JP2011222698A - Method of processing optical device wafer - Google Patents

Abstract

An optical device wafer processing method that can be divided into individual optical devices without degrading the quality of the optical device.
A break starting point forming step of cutting along a street from a back surface side of a substrate using a cutting blade 423 mainly composed of diamond abrasive grains to form a cutting groove serving as a break starting point on the back surface of the substrate; Including a wafer dividing step of applying an external force to the optical device wafer on which the starting point forming step has been performed, breaking along the streets on which the cutting grooves are formed, and dividing the wafer into individual optical devices, and performing the break starting point forming step The cutting blade 423 includes a central abrasive layer 423a and both side abrasive layers 423b and 423c. Both side abrasive layers 423b and 423c are formed of fine diamond grains, and the central abrasive layer 423a is formed on both side abrasive grains. The layers 423b and 423c are formed by diamond abrasive grains having a larger particle diameter than the layers 423b and 423c.
[Selection] Figure 4

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 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 rotary 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,
Cutting along the street using a cutting blade mainly composed of diamond abrasive grains from the back side of the substrate, and forming a fracture start point forming a cutting groove serving as a fracture start point on the back surface of the substrate;
A wafer dividing step of applying an external force to the optical device wafer on which the breakage starting point forming step has been performed, breaking along the streets where the cutting grooves are formed, and dividing the wafer into individual optical devices,
The cutting blade for carrying out the rupture starting point forming step is composed of a central abrasive layer and double-sided abrasive layers provided on both sides of the central abrasive layer, and the double-sided abrasive layer is made of fine diamond grains. Formed, the central abrasive layer is formed by diamond abrasive grains having a larger particle size than the double-sided abrasive layer,
An optical device wafer processing method is provided.

In addition, according to the present invention, an optical device wafer 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 along a street is provided. An optical device wafer processing method for dividing into individual optical devices,
A fracture starting point forming step of cutting along the street using a cutting blade mainly composed of diamond abrasive grains from the surface side of the optical device wafer to form a cutting groove serving as a fracture starting point reaching the substrate on the surface of the optical device wafer; ,
A wafer dividing step of applying an external force to the optical device wafer on which the breakage starting point forming step has been performed, breaking along the streets where the cutting grooves are formed, and dividing the wafer into individual optical devices,
The cutting blade for carrying out the rupture starting point forming step is composed of a central abrasive layer and double-sided abrasive layers provided on both sides of the central abrasive layer, and the double-sided abrasive layer is made of fine diamond grains. Formed, the central abrasive layer is formed by diamond abrasive grains having a larger particle size than the double-sided abrasive layer,
An optical device wafer processing method is provided.

Furthermore, according to the present invention, an optical device wafer 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, is provided along the street. An optical device wafer processing method for dividing into individual optical devices,
Cutting along the street using a cutting blade mainly composed of diamond abrasive grains from the back side of the substrate, and a first break starting point forming step of forming a cutting groove serving as a break starting point on the back surface of the substrate;
A second break start point that cuts along the street from the surface side of the optical device wafer using a cutting blade mainly composed of diamond abrasive grains to form a cutting groove that reaches the substrate on the surface of the optical device wafer. Forming process;
Wafers that apply an external force to the optical device wafer on which the first break start point forming step and the second break start point forming step have been performed, break along the streets where the cutting grooves are formed, and are divided into individual optical devices. Dividing step, and
The cutting blade for carrying out the rupture starting point forming step is composed of a central abrasive layer and double-sided abrasive layers provided on both sides of the central abrasive layer, and the double-sided abrasive layer is made of fine diamond grains. Formed, the central abrasive layer is formed by diamond abrasive grains having a larger particle size than the double-sided abrasive layer,
An optical device wafer processing method is provided.

  The grain size of diamond abrasive grains forming the double-sided abrasive grain layer is set to 1 to 3 μm, and the grain diameter of diamond abrasive grains forming the central abrasive grain layer is set to 10 to 20 μm.

  In the method for processing an optical device wafer according to the present invention, the cutting blade for forming a cutting groove serving as a fracture starting point on the back surface of the substrate and / or the surface of the optical device wafer constituting the optical device wafer in the fracture starting point forming step is a central abrasive. It is composed of a grain layer and a double-sided abrasive grain layer, the double-sided abrasive grain layer is formed by fine diamond grain grains, and the central abrasive grain layer is formed by diamond grain grains having a larger grain size than the double-sided abrasive grain layers. Therefore, when forming the cutting groove, a crack is generated from the bottom of the cutting groove. Therefore, in the wafer dividing process in which the optical device wafer is broken along the street and divided into individual optical devices, cracks generated from the bottom of the cutting groove can grow and be effectively divided. As a result, a denatured substance that absorbs light and lowers the luminance is not generated, so that the luminance of the optical device does not decrease. In addition, since the cutting groove that is the starting point of the break is formed by a cutting blade mainly composed of diamond abrasive grains, the cutting groove is processed into a rough surface, so that the light of the optical device is effectively emitted and the brightness is improved. To do.

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 cutting device for enforcing the fracture start point formation process in the processing method of the optical device wafer by the present invention. Sectional drawing of the cutting blade with which the cutting apparatus shown in FIG. 3 is equipped. Explanatory drawing of the fracture start point formation process in 1st Embodiment of the processing method of the optical device wafer by this invention. Explanatory drawing of the wafer support process in 1st Embodiment of the processing method of the optical device wafer by this invention. The perspective view of the wafer division | segmentation 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. Explanatory drawing of the wafer support process in 2nd Embodiment of the processing method of the optical device wafer by this invention. Explanatory drawing of the fracture start point formation process in 2nd Embodiment of the processing method of the optical device wafer by this invention. Explanatory drawing of the fracture start point formation process in 2nd Embodiment of the processing method of the optical device wafer by this invention. Sectional drawing which expands and shows the principal part of the optical device wafer in which the 1st fracture start point formation process and 2nd fracture start point formation process in 3rd Embodiment of the processing method of the optical device wafer by this invention were implemented.

  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.

A first embodiment of a method for processing an optical device wafer according to the present invention will be described with reference to FIGS.
In the first embodiment of the optical device wafer processing method according to the present invention, 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, the optical device wafer 2 of the optical device wafer 2 is protected. A protective member attaching step for attaching the protective member to the surface 2a 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 to the surface 2a of the optical device wafer 2 by carrying out the protective member sticking step described above, it is applied to the street from the back side of the substrate using a cutting blade mainly composed of diamond abrasive grains. A break start point forming step is performed in which a cutting groove is formed along the back surface of the substrate to form a cut groove serving as a break start point. In the illustrated embodiment, the fracture starting point forming step is performed using a cutting device 4 shown in FIG. The cutting apparatus 4 shown in FIG. 3 includes a chuck table 41 that holds a workpiece, a cutting means 42 that cuts the workpiece held on the chuck table 41, and a workpiece held on the chuck table 41. An image pickup means 43 for picking up images is provided. The chuck table 41 is configured to suck and hold a workpiece. The chuck table 41 is moved in a machining feed direction indicated by an arrow X in FIG. 3 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 42 includes a spindle housing 421 arranged substantially horizontally, a rotating spindle 422 rotatably supported by the spindle housing 421, and a cutting blade 423 attached to the tip of the rotating spindle 422. The rotating spindle 422 can be rotated in the direction indicated by the arrow A by a servo motor (not shown) disposed in the spindle housing 421. As shown in FIG. 4, the cutting blade 423 is an electroformed blade in which diamond abrasive grains are hardened by nickel plating on the side surface of the base 424, and has a thickness of 20 to 30 μm. The cutting blade 423 includes a central abrasive layer 423a and double-sided abrasive layers 423b and 423c provided on both sides of the central abrasive layer 423a. The central abrasive layer 423a is formed of diamond abrasive grains having a larger particle size than the double-sided abrasive grain layers 423b and 423c. The grain size of the diamond abrasive grains forming the double-sided abrasive grain layers 423b and 423c of the cutting blade 423 thus configured is set to 1 to 3 μm, and the grain diameter of the diamond abrasive grains forming the central abrasive grain layer 423a is 10 It is set to ˜20 μm.

  The imaging means 43 is mounted at the tip of the spindle housing 421, and illuminates the object to be processed, 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 perform the break starting point forming step using the cutting device 4 described above, the protective tape 3 side adhered to the surface of the optical device wafer 2 is placed on the chuck table 41 as 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 means 43 by a cutting feed means (not shown).

  When the chuck table 41 is positioned immediately below the image pickup means 43, an alignment operation for detecting a region to be processed of the optical device wafer 2 is executed by the image pickup means 43 and a control means (not shown). That is, the imaging unit 43 and a control unit (not shown) perform alignment for aligning the street 22 formed in a predetermined direction of the optical device wafer 2 and the cutting blade 423 (alignment process). Further, the alignment of the processing region is similarly performed on the street 22 formed on the optical device wafer 2 in the 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 alignment for detecting the processing region of the optical device wafer 2 held on the chuck table 41 is performed as described above, the chuck table 41 holding the optical device wafer 2 by suction is moved below the cutting blade 423. Move to the machining start position of a certain machining area. Then, as shown in FIG. 5 (a), one end (the left end in FIG. 5 (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 directly below the cutting blade 423. (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 423 is rotated in the direction indicated by the arrow A 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. In this cutting feed position, the lower end of the outer peripheral edge of the cutting blade 423 is set, for example, at a position 20 μm below the back surface 20b (upper surface) of the sapphire substrate 20 constituting the optical device wafer 2. If the cutting depth is deeper than 20 μm, a load is applied to the cutting blade and chipping or cracking occurs on the upper surface of the sapphire substrate, so the cutting depth is limited to 20 μm.

  Next, as shown in FIG. 5A, the cutting blade 423 is rotated at a predetermined rotational speed in the direction indicated by the arrow A, while the chuck table 41, that is, the optical device wafer 2 is moved to the arrow X1 in FIG. Is fed at a predetermined feed rate in the direction indicated by (break start point forming step). As a result, as shown in FIGS. 5 (b) and 5 (c), the back surface 20 b (upper surface) of the sapphire substrate 20 constituting the optical device wafer 2 has a depth of 20 μm as a fracture starting point along the street 22. A cutting groove 201 is formed. As described above, the cutting blade 423 that forms the cutting groove 201 serving as a rupture starting point in the rupture starting point forming step includes a central abrasive layer 423a and both side abrasive layer 423b and 423c provided on both sides of the central abrasive layer 423a. Since both side abrasive grain layers 423b and 423c are formed of fine diamond grain grains, the side face of the cutting groove 201 formed in the sapphire substrate 20 is hardly damaged, and the central abrasive grain layer 423a Cracks 201a are generated from the bottom of the cutting groove 201 when the cutting groove 201 is formed because it is formed of diamond abrasive grains having a particle size larger than the double-sided abrasive grain layers 423b and 423c. Further, in the break starting point forming step, the cut depth is limited as described above, but the cut depth is about 20 μm and is relatively small, so even the sapphire substrate 20 which is a hard substrate is relatively easy to break. A cutting groove 201 can be formed. When the chuck table 41, that is, the other end of the optical device wafer 2 (the right end in FIG. 5B) reaches a predetermined amount to the left of the cutting blade 423, the movement of the chuck table 41 is stopped. Then, the cutting blade 423 is raised and positioned at the retracted position indicated by the two-dot chain line.

The processing conditions in the break starting point forming step are set as follows, for example.
Cutting blade: Electroforming blade of diamond abrasive having a thickness of 20 to 30 μm Cutting blade rotation speed: 20000 rpm
Cutting depth: 20 μm
Processing feed rate: 50 to 150 mm / sec

  As described above, when the break starting point is implemented along all the streets 22 extending in the predetermined direction of the optical device wafer 2, the chuck table 41 is rotated 90 degrees to The said fracture | rupture starting point formation process is implemented along each street 22 formed in the orthogonal direction.

  If the break starting point forming 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 formed. A wafer supporting step for peeling off the protective member attached to the wafer is carried out. That is, as shown in FIGS. 6 (a) and 6 (b), the breaking start point forming step was performed on the surface of the dicing tape 6 having the outer peripheral portion mounted so as to cover the inner opening of the annular frame 5. The back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 is attached. Then, the protective tape 3 attached to the surface 2a of the optical device wafer 2 is peeled off (wafer support step).

  Next, an external force is applied to the optical device wafer, and a wafer dividing step is performed in which the optical device wafer is broken along the street where the cutting groove 201 serving as a breakage starting point is formed and divided into individual optical devices. This wafer dividing step is carried out using a wafer dividing apparatus 7 shown in FIG. The wafer dividing device 7 shown in FIG. 7 includes a base 71 and a moving table 72 disposed on the base 71 so as to be movable in the direction indicated by the arrow Y. The base 71 is formed in a rectangular shape, and two guide rails 711 and 712 are arranged in parallel to each other in the direction indicated by the arrow Y on the upper surface of both side portions. A moving table 72 is movably disposed on the two guide rails 711 and 712. The moving table 72 is moved in the direction indicated by the arrow Y by the moving means 73. On the moving table 72, frame holding means 74 for holding the annular frame 5 is disposed. The frame holding means 74 includes a cylindrical main body 741, an annular frame holding member 742 provided at the upper end of the main body 741, and a plurality of clamps 743 as fixing means disposed on the outer periphery of the frame holding member 742. It is made up of. The frame holding means 74 configured in this manner fixes the annular frame 5 placed on the frame holding member 742 with a clamp 743. Further, the wafer dividing apparatus 7 shown in FIG. 7 includes a rotating means 75 for rotating the frame holding means 74. The rotating means 75 is wound around a pulse motor 751 disposed on the moving table 72, a pulley 752 attached to a rotation shaft of the pulse motor 751, and the pulley 752 and a cylindrical main body 741. An endless belt 753 is included. The rotation means 75 configured in this manner rotates the frame holding means 74 via the pulley 752 and the endless belt 753 by driving the pulse motor 751.

  The wafer dividing apparatus 7 shown in FIG. 7 has a tensile force in a direction perpendicular to the street 22 on the optical device wafer 2 supported by the annular frame 5 held by the annular frame holding member 742 via the dicing tape 6. There is provided a tension applying means 76 for acting. The tension applying means 76 is disposed in the annular frame holding member 74. The tension applying means 76 includes a first suction holding member 761 and a second suction holding member 762 each having a rectangular holding surface that is long in a direction orthogonal to the arrow Y direction. The first suction holding member 761 has a plurality of suction holes 761a, and the second suction holding member 762 has a plurality of suction holes 762a. The plurality of suction holes 761a and 762a communicate with suction means (not shown). Further, the first suction holding member 761 and the second suction holding member 762 can be moved in the arrow Y direction by a moving means (not shown).

  The wafer dividing apparatus 7 shown in FIG. 7 is a detecting means for detecting the street 22 of the optical device wafer 2 supported by the annular frame 5 held by the annular frame holding member 742 via the dicing tape 6. 77. The detection means 77 is attached to an L-shaped support column 771 disposed on the base 71. The detection means 77 is composed of an optical system, an image pickup device (CCD), and the like, and is disposed above the tension applying means 76. The detection means 77 configured in this manner images the street 22 of the optical device wafer 2 supported by the annular frame 5 held by the annular frame holding member 742 via the dicing tape 6, It is converted into an electric signal and sent to a control means (not shown).

A wafer dividing process performed using the wafer dividing apparatus 7 will be described with reference to FIG.
As shown in FIG. 8 (a), an annular frame 5 that supports the optical device wafer 2 on which the above-described first break start point forming step and second break start point forming step have been performed via a dicing tape 6 is shown. It is placed on the frame holding member 742 and fixed to the frame holding member 742 by a clamp 743. Next, the moving means 73 is operated to move the moving table 72 in the direction indicated by the arrow Y (see FIG. 7), and the 1 formed on the optical device wafer 2 in a predetermined direction as shown in FIG. The street 22 of the book (the leftmost street in the illustrated embodiment) is positioned between the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762 constituting the tension applying means 76. . At this time, the street 22 is imaged by the detection unit 77, and the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762 are aligned. In this way, when one street 22 is positioned between the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762, the suction means (not shown) is operated to perform suction. By applying negative pressure to the holes 761a and 762a, the optical device wafer 2 is sucked and held on the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762 via the dicing tape 6. (Holding process).

  When the holding step described above is performed, the moving means (not shown) constituting the tension applying means 76 is operated, and the first suction holding member 761 and the second suction holding member 762 are as shown in FIG. Move them away from each other. As a result, a tensile force acts in a direction perpendicular to the street 22 on the street 22 positioned between the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762, The device wafer 2 is ruptured along the street 22 with the cutting groove 201 and a crack 201a generated from the bottom of the cutting groove 201 as a starting point of rupture (breaking step). By carrying out this breaking process, the dicing tape 6 slightly extends. In this breaking process, since the optical device wafer 2 is formed with cutting grooves 201 and cracks 201a along the streets 22 to reduce the strength, the first suction holding member 761 and the second suction holding member 762 are removed. By moving about 0.5 mm in the direction away from each other, the cutting groove 201 formed in the sapphire substrate 20 can be broken along the street 22 as a starting point of the breakage of the crack 201a.

  As described above, when the breaking process of breaking along one street 22 formed in a predetermined direction is performed, the optical device wafer 2 by the first suction holding member 761 and the second suction holding member 762 described above. Release suction hold. Next, the moving means 73 is actuated to move the moving table 72 in the direction indicated by the arrow Y (see FIG. 7) by an amount corresponding to the interval of the streets 22, and the street 22 next to the street 22 on which the breaking process is performed. Is positioned between the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762 constituting the tension applying means 76. And the said holding process and a fracture | rupture process are implemented.

  As described above, when the holding process and the breaking process are performed on all the streets 22 formed in the predetermined direction, the rotating means 75 is operated to rotate the frame holding means 74 by 90 degrees. As a result, the optical device wafer 2 held by the frame holding member 742 of the frame holding means 74 is also turned 90 degrees, and is formed in a direction perpendicular to the street 22 formed in a predetermined direction and subjected to the breaking process. The street 22 is positioned in a state parallel to the holding surface of the first suction holding member 761 and the holding surface of the second suction holding member 762. Next, the optical device wafer 2 extends along the street 22 by performing the above-described holding step and the breaking step on all the streets 22 formed in the direction orthogonal to the street 22 on which the breaking step is performed. The device is divided into individual devices 23 (wafer dividing step).

  In the embodiment described above, the cutting blade 423 that forms the cutting groove 201 serving as the starting point of breakage on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 includes the central abrasive layer 423a and both sides of the central abrasive layer 423a. The double-sided abrasive grain layers 423b and 423c are formed on the two-sided abrasive grain layers 423b and 423c. The double-sided abrasive grain layers 423b and 423c are formed of fine-grained diamond abrasive grains. Since it is formed of diamond abrasive grains having a large particle size, a crack 201a is generated from the bottom of the cutting groove 201 when the cutting groove 201 is formed. Therefore, in the wafer dividing process in which the optical device wafer 2 is broken along the street and divided into individual optical devices, the crack 201a generated from the bottom of the cutting groove 201 can grow and be divided effectively. At the same time, since a denatured material that absorbs light and causes a decrease in luminance is not generated, the luminance of the optical device 23 does not decrease. Further, since the cutting groove 201 serving as the starting point of breakage is formed by a cutting blade mainly composed of diamond abrasive grains, the cutting groove 201 is processed into a rough surface. Will improve.

Next, a second embodiment of the optical device wafer processing method according to the present invention will be described.
In the second embodiment of the optical device wafer processing method according to the present invention, first, as shown in FIGS. 9A and 9B, the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 is formed into an annular frame. 5 is attached to the surface of the dicing tape 6 attached to the wafer 5 (wafer support step).

When the wafer support process described above is performed, the wafer is cut along the street 22 from the surface side of the optical device wafer 2 using a cutting blade mainly composed of diamond abrasive grains, and reaches the substrate on the surface of the optical device wafer 2. A rupture start point forming step for forming a cutting groove to be a rupture start point is performed. This breakage starting point forming step can be carried out using the cutting device 4 shown in FIG.
In order to perform the break starting point forming step using the cutting device 4 described above, the dicing tape 6 in which the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 is adhered on the chuck table 41 as shown in FIG. The optical device wafer 2 is sucked and held on the chuck table 41 by operating a suction means (not shown) by placing the side (wafer holding step). Therefore, the surface 2a of the optical device wafer 2 held on the chuck table 41 is on the upper side. In FIG. 10, the annular frame 5 on which the dicing tape 6 is mounted is omitted, but the annular frame 5 is fixed by a clamp mechanism disposed on the chuck table 41. In this way, the chuck table 41 that sucks and holds the optical device wafer 2 is positioned directly below the imaging means 43 by a cutting feed means (not shown).

  When the chuck table 41 is positioned immediately below the image pickup means 43, an alignment operation for detecting a region to be processed of the optical device wafer 2 is executed by the image pickup means 43 and a control means (not shown). That is, the imaging unit 43 and a control unit (not shown) perform alignment for aligning the streets 22 formed in the predetermined direction on the surface 2a of the optical device wafer 2 and the cutting blade 423 (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.

  If the alignment for detecting the processing region of the optical device wafer 2 held on the chuck table 41 is performed as described above, the chuck table 41 holding the optical device wafer 2 by suction is moved below the cutting blade 423. Move to the machining start position of a certain machining area. Then, as shown in FIG. 11 (a), one end (the left end in FIG. 11 (a)) of the street 22 to be processed of the optical device wafer 2 is positioned so as to be located to the right by a predetermined amount from directly below the cutting blade 423. (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 423 is rotated in the direction indicated by the arrow A while 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 indicated 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 423 is, for example, 20 μm below the surface 2 a (upper surface) of the optical device wafer 2.

  Next, as shown in FIG. 11 (a), the cutting blade 423 is rotated at a predetermined rotational speed while rotating in the direction indicated by the arrow A, and the chuck table 41, that is, the optical device wafer 2 is moved in FIG. 11 (a). Process feed is performed at a predetermined process feed speed in the direction indicated by arrow X1 (break start point forming step). The processing conditions in the break starting point forming step may be the same as the processing conditions in the break starting point forming step shown in FIG. 5 in the first embodiment described above. As a result, on the surface 2a of the optical device wafer 2, as shown in FIGS. 11 (b) and 11 (c), a cutting groove 202 having a depth of 20 μm serving as a breakage starting point reaching the sapphire substrate 20 along the street 22 is formed. It is formed. As described above, the cutting blade 423 that forms the cutting groove 202 serving as the rupture starting point in the rupture starting point forming step includes the central abrasive layer 423a and the double-sided abrasive grain layers 423b and 423c provided on both sides of the central abrasive layer 423a. Since both side abrasive grain layers 423b and 423c are formed of fine diamond grain grains, the side face of the cutting groove 201 formed in the sapphire substrate 20 is hardly damaged, and the central abrasive grain layer 423a Cracks 201a are generated from the bottom of the cutting groove 201 when the cutting groove 201 is formed because it is formed of diamond abrasive grains having a particle size larger than the double-sided abrasive grain layers 423b and 423c. Further, in the break starting point forming step, the cutting depth is about 20 μm and relatively small, so that even the sapphire substrate 20 that is a hard substrate can form the cutting groove 202 that becomes the break starting point relatively easily. When the chuck table 41, that is, the other end of the optical device wafer 2 (the right end in FIG. 11B) reaches a predetermined amount to the left of the cutting blade 423, the movement of the chuck table 41 is stopped. Then, the cutting blade 423 is raised and positioned at the retracted position indicated by the two-dot chain line.

  As described above, when the break starting point is implemented along all the streets 22 extending in the predetermined direction of the optical device wafer 2, the chuck table 41 is rotated 90 degrees to The said fracture | rupture starting point formation process is implemented along each street 22 formed in the orthogonal direction.

  If the break starting point forming step is performed as described above, an external force is applied to the optical device wafer, the wafer is divided along the streets where the cutting grooves 202 serving as the break starting point are formed, and divided into individual optical devices. Perform the process. This wafer dividing step is performed in the same manner as the operation step shown in FIG. 8 in the first embodiment described above using the wafer dividing apparatus 7 shown in FIG.

  Also in the second embodiment of the optical device wafer processing method according to the present invention described above, the fracture start point forming step for forming the cutting groove 202 serving as the fracture start point reaching the sapphire substrate 20 on the surface of the optical device wafer 2 is performed as described above. 4, a cutting blade 423 (consisting of a central abrasive layer 423a and double-sided abrasive grain layers 423b and 423c, the double-sided abrasive grain layers 423b and 423c are formed by fine diamond abrasive grains, and the central abrasive grain layer 423a is formed on both sides. In this case, the crack 202a is generated from the bottom of the cutting groove 202 when the cutting groove 202 is formed. Therefore, in the wafer dividing process in which the optical device wafer 2 is broken along the street and divided into individual optical devices, the crack 202a generated from the bottom of the cutting groove 202 can grow and be divided effectively. At the same time, since a denatured material that absorbs light and causes a decrease in luminance is not generated, the luminance of the optical device 23 does not decrease. Further, since the cutting groove 202 serving as the starting point of breakage is formed by a cutting blade mainly composed of diamond abrasive grains, the cutting groove 202 is processed into a rough surface. Will improve.

Next, a third embodiment of the optical device wafer processing method according to the present invention will be described.
In the third embodiment of the method for processing an optical device wafer according to the present invention, first, as in the first embodiment, the protective member is attached to the surface 2a of the optical device wafer 2 shown in FIG. Cutting is performed along the streets 22 using a cutting blade 523 mainly composed of diamond abrasive grains from the back side of the substrate 20 shown in FIG. 3 to FIG. A fracture starting point forming step (first fracture starting point forming step) for forming the groove 201 is performed.

  Next, after carrying out the wafer supporting step shown in FIG. 6 as in the first embodiment, cutting along the street from the surface side of the optical device wafer 2 using a cutting blade mainly composed of diamond abrasive grains. Then, a second break start point forming step for forming a cutting groove serving as a break start point reaching the substrate 20 on the surface of the optical device wafer 2 is performed. This second break start point forming step is performed in the same manner as the break start point forming step shown in FIGS. 9 and 10 in the second embodiment.

  The optical device wafer 2 that has been subjected to the first break starting point forming step and the second break starting point forming step described above is formed on the street 22 on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2, as shown in FIG. A cutting groove 201 and a crack 201a are formed along the street 2 along the street 22 and a cutting groove 202 and a crack 202a are formed along the street 22 on the surface 2a of the optical device wafer 2. .

  If the first break start point forming step and the second break start point forming step are performed as described above, an external force is applied to the optical device wafer, and along the streets where the cutting grooves 201 and 202 serving as the break start points are formed. Then, a wafer dividing process is performed in which the wafer is broken and divided into individual optical devices. This wafer dividing step is performed in the same manner as the work step shown in FIG. 8 by using the wafer dividing apparatus 7 shown in FIG. In this wafer dividing step, the optical device wafer 2 is formed with a cutting groove 201 and a crack 201a serving as a starting point along the street 22 on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 as shown in FIG. In addition, since the cutting groove 202 and the crack 202a that are the starting points of the break reaching the sapphire substrate 20 along the street 22 are formed on the surface 2a of the optical device wafer 2, the optical device wafer 2 is moved along the street 22 along the street 22. It can be easily broken. Since the cutting grooves 201 and 202 that are the starting points of the breakage are formed by the cutting blade mainly composed of diamond abrasive grains as described above, the cutting grooves 201 and 202 are processed into a rough surface, and thus are individually divided. In the optical device, light is effectively emitted and luminance is improved.

2: Optical device wafer 20: Sapphire substrate 21: Light emitting layer (epi layer) as an optical device layer
3: protective tape 4: cutting device 41: chuck table of cutting device 42: cutting means 423: cutting blade 5: annular frame 6: dicing tape 7: wafer dividing device 71: base 72: moving table 73: moving means 74 : Frame holding means 75: rotating means 76: tension applying means 77: detecting means

Claims (6)

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,
Cutting along the street using a cutting blade mainly composed of diamond abrasive grains from the back side of the substrate, and forming a fracture start point forming a cutting groove serving as a fracture start point on the back surface of the substrate;
A wafer dividing step of applying an external force to the optical device wafer on which the breakage starting point forming step has been performed, breaking along the streets where the cutting grooves are formed, and dividing the wafer into individual optical devices,
The cutting blade for carrying out the rupture starting point forming step is composed of a central abrasive layer and double-sided abrasive layers provided on both sides of the central abrasive layer, and the double-sided abrasive layer is made of fine diamond grains. Formed, the central abrasive layer is formed by diamond abrasive grains having a larger particle size than the double-sided abrasive layer,
An optical device wafer processing method characterized by the above.   The grain size of diamond abrasive grains forming the double-sided abrasive grain layer is set to 1 to 3 µm, and the grain diameter of diamond abrasive grains forming the central abrasive grain layer is set to 10 to 20 µm. Method of optical device wafers. 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 fracture starting point forming step of cutting along the street using a cutting blade mainly composed of diamond abrasive grains from the surface side of the optical device wafer to form a cutting groove serving as a fracture starting point reaching the substrate on the surface of the optical device wafer; ,
A wafer dividing step of applying an external force to the optical device wafer on which the breakage starting point forming step has been performed, breaking along the streets where the cutting grooves are formed, and dividing the wafer into individual optical devices,
The cutting blade for carrying out the rupture starting point forming step is composed of a central abrasive layer and double-sided abrasive layers provided on both sides of the central abrasive layer, and the double-sided abrasive layer is made of fine diamond grains. Formed, the central abrasive layer is formed by diamond abrasive grains having a larger particle size than the double-sided abrasive layer,
An optical device wafer processing method characterized by the above.   The particle diameter of the diamond abrasive grain which forms this double-sided abrasive grain layer is set to 1-3 micrometers, The particle diameter of the diamond abrasive grain which forms this center abrasive grain layer is set to 10-20 micrometers. Method of optical device wafers. 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,
Cutting along the street using a cutting blade mainly composed of diamond abrasive grains from the back side of the substrate, and a first break starting point forming step of forming a cutting groove serving as a break starting point on the back surface of the substrate;
A second break start point that cuts along the street from the surface side of the optical device wafer using a cutting blade mainly composed of diamond abrasive grains to form a cutting groove that reaches the substrate on the surface of the optical device wafer. Forming process;
Wafers that apply an external force to the optical device wafer on which the first break start point forming step and the second break start point forming step have been performed, break along the streets where the cutting grooves are formed, and are divided into individual optical devices. Dividing step, and
The cutting blade for carrying out the rupture starting point forming step is composed of a central abrasive layer and double-sided abrasive layers provided on both sides of the central abrasive layer, and the double-sided abrasive layer is made of fine diamond grains. Formed, the central abrasive layer is formed by diamond abrasive grains having a larger particle size than the double-sided abrasive layer,
An optical device wafer processing method characterized by the above.   The grain size of diamond abrasive grains forming the double-sided abrasive grain layer is set to 1 to 3 μm, and the grain diameter of diamond abrasive grains forming the central abrasive grain layer is set to 10 to 20 μm. Method of optical device wafers.

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