JP2012023085A - Method for processing optical device wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing an optical device wafer, in which handling, control, recovery, disposal, and the like of an etchant is more easily conducted and which has a low environmental load.SOLUTION: A method for processing an optical device wafer W having a plurality of scheduled dicing lines and optical devices formed in respective areas partitioned by the scheduled dicing lines comprises the steps of: covering a surface of the optical device wafer with a protection film 98; forming dicing starting point grooves 102 along the scheduled dicing lines of the optical device wafer covered with the protection film; applying dry etching to the optical device wafer in which the dicing starting point grooves are formed and etching side surfaces of the dicing starting point grooves; after the etching, dicing the optical device wafer into discrete chips in such a manner that the dicing starting point grooves serve as a starting point, by adding an external force to the optical device wafer; and removing the protection film before or after performing the dicing.

Description

  The present invention relates to a method of processing an optical device wafer having a plurality of division lines formed on a surface in a grid pattern and optical devices formed in each region partitioned by the division lines.

  In the manufacturing process of an optical device, a light emitting diode (LED) or laser diode (LD) is formed in each region partitioned by a plurality of division lines formed in a lattice pattern on the surface of a crystal growth substrate such as a sapphire substrate or a silicon carbide substrate. ) And the like to form an optical device wafer.

  Then, the substrate side for crystal growth of the optical device wafer is ground with a grinding machine to thin it to a predetermined thickness, and after further forming an electrode, each optical device (chip) is divided along the planned dividing line. Is manufacturing.

  For example, a cutting device or a scribing device disclosed in Japanese Patent Application Laid-Open No. 2003-124151 is used for dividing the optical device wafer. After forming grooves on the surface of the optical device wafer by a cutting device or a scribe device, the grooves are divided into individual chips starting from the grooves.

  On the other hand, in recent years, a laser processing groove is formed by irradiating a wafer with a pulsed laser beam having a wavelength that is absorptive to an optical device wafer. A method of dividing the chip into chips has been proposed (see, for example, JP-A-10-305420).

  The formation of the laser processing groove by the laser processing apparatus can increase the processing speed as compared with the dicing method by the dicer, and also compares it with an optical device wafer having a crystal growth substrate such as sapphire or SiC having a high hardness. Can be processed easily. In addition, since the processing groove can be made to have a narrow width of, for example, 10 μm or less, the amount of devices taken per wafer can be increased as compared with the case of processing by the dicing method.

  Distortion is formed on the side surface of the processed groove formed by cutting, scribing or laser processing. In order to remove this strain before breaking the optical device wafer into individual chips with a breaking device The optical device wafer is subjected to wet etching. By removing the strain by wet etching, the luminance of the manufactured optical device is improved.

JP 2003-124151 A JP-A-10-305420

  However, sapphire substrates and silicon carbide substrates used for crystal growth substrates generally have poor etching properties, and phosphoric acid is mainly used for wet etching. Phosphoric acid requires a great deal of care in handling and management, and it takes a lot of time and money to recover and dispose of it after use, resulting in high environmental impact.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method of processing an optical device wafer that is easier to handle, manage, collect, and discard an etchant and has a lower environmental impact. That is.

  According to the present invention, there is provided an optical device wafer processing method comprising a plurality of division lines formed on a surface and an optical device formed in each region partitioned by the division lines. A protective film coating step of coating the protective film with the protective film, a groove forming step of forming a split starting groove along the planned split line of the optical device wafer coated with the protective film, and a light having the split starting groove formed An etching step in which the device wafer is dry-etched to etch the side surfaces of the split starting groove, and after the etching step, an external force is applied to the optical device wafer to start the optical device wafer from the split starting groove. A dividing step for dividing the chip into individual chips, and a protective film removing step for removing the protective film before or after performing the dividing step. When, the optical device wafer processing method characterized by comprising the is provided.

  Preferably, the protective film is composed of a water-soluble protective film, and the groove forming step is performed by irradiating the optical device wafer with a laser beam having an absorptive wavelength from the surface side of the optical device wafer. A groove is formed, and in the protective film removing step, the protective film is removed using water.

  In the method for processing an optical device wafer according to the present invention, the side surfaces of the division starting groove are etched by dry etching. Since no acid is used, an optical device wafer processing method is provided that is easier to handle, manage, recover, and discard the etchant and has a lower environmental impact.

  Furthermore, since a water-soluble protective film can be used, the protective film can be easily coated and removed.

It is an external appearance perspective view of a laser processing apparatus. It is a perspective view which shows the optical device wafer supported by the cyclic | annular flame | frame via the dicing tape. It is a block diagram of a laser beam irradiation unit. It is a partially broken perspective view of a protective film coating apparatus. It is a longitudinal cross-sectional view of the protective film coating apparatus in a state where the spinner table is raised and the optical device wafer is held on the spinner table. It is a longitudinal cross-sectional view of the protective film coating | coated apparatus of the state which apply | coats water-soluble resin to the optical device wafer surface. It is an expanded sectional view of the optical device wafer with which the protective film was coat | covered. It is sectional drawing which shows a laser processing step. It is sectional drawing which shows an etching step. It is a longitudinal cross-sectional view of the protective film coating apparatus which shows a protective film removal step. It is sectional drawing which shows a division | segmentation step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, an appearance of a laser processing apparatus 2 suitable for forming a split starting groove by the optical device wafer processing method of the present invention is shown.

  On the front side of the laser processing apparatus 2, operation means 4 is provided for an operator to input instructions to the apparatus such as processing conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  As shown in FIG. 2, on the surface of the optical device wafer W to be processed, the first street S1 and the second street S2 are formed orthogonally, and the first street S1 and the second street are formed. A large number of optical devices D are formed in the region partitioned by S2.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the annular frame F via the dicing tape T, and a plurality of wafers (for example, 25 sheets) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, loading / unloading means 10 is provided for unloading the wafer W before laser processing from the wafer cassette 8 and loading the processed wafer into the wafer cassette 8.

  Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be loaded / unloaded is temporarily placed, is provided. A wafer W is fixed in the temporary placement area 12. Positioning means 14 for positioning to the position of is arranged.

  Reference numeral 30 denotes a protective film coating apparatus. The protective film coating apparatus 30 also serves as a cleaning apparatus for cleaning the processed wafer. Reference numeral 35 denotes a lid of the protective film coating apparatus 30. In the vicinity of the temporary placement region 12, a transport unit 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed.

  The wafer W carried out to the temporary placement region 12 is adsorbed by the transport means 16 and transported to the protective film coating apparatus 30. In the protective film coating apparatus 30, as will be described in detail later, the processed surface of the wafer W is coated with a protective film.

  The wafer W whose processing surface is coated with a protective film is attracted by the conveying means 16 and conveyed onto the chuck table 18 and is sucked by the chuck table 18, and the frame F is fixed by a plurality of fixing means (clamps) 19. As a result, the chuck table 18 is held.

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, an alignment unit 20 that detects a street of the wafer W to be laser processed. Is arranged.

  The alignment unit 20 includes an imaging unit 22 that images the surface of the wafer W, and can detect a street to be laser processed by image processing such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  A laser beam irradiation unit 24 that irradiates the wafer W held on the chuck table 18 with a laser beam is disposed on the left side of the alignment means 20. The laser beam irradiation unit 24 is movable in the Y axis direction.

  The casing 26 of the laser beam irradiation unit 24 accommodates laser beam oscillation means and the like which will be described in detail later, and a condenser (a light collector for condensing the laser beam on the wafer to be processed) at the tip of the casing 26. A laser head) 28 is attached.

  In the casing 26 of the laser beam irradiation unit 24, a laser beam oscillation means 34 and a laser beam modulation means 36 are disposed as shown in the block diagram of FIG. As the laser beam oscillation means 34, a YAG laser oscillator or a YVO4 laser oscillator can be used. The laser beam modulating unit 36 includes a repetition frequency setting unit 38, a laser beam pulse width setting unit 40, and a laser beam wavelength setting unit 42.

  The repetition frequency setting means 38, the laser beam pulse width setting means 40, and the laser beam wavelength setting means 42 constituting the laser beam modulation means 36 are of known forms, and detailed description thereof is omitted in this specification.

  Next, a protective film coating apparatus 30 for coating a protective film on the surface of the optical device wafer W will be described with reference to FIGS. First, referring to FIG. 4, a partially broken perspective view of the protective film coating apparatus 30 is shown.

  The protective film coating apparatus 30 includes a spinner table mechanism 44 and a cleaning water receiving mechanism 46 that surrounds the spinner table mechanism 44. The spinner table mechanism 44 includes a spinner table (holding table) 48, an electric motor 50 that rotationally drives the spinner table 48, and a support mechanism 52 that supports the electric motor 50 so as to be movable in the vertical direction.

  The spinner table 48 includes a suction chuck (holding surface) 48a formed of a porous material, and the suction chuck 48a communicates with suction means (not shown). Accordingly, the spinner table 48 holds the wafer on the suction chuck 48a by placing the wafer on the suction chuck 48a and applying a negative pressure by suction means (not shown).

  The spinner table 48 is provided with a pair of pendulum type clamps 49. When the spinner table 48 is rotated, the clamp 49 swings by a centrifugal force to clamp the annular frame F shown in FIG.

  The spinner table 48 is connected to the output shaft 50 a of the electric motor 50. The support mechanism 52 includes a plurality of (three in the present embodiment) support legs 54 and a plurality of (three in the present embodiment) air cylinders 56 respectively connected to the support legs 54 and attached to the electric motor 50. It consists of.

  The support mechanism 52 configured as described above operates the air cylinder 56 to move the electric motor 50 and the spinner table 48 at the wafer loading / unloading position, which is the lifted position shown in FIG. 5, and the lowered position, shown in FIG. It can be positioned at a certain work position.

  The cleaning water receiving mechanism 46 is attached to the cleaning water receiving container 58, three support legs 60 (only two are shown in FIG. 4) that support the cleaning water receiving container 58, and the output shaft 50 a of the electric motor 50. Cover member 62.

  As shown in FIG. 5, the washing water receiving container 58 includes a cylindrical outer wall 58a, a bottom wall 58b, and an inner wall 58c. A hole 51 into which the output shaft 50a of the electric motor 50 is inserted is provided at the center of the bottom wall 58b, and the inner wall 58c is formed so as to protrude upward from the periphery of the hole 51.

  As shown in FIG. 4, a waste liquid port 59 is provided on the bottom wall 58 b, and a drain hose 64 is connected to the waste liquid port 59. The cover member 62 is formed in a disc shape, and includes a cover portion 62a that protrudes downward from the outer periphery thereof.

  When the electric motor 50 and the spinner table 48 are positioned at the work position shown in FIG. 6, the cover member 62 configured as described above has a gap on the outside of the inner wall 58 c that constitutes the cleaning water receiving container 58. It is positioned so as to overlap.

  The protective film coating apparatus 30 includes an application unit 66 that applies a water-soluble resin to the unprocessed wafer W held by the spinner table 48. The application unit 66 includes a water-soluble resin supply nozzle 68 that supplies a water-soluble resin toward the processed surface of the wafer before processing held by the spinner table 48, and a substantially L-shaped arm that supports the water-soluble resin supply nozzle 68. 70 and an electric motor 72 capable of normal / reverse rotation that swings the water-soluble resin supply nozzle 68 supported by the arm 70. The water-soluble resin supply nozzle 68 is connected to a water-soluble resin supply source (not shown) via the arm 70.

  The protective film coating apparatus 30 also serves as a cleaning apparatus for cleaning the wafer after laser processing. Therefore, the protective film coating apparatus 30 includes cleaning water supply means 74 and air supply means 76 for cleaning the processed wafer held on the spinner table 48.

  The cleaning water supply means 74 includes a cleaning water nozzle 78 that ejects cleaning water toward the processed wafer held by the spinner table 48, an arm 80 that supports the cleaning water nozzle 78, and a cleaning that is supported by the arm 80. The electric motor 82 is configured to be able to rotate normally and reversely so as to swing the water nozzle 78. The cleaning water jet nozzle 78 is connected to a cleaning water supply source (not shown) via the arm 80.

  The air supply means 76 includes an air nozzle 84 that blows air toward the cleaned wafer held by the spinner table 48, an arm 86 that supports the air nozzle 84, and a positive that swings the air nozzle 84 that is supported by the arm 86. An electric motor (not shown) capable of rotating and reversing is provided. The air nozzle 84 is connected to an air supply source (not shown) via an arm 86.

  Next, the operation of the protective film coating apparatus 30 configured as described above will be described. The wafer before processing is transported to the spinner table 48 of the protective film coating apparatus 30 by the turning operation of the wafer transport means 16, and is sucked and held by the suction chuck 48a as shown in FIG.

  At this time, the water-soluble resin supply nozzle 68, the washing water nozzle 78, and the air nozzle 84 are positioned at a standby position separated from above the spinner table 48, as shown in FIGS.

  If the wafer W is sucked and held by the spinner table 48, a protective film coating step is performed in which a water-soluble resin is applied to the surface that is the processed surface of the wafer W to cover the protective film. In order to perform the protective film coating step, the water-soluble resin supply nozzle 68 is formed in the central region of the processing surface of the wafer W while rotating the spinner table 48 at 10 to 100 rpm (preferably 30 to 50 rpm) as shown in FIG. Water-soluble resin 69 is dropped from the above.

  Since the spinner table 48 is rotated, the dropped water-soluble resin 69 is spin-coated on the processed surface of the wafer W, and a protective film 98 is formed on the processed surface of the wafer W as shown in FIG.

  The liquid resin forming the protective film 98 is preferably a water-soluble resist such as PVA (polyvinyl alcohol) PEG (polyethylene glycol), PEO (polyethylene oxide), or the like.

  If the protective film 98 is coated on the surface of the semiconductor wafer W by the protective film coating step, the spinner table 48 is positioned at the wafer loading / unloading position shown in FIG. 5 and the wafer held by the spinner table 48 is sucked and held. Is released.

  The wafer W on the spinner table 48 is transported to the chuck table 18 by the wafer transport means 16 and sucked and held by the chuck table 18. Further, the chuck table 18 moves in the X-axis direction, and the wafer W is positioned immediately below the imaging means 22.

  Image processing such as pattern matching for aligning the condenser 28 and the street S of the laser beam irradiation unit 24 that irradiates the laser beam by imaging the processing area of the wafer W by the imaging means 22 is executed. The alignment of the laser beam irradiation position is performed.

  In this way, if the street S1 or S2 of the wafer W held on the chuck table 18 is detected and the alignment of the laser beam irradiation position is performed, the condenser that irradiates the chuck table 18 with the laser beam. The laser beam is moved to the laser beam irradiation region where the wafer 28 is located, and the laser beam is irradiated from the condenser 28 along the street S1 or S2 of the wafer W through the protective film 98 to form a laser processing groove serving as a division starting groove.

  In the laser processing groove forming step, as shown in FIG. 8, from the condenser 28 of the laser beam irradiation unit 24 for irradiating a laser beam, from the surface side, which is the processing surface of the wafer W, to the predetermined street S through the protective film 98. The chuck table 18 is moved in the X-axis direction at a predetermined feed rate (for example, 100 mm / second) while irradiating the pulse laser beam.

  The laser processing conditions are as follows, for example.

Light source: YAG laser Wavelength: 355 nm (third harmonic of YAG laser)
Output: 3.0W
Repetition frequency: 20 kHz
Condensing spot diameter: 1.0 μm
Feeding speed: 100 mm / second

  By performing the laser processing groove forming step, the laser processing groove 102 is formed along the street S on the wafer W. At this time, even if the debris 100 is generated by the irradiation of the laser beam as shown in FIG. 8, the debris 100 is blocked by the protective film 98 and does not adhere to the electronic circuit and the bonding pad of the device D.

  When the laser processing groove 102 is formed in the wafer W in this way, the chuck table 18 is first returned to the position where the wafer W is sucked and held, and here, the wafer W is released from sucking and holding.

  Next, the optical device wafer W supported by the annular frame F is taken out from the laser processing apparatus 2 and carried into the chamber of the plasma etching apparatus 104 as shown in FIG. Then, as shown by an arrow A, plasma etching using SF6 or CF4 is performed on the optical device wafer W, and the side surface 102a of the division start groove (laser processing groove) 102 is etched to remove strain from the side surface 102a. Since the surface (device formation surface) of the optical device wafer W is covered with the protective film 98, the device D is not etched.

  After the plasma etching is completed, the optical device wafer W is mounted again on the chuck table 18 of the laser processing apparatus 2, and the optical device wafer W is transported to the spinner table 40 of the protective film forming apparatus 30 by the transport means 32, and the suction chuck 48a. Hold by suction.

  At this time, the water-soluble resin supply nozzle 68, the washing water nozzle 78, and the air nozzle 84 are positioned at a standby position separated from the upper side of the spinner table 48 as shown in FIGS.

  Then, as shown in FIG. 10, the wafer W is rotated at a low speed (for example, 300 rpm) while jetting cleaning water composed of pure water and air from a cleaning water nozzle 78 connected to the pure water source and the air source. Wash.

  As a result, since the protective film 98 coated on the surface of the wafer W is formed of a water-soluble resin, the protective film 98 can be easily washed away, and debris 100 generated during laser processing is also removed. .

  When the cleaning process is completed, a drying process is performed. That is, the cleaning water nozzle 78 is positioned at the standby position, and the outlet of the air nozzle 84 is positioned above the outer peripheral portion of the wafer W held on the spinner table 48.

  Then, air is ejected from the air nozzle 84 toward the wafer W held on the spinner table 48 while rotating the spinner table 48 at, for example, 3000 rpm. At this time, the air ejected from the air nozzle 84 is swung within a swing range from a position where it hits the outer peripheral portion of the wafer W held by the spinner table 48 to a position where it hits the center portion. As a result, the surface of the wafer W is dried.

  After the wafer W is dried, the wafer W is adsorbed by the conveying means 16 and returned to the temporary storage area 12, and the wafer W is returned to the original storage location of the wafer cassette 8 by the carry-in / out means 10.

  After removing the protective film 98 from the surface of the optical device wafer W in this manner, the optical device wafer W is separated into individual chips (devices) starting from the divided starting groove 102 using a braking device 106 as shown in FIG. A division step of dividing into D is performed.

  In this dividing step, the annular frame F is placed on the placement surface of the cylinder 108 of the braking device 106, and the annular frame F is clamped by the clamp 110. A bar-shaped dividing jig 112 is disposed in the cylinder 108.

  The split jig 112 has an upper stage holding surface 114a and a lower stage holding surface 114b, and a vacuum suction path 116 opened to the lower stage holding surface 114b is formed. Here, the detailed structure of the dividing jig 112 is disclosed in Japanese Patent No. 4361506, so please refer to it.

  In order to carry out the dividing step by the dividing jig 112, the upper holding surface 114a and the lower holding surface 114b of the dividing jig 112 are lowered while the vacuum suction path 116 of the dividing jig 112 is vacuumed as indicated by an arrow 118. The dividing jig 112 is moved in the direction of arrow A by contacting the dicing tape T from the side. That is, the dividing jig 112 moves in a direction perpendicular to the street S1 to be divided.

  As a result, when the split starting groove 102 moves to a position directly above the inner edge of the upper holding surface 114a of the split jig 112, bending stress is concentrated on the portion of the street S1 having the split starting groove 102, and this bending stress is generated. Thus, the optical device wafer W is cleaved along the street S1.

  When the division along all the first streets S1 is completed, the dividing jig 112 is rotated 90 degrees, or the cylinder 108 is rotated 90 degrees, and the second street S2 orthogonal to the first street S1 is obtained. Is divided in the same way. As a result, the optical device wafer W is divided into individual optical devices D.

  In the above-described embodiment, the dividing step is performed after the protective film removing step is performed. However, the protective film removing step may be performed after the optical device wafer W is divided into the individual optical devices D. Good.

  As described above, in the above-described embodiment, the strain is removed by etching the side surface 102a of the division start groove 102 by plasma etching which is a kind of dry etching. Since no acid is used, it is possible to provide a method of processing an optical device wafer that is easier to handle, manage, recover, and discard the etchant and has a lower environmental impact.

2 Laser processing device 18 Chuck table 24 Laser beam irradiation unit 28 Condenser 30 Protective film coating device 48 Spinner table 66 Water-soluble resin coating means 68 Water-soluble resin supply nozzle 74 Cleaning means 78 Washing water nozzle 98 Protective film 100 Debris 102 Division Starting groove 102a Side surface 104 of dividing starting groove 104 Plasma etching apparatus 106 Breaking apparatus 112 Dividing jig

Claims (2)

An optical device wafer processing method comprising a plurality of division lines formed on a surface and an optical device formed in each region partitioned by the division lines,
A protective film coating step for coating the surface of the optical device wafer with a protective film;
A groove forming step of forming a split starting groove along the planned split line of the optical device wafer coated with the protective film;
An etching step of performing dry etching on the optical device wafer in which the division start groove is formed, and etching a side surface of the division start groove;
After performing the etching step, a dividing step of applying an external force to the optical device wafer to divide the optical device wafer into individual chips from the dividing starting groove as a starting point;
A protective film removing step for removing the protective film before or after performing the dividing step;
An optical device wafer processing method characterized by comprising: The protective film is composed of a water-soluble protective film,
In the groove forming step, the split starting groove is formed by irradiating a laser beam having a wavelength having an absorptivity to the optical device wafer from the surface side of the optical device wafer.
The method of processing an optical device wafer according to claim 1, wherein in the protective film removing step, the protective film is removed using water.

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