JP5495876B2 - Processing method of optical device wafer - Google Patents

Description

  The present invention relates to an optical device wafer in which optical devices are formed in a plurality of regions partitioned by a plurality of streets formed by laminating optical device layers on the surface of a substrate, and each optical device along the streets. The present invention relates to a method for processing an optical device wafer to be divided into two.

  In the optical device manufacturing process, an optical device layer made of a gallium nitride compound semiconductor is laminated on the surface of a substantially disc-shaped sapphire substrate or silicon carbide substrate, and is partitioned by a plurality of streets formed in a lattice shape. Optical devices such as light emitting diodes and laser diodes are formed in the region to constitute an optical device wafer. Then, the optical device wafer is cut along the streets to divide the region where the optical device is formed to manufacture individual optical devices.

  The above-mentioned cutting along the street of the optical device wafer is usually performed by a cutting device called a dicer. The cutting apparatus includes a chuck table for holding a workpiece, a cutting means for cutting the workpiece held on the chuck table, and a cutting feed means for relatively moving the chuck table and the cutting means. It has. The cutting means includes a rotary spindle, a cutting blade mounted on the spindle, and a drive mechanism that rotationally drives the rotary spindle. The cutting blade is composed of a disk-shaped base and an annular cutting edge mounted on the outer periphery of the side surface of the base. The cutting edge is fixed to the base by electroforming, for example, diamond abrasive grains having a particle size of about 3 μm. It is formed to a thickness of about 20 μm.

  However, since the sapphire substrate, the silicon carbide substrate and the like constituting the optical device wafer have high Mohs hardness, cutting with the cutting blade is not always easy. Therefore, the cutting amount of the cutting blade cannot be increased, and the optical device wafer is cut by performing the cutting process a plurality of times, so that the productivity is poor.

  In order to solve the above-mentioned problems, as a method of dividing the optical device wafer along the street, laser processing that becomes the starting point of breakage by irradiating the wafer with a pulsed laser beam having a wavelength that absorbs the wafer. There has been proposed a method of forming a groove and cleaving it by applying an external force along the street where the laser-processed groove that is the starting point of the fracture is formed. (For example, refer to Patent Document 1.)

JP-A-10-305420

  However, when a laser processing groove is formed by irradiating a laser beam having an absorptive wavelength to the sapphire substrate along the street formed on the surface of the sapphire substrate constituting the optical device wafer, an optical device such as a light-emitting diode is formed. There is a problem in that a denatured substance generated during laser processing adheres to the side wall surface, the luminance of the optical device is lowered, and the quality of the optical device is lowered.

  The present invention has been made in view of the above facts, and its main technical problem is to provide an optical device wafer processing method that can be divided into individual optical devices without degrading the quality of the optical device. is there.

In order to solve the above main technical problem, according to the present invention, an optical device in which an optical device is formed in a plurality of regions partitioned by a plurality of streets formed by laminating an optical device layer on a surface of a substrate and forming a lattice shape. An optical device wafer processing method for dividing a wafer into individual optical devices along a street,
A laser processing groove forming step of irradiating a laser beam of a wavelength having an absorptivity with respect to the substrate of the optical device wafer along the street to form a laser processing groove serving as a fracture base point on the front surface or the back surface of the substrate;
It is generated at the time of laser processing groove formation by positioning a cutting blade mainly composed of diamond abrasive grains in the laser processing groove formed on the substrate, and rotating the cutting blade relative to the wall surface of the laser processing groove while scratching. The altered material removal step of removing the altered material and processing the wall surface of the laser processing groove into a rough surface,
A wafer dividing step of applying an external force to the optical device wafer, breaking the optical device wafer along the processed groove from which the degenerated material is removed, and dividing the wafer into individual optical devices.
An optical device wafer processing method is provided.

The laser processing groove forming step irradiates a laser beam along the street from the back surface side of the substrate to form a laser processing groove on the back surface of the substrate.
Also, the optical device layer of the optical device wafer with the laser processing groove formed on the back side of the substrate is cut along the street using a cutting blade mainly composed of diamond abrasive grains, and the optical device layer is separated along the street. It is desirable to perform the optical device layer separation process.

  In the method of processing an optical device wafer according to the present invention, a laser processing groove forming step is performed, and a cutting blade mainly composed of diamond abrasive grains is positioned in a laser processing groove formed on the substrate of the optical device wafer, and the cutting blade is rotated. However, by moving relative to the wall surface of the laser processed groove while removing, the altered material generated at the time of forming the laser processed groove is removed and the altered material removing process for processing the wall surface of the laser processed groove into a rough surface is performed. Individually divided optical devices are processed into a rough surface in addition to the removal of denatured materials that cause the substrate's side walls to absorb light and reduce brightness, so that light is effectively emitted. Brightness is improved.

The perspective view and principal part expanded sectional view which show the optical device wafer processed according to the processing method of the optical device wafer by this invention. Explanatory drawing of the protection member sticking process in the processing method of the optical device wafer by this invention. The principal part perspective view of the laser processing apparatus for implementing the laser processing groove | channel formation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the laser processing groove | channel formation process in the processing method of the optical device wafer by this invention. The principal part perspective view of the cutting device for implementing the altered substance removal process in the processing method of the optical device wafer by this invention. Explanatory drawing of the altered substance removal process in the processing method of the optical device wafer by this invention. Explanatory drawing of the wafer support process in the processing method of the optical device wafer by this invention. Explanatory drawing of the optical device layer separation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the optical device layer separation process in the processing method of the optical device wafer by this invention. The perspective view of the tape expansion apparatus for implementing the wafer division | segmentation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the wafer division | segmentation process in the processing method of the optical device wafer by this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a method for processing an optical device wafer according to the present invention will be described in detail with reference to the accompanying drawings.

  1A and 1B show a perspective view of an optical device wafer processed in accordance with the optical device wafer processing method according to the present invention and a cross-sectional view showing an enlarged main part. An optical device wafer 2 shown in FIGS. 1A and 1B has a light emitting layer (epilayer) 21 as an optical device layer made of a nitride semiconductor on a surface 20a of a sapphire substrate 20 having a thickness of 100 μm, for example. It is laminated by thickness. An optical device 23 such as a light emitting diode or a laser diode is formed in a plurality of regions partitioned by a plurality of streets 22 in which a light emitting layer (epi layer) 21 is formed in a lattice shape. Hereinafter, a processing method for dividing the optical device wafer 2 into the individual optical devices 23 along the streets 22 will be described.

  First, in order to protect the optical device 23 formed on the surface 20a of the sapphire substrate 20 constituting the optical device wafer 2, a protective member attaching step for attaching a protective member to the surface 2a of the optical device wafer 2 is performed. . That is, as shown in FIG. 2, a protective tape 3 as a protective member is attached to the surface 2a of the optical device wafer 2. In the embodiment shown in the drawing, the protective tape 3 has an acrylic resin paste of about 5 μm thick on the surface of a sheet base material made of polyvinyl chloride (PVC) having a thickness of 100 μm.

  If the protective tape 3 is stuck on the surface 2a of the optical device wafer 2 by carrying out the protective member sticking step described above, a laser beam having a wavelength that absorbs the substrate of the optical device wafer along the street. Irradiation is performed, and a laser processing groove forming step for forming a laser processing groove serving as a fracture base point is performed. This laser processing groove forming step is performed using the laser processing apparatus 4 shown in FIG. A laser processing apparatus 4 shown in FIG. 3 includes a chuck table 41 that holds a workpiece, laser beam irradiation means 42 that irradiates a workpiece held on the chuck table 41 with a laser beam, and a chuck table 41 that holds the workpiece. An image pickup means 43 for picking up an image of the processed workpiece is provided. The chuck table 41 is configured to suck and hold the workpiece. The chuck table 41 is moved in a processing feed direction indicated by an arrow X in FIG. 3 by a processing feed means (not shown) and is also shown in FIG. It can be moved in the index feed direction indicated by the arrow Y.

  The laser beam application means 42 includes a cylindrical casing 421 arranged substantially horizontally. In the casing 421, pulse laser beam oscillation means including a pulse laser beam oscillator and repetition frequency setting means (not shown) are arranged. A condenser 422 for condensing the pulse laser beam oscillated from the pulse laser beam oscillating means is attached to the tip of the casing 421. The laser beam irradiating unit 42 includes a condensing point position adjusting unit (not shown) for adjusting the condensing point position of the pulsed laser beam condensed by the condenser 422.

  The image pickup means 43 attached to the tip of the casing 421 constituting the laser beam irradiation means 42 includes an illumination means for illuminating the workpiece, an optical system for capturing an area illuminated by the illumination means, and the optical system. An image pickup device (CCD) or the like for picking up the captured image is provided, and the picked-up image signal is sent to a control means (not shown).

Laser that irradiates the sapphire substrate 20 constituting the optical device wafer 2 with a laser beam having an absorptive wavelength along the street using the laser processing apparatus 4 described above to form a laser processing groove serving as a fracture base point. The process groove forming step will be described with reference to FIGS. 3 and 4.
First, the protective tape 3 attached to the surface of the optical device wafer 2 is placed on the chuck table 41 of the laser processing apparatus 4 shown in FIG. Then, the optical device wafer 2 is held on the chuck table 41 via the protective tape 3 by operating a suction means (not shown) (wafer holding step). Accordingly, in the optical device wafer 2 held on the chuck table 41, the back surface 20b of the sapphire substrate 20 is on the upper side. In this way, the chuck table 41 that sucks and holds the optical device wafer 2 is positioned directly below the imaging unit 43 by a processing feed unit (not shown).

  When the chuck table 41 is positioned immediately below the image pickup means 43, an alignment operation for detecting a processing region to be laser processed of the optical device wafer 2 is executed by the image pickup means 43 and a control means (not shown). That is, the image pickup means 43 and the control means (not shown) are arranged between the street 22 formed in a predetermined direction of the optical device wafer 2 and the position of the condenser 422 of the laser beam irradiation means 42 that irradiates the laser beam along the street 22. Image processing such as pattern matching for alignment is executed, and alignment of the laser beam irradiation position is performed (alignment process). Similarly, alignment of the laser beam irradiation position is performed on the street 22 formed on the optical device wafer 2 in a direction orthogonal to the predetermined direction. At this time, although the surface of the light emitting layer (epi layer) 21 on which the streets 22 are formed in the optical device wafer 2 is positioned on the lower side, the sapphire substrate 20 constituting the optical device wafer 2 is a transparent body. The street 22 can be imaged from the back surface 20b side of the sapphire substrate 20.

  If the street 22 formed on the surface of the light emitting layer (epi layer) 21 constituting the optical device wafer 2 held on the chuck table 41 is detected as described above, and the alignment of the laser beam irradiation position is performed. For example, as shown in FIG. 4A, the chuck table 41 is moved to the laser beam irradiation region where the condenser 422 of the laser beam irradiation means 42 is located, and one end of the predetermined street 22 (the left end in FIG. 4A). ) Is positioned immediately below the condenser 422 of the laser beam irradiation means 42. And the condensing point P of the pulse laser beam irradiated from the collector 422 is matched with the back surface 20b (upper surface) of the sapphire substrate 20 which comprises the optical device wafer 2. FIG. Next, the chuck table 41 is moved at a predetermined processing feed rate in the direction indicated by the arrow X1 in FIG. 4A while irradiating the sapphire substrate 20 with a pulsed laser beam having an absorptive wavelength from the condenser 422. Let me. 4B, when the irradiation position of the condenser 422 of the laser beam irradiation means 42 reaches the position of the other end of the street 22 (the right end in FIG. 4B), the pulse laser beam irradiation is performed. And the movement of the chuck table 41 is stopped. As a result, on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2, a continuous laser processing groove 201 along the street 22 is formed as shown in FIG. 4 (b) and FIG. 4 (c). (Laser processing groove forming process). Note that, as shown in FIG. 4C, the altered material 202 generated at the time of forming the laser processing groove adheres to the wall surface of the laser processing groove 201.

The processing conditions in the laser processing groove forming step are set as follows, for example.
Light source: Semiconductor pumped solid-state laser (Nd: YAG)
Wavelength: 355 nm pulse laser Pulse energy: 35 μJ
Pulse width: 180ns
Repetition frequency: 100 kHz
Condensing spot diameter: φ10μm
Processing feed rate: 60 mm / second Groove depth: 15 μm

  When the laser processing groove forming step is performed along all the streets 22 extending in the predetermined direction of the optical device wafer 2 as described above, the chuck table 41 is rotated by 90 degrees to perform the predetermined direction. The laser processing groove forming step is performed along each street 22 formed in a direction orthogonal to the direction.

  If the laser processing groove forming process described above is performed, a cutting blade mainly composed of diamond abrasive grains is positioned in the laser processing groove formed on the substrate, and the wall of the laser processing groove is moved relative to the laser processing groove while rotating the cutting blade. By moving, an altered substance removing step of removing the altered substance generated at the time of forming the laser machined groove and machining the wall surface of the laser machined groove into a rough surface is performed. In the illustrated embodiment, this altered substance removing step is performed using a cutting device 5 shown in FIG. The cutting device 5 shown in FIG. 5 includes a chuck table 51 that holds a workpiece, a cutting means 52 that cuts the workpiece held on the chuck table 51, and a workpiece held on the chuck table 51. The image pickup means 53 for picking up images is provided. The chuck table 51 is configured to suck and hold a workpiece. The chuck table 51 is moved in a cutting feed direction indicated by an arrow X in FIG. 5 by a cutting feed means (not shown) and is indicated by an arrow Y by an index feed means (not shown). It can be moved in the index feed direction shown.

  The cutting means 52 includes a spindle housing 521 arranged substantially horizontally, a rotating spindle 522 rotatably supported on the spindle housing 521, and a cutting blade 523 mounted on the tip of the rotating spindle 522. The rotating spindle 522 is rotated in the direction indicated by the arrow 523a by a servo motor (not shown) disposed in the spindle housing 521. In the illustrated embodiment, the cutting blade 523 is an electroformed blade obtained by solidifying diamond abrasive grains having a particle diameter of 3 μm by nickel plating, and has a thickness of 20 μm. The imaging means 53 is attached to the tip of the spindle housing 521, and illuminates the work piece, an optical system that captures an area illuminated by the illumination means, and an image captured by the optical system. An image pickup device (CCD) or the like for picking up images is provided, and the picked-up image signal is sent to a control means (not shown).

  In order to carry out the altered substance removing step using the cutting device 5 described above, it was stuck on the surface of the optical device wafer 2 on which the laser processing groove forming step was carried out on the chuck table 51 as shown in FIG. Place the protective tape 3 side. Then, by operating a suction means (not shown), the optical device wafer 2 is held on the chuck table 51 via the protective tape 3 (wafer holding step). Accordingly, in the optical device wafer 2 held on the chuck table 51, the back surface 20b of the sapphire substrate 20 is on the upper side. In this way, the chuck table 51 that sucks and holds the optical device wafer 2 is positioned directly below the imaging means 53 by a cutting feed means (not shown).

  When the chuck table 51 is positioned immediately below the image pickup means 53, an alignment operation for detecting a region to be processed of the optical device wafer 2 is executed by the image pickup means 53 and a control means (not shown). In other words, the imaging unit 53 and the control unit (not shown) perform alignment between the laser processing groove 201 formed in the predetermined direction on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 and the cutting blade 523. (Alignment process). In addition, alignment of the processing region is similarly performed on the laser processing groove 201 formed on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 in a direction orthogonal to the predetermined direction.

  When the alignment for detecting the processing region of the optical device wafer 2 held on the chuck table 51 is performed as described above, the chuck table 51 holding the optical device wafer 2 by suction is moved below the cutting blade 523. Move to the machining start position of a certain machining area. Then, as shown in FIG. 6A, one end (the left end in FIG. 6A) of the laser processing groove 201 to be processed of the optical device wafer 2 is positioned to the right by a predetermined amount from directly below the cutting blade 523. (Processing feed start position positioning step). When the optical device wafer 2 is positioned at the machining start position of the machining area in this way, the cutting blade 523 is rotated in the direction indicated by the arrow 523a and from the standby position indicated by the two-dot chain line in FIG. The feed is cut downward and positioned at a predetermined cut feed position as shown by the solid line in FIG. The cutting feed position is set such that the lower end of the outer peripheral edge of the cutting blade 523 is, for example, 20 μm below the back surface 20 b (upper surface) of the sapphire substrate 20 constituting the optical device wafer 2.

  Next, as shown in FIG. 6A, the cutting blade 523 is rotated at a predetermined rotational speed (for example, 20000 rpm) while rotating in the direction indicated by the arrow 523a, and the chuck table 51, that is, the optical device wafer 2 is rotated as shown in FIG. In (a), processing feed is performed at a predetermined processing feed speed in the direction indicated by the arrow X1 (modified substance removing step). In the altered substance removing step, the cutting blade 523 moves relative to the laser processing groove 201 while razing. As a result, the thickness (20 μm) of the cutting blade 523 is set to be thicker than the width of the laser processing groove 201 (formed by a pulse laser beam having a focused spot diameter of φ10 μm). As shown in FIG. 6, the altered material 202 adhering to the wall surface of the laser processed groove 201 is removed, and a processed groove 203 having a rough wall surface is formed as shown in FIG. In this denatured substance removing step, the cutting blade 523 processes the denatured substance 202 adhering to the wall surface of the laser machining groove 201 while razoring, so that the denatured substance 202 can be easily removed and the laser machined groove 201 is removed. Can be easily formed into a rough surface. When the chuck table 51, that is, the other end of the optical device wafer 2 (the right end in FIG. 6B) reaches a predetermined amount to the left of the cutting blade 523, the movement of the chuck table 51 is stopped. Then, the cutting blade 523 is raised and positioned at the retreat position indicated by the two-dot chain line.

The processing conditions in the altered substance removing step are set as follows, for example.
Cutting blade: Electroforming blade of diamond abrasive with a thickness of 20 μm Cutting depth: 20 μm
Processing feed rate: 60 mm / sec

  As described above, when the denatured substance removing step is performed along all the streets 22 extending in the predetermined direction of the optical device wafer 2, the chuck table 51 is rotated by 90 degrees in the predetermined direction. The altered substance removing step is performed along each laser processing groove 201 formed in a direction perpendicular to the laser processing groove 201.

  If the altered substance removing step is performed as described above, the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 is attached to the surface of the dicing tape mounted on the annular frame and the surface of the optical device wafer 2 is attached. A wafer supporting step for peeling off the protective member attached to the wafer is carried out. That is, as shown in FIGS. 7A and 7B, the sapphire substrate that constitutes the optical device wafer 2 on the surface of the dicing tape 7 with the outer peripheral portion mounted so as to cover the inner opening of the annular frame 6. The back surface 20b of 20 is stuck. Then, the protective tape 3 attached to the surface 2a of the optical device wafer 2 is peeled off.

Next, an optical device layer separation step is performed in which the light emitting layer (epi layer) 21 as an optical device layer formed by being laminated on the surface 20 a of the sapphire substrate 20 constituting the optical device wafer 2 is separated along the streets 22. To do. This optical device layer separation step can be performed using the cutting device 5 shown in FIG.
In order to carry out the optical device layer separation step using the cutting device 5 described above, the dicing tape 7 in which the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 is adhered on the chuck table 51 as shown in FIG. The optical device wafer 2 is sucked and held on the chuck table 51 by operating a suction means (not shown). Therefore, the surface 2a of the optical device wafer 2 held on the chuck table 51 is on the upper side. In FIG. 8, the annular frame 6 on which the dicing tape 7 is mounted is omitted, but the annular frame 6 is fixed by a clamping mechanism disposed on the chuck table 51. In this way, the chuck table 51 that sucks and holds the optical device wafer 2 is positioned directly below the imaging means 53 by a cutting feed means (not shown).

  When the chuck table 51 is positioned immediately below the image pickup means 53, an alignment operation for detecting a region to be processed of the optical device wafer 2 is executed by the image pickup means 53 and a control means (not shown). That is, the imaging unit 53 and a control unit (not shown) perform alignment for aligning the street 22 formed in the predetermined direction on the surface 2a of the optical device wafer 2 and the cutting blade 523 (alignment process). In addition, the alignment of the processing region is similarly performed on the street 22 formed on the surface 2a of the optical device wafer 2 in a direction orthogonal to the predetermined direction.

  When the alignment for detecting the processing region of the optical device wafer 2 held on the chuck table 51 is performed as described above, the chuck table 51 holding the optical device wafer 2 by suction is moved below the cutting blade 523. Move to the machining start position of a certain machining area. Then, as shown in FIG. 9 (a), one end (the left end in FIG. 9 (a)) of the street 22 to be processed of the optical device wafer 2 is positioned so as to be positioned to the right by a predetermined amount from just below the cutting blade 523. (Processing feed start position positioning step). When the optical device wafer 2 is positioned at the machining start position in the machining area in this way, the cutting blade 523 is rotated in the direction indicated by the arrow 523a from the standby position indicated by the two-dot chain line in FIG. It cuts and feeds downward, and is positioned at a predetermined cutting and feeding position as shown by a solid line in FIG. The cutting feed position is set such that the lower end of the outer peripheral edge of the cutting blade 523 is, for example, 8 μm below the surface 2 a (upper surface) of the optical device wafer 2.

  Next, as shown in FIG. 9 (a), the cutting blade 523 is rotated at a predetermined rotational speed (for example, 20000 rpm) while rotating in the direction indicated by the arrow 523a, and the chuck table 51, that is, the optical device wafer 2 is rotated as shown in FIG. In (a), processing feed is performed at a predetermined processing feed rate in the direction indicated by arrow X1 (optical device layer separation step). As a result, a cut groove 204 is formed along the street 22 on the surface 2a of the optical device wafer 2 as shown in FIGS. 9B and 9C, and a light emitting layer (epi layer) 21 as an optical device layer is formed. Are separated along the streets 22, and cutting marks 205 are formed along the streets 22 on the surface of the sapphire substrate 20. In this optical device layer separation step, since the light emitting layer (epi layer) 21 as an optical device layer formed by being laminated on the surface 20a of the sapphire substrate 20 is cut, it can be easily cut by the cutting blade 523. . When the chuck table 51, that is, the other end of the optical device wafer 2 (the right end in FIG. 9B) reaches a predetermined amount to the left of the cutting blade 523, the movement of the chuck table 51 is stopped. Then, the cutting blade 523 is raised and positioned at the retreat position indicated by the two-dot chain line.

The processing conditions in the optical device layer separation step are set as follows, for example.
Cutting blade: Electroforming blade of diamond abrasive with a thickness of 20 μm Cutting depth: 8 μm
Processing feed rate: 50 mm / sec

  When the optical device layer separation step is performed along all the streets 22 extending in the predetermined direction of the optical device wafer 2 as described above, the chuck table 51 is rotated by 90 degrees to perform the predetermined direction. The optical device layer separation step is performed along each street 22 formed in a direction orthogonal to the direction.

  Next, an external force is applied to the optical device wafer 2 to break the optical device wafer 2 along the processed groove 203 from which the denatured material has been removed, and a wafer dividing step for dividing the optical device wafer 2 into individual optical devices 23 is performed. The wafer dividing step is performed using a tape expansion device 8 shown in FIG. 10 includes a frame holding means 81 for holding the annular frame 6 and a tape extending means for expanding the dicing tape 7 attached to the annular frame 6 held by the frame holding means 81. 82 and a pickup collet 83. The frame holding means 81 includes an annular frame holding member 811 and a plurality of clamps 812 as fixing means disposed on the outer periphery of the frame holding member 811. An upper surface of the frame holding member 811 forms a mounting surface 811a on which the annular frame 6 is mounted, and the annular frame 6 is mounted on the mounting surface 811a. The annular frame 6 placed on the placement surface 811 a is fixed to the frame holding member 811 by a clamp 812. The frame holding means 81 configured as described above is supported by the tape expanding means 82 so as to be able to advance and retreat in the vertical direction.

  The tape expansion means 82 includes an expansion drum 821 disposed inside the annular frame holding member 811. The expansion drum 821 has an inner diameter and an outer diameter smaller than the inner diameter of the annular frame 6 and larger than the outer diameter of the optical device wafer 2 attached to the dicing tape 7 attached to the annular frame 6. The expansion drum 821 includes a support flange 822 at the lower end. The tape expansion means 82 in the illustrated embodiment includes support means 823 that can advance and retract the annular frame holding member 811 in the vertical direction. The support means 823 includes a plurality of air cylinders 823 a arranged on the support flange 822, and the piston rod 823 b is connected to the lower surface of the annular frame holding member 811. In this way, the support means 823 including the plurality of air cylinders 823a is configured such that the annular frame holding member 811 and the mounting surface 811a are substantially at the same height as the upper end of the expansion drum 821, as shown in FIG. Then, as shown in FIG. 11 (b), it is moved in the vertical direction between the extended positions below the upper end of the expansion drum 821 by a predetermined amount.

  A wafer dividing process performed using the tape expansion device 8 configured as described above will be described with reference to FIG. That is, the annular frame 6 on which the dicing tape 7 to which the optical device wafer 2 is attached is attached to the mounting surface of the frame holding member 811 constituting the frame holding means 81 as shown in FIG. 811a, and is fixed to the frame holding member 811 by the clamp 812 (frame holding step). At this time, the frame holding member 811 is positioned at the reference position shown in FIG. Next, the plurality of air cylinders 823a as the supporting means 823 constituting the tape extending means 82 are operated to lower the annular frame holding member 811 to the extended position shown in FIG. Accordingly, the annular frame 6 fixed on the mounting surface 811a of the frame holding member 811 is also lowered, so that the dicing tape 7 mounted on the annular frame 6 is an expansion drum as shown in FIG. Expansion is performed in contact with the upper edge of 821 (tape expansion process). As a result, a tensile force acts radially on the optical device wafer 2 adhered to the dicing tape 7. When a radial force is applied to the optical device wafer 2 in this manner, the processing groove 203 is formed along the street 22 on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2, and the sapphire substrate 20 Since the cut marks 204 are formed along the streets 22 on the surface 20a, the optical device wafer 2 is broken along the streets 22 with the processing grooves 203 and the cut marks 204 as starting points of breakage, and the optical device wafer 2 is cut. Are divided into individual optical devices 23 (wafer dividing step). Thus, a gap S is formed between the optical devices 23 divided individually.

Next, as shown in FIG. 11 (c), the pickup collet 83 is operated to adsorb the optical device 23, peeled off from the dicing tape 7, and picked up (pickup process). In the pickup process, since the gap S is formed between the individual optical devices 23 adhered to the dicing tape 7 as described above, the pickup can be easily performed without contacting the adjacent optical devices 23. can do. In the optical device 23 thus divided, the side wall surface of the sapphire substrate 20 absorbs light by performing the above-mentioned denatured material removal step, and in addition to the denatured material that causes a reduction in luminance, Since the surface is processed, light is effectively emitted and luminance is improved.
In the above-described embodiment, an example in which the optical device layer separation step is performed before the wafer splitting step is shown. However, after the altered substance removing step is performed without performing the optical device layer separation step. A wafer breaking step may be performed.

2: Optical device wafer 20: Sapphire substrate 21: Light emitting layer (epi layer) as an optical device layer
3: protective tape 4: laser processing device 41: chuck table of laser processing device 42: laser beam irradiation means 422: light collector 5: cutting device 51: chuck table of cutting device 52: cutting means 523: cutting blade 6: annular Frame 7: Dicing tape 8: Tape expansion device 81: Frame holding means 82: Tape expansion means 83: Pickup collet

Claims (3)

Light that divides an optical device wafer in which optical devices are formed in multiple areas partitioned by multiple streets that are formed in a lattice pattern by laminating optical device layers on the surface of the substrate, into individual optical devices along the streets A device wafer processing method,
A laser processing groove forming step of irradiating a laser beam of a wavelength having an absorptivity with respect to the substrate of the optical device wafer along the street to form a laser processing groove serving as a fracture base point on the front surface or the back surface of the substrate;
It is generated at the time of laser processing groove formation by positioning a cutting blade mainly composed of diamond abrasive grains in the laser processing groove formed on the substrate, and rotating the cutting blade relative to the wall surface of the laser processing groove while scratching. The altered material removal step of removing the altered material and processing the wall surface of the laser processing groove into a rough surface,
A wafer dividing step of applying an external force to the optical device wafer, breaking the optical device wafer along the processed groove from which the degenerated material is removed, and dividing the wafer into individual optical devices.
An optical device wafer processing method characterized by the above.   2. The optical device wafer processing method according to claim 1, wherein the laser processing groove forming step irradiates a laser beam along the street from the back side of the substrate to form a laser processing groove on the back surface of the substrate.   Light that separates the optical device layer along the street by cutting the optical device layer of the optical device wafer with the laser processing groove formed on the back surface of the substrate along the street with a cutting blade mainly composed of diamond abrasive grains. The method for processing an optical device wafer according to claim 2, comprising a device layer separation step.

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