JP6510933B2 - Optical device wafer processing method - Google Patents

Description

  According to the present invention, an optical device wafer having a light emitting layer formed on the surface of a sapphire substrate and an optical device formed in a plurality of areas partitioned by a plurality of grid-like division lines is divided into individual optical devices along the division lines. The present invention relates to a method of processing an optical device wafer divided into two.

  In the optical device manufacturing process, light is emitted in a plurality of regions divided by a plurality of planned division lines formed in a lattice shape, in which a light emitting layer composed of a gallium nitride compound semiconductor is stacked on the surface of a substantially discoid sapphire substrate. An optical device wafer such as a diode or a laser diode is formed to constitute an optical device wafer. Then, the optical device wafer is cut along the dividing lines to divide the area where the optical devices are formed, thereby manufacturing individual optical devices.

  The above-described cutting along the planned dividing line 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 by the chuck table, and a cutting feed means for relatively moving the chuck table and the cutting means. Equipped with The cutting means includes a rotating spindle, a cutting blade mounted on the spindle, and a drive mechanism for rotationally driving the rotating 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, and the cutting edge is fixed to the base by electroforming, for example, diamond abrasive of about 3 μm in particle diameter. It is formed to a thickness of about 20 μm.

  However, since the sapphire substrate constituting the optical device wafer has a high Mohs hardness, cutting by the cutting blade is not always easy. Furthermore, since the cutting blade has a thickness of about 20 μm, it is necessary to have a width of about 50 μm as a planned dividing line for dividing the device. For this reason, there is a problem that the area ratio occupied by the planned dividing line becomes high, and the productivity is bad.

  In order to solve the above-mentioned problems, as a method of dividing the optical device wafer along the planned dividing line, breakage is caused by irradiating the sapphire substrate with a pulse laser beam having an absorbing wavelength along the planned dividing line. There has been proposed a method of forming a laser-processed groove as a starting point and cutting by applying an external force along a planned dividing line on which a laser-processed groove as a starting point of fracture is formed (see, for example, Patent Document 1) ).

  However, when a laser beam is irradiated along a planned dividing line formed on the surface of the sapphire substrate constituting the optical device wafer to form a laser processed groove, the outer periphery of the optical device such as a light emitting diode is ablated and melted called debris. There is a problem that the luminance is reduced due to the adhesion of an object, and the quality of the optical device is reduced.

  In order to solve such a problem, focusing point of laser light of wavelength having transparency to the sapphire substrate is located from the back side of the sapphire substrate where the light emitting layer (epi layer) is not formed, and division is planned Irradiating along the line and forming the modified layer along the planned dividing line inside the sapphire substrate, along the planned dividing line whose strength is reduced by forming the modified layer on the sapphire substrate A processing method of dividing into two is disclosed in Patent Document 2 below.

  However, when the modified layer is formed along the planned dividing line inside the sapphire substrate, the outer periphery of the optical device is covered with the modified layer, and the bending strength of the optical device is lowered, and the vertical from the back surface to the front surface There is a problem that it can not be divided.

  In order to solve such a problem, the value obtained by dividing the numerical aperture (NA) of the focusing lens for focusing the pulse laser beam by the refractive index (N) of the single crystal substrate is in the range of 0.05 to 0.2. The numerical aperture (NA) of the condenser lens is set, and the pulse laser beam condensed by the condenser lens is irradiated, and a narrow spot is formed between the condensing point positioned on the single crystal substrate and the side where the pulse laser beam is incident. Patent Document 3 discloses a laser processing method of growing a hole and an amorphous that shields the hole to form a shield tunnel.

JP 10-305420 A Patent No. 3408805 JP, 2014-221483, A

By subjecting an optical device wafer made of a sapphire substrate to a laser processing along a planned dividing line by the laser processing method described in Patent Document 3 above, the pores and the pores are shielded from the back surface to the front surface of the sapphire substrate. Can be grown to form a shield tunnel, so that the optical device wafer can be divided vertically along the planned dividing line, and the deterioration of the quality and the bending strength of the optical device can be prevented. be able to.
However, according to the experiments of the present inventors, in an optical device wafer made of a sapphire substrate, division lines formed in a direction parallel to the orientation flat representing crystal orientation and divisions formed in the direction orthogonal to the orientation flat If a shield tunnel is formed under the same processing conditions with respect to the planned line, there is a problem that the planned dividing line formed in the direction parallel to the orientation flat is more difficult to break than the planned planned line formed in the direction orthogonal to the orientation flat. It turned out that there was.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem is that the optical device wafer made of a sapphire substrate is orthogonal to the planned dividing line and the orientation flat formed in the direction parallel to the orientation flat. It is an object of the present invention to provide a method of processing an optical device wafer, which can be divided by a uniform force with a planned dividing line formed in the above.

In order to solve the above-mentioned main technical problems, according to the present invention, a light emitting layer is formed on the surface of a sapphire substrate on which an orientation flat representing a crystal orientation is formed, and a plurality of regions partitioned by a plurality of grid-like planned division lines. What is claimed is: 1. A method of processing an optical device wafer, comprising: dividing an optical device wafer on which optical devices are formed into individual optical devices;
A condensing spot of a pulse laser beam of a wavelength having transparency to the sapphire substrate is positioned from the back side of the sapphire substrate to the inside and irradiated along a planned dividing line, and pores and an amorphous that shields the pores Forming a shield tunnel along a planned dividing line by growing the shield tunnel, and
Applying an external force to the optical device wafer subjected to the shield tunnel forming step, and dividing the optical device wafer into individual optical devices along a planned dividing line,
When the shield tunnel forming step is performed on a planned dividing line formed in a direction parallel to the orientation flat, the end of the shield tunnel is not exposed to the back surface of the sapphire substrate, and the sapphire substrate is isolated from the end of the shield tunnel The first shield tunnel formation process which is performed by positioning the focusing point of the pulse laser beam inside so that the crack to the back surface of the surface is generated, and the division planned line formed in the direction orthogonal to the orientation flat And performing a second shield tunnel forming step of positioning the focus of the pulse laser beam inside the sapphire substrate so as to expose the end of the shield tunnel on the back surface of the sapphire substrate.
A method of processing an optical device wafer is provided.

  In the laser processing method according to the present invention, the focusing point of the pulse laser beam having a wavelength having transparency to the sapphire substrate is positioned from the back surface side of the sapphire substrate to the inside and irradiated along the planned dividing line. The shield tunnel formation step of growing the amorphous which shields the pores and forming the shield tunnel along the planned dividing line is performed when performing the planned planned dividing line formed in the direction parallel to the orientation flat. The first step is to position the focusing point of the pulsed laser beam inside so that a crack from the end of the shield tunnel to the back of the sapphire substrate is generated without exposing the end of the shield tunnel to the back of the sapphire substrate. Shield tunnel formation process and formed in the direction orthogonal to the orientation flat And a second shield tunnel forming step of positioning the focusing point of the pulse laser beam inside the sapphire substrate so as to expose the end of the shield tunnel on the back surface of the sapphire substrate when performing the process on the planned line As a result, a shield tunnel and a crack from the end of the shield tunnel to the back surface are generated in the first planned dividing line formed in the direction parallel to the orientation flat which is hard to be broken by the application of external force Therefore, the division can be performed with substantially the same force as the second planned division line formed in the direction orthogonal to the orientation flat in which only the shield tunnel is formed. Thus, the optical device wafer can be divided into individual optical devices with uniform force.

FIG. 2A is a perspective view of a wafer processed by the method of processing an optical device wafer according to the present invention, and FIG. FIG. 2 is a perspective view showing a state in which the optical device wafer shown in FIG. 1 is attached to the surface of a dicing tape whose outer peripheral portion is mounted so as to cover an inner opening of an annular frame. The principal part perspective view of the laser processing apparatus for implementing the shield tunnel formation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the 1st shield tunnel formation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the 2nd shield tunnel formation process in the processing method of the optical device wafer by this invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a dividing device for performing a dividing step in a laser processing method according to the present invention. Explanatory drawing of the division | segmentation process in the laser processing method by this invention.

  Hereinafter, the method of processing an optical device wafer according to the present invention will be described in more detail with reference to the attached drawings.

  FIGS. 1A and 1B show a perspective view of an optical device wafer divided into individual optical devices by the method of processing an optical device wafer according to the present invention and a cross-sectional view showing an enlarged main part. ing. The optical device wafer 2 shown in (a) and (b) of FIG. 1 has a light emitting layer (epi layer) 21 with a thickness of 10 μm made of a nitride semiconductor on the surface 20 a of a sapphire substrate 20 which is a single crystal substrate with a thickness of 500 μm. Are stacked. An orientation flat 201 representing a crystal orientation is formed on the sapphire substrate 20 constituting the optical device wafer 2. The light emitting layer (epi layer) 21 stacked on the surface of the sapphire substrate 20 thus formed has a plurality of first planned division lines 221 formed in the direction parallel to the orientation flat 201 on the surface 21 a and the orientation flat A plurality of regions are partitioned by a plurality of second planned division lines 222 formed in a direction orthogonal to 201, and an optical device 23 such as a light emitting diode or a laser diode is formed in the partitioned regions. .

  In order to divide the optical device wafer 2 described above along the first planned dividing line 221 and the second planned dividing line 222, the optical device wafer 2 is first attached to an annular frame in the illustrated embodiment. A wafer supporting step of sticking on the surface of the dicing tape is carried out. That is, as shown in FIG. 2, the surface 21a of the light emitting layer (epi layer) 21 constituting the optical device wafer 2 on the surface of the dicing tape 4 whose outer periphery is attached to cover the inner opening of the annular frame 3. Stick Accordingly, in the optical device wafer 2 attached to the front surface of the dicing tape 4, the back surface 20 b of the sapphire substrate 20 is on the upper side.

  After the above-described wafer supporting process is performed, the condensing point of the pulse laser beam having a wavelength having transparency to the sapphire substrate 20 is positioned from the back surface side of the sapphire substrate 20 to the inside and irradiated along the planned dividing line. A shield tunnel formation step is performed in which a pore and an amorphous that shields the pore are grown to form a shield tunnel along a dividing line. When this shield tunnel formation step is performed on the first planned dividing line 221 formed in the direction parallel to the orientation flat 201, the shield tunnel end portion is not exposed on the back surface of the sapphire substrate. The first shield tunnel forming step is performed in which the focusing point of the pulse laser beam is positioned inside so as to generate a crack from the end to the back surface of the sapphire substrate 20, and formed in the direction orthogonal to the orientation flat 201 When the second planned dividing line 222 is implemented, the second embodiment is implemented by positioning the focusing point of the pulse laser beam inside the sapphire substrate 20 so that the end of the shield tunnel is exposed on the back surface of the sapphire substrate 20 And forming a shield tunnel.

  The first shield tunnel forming step and the second shield tunnel forming step are performed using the laser processing apparatus 5 shown in FIG. The laser processing apparatus 5 shown in FIG. 3 includes a chuck table 51 for holding a workpiece, laser beam irradiation means 52 for irradiating a laser beam to the workpiece held on the chuck table 51, and holding on the chuck table 51. The imaging means 53 which images the processed to-be-processed object is comprised. The chuck table 51 is configured to suction and hold the workpiece, and is moved in the processing feed direction (X-axis direction) indicated by the arrow X in FIG. It is made to move in the indexing feed direction shown by (Y-axis direction) in FIG. 3 by means.

The laser beam application means 52 includes a cylindrical casing 521 disposed substantially horizontally. In the casing 521, a pulse laser beam oscillation means (not shown) provided with a pulse laser beam oscillator and a repetition frequency setting means is disposed. At the front end of the casing 521, a condenser 522 provided with a condenser lens 522a for condensing the pulse laser beam oscillated from the pulse laser beam oscillation means is mounted. The numerical aperture (NA) of the condenser lens 522 a of the condenser 522 is set as follows. That is, the numerical aperture (NA) of the condenser lens 522 a is set to a value obtained by dividing the numerical aperture (NA) by the refractive index of the sapphire (Al ₂ O ₃ ) substrate in the range of 0.05 to 0.2. Therefore, since the refractive index of the sapphire (Al ₂ O ₃ ) substrate is 1.7, the numerical aperture (NA) of the condenser lens 522 a is set in the range of 0.085 to 0.34. The laser beam application means 52 is provided with focusing point position adjusting means (not shown) for adjusting the focusing point position of the pulse laser beam focused by the focusing lens 522 a of the focusing device 522. .

  The image pickup means 53 mounted on the tip of the casing 521 constituting the laser beam irradiation means 52 is an infrared illumination means for irradiating an infrared ray onto a workpiece, in addition to a normal image pickup device (CCD) for imaging with visible light. An optical system for capturing infrared light emitted by the infrared illumination means, and an image pickup device (infrared CCD) for outputting an electrical signal corresponding to the infrared light captured by the optical system; Send to control means not shown.

  In order to perform the first shield tunnel forming step of the shield tunnel forming step using the above-described laser processing apparatus 5, first, the optical device wafer 2 is placed on the chuck table 51 of the above-described laser processing apparatus 5 shown in FIG. Is placed on the side of the dicing tape 4 to which the surface of the light emitting layer (epi layer) 21 constituting the light emitting device is attached. Then, the optical device wafer 2 is held on the chuck table 51 via the dicing tape 4 by operating suction means (not shown) (wafer holding step). Therefore, in the optical device wafer 2 held by 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 holding the optical device wafer 2 by suction is positioned directly below the imaging means 53 by the processing and feeding means (not shown).

  When the chuck table 51 is positioned directly below the imaging means 53, an alignment operation is performed to detect the processing area of the optical device wafer 2 to be laser-processed by the imaging means 53 and the control means (not shown). That is, the imaging unit 53 and the control unit (not shown) irradiate the laser beam along the first planned dividing line 221 formed in the direction parallel to the orientation flat 201 of the optical device wafer 2 and the first planned dividing line 221. Image processing such as pattern matching for aligning the position of the laser beam application means 52 with the light collector 522 is performed, and a first alignment of the laser beam application position is performed (first alignment step). In this first alignment step, the first planned dividing line 221 is adjusted to be parallel to the X-axis direction. Further, the alignment of the laser beam irradiation position is similarly performed even with respect to the second planned division line 222 formed in the direction orthogonal to the orientation flat 201 of the optical device wafer 2 (second alignment step). In this second alignment step, the second planned dividing line 222 is adjusted to be parallel to the X-axis direction. At this time, the surface 21 a of the light emitting layer (epi layer) 21 constituting the optical device wafer 2 on which the first planned dividing line 221 and the second planned dividing line 222 of the optical device wafer 2 are formed is positioned downward. However, as described above, the imaging unit 53 includes the imaging unit configured by the infrared illumination unit, the optical system that captures the infrared light, and the imaging device (infrared CCD) that outputs the electric signal corresponding to the infrared radiation. The first planned dividing line 221 and the second planned dividing line 222 can be imaged by watermarking from the back surface 20 b of the sapphire substrate 20 constituting the optical device wafer 2.

  When the first alignment step and the second alignment step described above are performed, as shown in FIG. 4A, the laser beam is positioned at which the condenser 522 of the laser beam application means 52 for applying the laser beam to the chuck table 51 is located. Moving to the irradiation area, the predetermined first dividing planned line 221 is positioned directly below the light collector 522. At this time, as shown in FIG. 4A, in the optical device wafer 2, one end (the left end in FIG. 4A) of the first planned division line 221 is positioned immediately below the light collector 522. Be positioned. Then, a collection point (not shown) is provided so that the focusing point P of the pulse laser beam LB focused by the focusing lens 522 a of the focusing device 522 is positioned at a desired position in the thickness direction of the sapphire substrate 20 constituting the optical device wafer 2. The light spot position adjusting means is operated to move the light collector 522 in the optical axis direction (positioning process). In the illustrated embodiment, the condensing point P of the pulse laser beam is set at a position of 100 μm from the upper surface (rear surface 20 b) on the sapphire substrate 20 of the optical device wafer 2 on which the pulse laser beam is incident. There is.

  After the positioning process is performed as described above, the laser beam application means 52 is operated to irradiate the pulse laser beam LB from the condenser 522 and the focusing point P located on the sapphire substrate 20 constituting the optical device wafer 2 A pore and an amorphous that shields the pore are formed from the vicinity toward the lower surface (surface 20a) to form a shield tunnel, and the end of the shield tunnel is not exposed on the back surface of the sapphire substrate. A first shield tunnel forming step is performed to generate a crack from the end to the back surface of the sapphire substrate 20. That is, the chuck table 51 is directed in the direction indicated by the arrow X1 in FIG. 4A while irradiating the pulsed laser beam LB having a wavelength having transparency to the sapphire substrate 20 constituting the optical device wafer 2 from the light collector 522. It is moved at a predetermined feed speed (first shield tunnel formation step). Then, when the other end (right end in (b) of FIG. 4) of the planned division line 221 reaches the irradiation position of the condenser 522 of the laser beam irradiation means 52 as shown in (b) of FIG. And stop the movement of the chuck table 51.

The first shield tunnel forming step is set to the processing conditions shown below.
Wavelength: 1030 nm
Repetition frequency: 50kHz
Pulse width: 10 ps
Average power: 3W
Spot diameter: 10 μm
Processing feed rate: 500 mm / sec. Numerical aperture of condenser lens: 0.25

  By performing the first shield tunnel forming step described above, as shown in (c) of FIG. 4, from the vicinity of the focusing point P of the pulse laser beam LB inside the sapphire substrate 20 constituting the optical device wafer 2 The pores 251 and the amorphous 252 formed around the pores 251 grow toward the lower surface (the surface 20a), and are separated along the first planned dividing lines 221 (in the illustrated embodiment, An amorphous shield tunnel 25 is formed at an interval of 10 μm (processing feed rate: 500 mm / sec) / (repetition frequency: 50 kHz) This shield tunnel 25 is shown in (d) and (e) of FIG. In the illustrated embodiment, it comprises a pore 251 having a diameter of about 1 μm and an amorphous 252 having a diameter of 10 μm formed around the pore 251. In the first shield tunnel forming step described above, the light condensing point P of the pulse laser beam LB is the optical device wafer 2. In the sapphire substrate 20 constituting the light emitting diode, it is set at a position of 100 μm from the top surface (back surface 20b) to which the pulse laser beam is incident. A crack 26 is generated from the upper end of 25 to the back surface 20b.

  As described above, when the first shield tunnel forming step is performed along the predetermined first dividing planned line 221, light emission constituting the optical device wafer 2 in the direction indicated by the arrow Y of the chuck table 51. The indexing movement is performed by an interval of the first planned dividing line 221 formed on the surface 21 a of the layer (epi layer) 21 (indexing process), and the first shield tunnel forming process is performed. When the first shield tunnel forming step is performed along all the first planned division lines 221 formed in parallel to the orientation flat 201 in this manner, the chuck table 51 is rotated 90 degrees, and the orientation is adjusted. The focusing point of the pulse laser beam is positioned inside the sapphire substrate 20 so that the end of the shield tunnel is exposed on the back surface of the sapphire substrate 20 with respect to the second planned dividing line 222 formed in the direction orthogonal to the flat 201 Implement the second shield tunnel formation step to be performed.

  To carry out the second shield tunnel formation step, as shown in FIG. 5A, the chuck table 51 is moved to the laser beam irradiation area where the condenser 522 of the laser beam irradiation means 52 for irradiating the laser beam is located, The predetermined second dividing scheduled line 222 is positioned immediately below the light collector 522. At this time, as shown in FIG. 5A, in the optical device wafer 2, one end (the left end in FIG. 5A) of the second planned division line 222 is positioned immediately below the light collector 522. Be positioned. Then, a collection point (not shown) is provided so that the focusing point P of the pulse laser beam LB focused by the focusing lens 522 a of the focusing device 522 is positioned at a desired position in the thickness direction of the sapphire substrate 20 constituting the optical device wafer 2. The light spot position adjusting means is operated to move the light collector 522 in the optical axis direction (positioning process). In the illustrated embodiment, the condensing point P of the pulsed laser beam is set at a position of 10 μm from the upper surface (back surface 20 b) on the sapphire substrate 20 of the optical device wafer 2 on which the pulsed laser beam is incident. There is.

After the positioning process is performed as described above, the laser beam application means 52 is operated to irradiate the pulse laser beam LB from the condenser 522 and the focusing point P located on the sapphire substrate 20 constituting the optical device wafer 2 A second shield tunnel formation step is performed to form a pore and an amorphous that shields the pore from the vicinity toward the lower surface (surface 20a) and expose the end of the shield tunnel to the back surface of the sapphire substrate 20 Do. That is, the chuck table 51 is directed in the direction indicated by the arrow X1 in FIG. 5A while irradiating the pulsed laser beam LB having a wavelength having transparency to the sapphire substrate 20 constituting the optical device wafer 2 from the light collector 522. It is moved at a predetermined feed speed (second shield tunnel formation step). Then, when the other end (right end in (b) of FIG. 5) of the planned division line 222 reaches the irradiation position of the condenser 522 of the laser beam irradiation means 52 as shown in (b) of FIG. And stop the movement of the chuck table 51.
The processing conditions in the second shield tunnel forming step are set to be the same as the processing conditions in the first shield tunnel forming step described above.

  By carrying out the second shield tunnel formation step described above, the sapphire substrate 20 constituting the optical device wafer 2 is located near the focusing point P of the pulse laser beam LB as shown in FIG. 5C. A pore 251 and an amorphous 252 formed around the pore 251 grow toward the lower surface (surface 20a), and the second planned dividing line 222 is formed as in the first shield tunnel forming step described above. An amorphous shield tunnel 25 is formed at intervals of 10 μm along the top surface of the sapphire substrate 20 constituting the optical device wafer 2 with the focusing point P of the pulse laser beam LB incident on the top surface (back surface 20 b) Of the shield tunnel 25 is exposed to the back surface 20b of the sapphire substrate 20, because It is tightened.

  As described above, when the second shield tunnel forming step is performed along the predetermined second dividing planned line 222, the light emission constituting the optical device wafer 2 in the direction indicated by the arrow Y of the chuck table 51. Index movement is performed by an interval of the second planned dividing line 222 formed on the surface 21 a of the layer (epi layer) 21 (indexing step), and the second shield tunnel forming step is performed. In this manner, the second shield tunnel formation step is performed along all the second planned division lines 222 formed in the direction orthogonal to the orientation flat 201.

  When the first shield tunnel forming step and the second shield tunnel forming step are performed as described above, an external force is applied to the optical device wafer 2 to form the shield tunnel 25 and the crack 26 in the optical device wafer 2. A division process is performed to divide the first divided planned line 221 and the second divided planned line 222 in which the shield tunnel 25 is formed in the individual optical devices. This division step is performed using the division device 6 shown in FIG. The dividing device 6 shown in FIG. 6 comprises a frame holding means 61 for holding the annular frame 3 and a tape expanding means for expanding the optical device wafer 2 mounted on the annular frame 3 held by the frame holding means 61. 62 and a pickup collet 63 are provided. The frame holding means 61 comprises an annular frame holding member 611 and a plurality of clamps 612 as fixing means disposed on the outer periphery of the frame holding member 611. The upper surface of the frame holding member 611 forms a placement surface 611 a on which the annular frame 3 is placed, and the annular frame 3 is placed on the placement surface 611 a. Then, the annular frame 3 placed on the placement surface 611 a is fixed to the frame holding member 611 by the clamp 612. The frame holding means 61 configured in this manner is supported by the tape expansion means 62 so as to be able to move up and down in the vertical direction.

  The tape expansion means 62 comprises an expansion drum 621 disposed inside the annular frame holding member 611. The expansion drum 621 has an inner diameter and an outer diameter smaller than the inner diameter of the annular frame 3 and larger than the outer diameter of the optical device wafer 2 attached to the dicing tape 4 mounted on the annular frame 3. Further, the extension drum 621 is provided with a support flange 622 at its lower end. The tape expansion means 62 in the illustrated embodiment comprises support means 623 capable of advancing and retracting the annular frame holding member 611 in the vertical direction. The support means 623 is composed of a plurality of air cylinders 623 a disposed on the support flange 622, and the piston rod 623 b is connected to the lower surface of the annular frame holding member 611. Thus, the support means 623 consisting of a plurality of air cylinders 623a is a reference position where the mounting surface 611a of the annular frame holding member 611 becomes approximately the same height as the upper end of the extension drum 621 as shown in FIG. 7A. As shown in FIG. 7B, the expansion position is moved up and down by a predetermined amount below the upper end of the expansion drum 621.

  The wafer dividing step performed using the dividing device 6 configured as described above will be described with reference to FIG. That is, as shown in (a) of FIG. 7, the annular frame 3 on which the dicing tape 4 to which the optical device wafer 2 is attached is attached is the mounting surface of the frame holding member 611 which constitutes the frame holding means 61. It mounts on 611a, and it fixes to the flame | frame holding member 611 by the clamp 612 (frame holding process). At this time, the frame holding member 611 is positioned at the reference position shown in FIG. Next, the plurality of air cylinders 623a as the support means 623 constituting the tape expansion means 62 are operated to lower the annular frame holding member 611 to the expansion position shown in FIG. 7B. Accordingly, since the annular frame 3 fixed on the mounting surface 611 a of the frame holding member 611 also descends, the dicing tape 4 mounted on the annular frame 3 as shown in FIG. It is expanded on the upper edge of 621 (tape expansion step). As a result, since tensile force acts radially on the optical device wafer 2 attached to the dicing tape 4, the first planned dividing line 221 and the shield tunnel 25 in which the shield tunnel 25 and the crack 26 are formed are formed. The individual light devices 23 are divided along the second planned division line 222, and a space S is formed between the light devices 23. At this time, the shield tunnel 25 and the crack 26 from the upper end of the shield tunnel 25 to the back surface 20 b are generated in the first planned dividing line 221 formed in the direction parallel to the orientation flat 201 which is hard to be broken by application of external force. Since it is easy, it can be divided with substantially the same force as the second planned division line 222 formed in the direction orthogonal to the orientation flat 201 in which only the shield tunnel 25 is formed. Thus, the optical device wafer 2 can be divided into individual optical devices 23 with uniform force.

  Next, as shown in FIG. 7C, the pickup collet 63 is operated to adsorb the optical device 23, peel it off from the dicing tape 4 and pick it up, and convey it to a tray or die bonding step (not shown). In the pick-up step, as described above, since the gaps S between the individual optical devices 23 attached to the dicing tape 4 are expanded, they are easily picked up without contacting the adjacent optical devices 23 be able to.

2: Optical device wafer 20: Sapphire substrate 201: Orientation flat 21: Light emitting layer (epi layer)
221: first division planned line 222: second division planned line 23: light device 25: shield tunnel 26: crack 3: annular frame 4: dicing tape 5: laser processing device 51: chuck table 52 of laser processing device : Laser beam application means 522: Condenser 6: Divider

Claims (1)

A light emitting layer is formed on the surface of a sapphire substrate on which an orientation flat representing a crystal orientation is formed, and an optical device wafer is formed with a plurality of optical devices in a plurality of areas divided by a plurality of grid division lines A method of processing an optical device wafer divided into
A condensing spot of a pulse laser beam of a wavelength having transparency to the sapphire substrate is positioned from the back side of the sapphire substrate to the inside and irradiated along a planned dividing line, and pores and an amorphous that shields the pores Forming a shield tunnel along a planned dividing line by growing the shield tunnel, and
Applying an external force to the optical device wafer subjected to the shield tunnel forming step, and dividing the optical device wafer into individual optical devices along a planned dividing line,
When the shield tunnel forming step is performed on a planned dividing line formed in a direction parallel to the orientation flat, the end of the shield tunnel is not exposed to the back surface of the sapphire substrate, and the sapphire substrate is isolated from the end of the shield tunnel The first shield tunnel formation process which is performed by positioning the focusing point of the pulse laser beam inside so that the crack to the back surface of the surface is generated, and the division planned line formed in the direction orthogonal to the orientation flat And performing a second shield tunnel forming step of positioning the focus of the pulse laser beam inside the sapphire substrate so as to expose the end of the shield tunnel on the back surface of the sapphire substrate.
A processing method of an optical device wafer characterized in that.