KR20120057483A - Method for machining optical device wafer - Google Patents

Abstract

PURPOSE: A method for processing a light device wafer is provided to prevent damage of the surface of a light-transmission molded resin by uniformly turning the light-transmission molded resin coated on the surface of the light device wafer through rotating byte. CONSTITUTION: The surface of a light device wafer(11) is coated with a light-transmission molded resin(35). A byte cutting unit comprises a housing(20), a spindle(22), a mount(24), and a byte wheel(25). The spindle is accepted within the housing which can be rotated. The byte wheel is detachably installed to the mount. A rinse nozzle washes a chuck table(30). The light device wafer is maintained by the chuck table in order to expose the light-transmission molded resin.

Description

Processing method of optical device wafer {METHOD FOR MACHINING OPTICAL DEVICE WAFER}

The present invention relates to a processing method of an optical device wafer having a plurality of division scheduled lines formed in a lattice shape on a surface thereof, an optical device formed in each region partitioned by the division scheduled lines, and the like.

In the manufacturing process of an optical device, an n-type semiconductor layer and a p-type semiconductor layer are laminated on a crystal growth substrate such as a sapphire substrate or a silicon carbide (SiC) substrate to form a light emitting layer (epitaxial layer), and a lattice is formed on the light emitting layer. An optical device wafer is manufactured by forming a light emitting element such as a light emitting diode (LED) or a laser diode (LD) in each region partitioned by a plurality of division scheduled lines formed in a shape.

Thereafter, the substrate for crystal growth of the optical device wafer is ground with a grinding apparatus, thinned to a predetermined thickness, and further formed with electrodes, and then divided along a division scheduled line by a laser processing apparatus or the like, thereby providing individual optical devices ( Chips).

The light emitting layer of an LED emitting blue light is generally formed of a nitride semiconductor, and has a relatively high output and little color unevenness due to temperature. However, there is a tendency that high output cannot be obtained in a long wavelength region of green or higher.

Therefore, LEDs are coated with a light-transmitting mold resin containing a fluorescent material such as YAG: Ce that absorbs blue light from the LED chip and emits yellow light, which is complementary, and thus emits white light. It is becoming.

However, as the light emitting device becomes smaller, light emission unevenness and chromaticity unevenness occur, and thus the optical characteristic is lowered. Proposed in the publication.

Japanese Patent No. 3589187

However, as described in Patent Literature 1, when the surface of the translucent mold resin is polished to expose the electrode, and the optical device wafer is finished to a desired thickness, the surface of the translucent mold resin is damaged and the quality is degraded. There is.

In addition, the light-transmissive mold resin is coated to embed electrodes such as gold or platinum protruding from the n-type semiconductor layer and the p-type semiconductor layer, and then the surface of the light-transmissive mold resin is polished to expose the electrode from the light-transmissive mold resin. There is a problem that there is a possibility that the electrodes are short-circuited due to the ductility.

This invention is made | formed in view of such a point, and the objective is to provide the processing method of the optical device wafer which does not cause damage to the surface of a translucent mold resin, and does not generate a short circuit between electrodes. .

According to the present invention, a plurality of optical devices are formed in a light emitting layer, and a processing method of an optical device wafer coated with a transparent mold resin for improving optical characteristics on the surface of the light emitting layer, wherein the optical device wafer is exposed so that the transparent mold resin is exposed. The holding step of holding on the chuck table and the light transmitting mold resin of the optical device wafer held on the chuck table are operated while rotating a bite to evenly turn the light transmitting mold resin to make the light transmitting mold resin to a desired thickness. A processing method of an optical device wafer is provided, including a turning step of finishing.

Preferably, the light emitting layer includes an n-type semiconductor layer, a p-type semiconductor layer stacked on the n-type semiconductor layer, a cathode protruding from the n-type semiconductor layer, and an anode protruding from the p-type semiconductor layer. And the light-transmissive mold resin is coated on the light emitting layer to embed the negative electrode and the positive electrode, and in the turning step, the light-transmissive mold resin is turned until the negative electrode and the positive electrode are exposed from the light-transmissive mold resin.

Preferably, the translucent mold resin is selected from epoxy resins, silicone resins, urethane resins, unsaturated polyester resins, acrylic urethane resins or polyimide resins.

In the present invention, the transparent mold resin coated on the surface of the optical device wafer by the rotating bite is evenly turned and finished to a desired thickness, so that the problem of damage to the surface of the transparent mold resin can be solved.

Moreover, since the electrode is exposed from the translucent mold resin by turning the surface of the translucent mold resin with a rotating bite, the ductility of the metal is suppressed and the short circuit between the electrodes can be solved.

1 is a front side perspective view of an optical device wafer.
2 is a perspective view of a bite cutting device equipped with a bite wheel.
3 is a perspective view of a bite wheel.
4 is an exploded perspective view of the bite unit.
FIG. 5A is a side view showing the attachment structure of the bite unit to the wheel base, and FIG. 5B is a partial cross-sectional front view thereof.
Fig. 6A is a side view showing the attachment structure of the balancing weight to the wheel base, and Fig. 6B is a partial cross-sectional front view thereof.
It is a schematic diagram which shows the turning process of the optical device wafer by a bite wheel.
FIG. 8A is a partially enlarged sectional view of an optical device wafer before processing, and FIG. 8B is a partially enlarged sectional view of an optical device wafer after rough processing, and FIG. 8C is a finish processing. It is a partial enlarged sectional view of a later optical device wafer.
FIG. 9A is a plan view of the optical device wafer before processing, FIG. 9B is a plan view of the optical device wafer after rough processing, and FIG. 9C is a plan view of the optical device wafer after finishing processing.
Fig. 10 is an exploded perspective view showing the state of adhering the surface of the optical device wafer to the adhesive tape attached to the annular frame.
FIG. 11 is a perspective view showing a modified layer formed inside a sapphire substrate by irradiating a laser beam from the back side of the optical device wafer.
12 is a block diagram of a laser beam irradiation unit.
FIG. 13 is a perspective view of an optical device wafer supported in an annular frame through an adhesive tape in which a modified layer is formed inside a sapphire substrate along all divided lines.
14 is a longitudinal cross-sectional view illustrating a division process.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a surface side perspective view of an optical device wafer. The optical device wafer 11 is formed by stacking an epitaxial layer (light emitting layer) 15 such as gallium nitride (GaN) on a sapphire substrate 13. The optical device wafer 11 has a surface 11a on which the light emitting layer 15 is stacked, and a back surface 11b on which the sapphire substrate 13 is exposed.

In the light emitting layer 15, a plurality of optical devices 19 such as LEDs are partitioned and formed by division scheduled lines (streets) 17 formed in a lattice shape. The optical device wafer 11 used as the object of the present invention is formed by coating a translucent mold resin (not shown) on the surface 11a.

That is, as shown in a partially enlarged sectional view of FIG. 8A, the light emitting layer 15 is formed on the n-type semiconductor layer 27 and the n-type semiconductor layer 27 stacked on the sapphire substrate 13. The stacked p-type semiconductor layer 29, an anode 31 protruding from the p-type semiconductor layer 29, and a cathode 33 protruding from the n-type semiconductor layer 27 are included.

The surface 11a of the optical device wafer 11 is covered with the translucent mold resin 35. Preferably, the translucent mold resin 35 contains a fluorescent material such as YAG: Ce, which is a fluorescent material capable of emitting yellow light. The translucent mold resin 35 is selected from an epoxy resin, a silicone resin, a urethane resin, an unsaturated polyester resin, an acrylic urethane resin or a polyimide resin.

Next, the bite cutting device 2 suitable for implementing the processing method of this invention is demonstrated with reference to FIG. Reference numeral 4 is a base (housing) of the bite cutting device 2, and a column 6 is erected behind the base 4. A pair of guide rails (only one line is shown) 8, which extends in the vertical direction, is fixed to the column 6.

Along the pair of guide rails 8, the bite cutting unit 10 is mounted to be movable in the vertical direction. The bite cutting unit 10 is attached to the movement base 12 in which the housing 20 moves up and down along a pair of guide rails 8.

The bite cutting unit 10 includes a housing 20, a spindle 22 (see FIG. 7) rotatably housed in the housing 20, a mount 24 fixed to the tip of the spindle 22, and a mount. And a bite wheel 25 detachably mounted at 24. The bite unit 26 is detachably attached to the bite wheel 25.

The bite cutting unit 10 is a bite cutting unit feed mechanism composed of a ball screw 14 and a pulse motor 16 for moving the bite cutting unit 10 in a vertical direction along a pair of guide rails 8 ( 18). When the pulse motor 16 pulse-drives, the ball screw 14 rotates and the movement base 12 moves to an up-down direction.

The chuck table mechanism 28 which has the chuck table 30 is arrange | positioned at the intermediate part of the base 4, and the chuck table mechanism 28 is moved to a Y-axis direction by the chuck table moving mechanism which is not shown in figure. Reference numeral 33 denotes a bellows and covers the chuck table mechanism 28.

In the front part of the base 4, the positioning mechanism 38 which has the 1st wafer cassette 32, the 2nd wafer cassette 34, the wafer conveyance robot 36, and the some positioning pin 40 is provided. ), A wafer carrying mechanism (loading arm) 42, a wafer carrying mechanism (unloading arm) 44, and a spinner cleaning unit 46 are disposed.

Moreover, the washing | cleaning water injection nozzle 48 which wash | cleans the chuck table 30 is provided in the substantially center part of the base 4. The washing water spray nozzle 48 sprays the washing water toward the chuck table 30 while the chuck table 30 is located in the wafer loading / unloading area in front of the apparatus.

Referring to FIG. 3, a perspective view of a bite wheel 25 is shown. The bite wheel 25 has the annular wheel base 50, the bite unit 26 detachably attached to the wheel base 50, and the bite unit 26 with respect to the rotation center of the wheel base 50. It is detachably attached to the wheel base 50 in the point symmetrical position with respect to the bite unit 26, and consists of the balancing weight (counter balance) 66 of the same weight. The bite wheel 25 is rotated in the direction of the arrow R to cut the translucent mold resin formed on the surface of the optical device wafer 11.

As shown in the exploded perspective view of FIG. 4, the bite unit 26 is a substantially rectangular shape shank (byte shank) 52, and the bite (cutting tool) detachably attached to the shank 52 ( 54). The bite 54 shows a plate shape, and the cutting edge 56 formed in the predetermined shape by diamond etc. is fixed to the surface side of the end part of a longitudinal direction. The bite 54 is formed with a circular hole 59 into which the screw 58 is inserted.

On one side of the shank 52, a pit 60 (pit) having a depth equivalent to the thickness of the bite 54 is formed. The pit 60 is formed with a screw hole 61. By inserting the bite 54 into the pit 60 of the shank 52 and screwing the screw 58 into the screw hole 61 through the circular hole 59 of the bite 54, the bite 54 It is fixed to the shank 52.

As shown in FIG. 5, the wheel base 50 is formed with a rectangular parallelepiped attachment hole 62 and a screw hole 63 opening through the attachment hole 62. By inserting the shank 52 of the bite unit 26 into the attachment hole 62 formed in the wheel base 50, and screwing and fastening the screw 64 to the screw hole 63, the bite unit 26 is It is fixed to the wheel base 50.

Meanwhile, the balancing weight 66 has the same weight as the bite unit 26, and as shown in FIGS. 3 and 6, with respect to the bite unit 26 with respect to the center of rotation of the wheel base 50. It is inserted in the attachment hole 68 formed in the wheel base 50 of a point symmetrical position, and is fixed to the wheel base 50 by screwing and fastening the screw 70 in the screw hole 69. As shown in FIG.

Next, the processing method of the optical device wafer of embodiment of this invention is demonstrated with reference to FIGS. In the processing method of this invention, first, as shown in FIG. 7, the optical device wafer 11 is hold | maintained in the chuck table 30 of the bite cutting device 2 so that the translucent mold resin 35 may be exposed. A partially enlarged sectional view of the optical device wafer 11 before cutting is shown in FIG. 8A.

Thus, after holding the optical device wafer 11 by the chuck table 30, the roughening process of turning (spinning cutting) the translucent mold resin 35 of the optical device wafer 11 is performed.

In this rough machining process, while rotating the spindle 22 at about 2000 rpm, the bite wheel feed mechanism 18 is driven to cut the cutting edge 56 of the bite unit 26 by 10 micrometers to the translucent mold resin 35. The translucent mold resin 35 is turned while placing the chuck table 30 at a feed rate of 1800 µm / sec in the arrow Y direction. In this turning operation, the chuck table 30 is machined and conveyed in the Y-axis direction without rotating.

A partially enlarged sectional view at the end of the rough working is shown in FIG. 8B, and a plan view is shown in FIG. 9B. As shown in FIG. 9B, when rough machining is performed, a slightly rough turning trace 72 is formed on the surface of the translucent mold resin 35. The rough working stops just before the electrodes 31 and 33 are exposed, as shown in Fig. 8B.

After finishing processing, finishing conditions are performed by changing the processing conditions using the same bite unit 26 as in rough processing. In this finishing process, while rotating the spindle 22 at about 2000 rpm, the bite wheel feed mechanism 18 is driven and the cutting edge 56 of the bite unit 26 is put into the transparent mold resin 35 by 2 m. The translucent mold resin 35 is turned along with the electrodes 31 and 33 while moving the chuck table 30 at a feed rate of 600 µm / sec in the arrow Y direction.

Partial enlarged cross-sectional view at the end of finishing is shown in FIG. 8C. When finish processing is finished, as shown in FIG. 8C, the electrodes 31 and 33 are exposed from the translucent mold resin 35, and as shown in FIG. 9C, the translucent mold resin. A dense turning trace 72a is formed on the surface of 35.

The translucent mold resin 35 of the optical device wafer 11 is turned to process the translucent mold resin 35 to a predetermined thickness, as shown in Fig. 8C, and then as shown in Fig. 10. The adhesive tape adhesion process of sticking the adhesive tape T on the surface of the optical device wafer 11 is performed.

Preferably, the outer peripheral part of the adhesive tape T is stuck to the annular frame F, and the optical device wafer 11 is supported by the annular frame F through the adhesive tape T. As shown in FIG. This facilitates the handling of the optical device wafer 11.

Subsequently, a division step of dividing the optical device wafer 11 into individual optical devices 19 is performed. Since the division hardness of the sapphire substrate 13 of the optical device wafer 11 is high, the 1st and 2nd processing methods using the irradiation of a laser beam are known.

In the first processing method, a laser beam is to be divided by placing a light collecting point of a laser beam having a transmittance with respect to the sapphire substrate 13 (for example, 1064 nm or 1560 nm) inside the substrate corresponding to the dividing line. Is irradiated along the surface to form a modified layer, and then an external force is applied to divide the optical device wafer 11 into individual optical devices 19.

In the second processing method, a division is used as a starting point of division by ablation processing by irradiating a region corresponding to a division line with a light-converging point of a laser beam having a wavelength (for example, 355 nm) having absorptivity with respect to the sapphire substrate 13. A starting point groove is formed, and then an external force is applied to divide the optical device wafer into individual optical devices along the split starting point groove.

Here, the first processing method will be described in detail with reference to FIGS. 11 to 14. In the modified layer forming step of the first processing method, as illustrated in FIG. 11, the chuck table of the laser processing apparatus 74 is attached to the optical device wafer 11 on which the back surface 11b is exposed through the adhesive tape T. 76) and the suction is maintained.

The laser beam irradiation unit 78 of the laser processing apparatus 74 is housed in the casing 80. As shown in Fig. 12, the laser beam irradiation unit 78 includes a laser oscillator 86 for oscillating an Er laser, a repetition frequency setting means 88, a pulse width adjusting means 90, and a power adjusting means. And (92). In Fig. 11, reference numeral 84 denotes an image pickup means.

The chuck table 76 which suction-held the optical device wafer 11 via the adhesive tape T is located directly under the imaging means 84 by a moving mechanism not shown. And the imaging means 84 performs alignment to detect the process area to be laser-processed of the optical device wafer 11.

That is, the imaging means 84 and the control means which are not shown are irradiated with the laser beam along the dividing scheduled line 17 extended in the 1st direction of the optical device wafer 11, and this dividing scheduled line 17. Image processing such as pattern matching for aligning the light collector 82 of the laser beam irradiation unit 78 is executed to perform alignment of the laser beam irradiation position.

At this time, although the surface 11a on which the division scheduled line 17 of the optical device wafer 11 is formed is located under the sapphire substrate 13, the sapphire substrate 13 is transparent to visible light. ), The division scheduled line 17 can be imaged by seeing from the back surface 11b side.

After the alignment process is performed as described above, the chuck table 76 is moved to the laser beam irradiation area where the light collector 82 for irradiating the laser beam is located, and one end of the division scheduled line 17 extending in the first direction. Is positioned directly below the condenser 82.

As shown in FIG. 12, a laser beam of a wavelength adjusted to a predetermined power by the power adjusting means 92 and having transparency to the sapphire substrate 13 is reflected by the mirror 83 of the light collector 82. Further, the condensing objective lens 85 is positioned and irradiated inside the sapphire substrate 13 corresponding to the dividing line 17 so as to illuminate the chuck table 76 in a predetermined direction in the arrow X direction. To form a modified layer 94 inside the sapphire substrate 13. The modifying layer 94 is formed as a melt stocking layer.

The processing conditions in this modified layer forming process are set as follows, for example.

Light source: Er pulse laser

Wavelength: 1560 nm

Average power: 0.8 W? 1.2 W

Repetition frequency: 90 kHz-200 kHz

Feed speed: 100 mm / s-300 mm / s

This modified layer formation process is performed along all the division plan lines 17 extended in a 1st direction, and then rotates the chuck table 76 by 90 degrees, and then extends all in the 2nd direction orthogonal to a 1st direction. This is performed along the division schedule line 17. 13 is a perspective view of the modified layer 94 formed inside the sapphire substrate 13 along all the division lines 17.

In the processing method of the optical device wafer 11 of this invention, after performing a modified layer formation process, an external force is given to the optical device wafer 11 in which the modified layer 94 was formed, and the modified layer 94 is made into light as a division origin. A division step of dividing the device wafer 11 into individual optical devices 19 along the division scheduled line 17 is performed.

Instead of using the modified layer 94 as the starting point of division, a laser beam having a wavelength (for example, 355 nm) absorbing with respect to the sapphire substrate 13 is corresponded to the division scheduled line 17 by the second processing method described above. It is also possible to irradiate a region to be formed so as to form a divided starting point groove which becomes a starting point of division by ablation processing.

The processing conditions in this peeling process are set as follows, for example.

Light source: YAG pulsed laser

Wavelength: 355 nm (third harmonic of the YAG laser)

Average power: 0.8 W? 1.2 W

Repetition frequency: 90 kHz? 200 kHz

Feed speed: 100 mm / s-300 mm / s

In this dividing step, for example, as shown in FIG. 14, the annular frame F is disposed on the mounting surface of the cylinder 96 and the annular frame F is clamped with the clamp 98. Then, the bar-shaped dividing jig 100 is arranged in the cylinder 96.

The dividing jig 100 has the upper holding surface 102a and the lower holding surface 102b, and the vacuum suction path 104 opened to the lower holding surface 102b is formed. Since the detailed structure of the dividing jig 100 is disclosed by Unexamined-Japanese-Patent No. 4361506, it references it.

In order to perform the dividing process by the dividing jig 100, the upper suction surface 102a of the dividing jig 100 and the vacuum suction path 104 of the dividing jig 100 are sucked under vacuum as indicated by arrow 106 and The lower holding surface 102b is brought into contact with the adhesive tape T from below, and the dividing jig 100 is moved in the direction of arrow A. FIG. That is, the division jig 100 is moved in the direction orthogonal to the division schedule line 17 to be divided.

Accordingly, when the modified layer 94 is moved immediately above the inner edge of the upper holding surface 102a of the split jig 100, bending stress is concentrated on the portion of the scheduled line 17 having the modified layer 94. The optical device wafer 11 is divided | segmented and cut along the dividing line 17 with the modified layer 94 as a division origin by this bending stress.

When the division along all the division scheduled lines 17 extending in the first direction is finished, the division scheduled line extending in the first direction by rotating the division jig 100 by 90 degrees or by rotating the cylinder 96 by 90 degrees. It divides similarly along the division planned line 17 extended in the 2nd direction orthogonal to (17). As a result, the optical device wafer 11 is divided into individual optical devices 19. In FIG. 14, reference numeral 95 denotes a division groove.

According to the processing method of the present embodiment described above, the translucent mold resin 35 coated on the surface of the optical device wafer 11 by the bite wheel 25 having the cutting edge 56 is evenly turned and finished to a desired thickness. Therefore, the transparent mold resin 35 can be finished to a desired thickness without causing damage to the surface of the transparent mold resin 35.

In the processing method of the present embodiment, the surface of the translucent mold resin 35 is turned with a bite wheel 25 having a cutting edge 56 to expose the electrodes 31 and 33 from the translucent mold resin 35. . Thus, since the electrodes 31 and 33 are cut by the turning cutting by the bite wheel 25, the ductility of a metal is suppressed and the problem which shorts between electrodes can be eliminated.

2: bite cutting device
10: bite cutting unit
11: optical device wafer
13: sapphire substrate
15: light emitting layer
19: optical device
25: Bite Wheel
26: byte unit
30: Chuck Table
31, 33: electrode
35: light transmitting mold resin
50: wheel base
54 bytes
56: cutting edge
72, 72a: Turning marks
82 condenser
94: modified layer
100: split jig

Claims (4)

As a processing method of the optical device wafer in which the some optical device is formed in the light emitting layer, and the translucent mold resin which coats the light property is improved on the surface of the said light emitting layer,
A holding step of holding the optical device wafer by the chuck table so that the translucent mold resin is exposed;
A turning process in which the light transmitting mold resin of the optical device wafer held by the chuck table is operated while rotating a bite to uniformly turn the light transmitting mold resin to finish the light transmitting mold resin to a desired thickness.
Process for processing an optical device wafer comprising a. The light emitting layer of claim 1, wherein the light emitting layer comprises an n-type semiconductor layer, a p-type semiconductor layer stacked on the n-type semiconductor layer, a cathode protruding from the n-type semiconductor layer, and a protruding portion from the p-type semiconductor layer. Contains the anode,
The light-transmitting mold resin is coated on the light emitting layer to embed the cathode and the anode,
In the turning step, the light transmitting mold resin is turned until the cathode and the anode are exposed from the light transmitting mold resin. The optical device wafer processing according to claim 1 or 2, wherein the light-transmissive mold resin is selected from the group consisting of an epoxy resin, a silicone resin, a urethane resin, an unsaturated polyester resin, an acrylic urethane resin, and a polyimide resin. Way. The optical device wafer processing method according to claim 1 or 2, further comprising a dividing step of dividing the optical device wafer into individual optical devices after the turning process.

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