TW201830725A - Method for manufacturing light emitting diode chip - Google Patents

Abstract

The present invention is to provide a method for manufacturing a light emitting diode chip capable of obtaining sufficient brightness. The method for manufacturing a light emitting diode chip comprises: a wafer preparation process of preparing a wafer having a laminate layer formed with a plurality of semiconductor layers including a light emitting layer on a transparent substrate for crystal growth, and having an LED circuit formed on each region divided by a plurality of division-scheduled lines intersecting each other on a surface of the laminate layer; an integration process of bonding a surface of the transparent substrate formed with a plurality of bubbles therein to form an integrated wafer, on a rear surface of the wafer; a transparent substrate processing process of forming a plurality of recesses corresponding to each LED circuit of the wafer on the rear surface of the transparent substrate of the integrated wafer after performing the integration process; and a dividing process of cutting the wafer with the transparent substrate along the division-scheduled lines to divide the integrated wafer into individual light emitting diode chips after performing the transparent substrate processing process.

Description

Manufacturing method of light emitting diode wafer

FIELD OF THE INVENTION The present invention relates to a method for manufacturing a light emitting diode wafer.

BACKGROUND OF THE INVENTION On the front surface of a substrate for crystal growth such as a sapphire substrate, a GaN substrate, and a SiC substrate, a multilayer body layer formed by laminating a plurality of n-type semiconductor layers, light-emitting layers, and p-type semiconductor layers is formed, and on the multilayer body layers A wafer in which a plurality of light emitting elements such as LEDs (Light Emitting Diodes) are formed in an area defined by a plurality of intersecting division lines is cut along the division line and divided into The light-emitting element wafers one by one, and the divided light-emitting element wafers can be widely used in various electric devices such as mobile phones, personal computers, and lighting equipment.

Since the light emitted from the light-emitting layer of the light-emitting element wafer is isotropic, even if it is irradiated to the inside of the substrate for crystal growth, the light is emitted from the back and sides of the substrate. However, since the light that has been irradiated to the inside of the substrate has an incident angle above the critical angle at the interface with the air layer, the light is totally reflected on the interface and is enclosed inside the substrate. Since it is emitted from the substrate to the outside, there is a problem that the brightness of the light emitting element wafer is reduced.

In order to solve this problem, Japanese Patent Laid-Open No. 2014-175354 has described a light-emitting diode (LED) that is formed on the substrate in order to prevent the light emitted from the light-emitting layer from being enclosed inside the substrate. A transparent member is attached to the back of the lens to increase brightness. Prior Art Literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2014-175354

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, in the light-emitting diode disclosed in Patent Document 1, although the brightness can be slightly improved by attaching a transparent member to the back surface of the substrate, there is still a problem that sufficient brightness cannot be obtained. .

The present invention has been made in view of such points, and an object thereof is to provide a method for manufacturing a light-emitting diode wafer capable of obtaining sufficient brightness. Means to solve the problem

According to the present invention, a method for manufacturing a light emitting diode wafer can be provided. The method for manufacturing the light emitting diode wafer is characterized by having: a wafer preparation step, preparing a wafer, and the wafer is transparent for crystal growth. The substrate has a laminated body layer, and an LED circuit is formed in each area defined by a plurality of predetermined division lines crossing each other on the front side of the laminated body layer, and the laminated body layer is formed with a plurality of semiconductor layers including a light emitting layer; Step of attaching the front side of the transparent substrate to the back of the wafer to form an integrated wafer, and the transparent substrate is formed with a plurality of bubbles inside; the transparent substrate processing step, after implementing the integration step, The back of the transparent substrate of the integrated wafer corresponds to each LED circuit of the wafer to form a plurality of depressions; and a dividing step, after the transparent substrate processing step is performed, the wafer and the The transparent substrates are cut together to divide the integrated wafer into individual light-emitting diode wafers.

Preferably, the cross-sectional shape of the depression formed in the transparent substrate processing step is any one of a triangle, a quadrangle, or a circle. Preferably, the depressions formed in the transparent substrate processing step are formed by any one of etching, sandblasting, and laser.

Preferably, the transparent substrate is formed of any one of transparent ceramic, optical glass, sapphire, and transparent resin, and in the integration step, the transparent substrate is adhered to the wafer using a transparent adhesive. Invention effect

Since the light-emitting diode wafer of the present invention has depressions formed on the back surface of the transparent member attached to the back of the LED and having a plurality of bubbles inside, it will not only increase the surface area of the transparent member, but also make the When a part of the light entering the transparent member irradiated by the light-emitting layer of the LED is emitted to the outside, it is refracted and emitted in a complicated manner in the recessed portion. Therefore, when light is emitted from the transparent member, the proportion of light whose incident angle at the interface between the transparent member and the air layer becomes greater than the critical angle is reduced, and the amount of light emitted from the transparent member is increased, and The brightness of the light-emitting diode wafer is improved.

Embodiments for Carrying Out the Invention Embodiments of the present invention will be described in detail below with reference to the drawings. Referring to FIG. 1, a front perspective view of an optical element wafer (hereinafter sometimes referred to as a wafer) 11 is shown.

The optical element wafer 11 is formed by laminating an epitaxial layer (laminated body layer) 15 such as gallium nitride (GaN) on the sapphire substrate 13. The optical element wafer 11 includes a front surface 11 a on which the crystal film layer 15 is laminated, and a back surface 11 b on which the sapphire substrate 13 is exposed.

Here, although the sapphire substrate 13 is used as the substrate for crystal growth in the optical element wafer 11 of this embodiment, a GaN substrate, a SiC substrate, or the like may be used instead of the sapphire substrate 13.

The laminated body layer (crystal film layer) 15 is an n-type semiconductor layer (for example, an n-type GaN layer), a semiconductor layer (for example, an InGaN layer) that becomes a light-emitting layer, and holes are formed by sequentially making electrons a majority carrier. A carrier p-type semiconductor layer (for example, a p-type GaN layer) is formed by crystal film growth.

The sapphire substrate 13 has a thickness of, for example, 100 μm, and the laminated body layer 15 has a thickness of, for example, 5 μm. The laminated body layer 15 is divided into a plurality of predetermined division lines 17 formed in a grid pattern to form a plurality of LED circuits 19. The wafer 11 includes a front surface 11 a on which the LED circuit 19 is formed, and a rear surface 11 b on which the sapphire substrate 13 is exposed.

According to the method for manufacturing a light-emitting diode wafer according to the embodiment of the present invention, first, a wafer preparation step of preparing an optical element wafer 11 as shown in FIG. 1 is performed. Next, an integration step is performed. As shown in FIG. 2 (A), the front surface 21 of the transparent substrate 21 having a plurality of bubbles 29 inside is attached to the back surface 11b of the wafer 11, so that the wafer 11 and the transparent substrate 25 are integrated. It is converted into an integrated wafer 25 as shown in FIG. 2 (B).

After the integration step is performed, a transparent substrate processing step is performed. The transparent substrate processing step is to form a plurality of depressions on the back surface 21 b of the transparent substrate 21 of the integrated wafer 25 corresponding to the LED circuit 19. In this transparent substrate processing step, for example, as shown in FIG. 3 (A), a mask 2 having a plurality of holes 4 corresponding to the LED circuit 19 of the wafer 11 is used.

As shown in FIG. 3 (B), the hole 4 of the mask 2 is made to correspond to each LED circuit 19 of the wafer 11, and the mask 2 is attached to the back surface 21b of the transparent substrate 21 of the integrated wafer 25. Then, as shown in FIG. 3 (C), a triangular depression 5 corresponding to the shape of the hole 4 of the mask 2 is formed on the back surface 21b of the transparent substrate 21 by wet etching or plasma etching. .

It can also be made: by changing the shape of the hole 4 of the mask 2 into a quadrangle or a circle, the back surface 21b of the transparent substrate 21 is formed with a quadrangular depression 5A as shown in FIG. 3 (D), or as shown in FIG. A circular recess 5B is formed on the back surface 21b of the transparent substrate 21 as shown in (E).

The laser processing device can also be used to form a plurality of depressions corresponding to the LED circuit 19 on the back surface 21 b of the transparent substrate 21, wherein the transparent substrate 21 has a plurality of air bubbles 29 inside. In the embodiment performed by the laser processing apparatus, as shown in FIG. 4 (A), the laser beam having a wavelength (for example, 266 nm) having an absorptivity to the transparent substrate 21 is intermittently removed from the condenser ( (Laser head) 24 is irradiated on the back surface 21b of the transparent substrate 21, and the work clamp stage (not shown) that has held the integrated wafer 25 is processed and fed in the direction of arrow X1, thereby ablating the transparent substrate 21 A recess 9 is formed on the back surface 21 b of the substrate 21.

The integrated wafer 25 is fed in increments of each pitch of the planned division line 17 of the wafer 11 in a direction orthogonal to the direction of the arrow X1, and the back surface 21b of the transparent substrate 21 is subjected to ablation processing to successively A depression 9 is formed as shown in FIG. 4 (B).

The transparent substrate 21 is formed of any one of transparent resin, optical glass, sapphire, and transparent ceramic. In this embodiment, the transparent substrate 21 is formed of a transparent resin such as polycarbonate or acrylic which is more durable than optical glass.

After the transparent substrate processing step of forming a plurality of depressions 9 on the back surface 21b of the transparent substrate 21 constituting the integrated wafer 25 is performed, a support step is performed. The support step is shown in FIG. The substrate 21 is attached to the dicing tape T whose outer peripheral portion has been attached to the annular frame F to form a frame unit, and the integrated wafer 25 is supported by the annular frame F through the dicing tape T.

After the supporting step is performed, a dividing step is performed, in which the frame unit is put into a cutting device, and the integrated wafer 25 is cut by the cutting device to be divided into individual light emitting diode wafers. This division step will be described with reference to FIG. 6.

As shown in FIG. 6, the cutting unit 10 of the cutting device includes a main shaft housing 12, a main shaft (not shown) rotatably inserted into the main shaft housing 12, and a cutting blade 14 installed at a front end of the main shaft.

The cutting edge of the cutting blade 14 is formed by an electroformed grindstone in which diamond abrasive grains are fixed by, for example, nickel plating, and the shape of the tip is triangular, quadrangular, or semicircular.

A substantially upper part of the cutting blade 14 is covered with a blade cover (wheel cover) 16. The blade cover 16 is provided with a horizontally elongated one on the back side and the front side of the cutting blade 14. Pairs (only one is shown) of cooling nozzles 18.

In the dividing step, the integrated wafer 25 is attracted and held on the work clamp table 20 of the cutting device via the dicing tape T of the frame unit, and the ring frame F is clamped and fixed by a clamp (not shown).

Then, the cutting blade 14 is cut into the planned division line 17 of the wafer 11 while rotating at high speed in the direction of the arrow R until the tip of the cutting blade 14 reaches the cutting tape T, and the cooling nozzle 18 is processed toward the cutting blade 14 and the wafer 11. The integrated wafer 25 is processed and fed in the direction of arrow X1 while the cutting fluid is supplied, thereby forming a cutting groove 27 that cuts the wafer 11 and the transparent substrate 21 along the planned division line 17 of the wafer 11.

The cutting unit 10 is fed in increments in the Y-axis direction, and the same cutting groove 27 is successively formed along a predetermined division line 17 extending in the first direction. Next, after the work clamp 20 is rotated by 90 °, the same cut grooves 27 are formed along all the planned division lines 17 that are extended in the second direction orthogonal to the first direction to form the state shown in FIG. 7. Thus, the integrated wafer 25 is divided into the light-emitting diode wafer 31 as shown in FIG. 8.

In the above-mentioned embodiment, the cutting device is used for the light-emitting diode wafer 31 that divides the integrated wafer 25 into individual wafers. However, it is also possible to make the wafer 11 and the transparent substrate 21 transparent. Laser beams of a characteristic wavelength are irradiated toward the wafer 11 along the planned division line 13, and a plurality of modified layers are formed in the thickness direction inside the wafer 11 and the transparent substrate 21, and then the integrated wafer 25 is formed. An external force is applied to divide the integrated wafer 25 into individual light-emitting diode wafers 31 with the reforming layer as a starting point for division.

The light-emitting diode wafer 31 shown in FIG. 8 has a transparent member 21A attached to the back surface of the LED 13A having the LED circuit 19 on the front side, and a plurality of bubbles 29 are formed inside the transparent member 21A. In addition, a depression 5, 5A, 5B, or 9 is formed on the back surface of the transparent member 21A.

Therefore, in the light-emitting diode wafer 31 shown in FIG. 8, since the recess 5, 5A, 5B, or 9 is formed on the back surface 21 b of the transparent member 21A, the surface area of the transparent member 21A is increased. In addition, a part of the light emitted from the LED circuit 19 of the light-emitting diode wafer 31 and entered into the transparent member 21A is refracted and complicatedly refracted in the recess 5, 5A, 5B, or 9 when emitted from the transparent member 21A. Shoot out.

Therefore, when the light is refracted outward from the transparent member 21A, the proportion of light whose incident angle at the interface between the transparent member 21A and the air layer becomes greater than a critical angle is reduced, and the light emitted from the transparent member 21A is reduced. The amount is increased, and the brightness of the light-emitting diode wafer 31 is increased.

2‧‧‧Mask

4‧‧‧ hole

5, 5A, 5B, 9‧‧‧ depression

10‧‧‧ cutting unit

11‧‧‧Optical element wafer (wafer)

11a, 21a‧‧‧ Front

11b, 21b‧‧‧ back

12‧‧‧ Spindle housing

13‧‧‧Sapphire substrate

13A‧‧‧LED

14‧‧‧ Cutter

15‧‧‧ Stratified body

16‧‧‧Blade cover

17‧‧‧ divided scheduled line

18‧‧‧ cooling nozzle

19‧‧‧LED circuit

20‧‧‧Work clamp table

21‧‧‧ transparent substrate

21A‧‧‧Transparent member

24‧‧‧ Condenser (laser head)

25‧‧‧Integrated wafer

27‧‧‧ cut off the trench

29‧‧‧ Bubble

31‧‧‧light-emitting diode chip

R, X1‧‧‧ arrows

T‧‧‧Cutting Tape

F‧‧‧ ring frame

X, Y, Z‧‧‧ directions

FIG. 1 is a front perspective view of an optical element wafer. FIG. 2 (A) is a perspective view showing an integration step of attaching a front surface of a transparent substrate to a back surface of a wafer to form an integration, and FIG. 2 (B) is a perspective view of an integrated wafer. FIG. 3 (A) is a perspective view showing a state where a mask having a plurality of holes corresponding to each LED circuit of the optical element wafer is attached to the back surface of the transparent substrate of the integrated wafer, and FIG. 3 (B) is a A perspective view of a state where the mask is attached to the back surface of the transparent substrate of the integrated wafer. FIGS. 3 (C) to 3 (E) are partial perspective views showing the shape of the recess formed on the back surface of the transparent substrate. FIG. 4 (A) is a perspective view showing a state where a plurality of grooves corresponding to the LED circuits of the optical element wafer are formed on the back surface of the transparent substrate of the integrated wafer by irradiation of a laser beam, and FIG. 4 (B) It is a partial perspective view showing a depressed shape. FIG. 5 is a perspective view showing a supporting step of supporting an integrated wafer with a ring frame through a dicing tape. FIG. 6 is a perspective view showing a step of dividing an integrated wafer into light emitting diode wafers. FIG. 7 is a perspective view of the integrated wafer after the dividing step. FIG. 8 is a perspective view of a light emitting diode wafer according to an embodiment of the present invention.

Claims (4)

A method for manufacturing a light-emitting diode wafer, comprising: a wafer preparation step, preparing a wafer, the wafer having a laminated body layer on a transparent substrate for crystal growth, and mutually facing each other on the front surface of the laminated body layer LED circuits are formed in each of the areas divided by the plurality of predetermined division lines, and the laminated body layer is formed with a plurality of semiconductor layers including a light emitting layer; an integration step of attaching the front side of the transparent substrate to the wafer The back surface is used to form an integrated wafer, and the transparent substrate is formed with a plurality of air bubbles therein. In the transparent substrate processing step, after the integration step is performed, the back surface of the transparent substrate of the integrated wafer corresponds to the wafer. Each LED circuit to form a plurality of depressions; and a slicing step. After the transparent substrate processing step is performed, the wafer is cut along with the transparent substrate along the predetermined division line to divide the integrated wafer into One light-emitting diode wafer. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein the cross-sectional shape of the depression formed in the transparent substrate processing step is any one of a triangle, a quadrangle, and a circle. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein in the step of processing the transparent substrate, the depression is formed by any one of etching, sandblasting, and laser. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein the transparent substrate is formed of any one of transparent ceramic, optical glass, sapphire, and transparent resin, and in the integration step, the transparent substrate is made of transparent adhesive. Agent to attach to the wafer.