TWI732047B - Method for manufacturing light-emitting diode chip and light-emitting diode chip - Google Patents

Abstract

[Problem] To provide a method for manufacturing a light-emitting diode wafer that can obtain sufficient brightness, and a light-emitting diode wafer. [Solution] A method for manufacturing a light-emitting diode wafer, which is characterized by having a wafer preparation step, a transparent substrate processing step, an integration step, and a dividing step; the wafer preparation step is to prepare a wafer, the wafer There is a laminate layer on a transparent substrate for crystal growth, and LED circuits are formed in each area divided by a plurality of predetermined dividing lines crossing each other on the front surface of the laminate layer, wherein the laminate layer is formed with a light-emitting layer The transparent substrate processing step is to form a plurality of recesses corresponding to each LED circuit of the wafer on the front surface of the transparent substrate with a plurality of bubbles formed inside, and the integration step is after the transparent substrate processing step Attach the front surface of the transparent substrate to the back surface of the wafer to form an integrated wafer, and the dividing step is to cut the wafer and the transparent substrate together along the predetermined dividing line to form the integrated wafer Divided into one LED chip.

Description

Method for manufacturing light-emitting diode chip and light-emitting diode chip

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

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 laminate layer is formed by laminating a plurality of n-type semiconductor layers, a light-emitting layer, and a p-type semiconductor layer, and on this laminate layer A wafer in which a plurality of light-emitting elements such as LEDs (Light Emitting Diode) are formed in an area divided by a plurality of intersecting planned dividing lines is cut along the planned dividing line to be divided into One by one light-emitting element chips, the divided light-emitting element chips can be widely used in various electrical equipment 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 inside the substrate for crystal growth, the light is emitted from the back and side surfaces of the substrate. However, because of the light that has been irradiated inside the substrate, the light whose incident angle on the interface with the air layer is above the critical angle will be totally reflected at the interface and be enclosed inside the substrate. In the case where it is emitted from the substrate to the outside, there is a problem that the brightness of the light-emitting device chip is reduced.

In order to solve this problem, Japanese Patent Laid-Open No. 2014-175354 has described the following light-emitting diode (LED): In order to prevent the light emitted from the light-emitting layer from being confined inside the substrate, it is formed on the substrate A transparent member is attached to the back of the device to improve the brightness. Prior Art Documents Patent Documents

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 of the substrate, there is still a problem that sufficient brightness cannot be obtained. .

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

According to the invention described in claim 1, it is possible to provide a method for manufacturing a light-emitting diode chip, the method for manufacturing a light-emitting diode chip is characterized by comprising: a wafer preparation step, preparing a wafer, the wafer being crystallized The transparent substrate for growth has a laminate layer, and on the front surface of the laminate layer, an LED circuit is formed in each area divided by a plurality of predetermined dividing lines that cross each other, and the laminate layer is formed with a plurality of layers including a light-emitting layer The semiconductor layer; the transparent substrate processing step, in which a plurality of bubbles are formed on the front surface of the transparent substrate corresponding to each LED circuit of the wafer to form a plurality of recesses; the integration step, after the transparent substrate processing step is performed, the transparent substrate The front surface of the substrate is attached to the back surface of the wafer to form an integrated wafer; and the dividing step is to cut the wafer and the transparent substrate together along the predetermined dividing line to divide the integrated wafer into one A light-emitting diode chip.

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

Preferably, the transparent substrate is formed of any one of transparent ceramics, optical glass, sapphire, and transparent resin, and in the integration step, the transparent substrate is bonded to the wafer with a transparent adhesive.

According to the invention described in claim 5, there can be provided a light-emitting diode chip comprising: a light-emitting diode having an LED circuit formed on the front side, and a transparent light-emitting diode attached to the back side of the light-emitting diode A member, the transparent member has a plurality of bubbles formed inside, and a depression is formed on the attachment surface of the transparent member and the light-emitting diode. Invention effect

Since the light-emitting diode chip of the present invention is attached to the back of the LED and has a recess formed on the front surface of a transparent member with a plurality of bubbles inside, it will not only increase the surface area of the transparent member, but also increase the surface area of the transparent member The light that is irradiated by the light-emitting layer of the LED and incident on the transparent member is complicatedly refracted in the recessed part, which reduces the proportion of light whose incident angle is above the critical angle at the interface between the transparent member and the air layer when emitted from the transparent member , And increase the amount of light emitted from the transparent member and increase the brightness of the light-emitting diode chip.

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

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

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

The laminate layer (crystalline film layer) 15 is an n-type semiconductor layer (e.g., n-type GaN layer) that sequentially turns electrons into a majority carrier (carrier), a semiconductor layer that becomes a light-emitting layer (e.g., InGaN layer), and a plurality of holes. The carrier p-type semiconductor layer (for example, p-type GaN layer) is formed by crystal film growth.

The sapphire substrate 13 has a thickness of, for example, 100 μm, and the laminate layer 15 has a thickness of, for example, 5 μm. The laminate layer 15 is divided by a plurality of planned dividing lines 17 formed in a grid shape to form a plurality of LED circuits 19. The wafer 11 has a front surface 11 a on which the LED circuit 19 is formed, and a back surface 11 b on which the sapphire substrate 13 is exposed.

According to the method for manufacturing a light-emitting diode wafer according to an embodiment of the present invention, first, a wafer preparation step of preparing the optical element wafer 11 as shown in FIG. 1 is performed. Then, a transparent substrate processing step is performed. The transparent substrate processing step is to form a plurality of recesses on the front surface 21a of the transparent substrate 21 to be attached to the back surface 11b of the wafer 11 corresponding to the LED circuit 19, wherein the transparent substrate 21 is inside There are a plurality of bubbles 29.

In this transparent substrate processing step, for example, as shown in FIG. 2(A), a mask 2 having a plurality of holes 4 corresponding to the LED circuits 19 of the wafer 11 is used. As shown in FIG. 2(B), the holes 4 of the mask 2 are attached to the front surface 21 a of the transparent substrate 21 corresponding to the LED circuits 19 of the wafer 11.

Then, by wet etching or plasma etching, a triangular depression corresponding to the shape of the hole 4 of the mask 2 is formed on the front surface 21a of the transparent substrate 21 as shown in FIG. 2(C) ( Recess) 5.

It can also be made: by changing the shape of the hole 4 of the mask 2 to a quadrangular or circular shape, a quadrangular recess 5A as shown in FIG. 2(D) is formed on the front surface 21a of the transparent substrate 21, or as shown in FIG. As shown in (E), a circular recess 5B is formed on the front surface 21a of the transparent substrate 21.

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.

As a modified example of this embodiment, it can also be made: by attaching the mask 2 to the front surface 21a of the transparent substrate 21 and then performing sandblasting, the transparent substrate 21 is formed on the front surface 21a of the transparent substrate 21 as shown in FIG. 2(C). A triangular depression 5, or a quadrangular depression 5A as shown in FIG. 2(D), or a circular depression 5B as shown in FIG. 2(E).

The laser processing device can also be used to form a plurality of recesses corresponding to the LED circuit 19 on the front surface 21a of the transparent substrate 21, wherein the transparent substrate 21 has a plurality of bubbles 29 inside. In the embodiment performed by laser processing, as shown in FIG. 3(A), a laser beam of a wavelength (for example, 266 nm) having absorption to the transparent substrate 21 is intermittently transmitted from a condenser (ray The shooting head) 24 irradiates the front surface 21a of the transparent substrate 21, while processing and feeding the work chuck, not shown in the figure, which has held the transparent substrate 21 in the direction of the arrow X1, thereby ablation on the transparent substrate 21 The front surface 21a is formed with a plurality of recesses 9 corresponding to the LED circuit 19 of the wafer 11.

The transparent substrate 21 is indexed and fed at each pitch of the planned dividing line 17 of the wafer 11 in the direction orthogonal to the arrow X1 direction, and the front surface 21a of the transparent substrate 21 is subjected to ablation processing to sequentially form plural numbers. A depression 9. The cross-sectional shape of the recess 9 is usually a circle as shown in FIG. 3(B) corresponding to the spot shape of the laser beam.

After the transparent substrate processing step is performed, an integration step is performed. The integration step is to attach the front surface 21 a of the transparent substrate 21 to the back surface 11 b of the wafer 11 to form an integrated wafer 25. In this integration step, as shown in FIG. 4(A), the back side 11b of the wafer 11 is adhered to the front side 21a with a plurality of recesses corresponding to the LED circuit 19 of the wafer 11 by a transparent adhesive. On the front surface 21a of the transparent substrate 21 of 9 as shown in FIG. 4(B), the wafer 11 and the transparent substrate 21 are integrated to form an integrated wafer 25.

After the integration step is implemented, the support step is implemented. As shown in FIG. 5, the support step is to attach the transparent substrate 21 of the integrated wafer 25 to the dicing tape T attached to the ring frame F on the outer periphery. The frame unit supports the integrated wafer 25 with the ring frame F through the dicing tape T.

After the supporting step is performed, a dividing step is performed. The dividing step is to put the frame unit into the cutting device, and use the cutting device to cut the integrated wafer 25 to be divided into individual light-emitting diode wafers. This segmentation step will be explained with reference to FIG. 6.

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

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

Roughly the upper half of the cutting blade 14 is covered with a blade cover (wheel cover) 16. The blade cover 16 is provided with a horizontally elongated inner side and a front side of the cutting blade 14 Yes (only one is shown in the figure) cooling nozzle 18.

In the dividing step, the integrated wafer 25 is sucked and held on the work chuck 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 jig not shown.

Then, the cutting blade 14 is rotated at a high speed in the direction of the arrow R while cutting into the planned dividing line 17 of the wafer 11 until the tip of the cutting blade 14 reaches the dicing tape T, and the cooling nozzle 18 is directed toward the cutting blade 14 and the wafer 11. While supplying cutting fluid, the integrated wafer 25 is processed and fed in the arrow X1 direction, thereby forming a cutting groove 27 for cutting the wafer 11 and the transparent substrate 21 along the planned dividing line 17 of the wafer 11.

The cutting unit 10 is indexed and fed in the Y-axis direction, and the same cutting grooves 27 are successively formed along the planned dividing line 17 elongated in the first direction. Next, after rotating the work chuck table 20 by 90°, the same cutting grooves 27 are formed along all the planned dividing lines 17 extending in the second direction orthogonal to the first direction to form the state shown in FIG. 7 In this way, the integrated wafer 25 is divided into the light-emitting diode wafer 31 as shown in FIG. 8.

In the above-mentioned embodiment, although the cutting device is used on the light-emitting diode wafer 31 that divides the integrated wafer 25 into individual light-emitting diode wafers 31, it can also be made to penetrate the wafer 11 and the transparent substrate 21. A laser beam of a flexible wavelength is irradiated to the wafer 11 along the planned dividing line 13, and multiple modified layers are formed in the thickness direction of the wafer 11 and the transparent substrate 21, and then the integrated wafer 25 An external force is applied to divide the integrated wafer 25 into individual light-emitting diode wafers 31 using the modified layer as a starting point for division.

The light emitting diode chip 31 shown in FIG. 8 has a transparent member 21A attached to the back of an LED 13A with an LED circuit 19 on the front, and a plurality of bubbles 29 are formed in the transparent member 21A. In addition, recesses 5, 5A, 5B or recesses 9 are formed on the front surface of the transparent member 21A.

Therefore, in the light-emitting diode wafer 31 shown in FIG. 8, since a recess is formed on the front surface 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 chip 31 and incident on the transparent member 21A enters the transparent member 21A after being refracted at the recessed portion.

Therefore, when light is refracted and emitted from the transparent member 21A to the outside, the proportion of light at the interface between the transparent member 21A and the air layer above the critical angle decreases, and the light emitted from the transparent member 21A The amount is increased, and the brightness of the light-emitting diode chip 31 is improved.

2‧‧‧Mask 4‧‧‧Hole 5, 5A, 5B, 9‧‧‧Recess 10‧‧‧Cutting unit 11‧‧‧Optical element wafer (wafer) 11a, 21a‧‧‧Front side 11b‧‧ ‧Back side 12‧‧‧Spindle housing 13‧‧‧Sapphire substrate 13A‧‧‧LED14‧‧‧Cutting knife 15‧‧‧Laminated body layer 16‧‧‧Blade cover 17‧‧‧Preparation line 18‧‧‧Cooling nozzle 19‧‧‧LED circuit 20‧‧‧Working clamp 21‧‧‧Transparent substrate 21A‧‧‧Transparent component 24‧‧‧Concentrator (laser head) 25‧‧‧Integrated wafer 27‧‧‧Cut Broken groove 29‧‧‧Bubble 31‧‧‧LED chip R, X1‧‧‧Arrow T‧‧‧Cutting tape F‧‧‧Ring frame X, Y, Z‧‧‧direction

Fig. 1 is a front perspective view of an optical element wafer. Fig. 2(A) is a perspective view showing a situation in which a mask having a plurality of holes corresponding to each LED circuit of the light element wafer is attached to the front surface of a transparent substrate, and Fig. 2(B) is a case where the mask has been attached Fig. 2(C)~Fig. 2(E) are partial perspective views showing the shape of the recess formed on the front surface of the transparent substrate. Fig. 3(A) is a perspective view showing a situation where a plurality of recesses corresponding to each LED circuit of the optical element wafer are formed on the front surface of the transparent substrate by the irradiation of a laser beam, and Fig. 3(B) is a perspective view showing the shape of the recesses Partial three-dimensional view. 4(A) is a perspective view showing the integration step of attaching a transparent substrate with a plurality of recesses on the front surface to the back surface of the wafer to form an integration, and FIG. 4(B) is a perspective view of the integrated wafer. FIG. 5 is a perspective view showing a supporting step of supporting the integrated wafer with a ring frame through a dicing tape. FIG. 6 is a perspective view showing the dividing step of dividing the integrated wafer into light-emitting diode chips. FIG. 7 is a perspective view of the integrated wafer after the dividing step is completed. Fig. 8 is a perspective view of a light emitting diode chip according to an embodiment of the present invention.

9‧‧‧Sag

11‧‧‧Optical component wafer (wafer)

11a, 21a‧‧‧Front

11b‧‧‧Back

21‧‧‧Transparent substrate

25‧‧‧Integrated wafer

29‧‧‧Bubble

Claims (5)

A method for manufacturing a light-emitting diode wafer, the method for manufacturing the light-emitting diode wafer is characterized by comprising: a wafer preparation step, preparing a wafer, the wafer having a laminated body layer on a transparent substrate for crystal growth, In addition, LED circuits are formed in each area divided by a plurality of predetermined dividing lines that intersect each other on the front surface of the laminated body layer. The laminated body layer is formed with a plurality of semiconductor layers including a light-emitting layer; the transparent substrate processing step is located inside The front surface of the transparent substrate on which a plurality of bubbles are formed corresponds to the LED circuits of the wafer to form a plurality of recesses; the integration step, after the transparent substrate processing step is implemented, the front surface of the transparent substrate is attached to the wafer The back side to form an integrated wafer; and the dividing step, cutting the wafer and the transparent substrate together along the predetermined dividing line to divide the integrated wafer into individual light-emitting diode chips, by In the light emitting diode chip obtained by the dividing step, the recess is arranged under the LED circuit in a manner corresponding to the LED circuit. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein the cross-sectional shape of the recess formed in the transparent substrate processing step is any of a triangle, a quadrangle, and a circle. According to the method for manufacturing a light-emitting diode wafer of claim 1, wherein in the transparent substrate processing step, the aforementioned depression is performed by etching, It is formed by either sandblasting or 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 ceramics, optical glass, sapphire, and transparent resin, and in the integration step, the transparent substrate is made of transparent adhesive The agent is attached to the wafer. A light-emitting diode chip, comprising: a light-emitting diode with an LED circuit formed on the front side, and a transparent member attached to the back of the light-emitting diode, the transparent member having a plurality of bubbles formed inside, and A recess is formed on the attachment surface of the transparent member and the light emitting diode, and the recess is arranged under the LED circuit in a manner corresponding to the LED circuit.

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