JP6506662B2 - Wafer processing method - Google Patents

Description

  The present invention relates to a method of processing a wafer.

  In the device manufacturing process, a plurality of devices are formed on a wafer by photolithography. The plurality of devices are partitioned by planned division lines formed in a grid. A device is formed on a wafer, and the back surface of the wafer is ground by a grinding apparatus to thin the wafer, and then the wafer is divided along a planned dividing line, whereby an IC (integrated circuit) or an LSI (large scale integration) Device chips are manufactured.

  In order to improve the throughput of devices, a method of manufacturing devices from a wafer in which a functional layer including a low dielectric insulator film (Low-k film) is laminated on the surface of a substrate such as a silicon substrate is put to practical use ing. The functional layer containing the low-k film is brittle. Therefore, when the wafer is divided by cutting with a cutting blade, there arises a problem that the functional layer is easily peeled off from the substrate. In order to cope with this problem, there is known a method in which the functional layer is ablated by irradiating the functional layer with a laser beam having an absorbing wavelength. The substrate is irradiated with a laser beam of a wavelength having transparency to form a modified layer serving as a fracture starting point inside the substrate, starting from the formed modified layer as a substrate along the planned dividing line. It is also known how to divide. The functional layer is ablated and the modified layer is formed on the substrate, whereby the wafer having the functional layer including the low-k film is smoothly divided.

  Also, in order to reduce the package size of the semiconductor device, a semiconductor package technology called wafer-level chip-scale package (WL-CSP) has attracted attention. In the WL-CSP, before the wafer is divided, the electrode formation of the device and the resin sealing of the device are performed, and the size of the device chip after the wafer is divided becomes the size of the package as it is. Contribute to the miniaturization and weight reduction of

  In the WL-CSP, the electrodes of the resin-sealed device are connected to the bumps via metal posts. The bumps are provided to protrude from the surface of the wafer. When the back surface of a wafer is ground using a grinding apparatus to thin the wafer, the front surface of the wafer on which the bumps are provided is supported by the chuck table of the grinding apparatus (see Patent Document 1).

Unexamined-Japanese-Patent No. 2013-21017

  The surface of the wafer includes a device area where devices are formed and an outer peripheral excess area where devices are not formed. The bumps are provided in the device area of the wafer and not in the peripheral excess area of the wafer. When the wafer is supported by the chuck table of the grinding apparatus, if the wafer is supported by the chuck table of the grinding apparatus, the phenomenon that the outer peripheral surplus area hangs down with respect to the device area occurs when there are areas where bumps are provided and not provided on the surface of the wafer. If grinding is performed in a state in which the peripheral excess area is hanging down, a phenomenon occurs in which the thickness of the wafer in the peripheral excess area becomes thicker than the thickness of the wafer in the device area. When the functional layer is ablated and the modified layer is formed on the substrate in a state where the thickness of the wafer in the outer peripheral surplus region is large, the modified layer formed on the inside of the substrate and the laser-processed groove formed on the functional layer The distance between and may be uneven. That is, there is a possibility that the distance between the laser-processed groove and the modifying layer in the outer peripheral surplus region may be larger than the distance between the laser-processed groove and the modifying layer in the device region. As a result, it is difficult for the crack extended with the modified layer as the fracture starting point to reach the laser processing groove in the outer peripheral surplus region, and there is a problem that the wafer is hardly broken in the outer peripheral surplus region.

  The present invention has been made in view of the above, and when dividing a wafer provided with bumps, a laser processing groove formed in a functional layer by ablation processing and a modified layer formed inside a substrate It is an object of the present invention to provide a wafer processing method capable of dividing a wafer smoothly by equalizing the distance between the two.

  In order to solve the problems described above and to achieve the object, the present invention provides a plurality of devices having electrodes in the areas divided by the planned division lines in which the functional layers stacked on the surface of the substrate are formed in a grid. A method of processing a wafer, comprising: a formed device region; and an outer peripheral surplus region surrounding the device region, wherein the device is provided with a protruding bump connected to the electrode. A protective member disposing step of disposing a protective member on the functional layer side, a grinding step of grinding the back surface of the wafer to thin the wafer after performing the protective member disposing step, and the grinding step Thereafter, a dicing tape is attached to the back surface of the wafer, and a reattaching step of removing the protective member from the front surface of the wafer, and after performing the reattaching step, absorption to the functional layer The chuck table holding the wafer and the laser beam irradiating means are relatively moved along the planned dividing line while irradiating the laser beam of the wavelength having along the planned dividing line from the surface side of the wafer, along the planned dividing line After performing the groove forming step of dividing the functional layer by the laser processed groove and the groove forming step, a laser beam of a wavelength having transparency to the substrate is irradiated along the planned dividing line from the back side of the wafer. While moving the chuck table holding the wafer and the laser beam irradiating means relative to each other along the planned dividing line, a modified layer is formed which becomes a breaking start point inside the substrate by a predetermined distance from the back surface of the wafer. Forming, in the groove forming step, the chuck table and the laser The relative movement speed with the light beam irradiation means is set to a lower speed from the inner periphery of the outer peripheral excess area toward the periphery of the wafer, and the depth of the laser processing groove in the outer peripheral excess area is closer to the outer periphery of the wafer. Provided is a method of processing a wafer characterized by forming deeply.

  According to the wafer processing method of the present invention, when forming the laser-processed groove by irradiating the functional layer with the laser beam, the relative moving speed between the chuck table and the laser beam application means in the outer peripheral surplus region The speed is set lower as the wafer approaches the periphery of the wafer from the periphery, and the depth of the laser-processed groove in the outer peripheral excess region is formed deeper as the wafer's periphery is approached, thereby modifying the wafer even if the bump is formed. The crack connecting the layer and the laser processing groove produces an effect that the wafer can be divided smoothly.

FIG. 1 is a perspective view showing a wafer according to the present embodiment. FIG. 2 is a side sectional view showing the wafer according to the present embodiment. FIG. 3 is a flowchart showing a method of processing a wafer according to the present embodiment. FIG. 4 is a perspective view showing a protective member disposing step according to the present embodiment. FIG. 5 is a side sectional view showing the protective member disposing step according to the present embodiment. FIG. 6 is a view showing a grinding step according to the present embodiment. FIG. 7 is a view schematically showing the behavior of the wafer at the time of grinding according to the present embodiment. FIG. 8 is a perspective view showing a bonding step according to the present embodiment. FIG. 9 is a functional block diagram showing a laser processing apparatus according to the present embodiment. FIG. 10 is a perspective view showing a laser processing apparatus according to the present embodiment. FIG. 11 is a view showing the operation of the laser processing apparatus in the groove forming step according to the present embodiment. FIG. 12 is a schematic view showing a laser processing groove formed in the functional layer according to the present embodiment. FIG. 13 is a perspective view showing the expand tape reattaching step according to the present embodiment. FIG. 14 is a perspective view showing a laser processing apparatus according to the present embodiment. FIG. 15 is a side view showing a laser processing apparatus according to the present embodiment. FIG. 16 is a schematic view showing a wafer on which a laser processing groove and a modified layer according to the present embodiment are formed. FIG. 17 is a side view showing the dividing step according to the present embodiment. FIG. 18 is a side view showing the dividing step according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

  In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ orthogonal coordinate system. One direction in the horizontal plane is taken as an X-axis direction, a direction orthogonal to the X-axis direction in a horizontal plane is taken as a Y-axis direction, and a direction orthogonal to each of the X-axis direction and the Y-axis direction is taken as a Z-axis direction. The XY plane including the X axis and the Y axis is parallel to the horizontal plane. The Z-axis direction orthogonal to the XY plane is the vertical direction.

  FIG. 1 is a perspective view showing a wafer 2 according to the present embodiment. FIG. 2 is a side sectional view showing the wafer 2 according to the present embodiment. As shown in FIG. 1 and FIG. 2, the wafer 2 has a substrate 20 and a functional layer 21 provided on the substrate 20. The wafer 2 is a substantially disk-shaped member, and has a front surface 2A and a back surface 2B facing in the opposite direction of the front surface 2A. The front surface 2A and the back surface 2B are substantially parallel.

  The substrate 20 includes at least one of a silicon substrate, a sapphire substrate, a lithium tantalate substrate, a lithium niobate substrate, and a ceramic substrate, and has a front surface 20A and a back surface 20B facing in the reverse direction of the front surface 20A. The functional layer 21 is a layer that forms a device, and is a low dielectric constant insulator composed of an inorganic film such as SiOF or BSG (SiOB) and an organic film that is a polymer film such as polyimide or parylene. It contains a film (Low-k film). The functional layer 21 is laminated on the surface 20 A of the substrate 20. The surface 2A of the wafer 2 includes the surface of the functional layer 21. The back surface 2B of the wafer 2 includes the back surface 20B of the substrate 20.

  The functional layer 21 is partitioned by dividing lines 23 formed in a lattice. A plurality of devices 22 having electrodes in the area divided by the dividing lines 23 are formed. The device 22 is partitioned by the dividing line 23. The devices 22 are arranged in a matrix on the wafer 2.

  The surface 2A of the wafer 2 includes a device area DA in which a plurality of devices 22 are formed, and an outer peripheral surplus area SA surrounding the device area DA. The device 22 is not formed in the outer peripheral surplus area SA. By dividing the wafer 2 along the dividing lines 23, device chips such as integrated circuits (ICs) or large scale integrations (LSIs) are manufactured.

  The device 22 is provided with a bump 24 that protrudes in connection with the electrode of the device 22. Bumps 24 are provided for each of the plurality of devices 22. The bumps 24 are provided to protrude from the surface 2 A of the wafer 2.

  In the present embodiment, the diameter of the wafer 2 is 8 [inch]. The diameter of the wafer 2 may be 12 [inch].

  Next, a method of processing the wafer 2 according to the present embodiment will be described. FIG. 3 is a flowchart showing a method of processing the wafer 2 according to the present embodiment. As shown in FIG. 3, in the method of processing the wafer 2, the protective member disposing step (SP 1) of disposing the protective member 6 on the functional layer 21 side of the surface 2 A of the wafer 2 and the protective member disposing step Then, after carrying out the grinding step (SP2) of grinding the back surface 2B of the wafer 2 to thin the wafer 2 and the grinding step, the dicing tape 7 is attached to the back surface 2B of the wafer 2 and the front surface 2A of the wafer 2 After performing the repositioning step (SP3) for removing the protective member 6 from the surface and the repositioning step, the laser beam LB1 of a wavelength having absorption to the functional layer 21 is made from the surface 2A side of the wafer 2 to the planned dividing line 23 The chuck table holding the wafer 2 and the laser beam application means are moved relative to each other along the planned dividing line 23 while being irradiated along the dividing planned line 23. After performing the groove forming step (SP4) of dividing the functional layer 21 by the laser processing groove 25 and the groove forming step, the expand tape 9 is disposed on the functional layer 21 side of the surface 2A of the wafer 2 After performing the expand tape reattaching step (SP5) for removing the dicing tape 7 from the back surface 2B, the groove forming step and the expanded tape reattaching step, the laser beam LB2 of a wavelength having transparency to the substrate 20 is transferred to the wafer 2 The chuck table holding the wafer 2 and the laser beam irradiating means are moved relative to each other along the planned dividing line 23 while irradiating along the planned dividing line 23 from the back surface 2B side of the substrate Step of forming a modified layer 26 serving as a fracture starting point in the inside of the step 20 (S Including 6), the external force applied to the wafer 2, the dividing step of dividing the wafer 2 to a plurality of device chips (SP7), a.

  The protective member arranging step (SP1) will be described. The protective member disposing step is a step of disposing the protective member 6 on the functional layer 21 side of the surface 2 A of the wafer 2. FIG. 4 is a perspective view showing a protective member disposing step according to the present embodiment. FIG. 5 is a side sectional view showing the protective member disposing step according to the present embodiment. As shown in FIGS. 4 and 5, a protection member 6 for protecting the device 22 and the bumps 24 is attached to the surface 2 A of the wafer 2. The protective member 6 is a sheet-like member. The size of the outline of the protective member 6 and the size of the outline of the wafer 2 are substantially equal. The entire surface 2 A of the wafer 2 is covered with a protective member 6. The protective member 6 protects the device 22 provided on the surface 2A of the wafer 2.

  As shown in FIG. 5, the protective member 6 has a base film 61 and an adhesive layer 62 laminated on the base film 61. The protective member 6 is adhered to the functional layer 21 of the wafer 2 by the adhesive layer 62, and the entire surface 2 A of the wafer 2 including the bumps 24 is covered by the protective member 6. The dimension of the adhesive layer 62 in the Z-axis direction orthogonal to the surface 2 A of the wafer 2 is larger than the dimension of the bumps 24. By bonding the protective member 6 to the functional layer 21 of the wafer 2, the bumps 24 are buried in the adhesive layer 62.

  Next, the grinding step (SP2) will be described. The grinding step is a step of grinding the back surface 2B of the wafer 2 by the grinding device 5 to thin the wafer 2. FIG. 6 is a view showing a grinding step according to the present embodiment.

  As shown in FIG. 6, the grinding apparatus 5 includes a chuck table 51 for detachably holding the wafer 2 via the protective member 6 and grinding means 52 for grinding the wafer 2 held by the chuck table 51.

  The chuck table 51 has a holding surface 51 H for holding the protective member 6. The holding surface 51H is substantially parallel to the XY plane. The chuck table 51 holds the wafer 2 via the protective member 6. The base film 61 of the protection member 6 faces the holding surface 51H. The wafer 2 is held on the chuck table 51 via the protective member 6 such that the back surface 2B faces upward.

  The chuck table 51 holds the wafer 2 via the protective member 6 so that the back surface 2B of the wafer 2 is parallel to the XY plane. In addition, the chuck table 51 holds the wafer 2 such that the center of the holding surface 51H in the XY plane coincides with the center of the back surface 2B of the wafer 2.

  The chuck table 51 detachably holds the protective member 6 and the wafer 2. A plurality of suction ports connected to a vacuum suction source including a vacuum pump are provided in the holding surface 51H. With the protective member 6 and the wafer 2 placed on the holding surface 51H of the chuck table 51, the vacuum suction source is activated, whereby the wafer 2 is held by suction on the chuck table 51 via the protective member 6. The wafer 2 and the protective member 6 are released from the chuck table 51 by stopping the operation of the vacuum suction source.

  The chuck table 51 is rotatable in a direction indicated by an arrow R51 about a central axis AX51 of the chuck table 51 by a rotational drive mechanism including an actuator.

  The grinding means 52 includes a spindle housing 521, a rotary spindle 522 rotatably supported by the spindle housing 521, a mounter 523 mounted on the lower end of the rotary spindle 522, and a grinding wheel 524 provided on the lower surface of the mounter 523. Have. The grinding wheel 524 has an annular base 525 and a grinding wheel 526 annularly provided on the lower surface of the base 525. The base 525 is fixed to the lower surface of the mounter 523 by a fastening bolt. The grinding wheel 524 is rotatable about a central axis AX52 of the grinding means 52 in a direction indicated by an arrow R52 by rotation of the rotary spindle 522 by a rotary drive mechanism including an actuator.

  In the grinding step, the wafer 2 is held on the holding surface 51 H of the chuck table 51 via the protective member 6. The chuck table 51 holds the wafer 2 via the holding member 6 so that the holding member 6 and the holding surface 51H of the chuck table 51 face each other and the back surface 2B of the wafer 2 faces upward. After the wafer 2 is held on the chuck table 51 via the protective member 6, the grinding wheel 524 of the grinding means 52 is rotated in the direction indicated by the arrow R52 while the chuck table 51 is rotated in the direction indicated by the arrow R51. With the chuck table 51 and the grinding wheel 524 rotating, the grinding wheel 526 and the back surface 2B of the wafer 2 are in contact with each other. As indicated by arrow F52, the grinding wheel 524 is ground downward to grind the back surface 2B of the wafer 2.

  By grinding the back surface 2B of the wafer 2, the thickness of the substrate 20 is reduced, and the wafer 2 is thinned. The grinding device 5 grinds the back surface 2B of the wafer 2 so that the thickness of the wafer 2 becomes a target thickness.

  FIG. 7 is a view schematically showing the behavior of the wafer 2 in the peripheral excess area SA in the grinding step. The bumps 24 are provided in the device area DA and not provided in the outer peripheral surplus area SA. The wafer 2 is supported by the chuck table 51 of the grinding apparatus 5 via the protective member 6. When the back surface 2B is pressed from above onto the grinding wheel 524 (grinding wheel 526) of the polishing apparatus 5, a phenomenon occurs in which the peripheral excess area SA of the wafer 2 where the bumps 24 do not exist sag downward. If grinding is performed in a state in which the peripheral excess area SA hangs down, the thickness of the wafer 2 in the peripheral excess area SA becomes thicker than the thickness of the wafer 2 in the device area DA, as shown in FIG. The phenomenon occurs.

  Next, the attaching / removing step (SP3) will be described. The reattaching step is a step of attaching the dicing tape 7 to the back surface 2B of the wafer 2 and removing the protective member 6 from the front surface 2A of the wafer 2. FIG. 8 is a perspective view showing a bonding step according to the present embodiment. As shown in FIG. 8, the dicing tape 7 is attached to the back surface 2B of the wafer 2. The dicing tape 7 is a sheet-like member. The size of the outline of the dicing tape 7 and the size of the outline of the wafer 2 are substantially equal. The entire area of the back surface 2B of the wafer 2 is covered with the dicing tape 7. After the dicing tape 7 is attached to the back surface 2B of the wafer 2, the protective member 6 is removed from the front surface 2A of the wafer 2. The peripheral portion of the dicing tape 7 may be fixed to an annular frame, and the dicing tape 7 and the frame may form a frame unit.

  Next, the groove forming step (SP4) will be described. The groove forming step is a step of forming a laser processing groove 25 in the functional layer 21 by irradiating the surface 2 A of the wafer 2 with the laser beam LB 1 by the laser processing device 3.

  FIG. 9 is a functional block diagram showing a laser processing apparatus 3 according to the present embodiment. FIG. 10 is a perspective view showing a laser processing apparatus 3 according to the present embodiment.

  As shown in FIGS. 9 and 10, the laser processing apparatus 3 has a chuck table 31 for holding the wafer 2 through the dicing tape 7 and a laser beam application means 32 for irradiating a laser beam onto the wafer 2 held by the chuck table 31. Image pickup means 33 for acquiring an optical image of the wafer 2 held by the chuck table 31, a movement device 37 for moving the chuck table 31, a position detection device 38 for detecting the position of the chuck table 31, and image data A display device 39 for displaying and a control means 40 for controlling the laser processing apparatus 3 are provided.

  The chuck table 31 has a holding surface 31 H for holding the wafer 2. The holding surface 31H is substantially parallel to the XY plane. The chuck table 31 holds the wafer 2 through the dicing tape 7. The dicing tape 7 and the holding surface 31H face each other. The wafer 2 is held on the chuck table 31 via the dicing tape 7 such that the surface 2A is directed upward.

  The chuck table 31 holds the wafer 2 such that the surface 2A of the wafer 2 is parallel to the XY plane. In addition, the chuck table 31 holds the wafer 2 such that the center of the holding surface 31H in the XY plane coincides with the center of the back surface 2B of the wafer 2.

  The chuck table 31 detachably holds the wafer 2. A plurality of suction ports connected to a vacuum suction source including a vacuum pump are provided in the holding surface 31H. With the dicing tape 7 and the wafer 2 placed on the holding surface 31 H of the chuck table 31, the vacuum suction source is activated, whereby the wafer 2 is held by suction on the chuck table 31 via the dicing tape 7. The wafer 2 and the dicing tape 7 are released from the chuck table 31 by stopping the operation of the vacuum suction source.

  The chuck table 31 is moved in the X-axis direction (processing feed direction) and the Y-axis direction (indexing feed direction) by a moving device 37 including an actuator. The position of the chuck table 31 in the X-axis direction and the Y-axis direction is detected by the position detection device 38.

  The laser beam application means 32 has a casing 34 accommodating the pulse laser beam oscillation means, and a condenser 35 mounted at the tip of the casing 34 for condensing the pulse laser beam oscillated from the pulse laser beam oscillation means. The pulsed laser beam oscillation means includes a pulsed laser beam oscillator and a repetition frequency setting means.

  The laser beam application means 32 is a first laser beam emission means capable of emitting a laser beam LB1 of a wavelength having absorption to the functional layer 21, and a laser beam LB2 of a wavelength having a transmission property to the substrate 20. And 2 laser beam emitting means. The first laser beam emitting means and the second laser beam emitting means are separate laser beam emitting means. In the following description, the first laser beam emitting means and the second laser beam emitting means will be collectively described as the laser beam emitting means 32. The laser beam LB1 is, for example, a laser beam having a wavelength of 355 [nm]. The laser beam LB2 is, for example, a laser beam of wavelength 1064 [nm].

  The imaging means 33 is supported by the casing 34. The imaging means 33 acquires an optical system, an illumination means for illuminating the wafer 2 disposed in the field of view of the optical system with an illumination beam, and an optical image of the wafer 2 illuminated with the illumination beam via the optical system. And an imaging element. The imaging means 33 includes a visible light imaging means 33A that illuminates with visible light and images the wafer 2, and an infrared imaging means 33B that illuminates with infrared light and images the wafer 2. The illumination means of the imaging means 33 includes a first illumination means for illuminating the wafer 2 with visible light, and a second illumination means for illuminating infrared light. The imaging device of the imaging means 33 includes a first imaging device for acquiring an optical image of the wafer 2 irradiated with visible light and a second imaging device for acquiring an optical image of the wafer 2 irradiated with infrared light. . Image data representing an optical image of the wafer 2 acquired by the imaging device is output to the control means 40.

  The control means 40 includes an arithmetic processing unit 41 having a microprocessor such as a CPU (central processing unit), a storage device 42 including a memory such as a ROM (read only memory) or a RAM (random access memory), And an interface device 43. The arithmetic processing unit 41 performs arithmetic processing in accordance with a computer program stored in the storage unit 42, and outputs a control signal for controlling the laser processing apparatus 3 through the input / output interface unit 43.

  In the groove forming step, the laser processing apparatus 3 is a chuck table holding the wafer 2 while irradiating the laser beam LB1 of a wavelength having absorption to the functional layer 21 from the surface 2A side of the wafer 2 along the planned dividing line 23 31 and the laser beam application means 32 are moved relative to each other along the planned dividing line 23, and the functional layer 21 is divided by the laser processing groove 25 along the planned dividing line 23.

  In the groove forming step, the functional layer 21 of all the dividing lines 23 of the wafer 2 is irradiated with the laser beam LB1 to carry out ablation processing. The laser processing groove 25 is formed at the center in the width direction of the functional layer 21 of the dividing line 23. The functional layer 21 is divided at the boundaries of the laser processing groove 25.

  As shown in FIG. 10, in the groove forming step, the dicing tape 7 attached to the back surface 2B of the wafer 2 faces the holding surface 31H of the chuck table 31 so that the front surface 2A of the wafer 2 faces upward. The chuck table 31 holds the wafer 2.

  After the wafer 2 is held on the chuck table 31, alignment processing between the laser beam LB1 and the wafer 2 is performed. The alignment process includes alignment between the irradiation position of the laser beam LB1 emitted from the laser beam irradiation means 32 and the planned dividing line 23 of the wafer 2. The irradiation position of the laser beam LB1 is a position directly below the light collector 35. In the alignment processing, the control means 40 controls the moving device 37 while detecting the position of the chuck table 31 by the position detection device 38, and the dividing planned line 23 extending in the X axis direction in the wafer 2 Arrange at the imaging position. The imaging position of the imaging unit 33 includes the visual field area of the optical system of the imaging unit 33, and includes the position directly below the imaging unit 33. The control unit 40 uses the imaging unit 33 to acquire image data of the wafer 2. Acquisition of image data in the groove forming step is performed by the visible light imaging means 33A. The visible light imaging means 33A illuminates the wafer 2 with visible light and acquires image data of the wafer 2. The control means 40 acquires the image data of the wafer 2 and carries out the image processing such as pattern matching to carry out the alignment processing of the irradiation position of the laser beam LB1 and the planned dividing line 23 of the wafer 2. Similarly, the alignment process is also performed on the planned dividing lines 23 extending in the Y-axis direction orthogonal to the X-axis direction in the wafer 2.

  After the end of the alignment process, the control means 40 controls the moving device 37 while detecting the position of the chuck table 31 by the position detection device 38 in order to irradiate the laser beam LB1 along the planned division line 23 to control the laser beam LB1. The position of the wafer 2 with respect to the irradiation position of

  For example, when irradiating the laser beam LB1 along the dividing planned line 23 extending in the X axis direction, the control means 40 controls the moving device 37 to divide the planned dividing line in the X axis direction at the irradiating position of the laser beam LB1. Position one end of 23 After one end portion of the planned dividing line 23 in the X-axis direction is disposed at the irradiation position of the laser beam LB1, the control means 40 emits the laser beam LB1 from the laser beam irradiation means 32 and the laser beam LB1 to the functional layer 21 of the wafer 2. Irradiate. The control means 40 controls the moving device 37 while irradiating the functional layer 21 of the wafer 2 with the laser beam LB1 to move the wafer 2 held by the chuck table 31 in the X-axis direction. The control means 40 moves the wafer 2 until the other end of the planned dividing line 23 in the X-axis direction is disposed at the irradiation position of the laser beam LB1.

  After the other end of the planned division line 23 in the X-axis direction is disposed at the irradiation position of the laser beam LB1, the control means 40 stops the emission of the laser beam LB1 from the laser beam irradiation means 32. Thereby, the laser processing groove 25 is formed along the planned dividing line 23 extending in the X-axis direction, and the functional layer 21 is divided.

  When the laser beam LB1 is irradiated along the planned dividing line 23 extending in the Y-axis direction, the control means 40 arranges one end of the planned dividing line 23 in the Y-axis direction at the irradiation position of the laser beam LB1, and then irradiates the laser beam. While emitting the laser beam LB1 from the means 32, move the wafer 2 held by the chuck table 31 in the Y-axis direction until the other end of the planned dividing line 23 in the Y-axis direction is arranged at the irradiation position of the laser beam LB1. Let Thereby, the laser processing groove 25 is formed along the planned dividing line 23 extending in the Y-axis direction, and the functional layer 21 is divided. The irradiation of the laser beam LB1 on the planned dividing line 23 extending in the Y-axis direction ends the irradiation of the laser beam LB1 on the planned dividing line 23 extending in the X-axis direction, and the chuck table 31 has 90 [90] in the XY plane. °] After being rotated.

  The control means 40 applies the laser beam LB1 to all of the planned division lines 23 formed in a lattice. Thus, the laser-processed grooves 25 are formed in a lattice shape.

  In the present embodiment, in the groove forming step, the relative movement speed between the chuck table 31 and the laser beam application means 32 in the outer peripheral excess area SA is set to be lower as it approaches the periphery of the wafer 2 from the inner periphery of the outer peripheral excess area SA. The depth of the laser-processed groove 25 in the peripheral excess area SA is formed deeper as it approaches the periphery of the wafer 2.

  FIG. 11 is a view showing the operation of the laser processing apparatus 3 in the groove forming step according to the present embodiment. FIG. 11 shows the position of the wafer 2 with respect to the irradiation position of the laser beam LB1 and the moving speed of the chuck table 31 in the X-axis direction when irradiating the laser beam LB1 along the planned division line 23 extending in the X axis direction The relationship with) is schematically shown.

  For example, in the case where the laser beam LB1 is irradiated along the planned dividing line 23 extending in the X-axis direction while moving the wafer 2 held by the chuck table 31 in the direction indicated by the arrow Xa in FIG. The positions P1, P2, P3 and P4 on the planned dividing line 23 of the wafer 2 held at 31 are sequentially arranged at the irradiation position of the laser beam LB1. The position P1, the position P2, the position P3, and the position P4 are arranged in the X axis direction at the dividing line 23.

  The position P1 is the periphery of the wafer 2 on the + X side. The position P4 is the periphery of the wafer 2 on the −X side. The position P1 includes the end on the + X side of the outer circumference surplus area SA. The position P4 includes the end on the −X side of the outer circumference surplus area SA. The position P2 and the position P3 are the boundaries between the outer peripheral surplus area SA and the device area DA, respectively.

  When irradiating one division planned line 23 with the laser beam LB1, the control means 40 maintains the output of the laser beam application means 32 (the illuminance of the laser beam LB1 emitted from the laser beam application means 32) at a constant value. When the laser beam LB1 is irradiated to one planned dividing line 23, the control means 40 maintains the pulse conditions (pulse width, peak value, repetition frequency) of the laser beam irradiation means 32 under constant conditions. In addition, when irradiating one divided planned line 23 with the laser beam LB1, the control means 40 keeps the distance between the laser beam emitting part of the condenser 35 and the wafer 2 and the spot diameter of the laser beam LB1 irradiated to the wafer 2 constant. Maintain the value.

  As shown in FIG. 11, when irradiating the laser beam LB1 to the planned dividing line 23 in the device area DA, the control means 40 maintains the moving speed (processing feed speed) of the wafer 2 with respect to the irradiation position of the laser light LB1 at a constant speed. .

  On the other hand, when irradiating the laser beam LB1 to the planned dividing line 23 in the outer peripheral surplus area SA, the control means 40 controls the moving speed (processing feed speed) of the wafer 2 with respect to the irradiation position of the laser light LB1 to the inner circumference of the outer peripheral surplus area SA The moving device 37 is controlled so that the speed becomes lower as it approaches the edge of the wafer 2 from the boundary between the outer peripheral surplus area SA and the device area DA). In the present embodiment, the processing feed speed of the chuck table 31 is controlled such that the moving speed of the wafer 2 decreases proportionally as it approaches the peripheral edge of the wafer 2 from the inner periphery of the outer peripheral excess area SA.

  When irradiating one division planned line 23 with the laser beam LB1, the moving device 37 arranges the irradiation position of the laser beam LB1 at the position P2 of the wafer 2 from the state where the irradiation position of the laser beam LB1 is arranged at the position P1 of the wafer 2. The wafer 2 is moved in the direction of arrow Xa while accelerating, until it is released.

  The moving device 37 moves the wafer 2 in the direction of the arrow Xa at a constant speed until the irradiation position of the laser beam LB1 is arranged at the position P3 of the wafer 2 from the state where the irradiation position of the laser beam LB1 is arranged at the position P2 of the wafer 2 Move it.

  The moving device 37 decelerates the wafer 2 in the direction of the arrow Xa while decelerating the wafer 2 until the irradiation position of the laser beam LB1 is arranged at the position P4 of the wafer 2 from the state where the irradiation position of the laser beam LB1 is arranged at the position P3 of the wafer 2 Move it.

  That is, when the laser beam LB1 is irradiated to one division planned line 23, the wafer 2 accelerates and then moves at a constant speed, and then decelerates.

  In the acceleration zone where the wafer 2 accelerates and the deceleration zone where the wafer 2 slows down, the laser beam LB1 is irradiated to the outer peripheral surplus area SA. The laser beam LB1 is applied to the device area DA in a constant velocity zone in which the wafer 2 moves at a constant velocity.

  The maximum velocity of the wafer 2 in the acceleration zone and the maximum velocity of the wafer 2 in the deceleration zone are equal to the moving velocity of the wafer 2 in the constant velocity zone. Further, as described above, the output of the laser beam application means 32 and the pulse conditions when the laser beam LB1 is applied to one planned division line 23 are constant. Therefore, the light amount (integrated light amount) of the laser beam LB1 to be irradiated becomes larger toward the peripheral edge of the wafer 2 in the peripheral excess region SA of one planned dividing line 23, and the laser beam is irradiated toward the inner periphery of the peripheral excess region SA. The light amount of LB1 (integrated light amount) decreases.

  In the present embodiment, the integrated light amount of the laser beam LB1 irradiated to the position P1 and the position P4 is the first light amount (maximum light amount), and the integrated light amount of the laser beam LB1 irradiated to the position P2 and the position P3 is the second light amount ( Minimum light amount). The distribution of the integrated light quantity of the laser beam LB1 irradiated to the outer circumference surplus area SA is highest at the peripheral edge of the outer circumference surplus area SA and lowest at the inner circumference of the outer circumference surplus area SA, and proportional to the first light quantity and the second light quantity Change. The distribution of the integrated light quantity of the laser beam LB1 irradiated to the device area DA is constant at the second light quantity.

  As an example, the output of the laser beam application means 32 is maintained at a constant value of 1.5 [W]. The repetition frequency of the laser beam application means 32 is maintained at a constant value of 160 [kHz]. When the laser beam LB1 is irradiated to the dividing planned line 23 in the device area DA, the moving speed (processing feed speed) of the wafer 2 with respect to the irradiation position of the laser beam LB1 is maintained at a constant value of 400 [mm / s]. When the laser beam LB1 is irradiated to the dividing line 23 at the peripheral edge of the outer peripheral excess area SA, the moving speed (processing feed speed) of the wafer 2 with respect to the irradiation position of the laser beam LB1 is 50 [mm / s]. The moving speed (processing feed speed) of the wafer 2 decreases proportionally between 400 [mm / s] and 50 [mm / s] as it approaches from the inner circumference of the outer circumference surplus area SA to the periphery of the outer circumference surplus area SA As a result, the processing feed speed of the chuck table 31 is controlled.

  FIG. 12 is a schematic view showing a laser processing groove 25 formed in the functional layer 21 according to the present embodiment. The integrated light amount of the laser beam LB1 irradiated to the functional layer 21 and the depth of the laser processing groove 25 formed in the functional layer 21 by the irradiation of the laser beam LB1 of the integrated light amount are substantially proportional to each other. The depth of the laser processing groove 25 is a depth based on the surface of the functional layer 21. Therefore, by adjusting the moving speed of the wafer 2 as described above and adjusting the integrated light amount of the laser beam LB1 irradiated to the functional layer 21, the depth of the laser processing groove 25 in the outer peripheral surplus area SA It can be formed deeper as it approaches the periphery. The depths of the laser-processed grooves 25 change proportionally in the outer peripheral surplus area SA. In addition, the depth of the laser processing groove 25 in the device area DA is formed to a constant depth.

  Next, the expand tape replacing step (SP5) will be described. The expand tape reattachment reattachment step is a step of disposing the expand tape 9 on the functional layer 21 side of the front surface 2A of the wafer 2 and removing the dicing tape 7 from the back surface 2B of the wafer 2. FIG. 13 is a perspective view showing the expand tape reattaching step according to the present embodiment. As shown in FIG. 13, an expand tape 9 for protecting the device 22 is attached to the surface 2 A of the wafer 2. The expand tape 9 is a sheet-like member. Expanded tape 9 has a substrate film and an adhesive material layer laminated on the substrate film. The expand tape 9 is adhered to the functional layer 21 of the wafer 2 by the adhesive layer, and the entire area of the surface 2 A of the wafer 2 including the bumps 24 is covered by the expand tape 9. The bumps 24 are buried in the adhesive layer of the expand tape 9.

  The expand tape 9 is attached to an annular frame 10. The wafer 2 is attached to the expand tape 9 so that the front surface 2A faces the expand tape 9 and the back surface 2B faces upward (+ Z direction). The entire surface 2 A of the wafer 2 is covered with the expand tape 9. Expanded tape 9 protects device 22 provided on surface 2A of wafer 2. After the expand tape 9 is attached to the front surface 2A of the wafer 2, the dicing tape 7 is removed from the back surface 2B of the wafer 2.

  Next, the modified layer forming step (SP6) will be described. The modified layer forming step is a step of forming the modified layer 26 inside the substrate 20 by irradiating the back surface 2B of the wafer 2 with the laser beam LB2 by the laser processing apparatus 3B.

  FIG. 14 is a perspective view showing a laser processing apparatus 3B according to the present embodiment. FIG. 15 is a side view showing a laser processing apparatus 3B according to the present embodiment. The laser processing apparatus 3B includes the same laser beam application means 32 as the above-described laser processing apparatus 3. The laser beam application means 32 can emit a laser beam LB2 of a wavelength having transparency to the substrate 20.

  The laser processing apparatus 3 </ b> B includes a chuck table 310 having a holding surface 31 </ b> HB for holding the wafer 2. The holding surface 31HB is substantially parallel to the XY plane. The chuck table 310 holds the wafer 2 via the expand tape 9. The expand tape 9 and the holding surface 31HB face each other. The wafer 2 is held by the chuck table 31B via the expand tape 9 so that the back surface 2B faces upward.

  The chuck table 310 holds the wafer 2 such that the back surface 2B of the wafer 2 is parallel to the XY plane. The chuck table 310 holds the wafer 2 such that the center of the holding surface 31HB in the XY plane coincides with the center of the back surface 2B of the wafer 2.

  The chuck table 310 detachably holds the wafer 2. A plurality of suction ports connected to a vacuum suction source including a vacuum pump are provided in the holding surface 31HB. With the expand tape 9 and the wafer 2 placed on the holding surface 31HB of the chuck table 310, the vacuum suction source is activated, whereby the wafer 2 is held by suction on the chuck table 310 via the expand tape 9. The wafer 2 and the expand tape 9 are released from the chuck table 310 by stopping the operation of the vacuum suction source.

  The laser processing apparatus 3B includes a frame holding device 320 for holding the frame 10. The frame holding device 320 holds the frame 10 between the arm member 330 provided on the side surface of the chuck table 310, the annular frame holding member 340 fixed to the arm member 330, and the upper surface 340H of the frame holding member 340. And a clamp mechanism 350. The upper surface 340H of the frame holding member 340 is a holding surface on which the frame 10 is held. The frame 10 mounted on the upper surface 340H is sandwiched between the clamp mechanism 350 and the frame holding member 340. The clamp mechanism 350 fixes the frame 10 to the frame holding member 340 by sandwiching the frame 10 with the frame holding member 340.

  The upper surface 340H of the frame holding member 340 is disposed below the holding surface 31HB of the chuck table 310 (in the -Z direction). The frame 10 held by the frame holding device 320 is disposed below the wafer 2 held by the chuck table 310. As the frame 10 is disposed below the wafer 2, the expand tape 9 is stretched.

  In the modified layer forming step, the chuck table 310 holding the wafer 2 and the laser beam irradiation while irradiating the laser beam LB2 of a wavelength having transparency to the substrate 20 along the planned dividing line 23 from the back surface 2B side of the wafer 2 The reformed layer 26 is moved relative to the means 32 along the planned dividing line 23 to form a modified layer 26 serving as a fracture starting point inside the substrate 2 at a predetermined distance from the back surface 2 B of the wafer 2. By irradiating the substrate 20 with the laser beam LB2 along all planned dividing lines 23 of the wafer 2, a lattice-shaped modified layer 26 is formed inside the substrate 20.

  As shown in FIGS. 14 and 15, in the modifying layer forming step, the expand tape 9 and the holding surface 31HB of the chuck table 310 face each other, and the expand tape 9 and the back surface 2B of the wafer 2 face upward. The wafer 2 is held on the chuck table 310.

  With the expandable tape 9 and the wafer 2 held by the chuck table 310, alignment processing between the laser beam LB2 and the wafer 2 is performed. The alignment process includes alignment between the irradiation position of the laser beam LB2 emitted from the laser beam irradiation means 32 and the planned dividing line 23 of the wafer 2. In the alignment processing, the control means 40 controls the moving device 37 while detecting the position of the chuck table 31 by the position detection device 38, and the dividing planned line 23 extending in the X axis direction in the wafer 2 Arrange at the imaging position. The control unit 40 uses the imaging unit 33 to acquire image data of the wafer 2. Acquisition of image data in the modified layer formation step is performed by the infrared imaging means 33B. The infrared imaging means 33B illuminates the wafer 2 with infrared light and acquires image data of the wafer 2. By using an infrared ray, the substrate 20 is penetrated, and the planned dividing line 23 or the laser processing groove 25 provided on the surface 2A of the wafer 2 is imaged. The control means 40 acquires the image data of the wafer 2 and carries out the image processing to carry out alignment processing with the irradiation position of the laser beam LB2 and the planned dividing line 23 of the wafer 2 or the laser processing groove 25. Similarly, the alignment process is also performed on the planned dividing lines 23 extending in the Y-axis direction orthogonal to the X-axis direction in the wafer 2.

  After completion of the alignment process, the control means 40 controls the moving device 37 to place the line to be divided 23 at the irradiation position of the laser beam LB2. The control means 40 controls the moving device 37 while detecting the position of the chuck table 31 by the position detection device 38, and the irradiation position of the laser beam LB2 is irradiated so that the laser beam LB2 is irradiated to one end of the planned dividing line 23. Adjust the position of the wafer 2.

  After one end of the dividing line 23 is disposed at the irradiation position of the laser beam LB2, the control means 40 emits the laser beam LB2 from the laser beam irradiation means 32 to irradiate the substrate 20 of the wafer 2 with the laser beam LB2. The control means 40 controls the moving device 37 while irradiating the substrate 20 of the wafer 2 with the laser beam LB2 to move the wafer 2 held by the chuck table 31 in the direction indicated by the arrow Xb in FIG. After the other end of the dividing line 23 is disposed at the irradiation position of the laser beam LB2, the control means 40 stops the emission of the laser beam LB2 from the laser beam irradiation means 32. Thus, the modified layer 26 is formed in the substrate 20 along the planned dividing line 23.

  The control means 40 applies the laser beam LB2 by the laser beam application means 32 to all of the planned division lines 23 formed in a lattice. The irradiation position of the laser beam LB2 corresponds to the planned dividing line 23 imaged by the infrared imaging means 33B or the laser processing groove 25 formed in the laser processing groove forming step. Thereby, the modified layer 26 is formed in a lattice shape.

  FIG. 16 is a schematic view showing the wafer 2 on which the laser processing groove 25 and the modifying layer 26 according to the present embodiment are formed. The outer periphery surplus area SA is formed thicker than the surface 2A of the device area DA by the grinding step. In FIG. 16, the back surface 2B of the outer periphery surplus area SA and the back surface 2B of the device area DA are illustrated as being disposed in the same plane in a flat surface, but the back surface 2B of the outer periphery surplus area SA and the device area DA The back surface 2B of the need not be flat. Before the irradiation of the laser beam LB2, the height of the back surface 2B is detected by the height detector, and the height of the focal point of the laser beam LB2 is controlled based on the detection result. Thereby, the modified layer 26 can be formed to a predetermined depth from the back surface 2B.

  The depth of the laser-processed groove 25 from the surface 2A in the peripheral excess area SA is formed deeper as it approaches the periphery of the wafer 2. The distance from the back surface 2B to the bottom of the laser processing groove 25 is constant in the device area DA and the peripheral excess area SA. Further, the distance (depth) from the back surface 2B to the modified layer 26 is constant in the device area DA and the outer peripheral surplus area SA. The distance between the laser-processed groove 25 and the modified layer 26 is constant in the device area DA and the peripheral excess area SA. That is, the distance HS between the laser processing groove 25 and the modification layer 26 in the outer peripheral excess area SA and the distance HD between the laser processing groove 25 and the modification layer 26 in the device area DA are substantially equal.

  Next, the division step (SP7) will be described. The dividing step is a step of applying an external force to the wafer 2 through the expand tape 9 to divide the wafer 2 into a plurality of device chips. 17 and 18 are side views showing the dividing step according to the present embodiment. In the dividing step, the dividing device 8 shown in FIGS. 17 and 18 is used in the dividing step.

  After completion of the modified layer forming step, the holding of the frame 10 by the frame holding device 320 is released, and the holding of the expanded tape 9 and the wafer 2 by the chuck table 310 is released. The expand tape 9 attached to the frame 10 and the wafer 2 attached to the expand tape 9 are conveyed from the laser processing apparatus 3 B to the dividing apparatus 8.

  As shown in FIG. 17, the wafer 2 attached to the expand tape 9 is placed on the dividing device 8. The dividing device 8 includes a frame holding means 81 for holding the frame 10, and a tape expansion means 82 for expanding the expand tape 9 mounted on the frame 10 held by the frame holding means 81.

  The frame holding means 81 has an annular frame holding member 811 and a plurality of clamp mechanisms 812 disposed on the outer periphery of the frame holding member 811. The upper surface 811 a of the frame holding member 811 is a mounting surface on which the frame 10 is mounted. The frame 10 placed on the upper surface 811 a is fixed to the frame holding member 811 by a clamp mechanism 812. The frame holding means 81 is vertically movable by the tape expanding means 82.

  The tape expansion means 82 has an expansion drum 821 disposed inside the frame holding member 811. The expansion drum 821 has an inner diameter and an outer diameter smaller than the inner diameter of the frame 10 and larger than the outer diameter of the wafer 2. The tape expansion means 82 has support means 83 for supporting the frame holding member 811 and movable means 84 capable of moving the expansion drum 821 in the vertical direction. The movable means 84 has a plurality of air cylinders 841. The piston rod 842 of the air cylinder 841 is connected to the expansion drum 821. In the present embodiment, the piston rod 842 and the expansion drum 821 are integrated. The movable means 84 including the plurality of air cylinders 841 has a reference position where the upper end of the extension drum 821 is substantially the same height as the upper surface 811 a of the frame holding member 811 and an extended position above the upper surface 811 a of the frame holding member 811 by a predetermined amount. The expansion drum 821 is moved so as to move up and down between them.

  Next, division steps using the dividing device 8 will be described. As shown in FIG. 17, the frame 10 supporting the wafer 2 via the expand tape 9 is placed on the upper surface 811 a of the frame holding member 811 of the frame holding means 81 and fixed to the frame holding member 811 by the clamp mechanism 812. Ru. At this time, the frame holding member 811 is positioned at the reference position shown in FIG.

  Next, the plurality of air cylinders 841 of the movable means 84 are actuated, and the upper surface 811a of the extension drum 821 is raised to the extended position shown in FIG. As a result, the protective tape between the extension drums 821 is raised with respect to the annular frame 6 fixed to the upper surface 811 a of the frame holding member 811. Therefore, as shown in FIG. 18, the expand tape 9 mounted on the annular frame 10 abuts on the upper end portion of the expansion drum 821 and expands. As a result, a radial external force (tensile force) is applied to the wafer 2 attached to the expand tape 9. Since the strength of the modified layer 26D formed on the wafer 2 is lowered, when radial tension is applied to the wafer 2, the modified layer 26D formed along the planned dividing line 23 is broken at the base point. As, the wafer 2 is divided along the dividing lines 23.

  As described above, according to the present embodiment, in the groove forming step, the relative movement speed between the chuck table 31 and the laser beam application means 32 in the outer peripheral excess area SA is set to the peripheral edge of the wafer 2 from the inner periphery of the outer peripheral excess area SA. By setting the speed to a lower speed as it approaches, the depth of the laser-processed groove 25 in the peripheral excess area SA is formed deeper as it approaches the periphery of the wafer 2. Therefore, by grinding the wafer 2 in which the bumps 24 are provided in the device area DA and the bumps 24 are not provided in the outer peripheral excess area SA while supported by the chuck table 51 of the grinding apparatus 5, A phenomenon occurs in which the thickness is thicker than the thickness of the wafer 2 in the device area DA, and even if the surface 2A of the outer peripheral excess area SA is formed to be convexer than the surface 2A of the device area DA, laser processing in the outer peripheral excess area SA The distance HS between the groove 25 and the modified layer 26 and the distance HD between the laser-processed groove 25 and the modified layer 26 in the device area DA can be made substantially equal. By equalizing the distance between the laser-processed groove 25 formed in the functional layer 21 and the modified layer 26 formed in the inside of the substrate 20, the modified layer is formed in the outer peripheral surplus area SA and the canvas area DA. The extended crack can be made to reach the laser-processed groove 25 simultaneously with 26 as the fracture start point. Therefore, even in the wafer 2 in which the bumps 24 are formed, the wafer 2 can be smoothly divided by the crack connecting the modified layer 26 and the laser processing groove 25.

  In the present embodiment, when adjusting the depth of the laser processing groove 25 in the peripheral excess area SA, it is not necessary to change the output of the laser beam LB1 or to adjust the distance between the laser beam application means 32 and the wafer 2. , Moving speed of the wafer 2 (chuck table 31). For example, when the laser beam LB1 is sequentially irradiated to a plurality of planned division lines 23 extending in the X-axis direction and arranged in the Y-axis direction, the wafer 2 scans and moves in the + X direction with respect to the laser beam LB1. Step movement in the Y-axis direction and then scan movement in the -X direction. That is, in the scan movement in the X-axis direction, the wafer 2 repeats acceleration movement, constant speed movement, and deceleration movement. The scan movement distance of the wafer 2 is suppressed by adjusting the position of the wafer 2 with respect to the laser beam LB1 so that the outer peripheral surplus area SA is arranged at the irradiation position of the laser beam LB1 when the wafer 2 moves accelerated and decelerated. can do. Therefore, the enlargement of the laser processing apparatus 3 is suppressed.

  In the present embodiment, the chuck table 31 holding the wafer 2 is moved relative to the laser beam application means 32 in the groove forming step. The laser beam application means 32 may move relative to the chuck table 31 holding the wafer 2 or both the chuck table 31 and the laser beam application means 32 may move.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

Reference Signs List 2 wafer 2A front surface 2B back surface 3 laser processing apparatus 3B laser processing apparatus 5 grinding apparatus 6 protective member 8 dividing apparatus 7 dicing tape 9 expanding tape 10 frame 20 substrate 21 functional layer 22 device 23 division planned line 24 bump 25 laser processing groove 26 Material layer 31 Chuck table 31H Holding surface 32 Laser beam application means 33 Imaging means 34 Casing 35 Condenser 37 Moving device 38 Position detection device 39 Display device 40 Control device 41 Arithmetic processing device 42 Memory device 43 I / O interface device 51 Chuck table 51H Holding surface 52 Grinding means 61 Substrate film 62 Adhesive material layer 81 Frame holding means 82 Tape extension means 310 Chuck table 320 Frame holding device 330 Arm member 340 Frame holding member 340 H Top surface 3 50 Clamping Mechanism 521 Spindle Housing 522 Rotating Spindle 523 Mounter 524 Grinding Wheel 525 Base 526 Grinding Wheel DA Device Area SA Peripheral Extra Area LB1 (Absorbable) Laser Beam LB2 (Transmissive) Laser Beam

Claims (1)

A device region in which a plurality of devices having electrodes are formed in a region divided by a planned division line in which a functional layer stacked on the surface of a substrate is formed in a lattice shape, and an outer peripheral surplus region surrounding the device region What is claimed is: 1. A method of processing a wafer, comprising: providing a bump connected to the electrode on the device.
Providing a protective member on the functional layer side of the front surface of the wafer;
A grinding step of grinding the back surface of the wafer to thin the wafer after carrying out the protective member disposing step;
Attaching the dicing tape to the back surface of the wafer after performing the grinding step, and replacing the protective member from the front surface of the wafer;
After carrying out the pasting step, the chuck table holding the wafer while irradiating the laser beam of a wavelength having absorption to the functional layer from the surface side of the wafer along the planned dividing line and the laser beam irradiating means A groove forming step of relatively moving along the planned dividing line, and dividing the functional layer with a laser processing groove along the planned dividing line;
After the groove forming step is performed, the chuck table holding the wafer and the laser beam irradiating means are divided while irradiating the laser beam of a wavelength having transparency to the substrate from the back side of the wafer along the planned dividing line. And d) forming a modified layer which is relatively moved along a predetermined line and which becomes a fracture starting point inside the substrate by a predetermined distance from the back surface of the wafer.
In the groove forming step,
The relative moving speed between the chuck table and the laser beam application means in the outer peripheral excess area is set to a lower speed as it approaches the periphery of the wafer from the inner periphery of the outer peripheral extra area, and the laser processing groove in the outer peripheral excess area is A method of processing a wafer, characterized in that the depth is formed deeper as the edge of the wafer is approached.

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