JP2017183401A - Processing method for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing method for a wafer for forming division starting points along predetermined dividing lines by radiating a laser beam of a wavelength having permeability from a front side of the wafer to the wafer without reducing productivity.SOLUTION: The present invention relates to a processing method for a wafer for dividing a wafer with which multiple devices are formed on a front face divided by predetermined dividing lines, into individual devices. The processing method for the wafer includes at least: a flattening processing step for irradiating the predetermined dividing lines that are formed on the front face of the wafer with a laser beam, applying annealing processing and flattening the front face; a division starting point forming step for positioning a laser beam of a wavelength having permeability with respect to the wafer on the predetermined dividing lines on which the flattening processing has been performed, radiating the laser beam along the predetermined dividing lines and forming division starting points insides; and a wafer dividing step for applying an external force to the wafer and dividing the wafer into individual devices from the division starting points.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wafer processing method in which processing is performed by irradiating a laser beam to a division line from the surface of the wafer, and the wafer is divided into individual devices along the division line.

  A wafer on which a device such as an IC or LSI is partitioned by a division line and is formed on the surface is divided into individual devices by a dicing apparatus having a cutting blade that is rotatable, and is used for an electric device such as a mobile phone or a personal computer.

  In addition, since it is dry and narrow processing is possible, a modified layer serving as a division starting point is formed by irradiating a condensing point of a laser beam having a wavelength that is transmissive to the wafer within an area corresponding to the division line. A technique referred to as internal processing that is formed along the planned division lines and is divided into individual devices by applying an external force to the planned division lines (see, for example, Patent Document 1), or a collection of condensing laser beams. A laser beam having a wavelength that is transparent to the wafer is applied to the division line so that a value obtained by dividing the numerical aperture (NA) of the optical lens by the refractive index of the wafer is a predetermined value, and the surface to be a division starting point is irradiated. A technology for forming pores reaching the back surface and amorphous surrounding the pores, so-called shield tunnels, along the planned dividing line, and applying external force to divide into individual devices (for example, See Patent Document 2.) It has been proposed.

Japanese Patent No. 3408805 JP 2014-2221483 A

  Here, the upper surface of the planned dividing line formed on the surface of the wafer substrate is an uneven surface as a result of various processing, for example, mask processing, etching processing, etc. in the process of forming a device on the wafer substrate. After the device is formed, even if a laser beam having a wavelength that is transmissive to the wafer is irradiated to form the above-described dividing starting point, the laser beam is irradiated on the uneven surface of the surface of the planned dividing line. There is a problem in that it is difficult to perform desired internal processing inside the line to be divided due to irregular reflection. Therefore, in order to deal with this problem, the division starting point is formed by irradiating the laser beam along the planned division line from the back side of the flat wafer on which the device or the like is not formed to the region corresponding to the planned division line. . However, when a laser beam is irradiated from the back side of the wafer to form a split starting point along the planned split line, the front side is irradiated with light having a wavelength that is transparent to the wafer. It is necessary to execute an alignment process in which the division line to be formed is detected by an imaging unit corresponding to the wavelength and aligned with the irradiation position of the laser beam. In addition, after performing the alignment step, it is necessary to perform laser processing to form the division starting point, and after processing from the back surface side of the wafer, it is necessary to hold the wafer surface side upward again in a later step. As a result, there are problems that the number of processes increases and productivity is poor.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is to emit a laser beam having a wavelength that is transparent to the wafer from the surface side of the wafer on which the device is formed without deteriorating the productivity. It is an object of the present invention to provide a wafer processing method for forming a division starting point along a line to be divided by irradiation.

  In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a wafer processing method for dividing a wafer formed on a surface defined by a plurality of division lines into individual devices, the wafer surface comprising: A flattening process step of flattening by irradiating a laser beam to the divisional line formed on the surface and performing an annealing process, and a laser beam having a wavelength having transparency to the wafer is applied to the flattened divisional line. A division starting point forming step of positioning and irradiating along the planned dividing line to form a division starting point inside, and a wafer dividing step of applying an external force to the wafer to divide the wafer into individual devices from the division starting point; A method for processing a wafer is provided.

  The dividing starting point forming step irradiates a condensing point of a laser beam having a wavelength that is transmissive to the wafer within the planned dividing line, and forms a modified layer along the dividing planned line to form the dividing starting point. It can be.

  Further, in the division starting point forming step, a condensing point of a laser beam having a wavelength that is transparent to the wafer is irradiated to the division planned line, and a pore extending from the surface to the back surface and an amorphous surrounding the pore A shield tunnel consisting of a shield tunnel made of can be formed along the planned split line and used as the split starting point.

  According to the wafer processing method of the present invention, there is a flattening process step of flattening by performing an annealing process by irradiating a laser beam to a division line formed on the surface of the wafer, and having transparency to the wafer. A division starting point forming step of positioning a laser beam of a wavelength on the planned division line that has been flattened and irradiating along the planned division line to form a division starting point inside, and applying an external force to the wafer to By dividing the wafer into the individual devices from the division starting point, the division line formed on the surface side of the wafer is flattened and is formed along the division line with respect to the wafer. The split starting point can be formed by irradiating a laser beam with a wavelength having transparency, and it has transparency to the wafer from the back side of the wafer. It is no longer necessary to perform an alignment process using a light source of a wavelength that is required, and it is also necessary to hold the wafer again so that the front side becomes the upper side after performing laser processing to form the division starting point from the back side. And the problem of poor productivity is solved.

The whole perspective view of the laser processing apparatus for implementing the planarization process process and division | segmentation starting point formation process in the processing method of the wafer of this invention. Explanatory drawing for demonstrating the planarization process process of this invention. Explanatory drawing for demonstrating the division | segmentation starting point formation process of this invention. Explanatory drawing for demonstrating the division | segmentation process of this invention. Explanatory drawing for demonstrating another embodiment of the division | segmentation starting point formation process shown in FIG.

  Hereinafter, a wafer processing method according to the present invention will be described in more detail with reference to the accompanying drawings.

  FIG. 1 is an overall perspective view of a laser processing apparatus that executes a flattening process step, a division starting point forming step, which constitute a part of the wafer processing method of the present invention, and a perspective view of a wafer as a workpiece. It is shown. The wafer 10 as a workpiece is made of, for example, a silicon carbide (SiC) substrate, and a plurality of planned dividing lines 12 are formed in a lattice shape on the surface of the wafer 10 having a substantially disc shape. A line 12 divides the surface of the wafer 10 into a plurality of regions. A SAW device 14 is formed in each of the plurality of regions, and the wafer 10 is held by attaching the back side to an adhesive tape T having an outer periphery attached to an annular frame F.

  A laser processing apparatus 40 shown in FIG. 1 includes a base 41, a holding mechanism 42 that holds the workpiece, a moving means 43 that moves the holding mechanism 42, and a laser beam applied to the workpiece held by the holding mechanism 42. Are provided with a laser beam irradiating means 44, an imaging means 45, and a control means (not shown) constituted by a computer, and each means is controlled by the control means.

  The holding mechanism 42 includes a rectangular X-direction movable plate 51 mounted on the base 41 so as to be movable in the X direction, and a rectangular Y-direction movable plate mounted on the X-direction movable plate 51 so as to be movable in the Y direction. 53, a cylindrical column 50 fixed to the upper surface of the Y-direction movable plate 53, and a rectangular cover plate 52 fixed to the upper end of the column 50. The cover plate 52 is formed with a long hole 52a extending in the Y direction. A circular suction chuck 56 made of a porous material and extending substantially horizontally is formed on the upper surface of the chuck table 54 as a holding means for holding a circular workpiece extending upward through the elongated hole 52a. Has been placed. The suction chuck 56 is connected to suction means (not shown) by a flow path passing through the support column 50. A plurality of clamps 58 are arranged on the periphery of the chuck table 54 at intervals in the circumferential direction. Note that the X direction is a direction indicated by an arrow X in FIG. 1, and the Y direction is a direction indicated by an arrow Y in FIG. 1 and is a direction orthogonal to the X direction. The plane defined by the X direction and the Y direction is substantially horizontal.

  The moving means 43 includes an X direction moving means 60, a Y direction moving means 65, and a rotating means (not shown). The X direction moving means 60 has a ball screw 60b extending in the X direction on the base 41 and a motor 60a connected to one end of the ball screw 60b. A nut portion (not shown) of the ball screw 60 b is fixed to the lower surface of the X-direction movable plate 51. The X-direction moving means 60 converts the rotational motion of the motor 60a into a linear motion by the ball screw 60b and transmits it to the X-direction movable plate 51, and moves the X-direction movable plate 51 along the guide rail 43a on the base 41. Advance and retreat in the X direction. The Y direction moving means 65 includes a ball screw 65b extending in the Y direction on the X direction movable plate 51, and a motor 65a connected to one end of the ball screw 65b. A nut portion (not shown) of the ball screw 65 b is fixed to the lower surface of the Y-direction movable plate 53. Then, the Y-direction moving means 65 converts the rotational motion of the motor 65a into a linear motion by the ball screw 65b, transmits it to the Y-direction movable plate 53, and moves in the Y-direction along the guide rail 51a on the X-direction movable plate 51. The plate 53 is advanced and retracted in the Y direction. The rotating means is built in the column 50 and rotates the suction chuck 56 with respect to the column 50.

  The laser beam irradiation means 44 is built in a frame 46 that extends upward from the upper surface of the base 41 and then extends substantially horizontally. The laser beam irradiating means 44 irradiates a laser beam along the upper surface of the division line 12 of the wafer 10 that is a workpiece, thereby heating and melting the surface to flatten the upper surface. The first laser beam irradiating means for irradiating the laser beam and the condensing point of the laser beam having a wavelength that is transmissive to the wafer 10 are positioned inside the planned division line 12 for irradiation, and along the planned division line 12 A second laser beam irradiating means for irradiating a laser beam for forming a modified layer and performing a split starting point forming step as the split starting point (not shown). Then, it was oscillated from one of the first and second laser beam irradiation means by appropriately switching between irradiation from the first laser beam irradiation means or irradiation from the second laser beam irradiation means. The laser beam is configured to be able to irradiate the wafer 10 held on the chuck table 54 via the condenser 44a.

  The laser processing apparatus 40 in the present embodiment includes a control unit (not shown). The control unit is configured by a computer and stores a central processing unit (CPU) that performs arithmetic processing according to a control program, a control program, and the like. A read-only memory (ROM), a read / write random access memory (RAM) for temporarily storing detected values, calculation results, and the like, an input interface, and an output interface are provided. In addition to the image signal from the imaging unit 45, a signal from an X direction and Y direction position detection unit (not shown) of the holding mechanism 42 is input to the input interface of the control unit. Further, an operation signal is transmitted from the output interface toward the first and second laser beam irradiation means, the X direction moving means 60, the Y direction moving means 65, and the like.

  The imaging means 45 is attached to the lower surface of the front end of the frame body 46, is located above the guide rail 43a, and is to be processed placed on the chuck table 54 by moving the chuck table 54 along the guide rail 43a. An object can be imaged. Note that the imaging means 45 of the present embodiment is configured by an imaging element (CCD) (not shown) that images the surface of the workpiece with visible light.

  The wafer processing method executed according to the present invention will be further described in order. First, as shown in FIG. 1, a wafer in which a SAW device 14 is formed in each region partitioned by a plurality of division lines 12 formed in a lattice shape and held on an annular frame F via an adhesive tape T. 10 is prepared. Then, the wafer 10 is placed on the chucking chuck 56 of the chuck table 54 with the adhesive tape T side down, the annular frame F is held by the clamp 58, and a suction means (not shown) is operated to make the negative. The pressure is applied to the suction chuck 56 to suck and hold the wafer 10. Although the surface of the wafer 10 is formed flat by polishing or the like before the SAW device 14 is formed on the surface, the surface of the wafer 10 is subjected to a mask process or the like performed in the process of forming the device. An uneven surface is formed on the upper surface of the planned dividing line 12. Further, the division line 12 formed on the surface of the wafer 10 is formed with a width of about 50 μm.

  If the wafer 10 is sucked and held on the suction chuck 56, the X-direction moving means 60 and the Y-direction moving means 65 are operated to move the chuck table 54, and the wafer 10 is positioned directly below the imaging means 45. When the chuck table 54 is positioned immediately below the image pickup means 45, the image pickup means 45 and a control means (not shown) execute an alignment process for detecting a region to be laser processed in a flattening process and a division starting point forming process described later. To do. That is, the image pickup means 45 and the control means include the division line 12 formed in a predetermined direction of the wafer 10 and the condenser 44a of the laser beam irradiation means 44 that irradiates the laser beam along the division line 12. Image processing such as pattern matching for alignment is executed to align the laser beam irradiation position. A similar alignment process is also performed along the planned division line 12 formed in a direction orthogonal to the predetermined direction.

  If the alignment process described above is executed, the chuck table 54 is moved to the laser beam irradiation area where the condenser 44a is located, and one end of the planned dividing line 12 formed in a predetermined direction is directly below the condenser 44a. Position to be. Then, a condensing point position adjusting unit (not shown) is operated to move the concentrator 44 a in the optical axis direction, and the condensing point is positioned at the surface height position of the planned dividing line 12.

  As described above, the laser beam irradiation means 44 of the present embodiment includes the first and second laser beam irradiation means. First, a flattening process step of flattening the upper surface of the division planned line 12 is performed. Accordingly, the laser beam is set to be irradiated by the first laser beam irradiation means.

The flattening process performed by the first laser beam irradiation means is performed under the following laser processing conditions, for example.
Wavelength: 1064nm
Light source: Continuous wave (CW)
Output: 40W
Spot diameter: φ50μm
Processing feed rate: 300 mm / sec

  When the above-described focusing point is positioned, the first laser beam irradiating means is operated, and the laser beam is irradiated to the planned dividing line 12 formed on the surface of the wafer 10 based on the laser processing conditions described above. Then, an annealing process for heating the surface is performed. More specifically, when laser beam irradiation is started under the above-described processing conditions, the X-direction moving unit 60 is operated to move the chuck table 54 in the direction indicated by the arrow X in FIG. Then, the laser beam is irradiated along the division line 12. As described above, the spot diameter of the laser beam irradiated by the first laser beam irradiation means is set to φ50 μm, and the diameter dimension is a value that matches the line width of the planned dividing line 12 formed on the wafer 10. It has become. In addition, the laser beam output and the processing feed rate are determined in consideration of the spot diameter set based on the width of the planned division line 12, and the planned division line of the wafer 10 formed of silicon carbide (SiC) is destroyed. Instead, it is set to a value in such a range that the upper surface is flattened by melting by heating and then re-solidifying. Then, by operating the first laser beam irradiation means, the chuck table 54, the X direction moving means 60, and the Y direction moving means 65, the upper surfaces of all the division lines 12 formed on the surface of the wafer 10 are flattened. (See FIG. 2), a flattened division line 12 'is formed, and the flattening process for the wafer 10 is completed.

  When the flattening process is completed, a split start point forming step for forming a modified layer 110 serving as a split start point along the flattened split planned line 12 ′ is performed inside the wafer 10. More specifically, the laser beam irradiation by the first laser beam irradiation unit disposed in the laser beam irradiation unit 44 of the laser processing apparatus 40 shown in FIG. 1 is stopped, and the second laser beam irradiation unit is started. Then, a laser beam having a wavelength that is transmissive to the wafer 10 is oscillated by a laser oscillator disposed in the second laser beam irradiation means, and a condensing point is positioned inside the wafer 10 via the condenser 44a. Then, the laser beam is irradiated along the flattened division line 12 ′, the X direction moving means 60 is operated, and the chuck table 54 is moved in the direction indicated by the arrow X in FIG. Move. Then, the above-described control means controls the laser beam irradiation means 44, the X-direction moving means 60, the Y-direction moving means 65, the rotating means for rotating the suction chuck 56, etc. A modified layer 110 serving as a division starting point is formed along (see FIG. 3B).

  Here, as described above, the upper surface of the planned dividing line 12 ′ is flattened by performing the flattening process and melting and resolidifying. Therefore, a laser beam having a wavelength that is transmissive to the wafer 10 is transmitted without being irregularly reflected on the upper surface of the division line 12 ′, and a desired modified layer 110 is formed at a height position set inside the wafer 10. Can be formed.

In addition, the division | segmentation starting point formation process performed by the said 2nd laser beam irradiation means is implemented on the following laser processing conditions, for example.
Wavelength: 1340nm
Average output: 1W
Repetition frequency: 50 kHz
Pulse width: 1 ns
Spot diameter: φ1μm
Numerical aperture: 0.8
Processing feed rate: 100 mm / sec

  If the division start point forming step is executed, a wafer dividing step for dividing the device into individual devices is executed. The dividing step is performed by a dividing device 70, a part of which is shown in FIG. 4. The dividing device 70 mounts a frame holding member 71 and an annular frame F on the upper surface thereof, and A clamp 72 for holding the annular frame F and an expansion drum 73 having a cylindrical shape opened at least upward for expanding the wafer 10 mounted on the annular frame F held by the clamp 72 are provided. . The frame holding member 71 is supported by a support means 723 configured to include a plurality of air cylinders 723a installed so as to surround the expansion drum 73 and piston rods 723b extending from the air cylinders 723a.

  The expansion drum 73 is set to be smaller than the inner diameter of the annular frame F and larger than the outer diameter of the wafer 10 attached to the adhesive tape T attached to the frame F of the annular frame F. Here, as shown in FIG. 4, the separating device 70 includes a frame holding member 71, a position (shown by a dotted line) where the upper surface portion of the expansion drum 73 is substantially at the same height, and the support means 723. The holding member 71 is lowered, and the upper end portion of the expansion drum 73 can be at a position (shown by a solid line) that is higher than the upper end portion of the frame holding member 71.

  When the frame holding member 71 is lowered and the upper end of the expansion drum 73 is relatively changed from the position indicated by the dotted line to a position higher than the frame holding member 71 indicated by the solid line, the annular frame F is formed. The attached adhesive tape T is pushed and expanded by the upper end edge of the expansion drum 73. As a result, since the tensile force acts radially on the wafer 10 adhered to the adhesive tape T, the individual modified layers 110 are formed along the planned dividing lines 12 'in the above-described dividing starting point forming step. The interval between the SAW devices 14 is increased. Then, in a state where the intervals between the individual SAW devices 14 are widened, the pickup collet 74 is operated to suck the SAW devices 14 in a state where the intervals are widened, and peels off and picks up from the adhesive tape T, not shown. It is transported to a tray or a processing device for the next process. Thus, the dividing step is completed, and the wafer processing method according to the present invention is completed. In addition, the division | segmentation process which provides external force is not limited to the said means, It is also possible to add another means further. For example, in the above-described dividing step, a resin roller positioned parallel to the planned dividing line 12 ′ is pressed from above on the upper surface of the wafer 10 held on the adhesive tape T to roll on the surface of the wafer 10. You may make it divide | segment along the division | segmentation planned line 12 'by moving and applying the downward force of the wafer 10. FIG.

  The present invention is not limited to this embodiment, and various modifications can be employed. For example, the second laser beam irradiation means in the division starting point forming step described above is configured to form the modified layer 110 by irradiating the laser beam along the planned division line 12 ′. Instead, FIG. As shown in FIG. 2, the condensing point of a laser beam having a wavelength that is transmissive to the wafer 10 is irradiated to the flattened division line 12 ′, and the pores 121 extending from the front surface side to the back surface side of the wafer 10. You may make it form the shield tunnel 120 which consists of the amorphous | non-crystalline substance 122 surrounding this pore along the division | segmentation planned line 12 '. Below, another embodiment of the division | segmentation origin formation process which forms the shield tunnel 120 as a division | segmentation origin is demonstrated.

  First, in the same manner as the division starting point forming step for forming the modified layer 110 described above, there is an alignment step for aligning the processing region of the division planned line 12 formed in a predetermined direction of the wafer 10 with the laser beam irradiation position. Further, a flattening process step is performed to flatten the upper surface of the planned dividing line 12 and form a flattened divided planned line 12 ′.

  When the flattening process is performed, the chuck table 54 is moved to the laser beam irradiation region where the condenser 44a is located, and one end of the planned dividing line 12 formed in a predetermined direction is directly below the condenser 44a. Position to be. Then, the condensing point position adjusting means (not shown) is operated to move the concentrator 44a in the optical axis direction, and the chuck table 54 is moved to the laser beam irradiation region where the concentrator 44a for irradiating the laser beam is positioned. It moves and positions one end part of the predetermined division | segmentation scheduled line 12 'so that it may be located just under the collector 44a. Then, the condensing point position adjusting means (not shown) is operated so that the condensing point of the pulse laser beam condensed by the condensing lens of the condenser 44a is positioned at a desired position in the thickness direction of the wafer 10. The device 44a is moved in the optical axis direction. Note that the condensing point P of the pulse laser beam in the present embodiment is set at a predetermined position adjacent to the back surface side where the pulse laser beam is incident on the wafer 10 as shown in FIG.

  As described above, when the wafer 10 is positioned at the condensing point position, as shown in FIGS. 5A and 5B, the second laser beam irradiation in which the processing conditions are set to form the shield tunnel 120 is used. The means is operated to irradiate a pulsed laser beam from the condenser 44a, and a fine point is formed between the condensing point positioned in the wafer 10 and the surface side and the back side of the division planned line 12 'where the pulsed laser beam is incident. While forming the shield tunnel 120 (see FIG. 5C) composed of the hole 121 and the amorphous 122 that shields the pore, the chuck table 54 is fed in a predetermined direction in the direction indicated by the arrow X in FIG. Move at speed. When the other end of the planned dividing line 12 ′ reaches the irradiation position of the condenser 44a, the irradiation of the pulse laser beam is stopped and the movement of the chuck table 54 is stopped. Then, the above-described control means controls the laser beam irradiation means 44, the X direction moving means 60, the Y direction moving means 65, the rotating means for rotating the suction chuck 56, etc., and divides along all the planned division lines 12 ′. A shield tunnel 120 as a starting point is formed. Once the shield tunnel 120 serving as the division starting point is formed for all the division planned lines 12 ′, the division process shown in FIG. 4 is performed to divide the individual SAW devices 14 as in the above-described embodiment. .

The laser processing conditions for performing the above-described split starting point forming step for forming the shield tunnel 120 are set as follows, for example.
Wavelength: 1030 nm
Average output: 3W
Repetition frequency: 50 kHz
Pulse width: 10 ps
Spot diameter: φ1μm
Numerical aperture / refractive index: 0.05-0.20
Processing feed rate: 500 mm / sec Shield tunnel: φ1 μm pore, φ10 μm amorphous

In the present embodiment, as described above, as an example of the flattening process for flattening the upper surface by irradiating a laser beam to the division line, an example of irradiating a continuous wave (CW) having a wavelength of 1064 nm is shown. However, the present invention is not limited to this, and various laser beams can be selected as long as the laser beam is in a condition that is heated and melted and then flattened by re-solidifying the surface. It is good also as irradiating a suitable laser beam. Note that the spot shape width (50 μm) is set to match the width dimension of the wafer division line, and the average output, repetition frequency, and energy density are melted without breaking the upper surface of the division line. Then, the value to be flattened is obtained and set by experiments or the like.
Wavelength: 308nm
Light source: Excimer laser Average output: 100W
Repeat frequency: 1kHz
Energy density: 0.5 J / cm ²
Spot shape: width 50 μm, length 100 mm
(Line beam using diffraction optical elements)

In this embodiment, the case where the wafer substrate to be processed is formed of silicon carbide (SiC) is shown, but the present invention is not limited to this, and lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO _3). It can also be applied to a substrate such as In the present embodiment, the SAW device is shown as a device formed on the wafer substrate. However, the present invention is not limited to this, and the present invention can also be applied to the case where an optical device such as an LED is formed. In addition, since the conditions for heating and melting differ depending on the material of the wafer substrate, the laser processing conditions performed in the above-described planarization process are appropriately determined according to the material of the selected wafer substrate. .

  Further, in the present embodiment, a first laser beam irradiation means for performing a flattening process step of flattening by irradiating a laser beam to a division planned line, and a laser beam having a wavelength that is transmissive to the wafer. A second laser beam irradiating means for performing a split starting point forming step of irradiating along the planned split line that has been flattened and irradiating along the planned split line and forming a split starting point therein, Although it is arranged in the apparatus and is appropriately switched to irradiate the wafer with the laser beam, the present invention is not limited to this, and the first laser beam irradiation unit and the second laser beam irradiation unit are provided. A laser processing apparatus that is provided in a separate laser processing apparatus and that exclusively performs the flattening process by the first laser beam irradiation means, and a second laser processing apparatus. A laser processing apparatus for exclusively performing the division start point forming step by Heather beam application means may be constituted by.

10: Wafer 12: Planned division line 14: SAW device 40: Laser processing apparatus 42: Holding mechanism 43: Moving means 44: Laser beam irradiation means 45: Imaging means 54: Chuck table 70: Dividing apparatus 110: Modified layer 120: Shield tunnel

Claims (3)

A wafer processing method for dividing a wafer formed on a surface defined by a plurality of devices by dividing lines into individual devices,
A flattening treatment step of flattening by performing annealing treatment by irradiating a laser beam to the planned division line formed on the surface of the wafer;
A division starting point forming step of forming a division starting point inside by irradiating a laser beam having a wavelength having transparency with respect to the wafer on the division dividing line that has been flattened and irradiating along the dividing planned line;
A wafer dividing step of applying an external force to the wafer to divide the wafer into individual devices from a division starting point;
A method for processing a wafer comprising at least   The dividing starting point forming step irradiates a condensing point of a laser beam having a wavelength that is transmissive to the wafer within the planned dividing line, and forms a modified layer along the dividing planned line to form the dividing starting point. The wafer processing method according to claim 1, wherein:   The split starting point forming step includes a condensing point of a laser beam having a wavelength that is transparent to the wafer and irradiating the planned split line with a pore extending from the surface to the back surface and an amorphous surrounding the pore. The wafer processing method according to claim 1, wherein a shield tunnel including a shield tunnel is formed along a planned division line and used as the division starting point.