Chuck Table

Abstract

To provide a chuck table where heat generation is suppressed.SOLUTION: A chuck table which holds a workpiece contains: a support base; a holding member including a holding surface holding the workpiece, and a bottom surface supported by the support base; a luminous body provided on a bottom side of the holding member; and a heat radiation space corresponding to a space between the holding member and the luminous body. The holding member is transmissive to light emitted by the luminous body, and the support base includes a connecting hole that communicates from the side of the support base to the heat radiation space.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a chuck table for holding a workpiece. [Background technology]

[0002] In the device chip manufacturing process, a wafer is used in which devices are formed in multiple areas partitioned by multiple streets (planned division lines) arranged in a grid pattern. By dividing this wafer along the streets, 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 wafers. The cutting device is equipped with a chuck table that holds the workpiece and a processing unit (cutting unit) that performs cutting processing on the workpiece, and an annular cutting blade is attached to the cutting unit. The workpiece is held by the chuck table, and the cutting blade is rotated while cutting into the workpiece, cutting and dividing the workpiece.

[0004] In recent years, development has also been underway for a process of dividing a wafer by laser processing using a laser processing device (see Patent Document 1). The laser processing device includes a chuck table that holds the workpiece, and a processing unit (laser irradiation unit) that irradiates the workpiece with a laser beam. The workpiece is held on the chuck table, and the laser irradiation unit irradiates the workpiece with a laser beam, thereby performing laser processing on the workpiece.

[0005] For example, ablation processing is performed on a wafer by irradiating a laser beam, and grooves (laser processing grooves) extending from the front surface to the back surface of the wafer are formed along streets, whereby the wafer is divided along the streets. However, due to various factors such as variations in the thickness of the wafer and various thin films formed on the surface of the wafer, a part of the groove may not reach the back surface of the wafer, and an area where the wafer is not properly divided may remain within the wafer. And if the wafer is carried out of the laser processing apparatus in an incompletely divided state and the subsequent process proceeds, it becomes difficult to reprocess the wafer and completely divide the wafer afterwards, and there is a risk that the yield of device chips decreases.

[0006] Therefore, after the formation of the grooves, a step of checking whether the grooves are properly formed in the wafer may be carried out. For example, a light emitter such as an LED (Light Emitting Diode) is provided inside the chuck table, and while irradiating the back surface side of the wafer with the light emitted from the light emitter, the front surface side of the wafer is imaged with a camera. Then, based on whether the light emitted from the light emitter is received by the camera through the grooves formed in the wafer, it is confirmed whether the grooves have reached the back surface of the wafer (see Patent Document 2).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] As described above, when the light emitter provided inside the chuck table is turned on to illuminate the workpiece to be imaged, the light emitter generates heat, and the heat of the light emitter is conducted to the chuck table and the base (table base) that supports the chuck table, which may result in the chuck table and table base generating heat and adversely affecting the processing of the workpiece.

[0009] For example, when laser processing is performed on a workpiece, the workpiece is held on the holding surface of a chuck table, and the positional relationship between the workpiece and the focal point of the laser beam is set precisely. However, when heat from the light emitter is conducted to the chuck table or table base, the chuck table or table base heats up and expands slightly, causing a change in the position and shape of the holding surface of the chuck table. As a result, it becomes difficult to adjust the position of the focal point of the laser beam with respect to the workpiece with high precision, and there is a risk of a decrease in processing accuracy.

[0010] The present invention has been made in consideration of the above problems, and has an object to provide a chuck table in which heat generation is suppressed. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a chuck table for holding a workpiece, the chuck table comprising: a support base; a holding member including a holding surface for holding the workpiece and a bottom surface supported by the support base; a light emitter provided on the bottom surface side of the holding member; and a heat dissipation space corresponding to a space between the holding member and the light emitter, the holding member being transparent to light emitted by the light emitter, and the support base being: a pair of communication holes that are arranged on a first line passing through the heat dissipation space so as to sandwich the heat dissipation space therebetween and communicate from a side surface of the support base to the heat dissipation space; and a pair of communication holes that are arranged on a second line passing through the heat dissipation space and perpendicular to the first line so as to sandwich the heat dissipation space therebetween and communicate from a side surface of the support base to the heat dissipation space; A chuck table including: Effect of the Invention

[0013] A chuck table according to one aspect of the present invention includes a heat dissipation space corresponding to the space between the holding member and the light emitter, and the heat dissipation space is connected to the outside of the chuck table via a communication hole provided in the support base, thereby forming a heat dissipation path that dissipates heat generated by the light emitter to the outside of the chuck table, thereby suppressing heat generation from the chuck table. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing a laser processing device. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a perspective view showing a chuck table. [Figure 4] FIG. 4(A) is a cross-sectional view showing the chuck table, and FIG. 4(B) is a plan view showing the chuck table. [Diagram 5] FIG. 2 is a cross-sectional view showing a chuck table for holding a workpiece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. First, an example of a processing device on which a chuck table according to this embodiment can be mounted will be described. Fig. 1 is a perspective view showing a laser processing device 2.

[0016] The laser processing device 2 is a processing device that performs laser processing on a workpiece by irradiating the workpiece with a laser beam. 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. The Z-axis direction (height direction, vertical direction, up-down direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0017] 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 a flat surface that is roughly parallel to the horizontal direction (XY plane direction), and a moving mechanism (moving unit) 6 is provided on the upper surface of the base 4. The moving mechanism 6 includes a Y-axis moving mechanism (Y-axis moving unit) 8, an X-axis moving mechanism (X-axis moving unit) 18, and a Z-axis moving mechanism (Z-axis moving unit) 30.

[0018] The Y-axis movement mechanism 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 mounted on the pair of Y-axis guide rails 10 so as to be slidable along the Y-axis guide rails 10.

[0019] A nut portion (not shown) is provided on the back surface (lower surface) side of the Y-axis moving table 12. A Y-axis ball screw 14 arranged 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 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 Y-axis guide rails 10.

[0020] The X-axis movement mechanism 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 flat X-axis movement table 22 is mounted on the pair of X-axis guide rails 20 so as to be slidable along the X-axis guide rails 20.

[0021] A nut portion (not shown) is provided on the back surface (lower surface) side of the X-axis moving table 22. An X-axis ball screw 24 arranged 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 X-axis guide rails 20.

[0022] 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) that is the object to be processed by the laser processing device 2. The upper surface of the chuck table 28 is a flat surface that is approximately parallel to the horizontal direction (XY plane direction) and constitutes a holding surface 28a that holds the workpiece 11.

[0023] When the Y-axis moving table 12 is moved along the Y-axis direction, the chuck table 28 moves along the indexing feed direction. When the X-axis moving table 22 is moved along the X-axis direction, the chuck table 28 moves along the processing feed direction. Furthermore, the chuck table 28 is connected to a rotation drive source (not shown) such as a motor that rotates the chuck table 28 around a rotation axis roughly parallel to the Z-axis direction.

[0024] A Z-axis moving mechanism 30 is provided at the rear end of the base 4 (rear of the Y-axis moving mechanism 8, the X-axis moving mechanism 18, and the chuck table 28). The Z-axis moving mechanism 30 includes a support structure 32 arranged on the upper surface of the base 4. The support structure 32 includes a rectangular parallelepiped base 32a fixed to the base 4, and a columnar support 32b protruding upward from the end of the base 32a. The surface (side surface) of the support 32b is formed flat along the Z-axis direction.

[0025] A pair of Z-axis guide rails 34 are provided along the Z-axis direction on the surface of the support portion 32b. A flat Z-axis moving plate 36 is attached to the pair of Z-axis guide rails 34 so as to be slidable along the Z-axis guide rails 34.

[0026] A nut portion (not shown) is provided on the back side of the Z-axis moving plate 36. A Z-axis ball screw (not shown) disposed along the Z-axis direction between a pair of Z-axis guide rails 34 is screwed into this nut portion. A Z-axis pulse motor 38 that rotates the Z-axis ball screw is connected to an end of the Z-axis ball screw. A support member 40 is fixed to the front side of the Z-axis moving plate 36. When the Z-axis ball screw is rotated by the Z-axis pulse motor 38, the Z-axis moving plate 36 and the support member 40 move in the Z-axis direction along the Z-axis guide rails 34.

[0027] The laser processing device 2 also includes a laser irradiation unit (processing unit) 42. Some components of the laser irradiation unit 42 (such as a laser processing head 44) ​​are supported by a support member 40. A laser beam 46 is irradiated from the laser processing head 44 to the workpiece 11 (see FIG. 2) held by the chuck table 28, whereby laser processing is performed on the workpiece 11.

[0028] The laser irradiation unit 42 is a YAG laser, a YVO 4 The laser processing head 44 includes a laser oscillator (not shown) such as a laser, and an optical system (not shown) that guides a laser beam 46 emitted from the laser oscillator to a workpiece 11 (see FIG. 2) held by a chuck table 28. The optical system is configured to include a plurality of optical elements, and controls the traveling direction, shape, etc. of the laser beam 46. Specifically, the optical system includes a condenser lens held inside the laser processing head 44. The condenser lens condenses the laser beam 46 emitted from the laser oscillator at a predetermined position.

[0029] In addition, an imaging unit 48 is attached to the laser irradiation unit 42. The imaging unit 48 includes an image sensor such as a CCD (Charged-Coupled Devices) sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, and captures an image of the workpiece 11 held by the chuck table 28. There is no limitation on the type of imaging unit 48, and a visible light camera or an infrared camera may be used, for example. The image acquired by the imaging unit 48 is used to check the state of the workpiece 11, align the workpiece 11 with the laser beam 46, and the like.

[0030] The Y-axis movement mechanism 8 and the X-axis movement mechanism 18 relatively move the chuck table 28, the laser beam 46 irradiated from the laser processing head 44, and the imaging unit 48 along the processing feed direction (X-axis direction) and the indexing feed direction (Y-axis direction). The Z-axis movement mechanism 30 moves (raise and lower) the laser processing head 44 and the imaging unit 48 along the Z-axis direction. This allows the focusing position of the laser beam 46 to be adjusted and the imaging unit 48 to be focused.

[0031] The laser processing apparatus 2 also includes a display unit (display section, display device) 50 that displays various information related to the laser processing apparatus 2. The display unit 50 is configured with various displays. For example, a touch panel display is used as the display unit 50. In this case, an operator of the laser processing apparatus 2 can input information to the laser processing apparatus 2 by touching the display unit 50. In other words, the display unit 50 also functions as an input unit (input section, input device) for inputting various information to the laser processing apparatus 2, and is used as a user interface. However, the input unit may be a mouse, a keyboard, etc. that are provided separately and independently from the display unit 50.

[0032] Furthermore, the laser processing apparatus 2 includes a control unit (control unit, control device) 52 that controls the laser processing apparatus 2. The control unit 52 is connected to each component (movement mechanism 6, chuck table 28, laser irradiation unit 42, imaging unit 48, display unit 50, etc.) that configures the laser processing apparatus 2. The control unit 52 outputs control signals to each component of the laser processing apparatus 2 to operate the laser processing apparatus 2.

[0033] For example, the control unit 52 is configured by a computer. Specifically, the control unit 52 includes a calculation section that performs calculations necessary for the operation of the laser processing device 2, and a storage section that stores information (data, programs, etc.) used for the operation of the laser processing device 2. The calculation section includes a processor such as a CPU (Central Processing Unit). The storage section includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0034] 2 is a perspective view showing a workpiece 11 to be processed by the laser processing device 2. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as single crystal silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. The workpiece 11 is divided into a plurality of rectangular regions by a plurality of streets (planned division lines) 13 arranged in a lattice pattern so as to intersect with each other.

[0035] Devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), MEMS (Micro Electro Mechanical Systems) devices, etc. are formed on the front surface 11a side of the multiple regions partitioned by the streets 13. By dividing the workpiece 11 along the streets 13, multiple device chips each including a device 15 are obtained.

[0036] However, 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 (substrate) 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.

[0037] When processing the workpiece 11 with the laser processing device 2, the workpiece 11 is supported by an annular frame 17 for ease of handling (transporting, holding, etc.) the workpiece 11. The frame 17 is made of a metal such as SUS (stainless steel), and a circular opening 17a is provided in the center of the frame 17, penetrating the frame 17 in the thickness direction. The diameter of the opening 17a is larger than the diameter of the workpiece 11.

[0038] A circular tape (protective tape) 19 is attached to the workpiece 11 and the frame 17. The diameter of the tape 19 is larger than the diameter of the opening 17a of the frame 17. With the workpiece 11 placed inside the opening 17a of the frame 17, the center of the tape 19 is attached to the back surface 11b of the workpiece 11 and the outer periphery of the tape 19 is attached to the frame 17, whereby the workpiece 11 is supported by the frame 17 via the tape 19.

[0039] Next, a description will be given of the details of the chuck table 28 mounted on the laser processing device 2. Fig. 3 is a perspective view showing the chuck table 28.

[0040] The chuck table 28 includes a cylindrical support base (main body) 60 made of metal such as SUS (stainless steel), glass, ceramics, resin, etc. The upper surface of the support base 60 is a flat surface that is generally parallel to the horizontal direction (XY plane direction) and configures a support surface 60a that supports the frame 17. The support base 60 also includes an annular side surface (outer peripheral surface) 60b that is generally perpendicular to the support surface 60a.

[0041] An annular frame 62 protruding upward from the support surface 60a is provided at the center of the support base 60. The diameter of the frame 62 is smaller than the diameter of the support surface 60a, and the support surface 60a and the frame 62 are arranged concentrically. The frame 62 may be integrated with the support base 60, or may be formed separately from the support base 60 and then fixed to the support surface 60a. An example of the material of the frame 62 is the same as that of the support base 60.

[0042] A disk-shaped holding member 64 is fitted inside the frame 62. The upper surface of the frame 62 and the upper surface of the holding member 64 are flat surfaces that are approximately parallel to the horizontal direction (XY plane direction), and constitute holding surfaces 62a, 64a that hold the workpiece 11. The height of the frame 62 and the thickness of the holding member 64 are approximately equal, and the holding surfaces 62a, 64a are arranged on approximately the same plane. The holding surfaces 62a, 64a constitute the holding surface 28a of the chuck table 28.

[0043] The support base 60 also includes a plurality of suction paths 60c that suck the frame 17. The plurality of suction paths 60c open on the support surface 60a and are arranged at approximately equal intervals along the circumferential direction of the support base 60. Although Fig. 3 shows an example in which four suction paths 60c are provided, there is no limit to the number of suction paths 60c.

[0044] Furthermore, the support base 60 has a plurality of communication holes 60d that open on the side surface 60b of the support base 60. The plurality of communication holes 60d are formed from the side surface 60b toward the center of the support base 60, and are arranged at approximately equal intervals along the circumferential direction of the support base 60.

[0045] 4(A) is a cross-sectional view showing the chuck table 28. The frame 62 has a bottom surface (lower surface) 62b that is generally parallel to the holding surface 62a, and the holding member 64 has a bottom surface (lower surface) 64b that is generally parallel to the holding surface 64a. The bottom surface 62b of the frame 62 and the outer periphery of the bottom surface 64b of the holding member 64 are supported by the support surface 60a of the support base 60. One end side (upper end side) of the suction path 60c is exposed at the support surface 60a, and the other end side (lower end side) of the suction path 60c is connected to a suction source 68 such as an ejector via a valve 66.

[0046] A cylindrical first groove (recess) 60e is provided on the support surface 60a side of the center of the support base 60. The support surface 60a and the first groove 60e are arranged concentrically. The diameter of the first groove 60e is smaller than the diameter of the holding member 64, and the holding member 64 is arranged to close the upper end of the first groove 60e.

[0047] A cylindrical second groove 60f connected to the first groove 60e is provided at the bottom of the first groove 60e. The second groove 60f is provided. The diameter of the second groove 60f is larger than the diameter of the first groove 60e, and the first groove 60e and the second groove 60f are arranged concentrically. The first groove 60e and the second groove 60f form an inverted T-shaped space in a cross-sectional view inside the support base 60.

[0048] The second groove 60f is provided with an illumination 70 that illuminates the workpiece 11 (see FIGS. 2 and 3). The illumination 70 includes a plurality of light emitters (light sources) 72 that emit light, and a cover 74 that covers the plurality of light emitters 72. For example, LEDs or the like are used as the light emitters 72, and the plurality of light emitters 72 are arranged at predetermined intervals along the X-axis direction and the Y-axis direction.

[0049] There are no limitations on the wavelength (color) of light emitted by the light emitter 72 as long as it can be received by the imaging unit 48 (see FIG. 1). For example, when a visible light camera is used as the imaging unit 48, an LED (red LED, green LED, blue LED, etc.) that emits visible light can be used as the light emitter 72. The illumination 70 may also be an organic EL illumination having an OLED (Organic Light-Emitting Diode) as the light emitter 72.

[0050] The cover 74 is transparent to the light emitted by the light emitter 72. The light emitted by the light emitter 72 is emitted from the cover 74 to the first groove 60e side, and is irradiated onto the holding member 64.

[0051] Further, a heat dissipation space 76 is provided between the holding member 64 and the light emitter 72. The heat dissipation space 76 corresponds to a cylindrical space surrounded by the inner wall of the first groove 60e, the holding member 64, and the light 70. The communication hole 60d of the support base 60 is formed along the radial direction of the support base 60 so as to communicate from the side surface 60b of the support base 60 to the heat dissipation space 76. Therefore, the heat dissipation space 76 is connected to the outside of the chuck table 28 via the communication hole 60d.

[0052] Fig. 4(B) is a plan view showing the chuck table 28. Fig. 4(B) illustrates the support base 60, the holding member 64, and the center O of the heat dissipation space 76. The multiple communication holes 60d are formed at positions that do not overlap with the suction passages 60c. There is no limit to the number and dimensions of the communication holes 60d, and they are set appropriately depending on the size of the support base 60, etc. For example, the support base 60 is formed with eight communication holes 60d with a diameter of about 6 mm.

[0053] When the laser processing apparatus 2 processes the workpiece 11, as shown in FIG. 3, the workpiece 11 is held by the chuck table 28. For example, the workpiece 11 is placed on the chuck table 28 such that the surface 11a side is exposed upward and the back surface 11b side (tape 19 side) faces the holding surface 28a. Further, the frame 17 is disposed directly on the support surface 60a of the support base 60 or via the tape 19. When the valve 66 (see FIG. 4(A)) is opened in this state, the suction force (negative pressure) of the suction source 68 (see FIG. 4(A)) acts on the support surface 60a through the plurality of suction passages 60c. As a result, the frame 17 is suction-held by the support base 60, and the workpiece 11 is fixed on the holding member 64.

[0054] Next, the workpiece 11 is irradiated with the laser beam 46 from the laser irradiation unit 42 (see FIG. 1), and the workpiece 11 is processed. For example, the laser beam 46 is focused on the surface 11a or inside of the workpiece 11 to perform laser processing on the workpiece 11.

[0055] The irradiation conditions of the laser beam 46 are set according to the content of the laser processing performed on the workpiece 11. For example, when ablation processing is performed on the workpiece 11, the wavelength of the laser beam 46 is set such that at least a part of the laser beam 46 is absorbed by the workpiece 11. That is, a laser beam having absorbability with respect to the workpiece 11 is used as the laser beam 46. Further, other irradiation conditions of the laser beam 46 (average output, repetition frequency, processing feed rate, etc.) are also appropriately set so that ablation processing is performed on the workpiece 11.

[0056] For example, when the workpiece 11 is a silicon wafer and ablation processing is performed on the silicon wafer, the irradiation conditions of the laser beam 46 can be set as follows. Wavelength: 355 nm Average output: 2 W Repetition frequency: 200 kHz Processing feed rate: 400 mm / s

[0057] When dividing the workpiece 11 along the streets 13, first, the chuck table 28 is rotated to align the length direction of one street 13 with the X-axis direction. In addition, the position of the chuck table 28 in the Y-axis direction is adjusted so that the focal point of the laser beam 46 is positioned so as to overlap with an extension line of one street 13.

[0058] Then, while irradiating the laser beam 46 from the laser processing head 44 (see FIG. 1), the chuck table 28 is moved along the X-axis direction (processing feed). As a result, the chuck table 28 and the laser beam 46 move relatively along the X-axis direction, and the laser beam 46 is irradiated along one street 13. Thereafter, by repeating the same procedure, the laser beam 46 is irradiated along all of the streets 13.

[0059] 5 is a cross-sectional view showing the chuck table 28 that holds the workpiece 11. When the laser beam 46 is irradiated onto the workpiece 11 as described above, the workpiece 11 is subjected to an ablation process. As a result, grooves (laser processed grooves) 11c extending from the front surface 11a to the back surface 11b are formed along the streets 13 in the workpiece 11, and the workpiece 11 is divided along the streets 13. If it is difficult to form the grooves 11c extending from the front surface 11a to the back surface 11b by irradiating the laser beam 46 once, the laser beam 46 may be irradiated along each street 13 multiple times.

[0060] After the grooves 11c are formed, a step is performed to check whether or not all of the grooves 11c reach the back surface 11b of the workpiece 11. Specifically, first, the chuck table 28 is moved by the moving mechanism 6 (see FIG. 1) to position the workpiece 11 directly below the imaging unit 48. Then, the light emitter 72 is made to emit light, and light is irradiated from the illumination 70 toward the holding member 64.

[0061] At least a part of the light emitted by the light-emitting body 72 passes through the holding member 64 and the tape 19 and is irradiated onto the workpiece 11. In other words, the holding member 64 and the tape 19 are transparent or semi-transparent members that are transparent to the light emitted by the light-emitting body 72.

[0062] For example, when the light emitter 72 emits visible light, the holding member 64 can be a transparent or semi-transparent member made of glass (quartz glass, borosilicate glass, soda-lime glass, alkali-free glass, etc.), sapphire, calcium fluoride, lithium fluoride, magnesium fluoride, etc. Also, for example, the tape 19 includes a film-like substrate formed into a circular shape and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, polyethylene terephthalate, etc. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive, etc. Note that the adhesive layer can also be made of an ultraviolet-curing resin that is cured by irradiation with ultraviolet light.

[0063] The light emitted by the light emitter 72 is transmitted through the holding member 64 and the tape 19 and irradiated onto the workpiece 11. In an area of ​​the workpiece 11 where the groove 11c reaching the back surface 11b is formed, the light passes through the groove 11c to reach the imaging unit 48 and is received by the imaging unit 48. On the other hand, in an area of ​​the workpiece 11 where the groove 11c reaching the back surface 11b is not formed, the light is reflected or absorbed by the workpiece 11 and is not received by the imaging unit 48, or the amount of light received is reduced.

[0064] When the back surface 11b of the workpiece 11 is illuminated by the illumination 70 and the front surface 11a of the workpiece 11 is imaged by the imaging unit 48, a captured image including an image of the workpiece 11 is obtained. In the captured image, a difference in shading occurs between an area where the groove 11c reaches the back surface 11b of the workpiece 11 and an area where it does not reach the back surface 11b. Therefore, by observing the captured image, it is possible to determine whether the groove 11c reaches the back surface 11b of the workpiece 11, that is, the division state of the workpiece 11 (whether the workpiece 11 is appropriately divided or not).

[0065] The division state may be determined manually by an operator visually checking the captured image, or automatically by the laser processing device 2 performing image processing on the captured image. When the division state is determined automatically, a program for executing image processing is stored in the control unit 52 (see FIG. 1) of the laser processing device 2. Then, when an image of the workpiece 11 is acquired by the imaging unit 48, the control unit 52 reads out and executes the program.

[0066] When the light emitter 72 is made to emit light, the light emitter 72 generates heat. If the heat from the light emitter 72 is conducted to the chuck table 28 (support base 60, frame 62, holding member 64, etc.) or the X-axis moving table 22 (see FIG. 1) and the chuck table 28 or the X-axis moving table 22 generates heat, this may adversely affect the machining of the workpiece 11.

[0067] For example, when laser processing is performed on the workpiece 11, the positional relationship between the workpiece 11 held by the holding surface 28a of the chuck table 28 and the focal point of the laser beam 46 (see FIG. 1) is set strictly. However, when heat from the light emitter 72 is conducted to the chuck table 28 or the X-axis moving table 22, the chuck table 28 or the X-axis moving table 22 generates heat and expands slightly, causing a change in the position and shape of the holding surface 28a. As a result, it becomes difficult to adjust the position of the focal point of the laser beam 46 with respect to the workpiece 11 with high precision, and there is a risk of a decrease in processing precision.

[0068] Meanwhile, in the chuck table 28, a heat dissipation space 76 is provided between the holding member 64 and the light emitter 72, and a plurality of communication holes 60d are connected to the heat dissipation space 76. This forms a heat dissipation path that dissipates the heat generated by the light emitter 72 to the outside of the chuck table 28. As a result, heat generation from the chuck table 28 and heat generation from the X-axis moving table 22 via the chuck table 28 are suppressed.

[0069] There is no limit to the number of communication holes 60d, and any number of communication holes 60d equal to or greater than one may be provided in the support base 60. However, in order to effectively suppress heat generation from the chuck table 28, the number of communication holes 60d is preferably two or more, and more preferably four or more. In addition, when two or more communication holes 60d are provided, it is preferable that a pair of communication holes 60d be provided so as to sandwich the heat dissipation space 76 therebetween.

[0070] 4(B) shows an example in which four pairs of communication holes 60d, totaling eight communication holes 60d, are provided in the support base 60. For example, the pair of communication holes 60d are provided on an imaginary straight line (imaginary line) 78 passing through a part of the heat dissipation space 76 (for example, the center O of the heat dissipation space 76) so as to sandwich the heat dissipation space 76. This makes it easier for gas that has entered the heat dissipation space 76 from one communication hole 60d to be discharged to the outside via the other communication hole 60d. As a result, an airflow that cools the inside of the chuck table 28 is easily generated.

[0071] Furthermore, a pair of communication holes 60d may be provided on each of two mutually perpendicular straight lines 78 (a first straight line 78A and a second straight line 78B) so as to sandwich the heat dissipation space 76. For example, a pair of communication holes 60d is provided on the first straight line 78A, and a pair of communication holes 60d is provided on a second straight line 78B perpendicular to the first straight line 78A. Then, for example, the angle of the chuck table 28 is adjusted so that the first straight line 78A is aligned along the X-axis direction and the second straight line 78B is aligned along the Y-axis direction.

[0072] When the chuck table 28 is moved along the X-axis direction or the Y-axis direction by the Y-axis moving mechanism 8 (see FIG. 1) or the X-axis moving mechanism 18 (see FIG. 1) before or after the image of the workpiece 11 is captured by the imaging unit 48 (see FIG. 5), an airflow is generated that passes through the pair of communication holes 60d provided on the first straight line 78A or the second straight line 78B and the heat dissipation space 76. Furthermore, when the next workpiece 11 is processed, an airflow is generated that passes through the pair of communication holes 60d provided on the first straight line 78A and the heat dissipation space 76 due to the processing feed of the chuck table 28. This allows the inside of the chuck table 28 to be efficiently cooled.

[0073] Furthermore, by providing eight or more communicating holes 60d at approximately equal intervals around the circumferential direction of the support base 60, the inside of the chuck table 28 is easily cooled even when the chuck table 28 moves in any direction other than the X-axis and Y-axis directions.

[0074] As described above, the chuck table 28 according to this embodiment includes the heat dissipation space 76 that corresponds to the space between the holding member 64 and the light emitter 72, and the heat dissipation space 76 is connected to the outside of the chuck table 28 via the communication hole 60d provided in the support base 60. This forms a heat dissipation path that dissipates the heat generated by the light emitter 72 to the outside of the chuck table 28, and heat generation in the chuck table 28 is suppressed.

[0075] Furthermore, the chuck table 28 according to this embodiment can suppress heat generation from the chuck table 28 with a simple configuration in which the communication holes 60d are connected to the heat dissipation space 76 provided inside the chuck table 28. This makes it possible to omit equipment such as a nozzle for supplying a cooling medium (air or the like) for cooling the chuck table 28 to the inside of the chuck table 28, simplifying the structure of the chuck table 28. However, the heat dissipation path formed by the heat dissipation space 76 and the communication holes 60d and equipment such as a nozzle for supplying a cooling medium can be used together.

[0076] In the above embodiment, the laser processing device 2 (see FIG. 1) has been described as an example of a processing device, but the chuck table 28 can be mounted on other processing devices. For example, the chuck table 28 can be mounted on a cutting device that cuts the workpiece 11.

[0077] Specifically, the cutting device includes a chuck table 28 and a processing unit (cutting unit) that grinds the workpiece 11. The grinding unit includes a cylindrical spindle, and an annular cutting blade that cuts the workpiece 11 is attached to the tip of the spindle. The workpiece 11 is held by the chuck table 28, and the cutting blade is rotated while cutting into the workpiece 11, thereby cutting the workpiece 11.

[0078] The cutting blade is caused to cut into the workpiece 11 along the streets 13 with a cutting depth reaching from the front surface 11a to the back surface 11b, so that the workpiece 11 is cut along the streets 13. Then, the workpiece 11 is divided into a plurality of device chips by causing the cutting blade to cut along all of the streets 13. Thereafter, as described above, the workpiece 11 is illuminated with the lighting 70 and an image of the workpiece 11 is taken by the imaging unit 48, so as to confirm whether the workpiece 11 has been appropriately divided.

[0079] 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]

[0080] 11 Workpiece 11a surface 11b Back side 11c Groove (Laser-machined groove) 13th Street (Planned division line) 15 Devices 17 Frame 17a aperture 19 Tape (protective tape) 2 Laser processing equipment 4 Foundation 6. Mobile mechanism (mobile unit) 8 Y-axis movement mechanism (Y-axis movement unit) 10 Y-axis guide rail 12 Y-axis moving table 14 Y-axis ball screw 16 Y-axis pulse motor 18 X-axis movement mechanism (X-axis movement unit) 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 Z-axis movement mechanism (Z-axis movement unit) 32 Support structure 32a base 32b Support part 34 Z-axis guide rail 36 Z-axis moving plate 38 Z-axis pulse motor 40 Support member 42 Laser irradiation unit (processing unit) 44 Laser processing head 46 Laser Beam 48 Imaging unit 50 Display unit (display unit, display device) 52 Control unit (control unit, control device) 60 Support base (main body) 60a Support surface 60b Side (outer surface) 60c suction path 60d communication hole 60e First groove (recess) 60f 2nd groove 62 Frame 62a Holding surface 62b Bottom surface (lower surface) 64 Retaining member 64a Holding surface 64b Bottom surface (lower surface) 66 Valve 68 Suction source 70 Lighting 72 Light source 74 Cover 76 Heat dissipation space 78 Straight line (imaginary line) 78A First Straight Line (First Virtual Line) 78B Second straight line (second virtual line)

Claims

[Claim 1] A chuck table for holding a workpiece, A support base; a holding member including a holding surface that holds the workpiece and a bottom surface that is supported by the support base; A light emitter provided on the bottom surface side of the holding member; a heat dissipation space corresponding to a space between the holding member and the light emitter, the holding member is transparent to the light emitted by the light emitter, the support base includes a pair of communication holes that are arranged on a first line passing through the heat dissipation space, sandwiching the heat dissipation space therebetween, and communicate from a side surface of the support base to the heat dissipation space, and a pair of communication holes that are arranged on a second line passing through the heat dissipation space and perpendicular to the first line, sandwiching the heat dissipation space therebetween, and communicate from the side surface of the support base to the heat dissipation space.

Images