JP2011108856A - Method of processing optical device wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of processing an optical device wafer, which is capable of easily forming an altered layer in a range not reaching an optical device layer and capable of forming devices so that they have a predetermined thickness. <P>SOLUTION: The wafer processing method for splitting a wafer, which has an optical device layer laminated on a surface thereof and includes optical devices formed in regions delimited by multiple streets formed in a lattice pattern, into individual optical devices includes a step of attaching a protective member 30 onto a surface 20a of an optical device wafer 2, a step of applying laser light having a wavelength permeable to a substrate 20 along the streets 22 from the rear surface 20b side of the substrate with a focal point positioned on the inside of the substrate to form an altered layer 210 along the streets on the rear surface side beyond the optical device layer 21 in the inside of the substrate, a step of grinding the rear surface 20b of the substrate so that the substrate has a predetermined thickness, and a step of applying an external force to the optical device wafer to split the optical device wafer along the streets 22 having the altered layer 210 into individual optical devices. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 a 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. Furthermore, since the cutting blade has a thickness of about 20 μm, the street that partitions the device needs to have a width of about 50 μm. For this reason, the area ratio which a street occupies becomes high, and there exists a problem that productivity is bad.

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

  However, when a laser processing groove is formed by irradiating a laser beam along the street formed on the surface of the sapphire substrate that constitutes the optical device wafer, the outer periphery of the optical device such as a light emitting diode is ablated, resulting in a decrease in luminance. There is a problem that the quality of the device is degraded.

  In order to solve such a problem, a laser beam having a wavelength that is transmissive to the sapphire substrate from the back side of the sapphire substrate on which the light emitting layer (epi layer) as the optical device layer is not formed is focused inside. The method of processing a sapphire substrate that irradiates along the street and forms an altered layer along the street inside the sapphire substrate to divide the sapphire substrate along the street where the altered layer is formed is as follows. It is disclosed in Document 2.

JP-A-10-305420 JP 2008-6492 A

  In the wafer dividing method disclosed in the above-mentioned Patent Document 2, first, after grinding the back surface of the wafer in order to make the wafer a predetermined thickness (for example, 100 μm or less), a wavelength having transparency to the wafer is obtained. A pulse laser beam is irradiated from the back side of the wafer along the street with the converging point inside, and an altered layer is formed inside the wafer that becomes the starting point of breakage along the street. When the light emitting layer (epi layer) is reached, the optical device layer is damaged and the luminance of the optical device is lowered. In order to solve such a problem, it is necessary to form a deteriorated layer within a range not reaching the optical device layer. However, it is very difficult to form a deteriorated layer in a range that does not reach the optical device layer when the wafer thickness is 100 μm or less.

  The present invention has been made in view of the above facts, and the main technical problem thereof is that the altered layer can be easily formed in a range not reaching the optical device layer, and the thickness of the optical device is formed to a predetermined thickness. An object of the present invention is to provide a method of processing an optical device wafer that can be performed.

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 protective member attaching step for attaching a protective member to the surface of the optical device wafer;
A laser beam having a wavelength that is transparent to the substrate of the optical device wafer is irradiated from the back side of the substrate to the inside of the substrate along the street, and the street is irradiated to the back side of the optical device layer from the optical device layer. An altered layer forming step of forming an altered layer along
A back surface grinding step of grinding the back surface of the substrate of the optical device wafer on which the altered layer forming step has been performed to form a predetermined thickness;
A wafer breaking step in which an external force is applied to the optical device wafer on which the back surface grinding process has been performed to break the optical device wafer along the street where the altered layer is formed, and to divide the wafer into individual optical devices.
An optical device wafer processing method is provided.

In the altered layer forming step, the altered layer is formed on the back side from the position of 20 to 60 μm from the surface of the substrate of the optical device wafer.
In the protective member attaching step, the surface of the optical device wafer is attached to a protective tape as a protective member attached to an annular frame, and the altered layer is formed in a state where the surface of the optical device wafer is attached to the protective tape. A process, a back grinding process, and a wafer breaking process are performed.
After performing the wafer breaking step, a deteriorated layer removing step is performed in which the deteriorated layer is removed by grinding the back surface of the substrate of the optical device wafer.
In the protective member attaching step, the surface of the optical device wafer is attached to a protective tape as a protective member attached to an annular frame, and the altered layer is formed in a state where the surface of the optical device wafer is attached to the protective tape. A process, a back grinding process, a wafer breaking process, and a deteriorated layer removing process are performed.

In the present invention, the deteriorated layer forming step is performed in a thick state before the back surface of the substrate constituting the optical device wafer is ground and formed to a predetermined thickness, so that the condensing point of the laser beam can be easily set at a desired position. The altered layer can be formed without damaging the optical device layer.
Further, in the present invention, after performing the deteriorated layer forming step, the back surface grinding step is performed to form the thickness of the optical device wafer to a predetermined thickness, and the optical device wafer is broken along the street where the deteriorated layer is formed. Therefore, the thickness of the deteriorated layer can be minimized and productivity is improved.

The perspective view and principal part expanded sectional view which show the optical device wafer as a wafer. The perspective view which shows the state which the protective member sticking process in the processing method of the optical device wafer by this invention was implemented, and the surface of the wafer was stuck on the protective tape with which the cyclic | annular flame | frame was mounted | worn. The principal part perspective view of the laser processing apparatus for implementing the deteriorated layer formation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the deteriorated layer formation process in the processing method of the optical device wafer by this invention. Explanatory drawing of the back surface grinding process in 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 back surface grinding process in the processing method of the optical device wafer by this invention was implemented. The perspective view of the wafer fracture | rupture apparatus for implementing the wafer fracture | rupture process in the processing method of the optical device wafer by this invention. Explanatory drawing of the wafer fracture | rupture process in the processing method of the optical device wafer by this invention. Explanatory drawing of the deteriorated layer removal process in 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 deteriorated layer removal process in the processing method of the optical device wafer by this invention was implemented. Explanatory drawing of the wafer transfer process in the processing method of the optical device wafer by this invention. The perspective view of the pick-up apparatus for implementing the pick-up process in the processing method of the optical device wafer by this invention. Explanatory drawing of the pick-up 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. In the optical device wafer 2 shown in FIGS. 1A and 1B, for example, a light emitting layer (epi layer) 21 as an optical device layer made of a nitride semiconductor is formed on the surface 20a of a sapphire substrate 20 having a thickness of 430 μm. They are stacked with a thickness of 10 μm. 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 individual optical devices 22 along the streets 21 will be described.

  First, in order to protect the optical device formed on the surface of the optical device wafer, a protective member attaching step of attaching a protective member to the surface of the optical device wafer is performed. That is, as shown in FIG. 2, the surface 2a of the optical device wafer 2 is adhered to the surface of the protective tape 30 as a protective member attached to the annular frame 3 formed of a metal material. In the illustrated embodiment, the protective tape 30 has an acrylic resin-based paste applied to the surface of a sheet base material made of polyvinyl chloride (PVC) having a thickness of 100 μm to a thickness of about 5 μm. This glue has a property of reducing the adhesive strength when irradiated with ultraviolet rays.

  If the surface 2a of the optical device wafer 2 is attached to the protective tape 30 attached to the annular frame 3 by carrying out the protective member attaching step described above, the optical device wafer 2 is permeable to the substrate. A deteriorated layer forming process in which a laser beam with a wavelength is irradiated from the back side of the substrate to the inside of the substrate along the street, and an altered layer is formed inside the substrate along the street from the optical device layer to the back side. To implement. This deteriorated layer forming step is performed using a 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. 3 by an index feed means (not shown). 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.

  In the illustrated embodiment, the image pickup means 43 mounted on the tip of the casing 421 constituting the laser beam irradiation means 42 is constituted by an image pickup device (CCD) that picks up an image with visible light, and captures the picked-up image signal. It sends to the control means which is not illustrated.

Using the laser processing apparatus 4 described above, a laser beam having a wavelength that is transparent to the sapphire substrate 20 constituting the optical device wafer 2 is focused on the inside of the sapphire substrate 20 from the back surface 20b side of the sapphire substrate 20. Refer to FIGS. 3 and 4 for the altered layer forming step of positioning and irradiating along the street 22 and forming the altered layer along the street 22 on the back surface 20b side from the light emitting layer (epi layer) 21 as an optical device layer. To explain.
First, the protective tape 30 having the optical device wafer 2 attached thereto is placed on the chuck table 41 of the laser processing apparatus 4 shown in FIG. Then, by operating a suction means (not shown), the optical device wafer 2 is held on the chuck table 41 via the protective tape 30 (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 FIG. 3, the annular frame 3 to which the protective tape 30 is attached is omitted, but the annular frame 3 is held by an appropriate frame holding means provided 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 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 on the 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. Then, the condensing point P of the pulsed laser beam irradiated from the condenser 422 is adjusted to a position above 55 μm, for example, from the surface 20 a (lower surface) of the sapphire substrate 20 constituting the optical device wafer 2. In order to position the condensing point P of the pulsed laser beam irradiated from the concentrator 422 at a predetermined position of the sapphire substrate 20 constituting the optical device wafer 2, for example, a chuck described in JP 2009-63446 A The height position of the upper surface of the optical device wafer 2 held on the chuck table 41 is detected using a height position detection device for the workpiece held on the table, and the detected height of the upper surface of the optical device wafer 2 is detected. By operating a condensing point position adjusting means (not shown) with the position as a reference, the condensing point P of the pulse laser beam is positioned at a predetermined position. 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 a pulsed laser beam having a wavelength transmissive to the sapphire substrate 20 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 sapphire substrate 20 constituting the optical device wafer 2, an altered layer 210 continuous along the street 22 is formed inside as shown in FIG. 4B and FIG. Altered layer formation step). The altered layer 210 is formed on the back surface 20b (upper surface) side of the front surface 20a (lower surface) of the sapphire substrate 20, that is, the light emitting layer (epi layer) 21. The above-mentioned deteriorated layer forming step is performed along all the streets 22 formed on the optical device wafer 2.

The processing conditions in the above-mentioned deteriorated layer forming step are set as follows, for example.
Light source: Yb laser: Ytterbium doped fiber laser Wavelength: 1045 nm pulse laser Repetition frequency: 100 kHz
Average output: 0.3W
Condensing spot diameter: φ1 ~ 1.5μm
Processing feed rate: 400 mm / sec

  When the above-described deteriorated layer forming step is performed under the above processing conditions, the deteriorated layer 210 of about 50 μm is formed in the vertical direction around the condensing point P of the pulse laser beam. Therefore, by performing the above-described deteriorated layer forming step, the deteriorated layer 210 of about 50 μm is formed on the back surface 20b (upper surface) side from the position of 30 μm from the front surface 20a (lower surface) of the sapphire substrate 20, that is, the light emitting layer (epi layer) 21. It is formed. The altered layer 210 formed inside the sapphire substrate 20 is preferably formed on the back surface 20b side from the position 20 to 60 μm from the surface 20a of the sapphire substrate 20, that is, the light emitting layer (epi layer) 21. Thus, in the deteriorated layer forming step, the deteriorated layer 210 is formed within the sapphire substrate 20 in a range that does not reach the light emitting layer (epi layer) 21, so that the light emitting layer (epi layer) 21 that is an optical device layer is formed. There is no damage. In addition, the deteriorated layer forming step is performed in a thick state (for example, 430 μm) before the back surface is ground and formed into a predetermined thickness as described later, so that the sapphire substrate 20 constituting the optical device wafer 2 is formed. The condensing point P can be easily positioned at a desired position, and the altered layer 210 can be formed without damaging the light emitting layer (epi layer) 21 that is an optical device layer.

  If the above-mentioned deteriorated layer forming step is performed, the back surface grinding step of grinding the back surface of the optical device wafer to form a predetermined thickness is performed. This back grinding process is performed using a grinding apparatus 5 shown in FIG. A grinding apparatus 5 shown in FIG. 5 includes a grinding tool 52 including a chuck table 51 that holds a workpiece and a grinding wheel 521 for grinding the workpiece held on the chuck table 51. . Note that the chuck table 51 is formed such that the central portion for holding the workpiece is high and the outer peripheral portion is lower than the central portion. In order to perform the back surface grinding process using the grinding apparatus 5 configured as described above, an optical device wafer in which the above-mentioned deteriorated layer forming process is performed on the chuck table 51 of the grinding apparatus 5 as shown in FIG. 2 is placed on the protective tape 30 side, the annular frame 3 is placed on the outer periphery of the chuck table 51, and a suction means (not shown) is operated to operate the optical device wafer 2 and the annular frame on the chuck table 51. 3 is sucked and held. Therefore, 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. When the optical device wafer 2 is sucked and held on the chuck table 51 in this way, the sapphire constituting the optical device wafer 2 by rotating the grinding tool 52 at 1000 rpm, for example, while rotating the chuck table 51 at 500 rpm, for example. While contacting the back surface 20b of the substrate 20, it is ground and fed by a predetermined amount. As a result, the back surface 20b of the sapphire substrate 20 is ground, and the sapphire substrate 20 constituting the optical device wafer 2 is formed to a predetermined thickness (for example, 80 μm). As a result, the altered layer 210 is exposed on the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 as shown in FIG. As described above, after the above-described deteriorated layer forming step is performed, the back surface grinding step is performed to form the wafer with a predetermined thickness, so that the thickness of the deteriorated layer can be minimized and the productivity is improved. .

  If the back grinding process described above is performed, an external force is applied to the optical device wafer to break the wafer along the street where the altered layer is formed, and the wafer breaking process is performed to divide the wafer into individual optical devices. This wafer breaking step is carried out using a wafer breaking device 6 shown in FIG. A wafer breaking device 6 shown in FIG. 7 includes a base 61 and a moving table 62 arranged on the base 61 so as to be movable in a direction indicated by an arrow Y. The base 61 is formed in a rectangular shape, and two guide rails 611 and 612 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 62 is movably disposed on the two guide rails 611 and 612. The moving table 62 is moved in the direction indicated by the arrow Y by the moving means 63. Frame holding means 64 for holding the annular frame 3 is disposed on the moving table 62. The frame holding means 64 includes a cylindrical main body 641, an annular frame holding member 642 provided at the upper end of the main body 641, and a plurality of clamps 643 as fixing means disposed on the outer periphery of the frame holding member 642. It is made up of. The frame holding means 64 configured as described above fixes the annular frame 3 placed on the frame holding member 642 by the clamp 643. Further, the wafer breaking device 6 shown in FIG. 7 includes a rotating means 65 for rotating the frame holding means 64. The rotating means 65 is wound around a pulse motor 651 disposed on the moving table 62, a pulley 652 mounted on the rotation shaft of the pulse motor 651, and the pulley 652 and a cylindrical main body 641. It consists of an endless belt 653. The rotation means 65 configured as described above rotates the frame holding means 64 via the pulley 652 and the endless belt 653 by driving the pulse motor 651.

  The wafer breaking device 6 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 3 held by the annular frame holding member 642 via the protective tape 30. There is provided a tension applying means 66 for acting. The tension applying means 66 is disposed in the annular frame holding member 64. The tension applying means 66 includes a first suction holding member 661 and a second suction holding member 662 each having a rectangular holding surface that is long in a direction orthogonal to the arrow Y direction. The first suction holding member 661 has a plurality of suction holes 661a, and the second suction holding member 662 has a plurality of suction holes 662a. The plurality of suction holes 661a and 662a communicate with suction means (not shown). Further, the first suction holding member 661 and the second suction holding member 662 can be moved in the arrow Y direction by a moving means (not shown).

  The wafer breaking device 6 shown in FIG. 7 is a detecting means for detecting the street 22 of the optical device wafer 2 supported by the annular frame 3 held by the annular frame holding member 642 via the protective tape 30. 67. The detection means 67 is attached to an L-shaped support column 671 disposed on the base 61. The detection means 67 is composed of an optical system, an image pickup device (CCD), and the like, and is disposed above the tension applying means 66. The detection means 67 configured in this manner images the street 22 of the optical device wafer 2 supported by the annular frame 3 held by the annular frame holding member 642 via the protective tape 30, It is converted into an electric signal and sent to a control means (not shown).

Wafer breakage performed using the wafer breaker 6 described above will be described with reference to FIG.
As shown in FIG. 8A, the annular frame 3 that supports the optical device wafer 2 on which the deteriorated layer forming step as the fracture starting point forming step is carried out is provided on the frame holding member 642 as shown in FIG. And fixed to the frame holding member 642 by the clamp 643. Next, the moving means 63 is actuated to move the moving table 62 in the direction indicated by the arrow Y (see FIG. 7), and 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 661 and the holding surface of the second suction holding member 662 constituting the tension applying means 66. . At this time, the street 22 is imaged by the detection means 67, and the holding surface of the first suction holding member 661 and the holding surface of the second suction holding member 662 are aligned. In this way, when one street 22 is positioned between the holding surface of the first suction holding member 661 and the holding surface of the second suction holding member 662, the suction means (not shown) is operated to perform suction. By applying a negative pressure to the holes 661a and 662b, the optical device wafer 2 is sucked and held via the protective tape 30 on the holding surface of the first suction holding member 661 and the holding surface of the second suction holding member 662. (Holding process).

  When the holding step described above is performed, the moving means (not shown) constituting the tension applying means 66 is operated, and the first suction holding member 661 and the second suction holding member 662 are shown in FIG. Move them away from each other. As a result, a tensile force acts on the street 22 positioned between the holding surface of the first suction holding member 661 and the holding surface of the second suction holding member 662 in a direction perpendicular to the street 22, In the device wafer 2, the altered layer 210 formed on the sapphire substrate 20 is broken along the streets 22 as a starting point of breaking (breaking step). By carrying out this breaking step, the protective tape 30 is slightly extended. In this breaking process, the optical device wafer 2 has the deteriorated layer 210 formed along the streets 22 to reduce the strength, so that the first suction holding member 661 and the second suction holding member 662 are separated from each other. By moving about 0.5 mm in the direction, the altered layer 210 formed on the sapphire substrate 20 of the optical device wafer 2 can be broken along the street 22 as a starting point of breakage.

  As described above, if 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 661 and the second suction holding member 662 described above. Release suction hold. Next, the moving means 63 is actuated to move the moving table 62 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 adjacent to the street 22 on which the above breaking process is performed. Is positioned between the holding surface of the first suction holding member 661 and the holding surface of the second suction holding member 662 constituting the tension applying means 66. 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 65 is operated to rotate the frame holding means 64 by 90 degrees. As a result, the optical device wafer 2 held by the frame holding member 642 of the frame holding means 64 is also rotated 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 661 and the holding surface of the second suction holding member 662. 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. It is divided into individual optical devices 23.

  If the wafer breaking step described above is performed, a deteriorated layer removing step is performed in which the deteriorated layer is removed by grinding the back surface of the optical device wafer. This deteriorated layer removing step is performed using the grinding apparatus 5 shown in FIG. That is, as shown in FIG. 9, the protective tape 30 side of the optical device wafer 2 (divided into individual optical devices 23) on which the wafer breaking process described above has been performed is placed on the chuck table 51 of the grinding apparatus 5. At the same time, the annular frame 3 is placed on the outer periphery of the chuck table 51, and the suction device (not shown) is operated to suck and hold the optical device wafer 2 and the annular frame 3 on the chuck table 51. Therefore, 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. When the optical device wafer 2 is sucked and held on the chuck table 51 in this way, the sapphire constituting the optical device wafer 2 by rotating the grinding tool 52 at 1000 rpm, for example, while rotating the chuck table 51 at 500 rpm, for example. While contacting the back surface 20b of the substrate 20, a predetermined amount is ground and fed to the position where the altered layer 210 is removed. As a result, the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 is ground, and the altered layer 210 remaining on the side surfaces of the optical devices 23 divided individually as shown in FIG. 10 is removed. In this manner, the altered layer 210 remaining on the side surfaces of the individually divided optical devices 23 is removed, so that the luminance of the optical devices 23 can be improved.

  If the deteriorated layer removal step described above is performed, the back surface of the optical device wafer divided into individual optical devices is attached to the surface of the protective tape attached to the annular frame, and the surface of the optical device wafer is attached. A wafer transfer process is performed to remove the annular frame 3 by peeling off the attached protective tape 30. In this wafer transfer step, as shown in FIG. 11 (a), the protective tape 30 attached to the annular frame 3 (the optical device wafer 2 divided into individual optical devices 23 is attached). Ultraviolet rays are irradiated from the ultraviolet irradiator 300. As a result, the adhesive paste of the protective tape 30 is cured and the adhesive force is reduced. Next, as shown in FIG. 11B, the back surface 20b of the sapphire substrate 20 constituting the optical device wafer 2 attached to the protective tape 30 attached to the annular frame 3 (FIG. 11B). In FIG. 11, the surface (the lower surface in FIG. 11B) of the protective tape 30a attached to the annular frame 3a is adhered. The annular frame 3a and the protective tape 30a may have substantially the same configuration as the annular frame 3 and the protective tape 30. Next, as shown in FIG. 11C, the optical device wafer 2 (divided into individual optical devices 23) whose surface is attached to the protective tape 30 is peeled off from the protective tape 30. At this time, as shown in FIG. 11A, the protective tape 30 is irradiated with ultraviolet rays, and the adhesive paste of the protective tape 30 is cured to reduce the adhesive force. Can be easily peeled off from the protective tape 30. Then, by removing the annular frame 3 to which the protective tape 30 is attached, the light divided into individual devices on the surface of the protective tape 30a attached to the annular frame 3a as shown in FIG. 11 (d). The device wafer 2 has been transferred. Thus, in the wafer transfer process, the above-mentioned altered layer process, back grinding process, wafer breaking process, and altered layer removal process are performed in a state where the wafer surface is adhered to the protective tape 30 attached to the annular frame 3. Then, since the optical device wafer 2 is divided into the individual devices 23, the optical device wafer 2 can be reversed and replaced with the protective tape 30a attached to the annular frame 3a without breaking. Accordingly, the continuity test of the optical device 23 can be performed in a state where the optical device wafer 2 divided into the individual optical devices 23 is replaced with the protective tape 30a attached to the annular frame 3a.

  If the wafer transfer process is carried out as described above, a pick-up process for separating and picking up the individually divided optical devices attached to the surface of the protective tape attached to the annular frame from the protective tape is performed. carry out. This pickup process is performed using the pickup device 7 shown in FIG. The pickup device 7 shown in FIG. 12 includes a frame holding means 71 for holding the annular frame 3a and a tape extending means 72 for extending the protective tape 30a attached to the annular frame 3a held by the frame holding means 71. And a pickup collet 73. The frame holding means 71 includes an annular frame holding member 711 and a plurality of clamps 712 as fixing means provided on the outer periphery of the frame holding member 711. An upper surface of the frame holding member 711 forms a mounting surface 711a on which the annular frame 3a is mounted, and the annular frame 3a is mounted on the mounting surface 711a. The annular frame 3 a placed on the placement surface 711 a is fixed to the frame holding member 711 by a clamp 712. The frame holding means 71 configured as described above is supported by the tape expanding means 72 so as to be able to advance and retreat in the vertical direction.

  The tape expansion means 72 includes an expansion drum 721 disposed inside the annular frame holding member 711. The expansion drum 721 has an inner diameter and an outer diameter that are smaller than the inner diameter of the annular frame 3a and larger than the outer diameter of the optical device wafer 2 (divided into individual optical devices 23) mounted on the annular frame 3a. is doing. The expansion drum 721 includes a support flange 722 at the lower end. The tape expansion means 72 in the illustrated embodiment includes support means 723 that can advance and retract the annular frame holding member 711 in the vertical direction. The support means 723 includes a plurality of air cylinders 723 a disposed on the support flange 722, and the piston rod 723 b is connected to the lower surface of the annular frame holding member 711. In this way, the support means 723 including the plurality of air cylinders 723a is configured such that the mounting position 711a is substantially the same height as the upper end of the expansion drum 721, as shown in FIG. Then, as shown in FIG. 13 (b), it is moved in the vertical direction between the extended positions below the upper end of the expansion drum 721 by a predetermined amount.

  A pickup process performed using the pickup device 7 configured as described above will be described with reference to FIG. That is, an annular frame 3a on which an outer protective tape 30a to which an optical device wafer 2 (divided into individual devices) is attached is attached to a frame holding means 71 as shown in FIG. Is mounted on the mounting surface 711a of the frame holding member 711, and fixed to the frame holding member 711 by the clamp 712 (frame holding step). At this time, the frame holding member 711 is positioned at the reference position shown in FIG. Next, the plurality of air cylinders 723a as the supporting means 723 constituting the tape extending means 72 are operated to lower the annular frame holding member 711 to the extended position shown in FIG. Accordingly, since the annular frame 3a fixed on the mounting surface 711a of the frame holding member 711 is also lowered, the protective tape 30a attached to the annular frame 3a is an expansion drum as shown in FIG. It is expanded in contact with the upper edge of 721 (tape expansion process). As a result, since the optical device wafer 2 attached to the protective tape 30a is divided into individual optical devices 23 along the street 21, the space between the individual devices 23 is widened, and a space S is formed. In this state, the pick-up collet 73 is operated to suck and hold the surface (upper surface) of the optical device 23, and the pick-up is peeled off from the protective tape 30a. At this time, as shown in FIG. 13B, the optical device 23 can be easily peeled from the protective tape 30a by pushing up the device 23 with the push-up needle 74 from the lower side of the protective tape 30a. Since the push-up needle 74 acts on the back surface of the optical device 23 and pushes it up, the surface of the optical device 23 is not damaged. In the pickup process, since the gap S between the individual optical devices 23 is widened as described above, the pickup can be easily performed without contacting the adjacent optical devices 23. As described above, since the optical device 23 picked up by the pickup collet 73 has the surface (upper surface) held by suction, it is not necessary to reverse the front and back of the optical device 23 thereafter.

  Although the present invention has been described based on the illustrated embodiment, the present invention is not limited to the embodiment, and various modifications are possible within the scope of the gist of the present invention. For example, in the embodiment described above, an example in which a tensile force acts in a direction perpendicular to the street where the altered layer that is the starting point of the fracture is formed as the wafer breaking step, and the wafer is broken along the street where the altered layer is formed. However, as a wafer breaking process, for example, as disclosed in Japanese Patent Application Laid-Open No. 2006-107273 and Japanese Patent Application Laid-Open No. 2006-128211, bending along the street is performed on the wafer whose strength is reduced along the street. Other breaking methods such as a method of breaking the wafer along the street by applying a stress may be used.

2: Optical device wafer 20: Sapphire substrate 21: Light emitting layer (epi layer) as an optical device layer
3: annular frame 30: protective tape 4: laser processing device 41: chuck table of laser processing device 42: laser beam irradiation means 422: condenser 5: grinding device 51: chuck table of grinding device 52: grinding tool 6: wafer Breaking device 66: Tension applying means 7: Pickup device 82: Tape expansion means 73: Pickup collet

Claims (5)

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 protective member attaching step for attaching a protective member to the surface of the optical device wafer;
A laser beam having a wavelength that is transparent to the substrate of the optical device wafer is irradiated from the back side of the substrate to the inside of the substrate along the street, and the street is irradiated to the back side of the optical device layer from the optical device layer. An altered layer forming step of forming an altered layer along
A back surface grinding step of grinding the back surface of the substrate of the optical device wafer on which the altered layer forming step has been performed to form a predetermined thickness;
A wafer breaking step in which an external force is applied to the optical device wafer on which the back surface grinding process has been performed to break the optical device wafer along the street where the altered layer is formed, and to divide the wafer into individual optical devices.
An optical device wafer processing method characterized by the above.   The optical device wafer processing method according to claim 1, wherein the deteriorated layer forming step forms the deteriorated layer on the back side from the position of 20 to 60 μm from the surface of the substrate of the optical device wafer.   In the protective member attaching step, the surface of the optical device wafer is attached to a protective tape as a protective member attached to an annular frame, and the altered layer is formed in a state where the surface of the optical device wafer is attached to the protective tape. The method of processing an optical device wafer according to claim 1 or 2, wherein the step, the back grinding step and the wafer breaking step are performed.   The optical device wafer processing method according to claim 1 or 2, wherein after the wafer breaking step, the deteriorated layer removing step of removing the deteriorated layer by grinding the back surface of the substrate of the optical device wafer.   In the protective member attaching step, the surface of the optical device wafer is attached to a protective tape as a protective member attached to an annular frame, and the altered layer is formed in a state where the surface of the optical device wafer is attached to the protective tape. The processing method of an optical device wafer according to claim 4, wherein the step, the back grinding step, the wafer breaking step, and the deteriorated layer removing step are performed.

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