 attached to the base table 60. For example, the protective plate 78 is formed in a disk shape and has an upper surface (front surface) 78a and a lower surface (back surface) 78b that are generally parallel to each other. The protective plate 78 is formed so that its diameter is larger than the diameter of the first groove 62 of the base table 60, and is disposed so as to cover the upper surface 60a of the base table 60 and the upper surface 74a of the support member 74.

[0059] 4(A) is a cross-sectional view showing the protective plate 78. The protective plate 78 has a circular central portion (central region) 78c including the center of the protective plate 78, and an annular outer peripheral portion (outer peripheral region) 78d including the outer peripheral edge of the protective plate 78 and surrounding the central portion 78c.

[0060] A plurality of through holes 80 are provided in a central portion 78c of the protective plate 78, penetrating the protective plate 78 in the thickness direction. For example, the through holes 80 are formed in a cylindrical shape exposed on an upper surface 78a and a lower surface 78b of the protective plate 78. On the other hand, no through holes 80 are formed in an outer peripheral portion 78d of the protective plate 78.

[0061] There is no limitation on the material of the protective plate 78. For example, the protective plate 78 is made of a transparent body such as glass (quartz glass, borosilicate glass, soda-lime glass, non-alkali glass, etc.), sapphire, calcium fluoride, lithium fluoride, magnesium fluoride, etc. Also, as the protective plate 78, a low-melting point glass having a melting point lower than that of soda-lime glass can be used.

[0062] In particular, it is preferable to use glass other than quartz glass (borosilicate glass, soda-lime glass, non-alkali glass, etc.) for the support member 74 and the protective plate 78. In this case, the material costs of the support member 74 and the protective plate 78 can be reduced, and processing of the support member 74 and the protective plate 78 (such as forming the grooves 76 and the through holes 80) can be easily performed.

[0063] There is also no limitation on the size, number, position, interval, etc. of the through holes 80. For example, the diameter of the through holes 80 is set to 500 μm or less, preferably 100 μm or less. More specifically, the diameter of the through holes 80 can be set to 5 μm or more and 40 μm or less, preferably 10 μm or more and 15 μm or less. There is also no limitation on the shape of the through holes 80. For example, the through holes 80 may be formed in a quadrangular prism shape. In this case, the width of the through holes 80 is set to 500 μm or less, preferably 100 μm or less. More specifically, the width of the through holes 80 can be set to 5 μm or more and 40 μm or less, preferably 10 μm or more and 15 μm or less.

[0064] There is also no limitation on the method of forming the through-holes 80. For example, filament-shaped pores called shield tunnels are formed in the protection plate 78 by irradiation with a laser beam. Fig. 4(B) is an enlarged cross-sectional view showing a part of the protection plate 78 in which the shield tunnels 82 are formed, and Fig. 4(C) is a perspective view showing the shield tunnels 82.

[0065] When the protective plate 78 is scanned with the laser beam while irradiating it with the laser beam with the focal point of the laser beam positioned inside the protective plate 78, a plurality of shield tunnels 82 are formed at predetermined intervals along the scanning direction of the laser beam. The shield tunnels 82 include pores 82a formed along the thickness direction of the protective plate 78 and amorphous regions 82b surrounding the pores 82a.

[0066] Each of the shield tunnels 82 is formed across the entire thickness direction of the protective plate 78. As a result, a plurality of pores 82a are formed that are exposed at the upper surface 78a and the lower surface 78b of the protective plate 78. In addition, the amorphous regions 82b of adjacent shield tunnels 82 are bonded to each other.

[0067] The irradiation conditions of the laser beam are appropriately set so that the shield tunnel 82 is appropriately formed in the protection plate 78. For example, when the protection plate 78 is made of glass (borosilicate glass), the irradiation conditions of the laser beam can be set as follows. Light source: YAG pulse laser Wavelength: 1064nm Energy: 40μJ Repetition frequency: 10kHz Machining feed speed: 100mm / s

[0068] The shield tunnels 82 are formed at predetermined intervals over the entire area of ​​the central portion 78c of the protection plate 78. The small holes 82a of the shield tunnels 82 are used as the through holes 80 (see FIG. 4(A)) of the protection plate 78. However, there is no limitation on the method of forming the through holes 80.

[0069] For example, the through holes 80 of a desired size can be formed at a desired interval by etching the protective plate 78. In this case, a member made of glass ceramics (crystallized glass) may be used as the protective plate 78, and the through holes 80 may be formed by processing the protective plate 78 by selective etching. Furthermore, before etching the protective plate 78, a region (central portion 78c) where the through holes 80 are to be formed may be subjected to a process such as ion doping, so that etching may proceed more easily partially in that region.

[0070] Alternatively, the material of the protective plate 78 may be poured into a predetermined mold and fired to manufacture the protective plate 78. In this case, a plurality of columnar members (protrusions) corresponding to the through holes 80 are provided inside the mold. When the material of the protective plate 78 is fired using this mold, the protective plate 78 having the plurality of through holes 80 is manufactured.

[0071] As described above, the protective plate 78 can be easily manufactured by simply forming a plurality of through holes 80 in a plate-like member. Therefore, the structure and manufacturing process of the protective plate 78 are extremely simple, and the effort and cost required to manufacture the protective plate 78 are small.

[0072] It is preferable that the protective plate 78 is formed thinner than the support member 74. For example, the thickness of the protective plate 78 is set to be 0.2 mm or more and 0.3 mm or less. If the protective plate 78 is thin, the material cost of the protective plate 78 is reduced, and the through-hole 80 penetrating the protective plate 78 is easily formed.

[0073] 3, the protective plate 78 is disposed on the base table 60 and the support member 74 such that the central portion 78c covers the upper surface 74a of the support member 74 and the outer peripheral portion 78d covers the upper surface 60a of the base table 60. As a result, the protective plate 78 is supported by the support member 74, and the multiple suction paths 68 provided in the base table 60 are covered by the protective plate 78. Note that there is no limit to the diameter of the protective plate 78 as long as the multiple suction paths 68 can be covered by the protective plate 78. Therefore, the dimensions of the protective plate 78 have a high degree of freedom.

[0074] Then, the workpiece 11 (see FIG. 2) is placed on the protective plate 78. That is, the workpiece 11 is supported by the support member 74 via the protective plate 78. Then, an upper surface 78a of the protective plate 78 corresponds to the holding surface 28a of the chuck table 28 (see FIG. 1).

[0075] 5 is a cross-sectional view showing the chuck table 28 holding the workpiece 11. The suction paths 68, 70, and 72 provided in the base table 60 are each connected to a suction source. Specifically, the suction path 68 is a suction path for suction-holding the outer peripheral portion 78d of the protective plate 78, and is connected to the suction source 86a via a valve 84a. The suction path 70 is a suction path for suction-holding the workpiece 11, and is connected to the suction source 86b via a valve 84b. The suction path 72 is a suction path for suction-holding the support member 74, and is connected to the suction source 86c via a valve 84c.

[0076] The valves 84a, 84b, and 84c are, for example, electromagnetic valves, and the opening and closing of the valves 84a, 84b, and 84c are controlled by the control unit 48 (see FIG. 1). Also, the suction sources 86a, 86b, and 86c are, for example, ejectors, and the operations of the suction sources 86a, 86b, and 86c are controlled by the control unit 48.

[0077] When the valve 84c is opened with the support member 74 fitted in the second groove 64 of the base table 60, the suction force (negative pressure) of the suction source 86c acts on the inside (third groove 66) of the base table 60. As a result, the support member 74 is sucked and held inside the base table 60 and fixed to the base table 60.

[0078] Furthermore, when the valve 84a is opened with the protective plate 78 placed on the base table 60 and the support member 74, the suction force (negative pressure) of the suction source 86a acts on the outer periphery 78d of the protective plate 78 where no through-hole 80 is formed. As a result, the protective plate 78 is held by suction on the base table 60 and the support member 74, and is fixed to the base table 60.

[0079] The workpiece 11 is placed on a protection plate 78 fixed to the base table 60 via a tape 17. A frame 19 supporting the workpiece 11 is held by a plurality of clamps 30.

[0080] When the valve 84b is opened in this state, the first groove 62 of the base table 60 covered by the support member 74 and the protective plate 78 is depressurized by the suction force (negative pressure) of the suction source 86b. The inside of the groove 76 of the support member 74 connected to the first groove 62 is also depressurized in the same manner. As a result, the suction force acts on the upper surface 78a of the protective plate 78 through the through hole 80 arranged in the area overlapping with the first groove 62 or the groove 76. That is, the through hole 80 functions as a flow path that transmits the suction force from the suction source 86b to the workpiece 11. As a result, the workpiece 11 is suction-held by the chuck table 28 via the tape 17.

[0081] The ratio of the volume of the multiple through holes 80 to the total volume of the protective plate 78 (porosity of the protective plate 78) is set so that a sufficient suction force acts on the workpiece 11 and the mechanical strength of the protective plate 78 is maintained at a certain level or higher. For example, the porosity of the protective plate 78 is set to 5% or more and 35% or less.

[0082] 1 irradiates a laser beam toward the workpiece 11, and laser processing is performed on the workpiece 11. Then, when processing of the workpiece 11 is completed, the valve 84b closes to release the suction of the workpiece 11, and the workpiece 11 is transported from the chuck table 28.

[0083] When the workpiece 11 is held by the chuck table 28, depending on the material of the tape 17, the tape 17 may adhere strongly to the upper surface 78a of the protective plate 78. When the workpiece 11 is subjected to laser processing, the laser beam may also be irradiated to a part of the tape 17 located outside the outer periphery of the workpiece 11, causing the tape 17 to melt and adhere to the upper surface 78a of the protective plate 78. In such a case, the workpiece 11 may be difficult to separate from the protective plate 78, and it may become difficult to properly transport the workpiece 11 from the chuck table 28.

[0084] Therefore, it is preferable that the density of the through holes 80 formed on the outer periphery of the protective plate 78 is greater than the density of the through holes 80 formed on the center of the protective plate 78. This makes it possible to reduce the contact area between the tape 17 and the protective plate 78 in the vicinity of the outer periphery of the workpiece 11. As a result, the tape 17 becomes more likely to separate from the protective plate 78 when the workpiece 11 is transported from on the chuck table 28, and the workpiece 11 is transported appropriately.

[0085] Specifically, the multiple through holes 80 are formed such that the diameter of the through holes 80 in a region (second region) outside the first region is larger than the diameter of the through holes 80 in the region (first region) located within a certain distance from the center of the protective plate 78. In this case, for example, the diameter of the through holes 80 formed in the first region can be set to less than 100 μm, and the diameter of the through holes 80 formed in the second region can be set to 100 μm or more and 500 μm or less.

[0086] When the workpiece 11 is processed by the laser beam irradiation unit 44, foreign matter such as chips (processing chips) generated by processing the workpiece 11 adheres to the workpiece 11. For example, during processing of the workpiece 11, the laser beam may be irradiated not only to the workpiece 11 but also to the tape 17, melting the tape 17 and causing the molten matter to adhere to the holding surface 28a. In addition, the laser beam may be irradiated to the holding surface 28a via the workpiece 11 or the tape 17, causing the holding surface 28a to be unintentionally processed. Furthermore, the holding surface 28a may be unintentionally damaged by repeatedly transporting the workpiece 11 to the chuck table 28. When such an inconvenience occurs to the holding surface 28a of the chuck table 28, it is necessary to replace the members constituting the holding surface 28a.

[0087] Here, in the chuck table 28 according to the present embodiment, the member for transmitting the suction force acting on the base table 60 to the workpiece 11 is separated into the support member 74 and the protective plate 78. Therefore, when an abnormality occurs in the holding surface 28a of the chuck table 28, only the protective plate 78 needs to be replaced, and there is no need to replace the support member 74. In addition, since the protective plate 78 is supported by the support member 74, even if the rigidity of the protective plate 78 itself is low, the protective plate 78 can hold the workpiece 11 in a flat state. Therefore, the protective plate 78 can be made thin, and the material cost of the protective plate 78 and the labor and cost required for processing the protective plate 78 can be reduced. As a result, the holding surface 28a of the chuck table 28 can be easily and inexpensively replaced.

[0088] The protective plate 78 can be easily replaced by controlling the opening and closing of the valve 84a. Specifically, first, the valve 84a is closed while the valve 84c is left open. This releases the suction of the used protective plate 78 while maintaining the suction hold of the support member 74. Then, the used protective plate 78 is removed from the base table 60, and a replacement protective plate 78 (an unused protective plate 78) is placed on the base table 60, after which the valve 84a is opened again. As a result, the replacement protective plate 78 is held by suction and fixed to the base table 60.

[0089] Although the above describes an example in which protective plate 78 is flat, there is no limitation on the shape of protective plate 78. For example, protective plate 78 may be formed so that it has a recess in central portion 78c and outer circumferential portion 78d is thicker than central portion 78c.

[0090] Fig. 6 is a cross-sectional view showing the chuck table 28 including a protective plate 78 in which a recess 78e is formed. A cylindrical recess 78e is provided on the lower surface 78b side of a central portion 78c of the protective plate 78 shown in Fig. 6. The diameter of the recess 78e is equal to or greater than the diameter of the support member 74. The support member 74 shown in Fig. 6 is formed such that an upper surface 74a protrudes from an upper surface 60a of the base table 60.

[0091] The protective plate 78 is placed on the support member 74 so that the upper surface 74a side of the support member 74 is fitted into the recess 78e. The height difference between the upper surface 60a of the base table 60 and the upper surface 74a of the support member 74 (the protruding amount of the support member 74) is set to be approximately the same as the depth of the recess 78e. Therefore, when the protective plate 78 is placed on the support member 74, the central portion 78c of the protective plate 78 (the bottom surface of the recess 78e) is supported by the support member 74, and the outer periphery 78d of the protective plate 78 is supported by the upper surface 60a of the base table 60.

[0092] When the recess 78e is formed in the central portion 78c of the protective plate 78, the central portion 78c is thinned, and it becomes easier to form a plurality of through holes 80 in the central portion 78c. On the other hand, since the recess 78e is not formed in the outer peripheral portion 78d of the protective plate 78, the outer peripheral portion 78d is maintained in a thick state. Therefore, the rigidity of the protective plate 78 is maintained by the thick outer peripheral portion 78d, and the protective plate 78 becomes less likely to deform. In other words, the outer peripheral portion 78d functions as a reinforcing portion that reinforces the protective plate 78. This makes it possible to prevent the protective plate 78 from being deformed and damaged when the protective plate 78 is handled.

[0093] Furthermore, the details of the configuration of the chuck table 28 can be changed as appropriate. For example, the chuck table 28 may be provided with a mechanism for suction-holding the frame 19 supporting the workpiece 11. In this case, the multiple clamps 30 (see FIGS. 1 and 5) can be omitted.

[0094] 7 is a cross-sectional view showing the chuck table 28 equipped with a plurality of frame holding mechanisms (frame holding portions) 90. A plurality of frame holding mechanisms 90 for holding the frame 19 are fixed to the side surface (outer peripheral surface) of the base table 60. For example, four frame holding mechanisms 90 are arranged at approximately equal intervals along the circumferential direction of the base table 60.

[0095] The frame holding mechanism 90 includes a base 92 fixed to the base table 60, and a suction pad 94 provided on the base 92. The suction pad 94 is made of, for example, rubber, resin, or the like. The upper surface of the suction pad 94 is formed along the horizontal direction and constitutes a holding surface 94a that holds the frame 19 by suction. The holding surface 94a is connected to a suction source 98 such as an ejector via a flow path (not shown) formed inside the suction pad 94 and a valve 96 such as an electromagnetic valve.

[0096] When the workpiece 11 is placed on the chuck table 28, the frame 19 is placed on the holding surfaces 94a of the multiple suction pads 94. When the valve 96 is opened in this state, the suction force (negative pressure) of the suction source 98 acts on the holding surfaces 94a, and the frame 19 is sucked and held by the multiple suction pads 94.

[0097] The suction path 68 and the suction path 72 may be connected to a common suction source (either suction source 86a or suction source 86c) via a common valve (either valve 84a or 84c). In this case, the support member 74 and the protective plate 78 are suction-held in conjunction with each other at the same time. The suction path 70 and the suction pad 94 may be connected to a common suction source (either suction source 86b or suction source 98) via a common valve (either valve 84b or 96). In this case, the workpiece 11 and the tape 17 are suction-held in conjunction with the frame 19 at the same time.

[0098] Furthermore, the processing device on which the chuck table according to this embodiment is mounted is not limited to the above-mentioned laser processing device 2 (see FIG. 1). FIG. 8 is a perspective view showing a laser processing device (second laser processing device) 100 having a structure different from that of the laser processing device 2. In FIG. 8, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0099] The laser processing apparatus 100 includes a base 102 that supports each of the components that make up the laser processing apparatus 100. The upper surface of the base 102 is formed along the horizontal direction (XY plane direction), and a rectangular parallelepiped support structure 104 is disposed along the Z-axis direction at the rear end of the base 102. In addition, a moving unit (moving mechanism) 106 is provided on the upper surface of the base 102. The moving unit 106 includes a Y-axis moving unit (Y-axis moving mechanism) 108 and an X-axis moving unit (X-axis moving mechanism) 118.

[0100] The Y-axis moving unit 108 and the X-axis moving unit 118 are configured similarly to the Y-axis moving unit 8 and the X-axis moving unit 18 of the laser processing apparatus 2 (see FIG. 1), respectively. Specifically, the Y-axis moving unit 108 includes a pair of Y-axis guide rails 110, a Y-axis moving table 112, a Y-axis ball screw 114, and a Y-axis pulse motor 116. In addition, the X-axis moving unit 118 includes a pair of X-axis guide rails 120, an X-axis moving table 122, an X-axis ball screw 124, and an X-axis pulse motor 126.

[0101] A chuck table (holding table) 128 for holding a workpiece 11 (see FIG. 2) to be processed by the laser processing device 100 is provided on the surface (upper surface) of the X-axis moving table 122. The upper surface of the chuck table 128 constitutes a holding surface 128a for holding the workpiece 11. The structure of the chuck table 128 will be described in detail later (see FIGS. 10(A) and 10(B)).

[0102] Additionally, a plurality of clamps 130 are provided around the chuck table 128 to grip and fix an annular frame 19 (see FIG. 2) that supports the workpiece 11. Note that instead of the clamps 130, a frame holding mechanism (see frame holding mechanism 90 in FIG. 7) that holds the frame 19 by suction may be used.

[0103] When the Y-axis moving table 112 is moved along the Y-axis direction, the chuck table 128 moves along the Y-axis direction. Also, when the X-axis moving table 122 is moved along the X-axis direction, the chuck table 128 moves along the X-axis direction.

[0104] A rotation unit (rotation mechanism) 132 is provided below the chuck table 128. The rotation unit 132 is provided on the X-axis moving table 122 of the moving unit 106, and the lower end side of the chuck table 128 is connected to the rotation unit 132. The rotation unit 132 includes a rotation drive source such as a motor, and rotates the chuck table 128 around a rotation axis that is approximately parallel to the Z-axis direction. This controls the angle (orientation) of the chuck table 128 in the horizontal direction.

[0105] The laser processing apparatus 100 also includes a columnar support arm 134 that protrudes forward from the front side of the support structure 104. A laser beam irradiation unit 136 that irradiates a laser beam onto the workpiece 11 held by the chuck table 128 is fixed to the tip of the support arm 134. The laser beam irradiation unit 136 can be configured in the same manner as the laser beam irradiation unit 44 of the laser processing apparatus 2 (see FIG. 1).

[0106] An imaging unit 138 that captures an image of the workpiece 11 held by the chuck table 128 from above is fixed to a position adjacent to the laser beam irradiation unit 136 at the tip of the support arm 134. The imaging unit 138 is composed of, for example, a visible light camera or an infrared camera.

[0107] A moving unit (moving mechanism, not shown) that moves the support arm 134 along the Z-axis direction may be connected to the support arm 134. In this case, the height positions of the laser beam irradiation unit 136 and the imaging unit 138 are controlled by the moving unit.

[0108] A moving unit (moving mechanism) 140 is provided below the support arm 134 and is fixed to the front side of the support structure 104. Fig. 9 is a perspective view showing the moving unit 140. The moving unit 140 has a pair of Z-axis guide rails 142 arranged along the Z-axis direction. A flat Z-axis moving plate 144 is attached to the pair of Z-axis guide rails 142 in a state where it can slide along the Z-axis guide rails 142.

[0109] A nut portion (not shown) is provided on the back side of Z-axis moving plate 144, and a Z-axis ball screw 146 arranged along the Z-axis direction between a pair of Z-axis guide rails 142 is screwed into this nut portion. In addition, a Z-axis pulse motor 148 that rotates Z-axis ball screw 146 is connected to an end of Z-axis ball screw 146. When Z-axis pulse motor 148 rotates Z-axis ball screw 146, Z-axis moving plate 144 moves in the Z-axis direction along the pair of Z-axis guide rails 142.

[0110] A columnar support arm 150 protruding forward from the Z-axis moving plate 144 is fixed to the front side of the Z-axis moving plate 144. In addition, an imaging unit 152 is provided on the upper surface side of the tip (front end) of the support arm 150 to image the workpiece 11 held by the chuck table 128 from below.

[0111] For example, the imaging unit 152 includes a pair of cameras 152a and 152b having different magnifications. The imaging unit 152 may capture images using one of the pair of cameras 152a and 152b, or may capture images using both of the cameras. For example, a visible light camera or an infrared camera is used as the cameras 152a and 152b.

[0112] The moving unit 140 moves the imaging unit 152 along the Z-axis direction, thereby controlling the height position of the imaging unit 152, and adjusting the focus and imaging range of the cameras 152a and 152b.

[0113] Each component of the laser processing apparatus 100 (moving unit 106, chuck table 128, clamp 130, rotating unit 132, laser beam irradiation unit 136, imaging unit 138, moving unit 140, imaging unit 152, etc.) is connected to a control unit (control section) 154. The control unit 154 generates control signals for controlling the operation of the components of the laser processing apparatus 100, and controls the operation of the laser processing apparatus 100. For example, the control unit 154 is configured by a computer, similar to the control unit 48 of the laser processing apparatus 2 (see FIG. 1).

[0114] The laser processing apparatus 100 can capture an image of the workpiece 11 held on the chuck table 128 by an imaging unit 138 provided above the chuck table 128 and an imaging unit 152 provided below the chuck table 128. An image of the upper surface side of the workpiece 11 is obtained by the imaging unit 138, and an image of the lower surface side of the workpiece 11 is obtained by the imaging unit 152.

[0115] Fig. 10(A) is a cross-sectional view showing chuck table 128, and Fig. 10(B) is a plan view showing chuck table 128. Note that the configuration of chuck table 128 is similar to that of chuck table 28 (see Figs. 3 to 7) except for the points described below.

[0116] The chuck table 128 holds the workpiece 11 via the tape 17. In Fig. 10(A), the tape 17 is attached to the surface 11a side (the device 15 side, see Fig. 2) of the workpiece 11, and the workpiece 11 is arranged so that the surface 11a side faces the chuck table 128.

[0117] The chuck table 128, like the chuck table 28 (see FIGS. 3 and 5), includes a support member 74 and a protective plate 78. However, the support member 74 and the protective plate 78 are made of transparent bodies. The chuck table 128 also includes a base table 60A that is partially different in configuration from the base table 60 (see FIGS. 3 and 5).

[0118] Similar to the base table 60, the base table 60A has an upper surface 60a, a first groove 62, a second groove 64, and suction paths 68, 70, and 72. However, the base table 60A does not have a third groove 66 (see FIGS. 3 and 5), and the support member 74 is supported by the bottom surface of the second groove 64. The suction path 72 is formed so as to open at the bottom surface of the second groove 64. The support member 74 is fixed to the base table 60A by the suction force of a suction source 86c acting on the lower surface side of the support member 74 via a valve 84c and the suction path 72.

[0119] A table support member 160 that supports the base table 60A is connected to the lower surface of the base table 60A. The table support member 160 is disposed so as to overlap only a portion of the base table 60A, and supports a portion of the base table 60A. For example, the upper surface of the table support member 160 is formed in a sector shape, and supports a sector-shaped area extending from the center to the outer periphery of the base table 60A. The lower end side of the table support member 160 is connected to the rotation unit 132 (see FIG. 8).

[0120] An area (space) 162 is provided below the base table 60A, which overlaps with the base table 60A but does not overlap with the table support member 160. An opening 164 is formed in the area of ​​the base table 60A that overlaps with the area 162, penetrating from the bottom surface of the second groove 64 to the lower surface of the base table 60A. Inside the opening 164, the lower surface side of the support member 74 is exposed downward.

[0121] The imaging unit 152 is positioned directly below the opening 164 of the base table 60A by controlling the position of the chuck table 128 with the moving unit 106 (see FIG. 8). Then, the imaging unit 152 captures an image of the front surface 11a side of the workpiece 11 through the opening 164 of the base table 60A, and the support member 74 and protective plate 78 made of a transparent body.

[0122] The materials of the support member 74 and the protective plate 78 are appropriately selected depending on the type of the imaging unit 152. For example, when the imaging unit 152 is configured as a visible light camera, the support member 74 and the protective plate 78 are made of a material that transmits visible light. Also, when the imaging unit 152 is configured as an infrared camera, the support member 74 and the protective plate 78 are made of a material that transmits infrared light.

[0123] By using the above-mentioned chuck table 128, it is possible to image a pattern such as the device 15 (see FIG. 2) formed on the surface 11a of the workpiece 11 even when the surface 11a of the workpiece 11 is held by the chuck table 128. This makes it possible to align the workpiece 11 with the laser beam irradiation unit 136, etc., using the pattern on the surface 11a of the workpiece 11 as a reference.

[0124] It is preferable that no groove 76 is provided in the region of the support member 74 that overlaps with the opening 164 of the base table 60A (see FIG. 10(A)). It is also preferable that no through-hole 80 is provided in a plurality of regions 78f (see FIGS. 10(A) and 10(B)) of the protective plate 78 that overlap with the opening 164 of the base table 60A. This makes it possible to avoid the groove 76 and the through-hole 80 from interfering with the imaging of the workpiece 11 by the imaging unit 152, and to obtain a clear image of the workpiece 11.

[0125] However, when the through-holes 80 are regularly provided in the region of the protective plate 78 overlapping with the opening 164 of the base table 60A, an image in which the through-holes 80 are not displayed or the through-holes 80 are not noticeable can be generated by performing image processing on the image acquired by the imaging unit 152. Even if the through-holes 80 are present in the region of the protective plate 78 overlapping with the opening 164 of the base table 60A, when the size of the through-holes 80 is smaller than the pixel size of the imaging unit 152, the through-holes 80 are unlikely to be captured in the image acquired by the imaging unit 152, so that the pattern on the front surface 11a side of the workpiece 11 may be observable.

[0126] In addition, although the above describes the chuck table 28, 128 mounted on the laser processing device 2, 100, the chuck table according to the present embodiment can also be mounted on processing devices other than the laser processing device. Examples of other processing devices include a cutting device equipped with a cutting unit that cuts the workpiece 11 with an annular cutting blade.

[0127] For example, the workpiece 11 is divided along the intended division lines 13 (see FIG. 2) by a cutting device equipped with the chuck table according to this embodiment. This produces a plurality of device chips, each of which includes a device 15 (see FIG. 2).

[0128] When the workpiece 11 is divided by a processing device, the multiple through holes 80 (see FIG. 4(A)) formed in the protective plate 78 are preferably arranged so that at least one through hole 80 overlaps with each device 15 (see FIG. 2). This allows each device chip to be sucked by the through hole 80 even after the workpiece 11 is divided into multiple device chips, and the arrangement of the device chips can be maintained.

[0129] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0130] 11 Workpiece 11a surface 11b Back side 13. Planned division line (street) 15 Devices 17 Tape 19 Frame 19a aperture 2 Laser processing equipment (first laser processing equipment) 4 Foundation 6 Mobile unit (mobile mechanism) 8 Y-axis movement unit (Y-axis movement mechanism) 10 Y-axis guide rail 12 Y-axis moving table 14 Y-axis ball screw 16 Y-axis pulse motor 18 X-axis movement unit (X-axis movement mechanism) 20 X-axis guide rail 22 X-axis moving table 24 X-axis ball screw 26 X-axis pulse motor 28 Chuck table (holding table) 28a Holding surface 30 Clamp 32 Z-axis movement unit (Z-axis movement mechanism) 34 Support structure 34a base 34b Support part 36 Z-axis guide rail 38 Z-axis moving table 40 Z-axis pulse motor 42 Support member 44 Laser beam irradiation unit 46 Imaging unit 48 Control unit (control section) 60,60A Base table (base) 60a top 62 First groove (first recess) 62a Bottom 62b Side (side wall) 64 Second groove (second recess) 64a Bottom 64b Side (side wall) 66 Third groove (third recess) 66a,66b Groove 68 Suction passage (protective plate suction passage) 70 Suction passage (support member suction passage) 72 Suction path (workpiece suction path) 74 Support member 74a Top 76 Groove (recess) 76a 1st groove 76b 2nd groove 78 Protective Plate 78a Top surface (front surface) 78b Bottom surface (back surface) 78c central part (central area) 78d Outer area (outer area) 78e Recess 78f area 80 Through Hole 82 Shield Tunnel 82a Pore 82b Amorphous region 84a, 84b, 84c Valves 86a,86b,86c Suction source 90 Frame holding mechanism (frame holding part) 92 Foundation 94 Suction Pad 94a Holding surface 96 Valve 98 Suction source 100 Laser processing equipment (second laser processing equipment) 102 Foundation 104 Support structure 106 Mobile unit (mobile mechanism) 108 Y-axis movement unit (Y-axis movement mechanism) 110 Y-axis guide rail 112 Y-axis moving table 114 Y-axis ball screw 116 Y-axis pulse motor 118 X-axis movement unit (X-axis movement mechanism) 120 X-axis guide rail 122 X-axis moving table 124 X-axis ball screw 126 X-axis pulse motor 128 Chuck table (holding table) 128a Retaining surface 130 Clamp 132 Rotating unit (rotating mechanism) 134 Support Arm 136 Laser beam irradiation unit 138 Imaging unit 140 Mobile unit (mobile mechanism) 142 Z-axis guide rail 144 Z-axis moving plate 146 Z-axis ball screw 148 Z-axis pulse motor 150 Support Arm 152 Imaging unit 152a, 152b Camera 154 Control unit (control section) 160 Table support member 162 Area (Space) 164 Aperture

Claims

1. A chuck table that suction-holds a workpiece, a base table having a suction passage connected to a suction source; A support member attached to the base table and supporting a workpiece; a protective plate that is disposed so as to cover an upper surface of the support member and protects the support member; The protective plate has a plurality of through holes for transmitting the suction force from the suction source to the workpiece.

2. 2. The chuck table according to claim 1, wherein the protection plate has a porosity of 5% to 35%.

3. The base table is a support member suction path for suction-holding the support member; a protective plate suction path formed on the outer circumferential side of the support member suction path for suction-holding an outer circumferential portion of the protective plate; 3. The chuck table according to claim 1, further comprising a workpiece suction passage for suction-holding the workpiece.

4. 4. The chuck table according to claim 1, wherein the protection plate is made of a transparent material.

5. 5. The chuck table according to claim 1, wherein the support member is made of a transparent material.

6. 6. The chuck table according to claim 1, wherein the outer periphery of the protection plate is thicker than the center of the protection plate.

7. 7. The chuck table according to claim 1, wherein the density of the through holes formed on the outer periphery of the protection plate is greater than the density of the through holes formed on the central side of the protection plate.

8. A chuck table according to any one of claims 1 to 7, a laser beam irradiation unit that irradiates a laser beam onto the workpiece held by the chuck table to process the workpiece; a moving unit for relatively moving the chuck table and the laser beam irradiation unit.

Images