TW201813149A - Method for manufacturing light-emitting diode wafer and light-emitting diode chip - Google Patents

Abstract

[Problem] To provide a method for manufacturing a light emitting diode wafer capable of obtaining sufficient brightness and a light emitting diode wafer. [Solution] A method for manufacturing a light emitting diode wafer, including a wafer preparation step, a wafer backside processing step, a transparent substrate processing step, an integration step, and a singulation step. The wafer preparation step is a preparation step. A wafer having a multilayer body including a plurality of semiconductor layers including a light-emitting layer formed on a transparent substrate for crystal growth, and each of the wafers is defined by a plurality of predetermined division lines crossing each other on the front surface of the multilayer body LED circuits are respectively formed in the regions. The wafer back surface processing step is to form a plurality of recesses or grooves corresponding to the LED circuits on the back surface of the wafer. The transparent substrate processing step is to form a plurality of through holes in the entire surface. The front side of the transparent substrate corresponds to each LED circuit of the wafer to form a plurality of depressions. The integration step is to attach the front side of the transparent substrate to the wafer after the wafer back surface processing step and the transparent substrate processing step are performed. The back surface of the wafer is formed into an integrated wafer, and the dividing step is to cut the wafer along with the transparent substrate along the predetermined dividing line to The integrated wafer is divided into the light emitting diode chip one by one.

Description

Manufacturing method of light emitting diode wafer and light emitting diode wafer

FIELD OF THE INVENTION The present invention relates to a method for manufacturing a light emitting diode wafer and 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 increased 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 and a light emitting diode wafer capable of obtaining sufficient brightness. Means to solve the problem

According to the invention described in claim 1, a method for manufacturing a light emitting diode wafer can be provided. The method for manufacturing the light emitting diode wafer includes: a wafer preparation step, preparing a wafer, and the wafer is crystallized. A growth substrate has a laminated body layer, and an LED circuit is formed in each of the areas defined by a plurality of predetermined division lines crossing each other on the front side of the laminated body layer. The laminated body layer is formed with a plurality of layers including a light emitting layer. A semiconductor layer; a wafer backside processing step to form a plurality of recesses or grooves corresponding to each LED circuit on the backside of the wafer; a transparent substrate processing step corresponding to the front side of a transparent substrate formed with a plurality of through-holes covering the entire surface Each LED circuit of the wafer to form a plurality of depressions; an integration step, after implementing the wafer back surface processing step and the transparent substrate processing step, attaching the front surface of the transparent substrate to the back surface of the wafer to form integration A wafer; and a dividing step, cutting the wafer and the transparent substrate together along the predetermined dividing line to divide the integrated wafer into All of the light emitting diode chip.

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 recesses or grooves formed in the wafer backside processing step are formed by any one of a cutter, etching, sandblasting, and laser, and the depressions formed in the transparent substrate processing step are It is 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.

According to the invention described in claim 5, it is possible to provide a light-emitting diode wafer including a light-emitting diode in which an LED circuit is formed on the front surface and a recess or groove is formed in the back surface, and the light-emitting diode wafer is attached to the light-emitting diode wafer. A transparent member having a plurality of through-holes is formed on the back surface of the light emitting diode, and a depression is formed on the transparent member's attaching surface with the light emitting diode. Invention effect

Since the light-emitting diode wafer of the present invention has recesses or grooves formed on the back surface of the LED and recesses are formed on the front surface of the transparent member having a plurality of through holes attached to the back surface, the surface area of the transparent member is increased in addition to In addition, the light emitted from the light-emitting layer of the LED and incident on the transparent member is also complicatedly refracted in the recessed portion or the groove portion, and the light emitted from the transparent member is also refracted intricately in the recessed portion. When the transparent member emits light, the proportion of light with an incident angle above the critical angle at the interface between the transparent member and the air layer decreases, and the amount of light emitted from the transparent member is increased and the light-emitting diode wafer is increased. The brightness is increased.

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 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 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. In addition, a wafer back surface processing step is performed in which a plurality of grooves 3 are formed on the back surface 11 b of the wafer 11 corresponding to the LED circuit 19.

This wafer back surface processing step is performed using a well-known cutting device, for example. As shown in FIG. 2 (A), 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 attached to 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 wafer back surface processing step in which a plurality of grooves 3 are formed on the back surface 11 b of the wafer 11, the front surface 11 a of the wafer 11 is sucked and held on a work clamp of a cutting device (not shown). Then, while rotating the cutter 14 at a high speed in the direction of the arrow R, the wafer 11 is cut into a predetermined depth on the back surface 11b of the wafer 11 and the wafer 11 held on the work clamp table (not shown) is processed in the direction of the arrow X1. In order to form the groove 3 extended in the first direction by cutting.

The wafer 11 is fed in the direction orthogonal to the direction of the arrow X1 at each pitch of the planned division line 17 of the wafer 11, and the back surface 11 b of the wafer 11 is cut as shown in FIG. 3 (A). A plurality of grooves 3 extending in the first direction are sequentially formed.

As shown in FIG. 3 (A), the plurality of grooves 3 formed on the back surface 11b of the wafer 11 may be in the form of being elongated in only one direction, or may be formed as shown in FIG. 3 (B). A plurality of grooves 3 are formed on the rear surface 11b of the rear surface 11b and extend in a first direction and a second direction orthogonal to the first direction.

The groove formed on the back surface 11b of the wafer 11 is a groove 3 with a triangular cross section as shown in FIG. 2 (B), or a groove 3A with a quadrangular cross section as shown in FIG. 2 (C), or as shown in FIG. 2 (D). Any of the grooves 3B shown in the semicircular shape may be used.

Instead of the embodiment in which a plurality of grooves 3, 3A, and 3B are formed by cutting on the back surface 11 b of the wafer 11, a plurality of recesses may be formed on the back surface 11 b of the wafer 11 corresponding to the LED circuit 19. In this embodiment, as shown in FIG. 4 (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. 4 (B), the hole 4 of the mask 2 is attached to the back surface 11 b of the wafer 11 corresponding to each LED circuit 19 of the wafer 11. Then, as shown in FIG. 4 (C), a triangular recess 5 corresponding to the shape of the hole 4 of the mask 2 is formed on the back surface 11b of the wafer 11 by wet etching or plasma etching. .

It can also be made: by changing the shape of the hole 4 of the mask 2 to a quadrangle or a circle, a quadrangular recess 5A as shown in FIG. 4 (D) is formed on the back surface 11b of the wafer 11, or as shown in FIG. 4 A circular recessed portion 5B is formed on the back surface 11b of the wafer 11 as shown in (E).

As a modified example of this embodiment, it is also possible to form the back surface 11b of the wafer 11 by attaching the mask 2 to the back surface 11b of the wafer 11 and then performing sandblasting, as shown in FIG. 4 (C). The triangular concave portion 5 or the rectangular concave portion 5A shown in FIG. 4 (D) or the circular concave portion 5B shown in FIG. 4 (E).

The laser processing device can also be used to form a plurality of grooves or a plurality of recesses corresponding to the LED circuit 19 on the back surface 11 b of the wafer 11. In the first embodiment by laser processing, as shown in FIG. 5 (A), a laser beam having a wavelength (for example, 266 nm) having an absorptivity to the wafer 11 is removed from the condenser (laser) The head) 24 is irradiated on the back surface 11b of the wafer 11, and the work clamp stage (not shown) holding the wafer 11 is processed and fed in the direction of arrow X1, thereby ablating the back surface of the wafer 11 by ablation. 11b forms a groove 7 extending in the first direction.

The wafer 11 is fed in the direction orthogonal to the direction of the arrow X1 at each pitch of the planned division line 17 of the wafer 11, and the back surface 11 b of the wafer 11 is subjected to ablation processing to sequentially form A plurality of grooves 7 extending in the first direction. The cross-sectional shape of the groove 7 may be, for example, a semicircular shape as shown in FIG. 5 (B), or may be another shape.

Alternatively, as shown in FIG. 5 (C), as an alternative embodiment, a pulsed laser beam having a wavelength (for example, 266 nm) having an absorptivity to the wafer 11 may be intermittently irradiated from the condenser 24 to A plurality of recesses 9 corresponding to the LED circuit 19 are formed on the back surface 11 b of the wafer 11. The shape of the concave portion 9 is generally a circle as shown in FIG. 5 (D) corresponding to the spot shape of the laser beam.

A transparent substrate processing step is performed after or before the wafer back surface processing step is performed. The transparent substrate processing step is a transparent substrate having a plurality of through holes 29 formed on the entire surface of the back surface 11b to be attached to the wafer 11. The front surface 21a of 21 corresponds to the LED circuit 19 to form a plurality of depressions.

In this transparent substrate processing step, for example, as shown in FIG. 6 (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. 6 (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, as shown in FIG. 6 (C), 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 by wet etching or plasma etching. Recessed portion) 35.

It can also be made: by changing the shape of the hole 4 of the mask 2 to a quadrangle or a circle, a rectangular recess 35A as shown in FIG. 6 (D) is formed on the front surface 21a of the transparent substrate 21, or as shown in FIG. 6 A circular recess 35B is formed in the front surface 21a of the transparent substrate 21 as shown in (E).

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 modification of this embodiment, it is also possible to form the front surface 21a of the transparent substrate 21 by attaching the mask 2 to the front surface 21a of the transparent substrate 21 and then performing sandblasting, as shown in FIG. 6 (C). The triangular depression 35, or the quadrangular depression 35A shown in FIG. 6 (D), or the circular depression 35B shown in FIG. 6 (E).

The laser processing device can also be used to form a plurality of depressions corresponding to the LED circuit 19 on the front surface 21 a of the transparent substrate 21. In the embodiment performed by laser processing, as shown in FIG. 7 (A), a 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 irradiates the front surface 21a of the transparent substrate 21, and feeds a work clamp (not shown) holding the transparent substrate 21 in the direction of arrow X1, thereby ablating the transparent substrate 21 by ablation. The front surface 21 a forms a plurality of depressions 39 corresponding to the LED circuits 19 of the wafer 11.

The transparent substrate 21 is fed in the direction orthogonal to the direction of the arrow X1 at each pitch of the planned division line 17 of the wafer 11, and the front surface 21a of the transparent substrate 21 is subjected to ablation processing to sequentially form a plurality of numbers. A depression 39. The cross-sectional shape of the depression 39 is generally circular as shown in FIG. 7 (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. 8 (A), the back surface 11b of the wafer 11 is adhered to the front surface 21a with a plurality of depressions corresponding to the LED circuit 19 of the wafer 11 by a transparent adhesive. As shown in FIG. 8 (B), the front surface 21a of the transparent substrate 21 of 39 is integrated with the transparent substrate 21 to form an integrated wafer 25.

After the integration step is performed, a support step is performed. The support step is formed by attaching the transparent substrate 21 of the integrated wafer 25 to the dicing tape T whose outer periphery has been attached to the ring frame F as shown in FIG. 9. The frame unit supports the integrated wafer 25 with the ring-shaped 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. 10.

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

Then, while cutting the cutter 14 at a high speed in the direction of the arrow R, it cuts into the planned division line 17 of the wafer 11 until the tip of the cutter 14 reaches the dicing tape T, and processes from the cooling nozzle 18 toward the cutter 14 and the wafer 11 Cutting fluid is supplied at a point to process and feed the integrated wafer 25 in the direction of the arrow X1, 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 of the planned division lines 17 extending in the second direction orthogonal to the first direction to form the state shown in FIG. 11. Thus, the integrated wafer 25 is divided into the light-emitting diode wafer 31 as shown in FIG. 12.

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. 12 is a transparent member 21A having a plurality of through-holes 29 attached to the back surface of the LED 13A having the LED circuit 19 on the front surface. In addition, depressions 35, 35A, 35B, or depressions 39 are formed on the front surface of the transparent member 21A.

Therefore, in the light-emitting diode wafer 31 shown in FIG. 12, since a recess or groove is formed on the back surface of the light-emitting diode, and a depression is formed on the front surface of the transparent member 21A, the surface area of the transparent member 21A is increased. Big. In addition, a part of the light emitted from the LED circuit 19 of the light-emitting diode wafer 31 and incident on the transparent member 21A is refracted into the transparent member 21A after being refracted.

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

3, 3A, 3B, 7‧‧‧ trench

4‧‧‧ hole

5, 5A, 5B, 9‧‧‧ recess

10‧‧‧ cutting unit

11‧‧‧Optical element wafer (wafer)

11a, 21a‧‧‧ Front

11b‧‧‧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‧‧‧through hole

31‧‧‧light-emitting diode chip

35, 35A, 35B, 39‧‧‧ depression

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 a back surface processing step of a wafer by a cutter, and FIGS. 2 (B) to 2 (D) are cross-sectional views showing the shape of a groove formed. FIG. 3 (A) is a perspective view of the back side of a wafer having a plurality of grooves formed on the back side of the wafer and extending in the first direction. FIG. 3 (B) is a back side of the wafer with the formed side facing the wafer. A perspective view of the back side of a wafer having a plurality of grooves extending in one direction and a second direction orthogonal to the first direction. FIG. 4 (A) is a perspective view showing a state where a mask is attached to the back surface of the wafer, and FIG. 4 (B) is a perspective view showing a state where a mask having a plurality of holes is attached to the back surface of the wafer. 4 (C) to 4 (E) are partial perspective views of a wafer showing the shape of a recessed portion formed on the back surface of the wafer. FIG. 5 (A) is a perspective view showing a situation where a groove is formed on the back of the wafer by a laser beam, FIG. 5 (B) is a partial cross-sectional view of the wafer showing a groove shape, and FIG. 5 (C) is a laser FIG. 5 (D) is a partial perspective view showing a wafer in which a circular concave portion is formed on the back surface of the wafer. FIG. 6 (A) is a perspective view showing a state where a mask is attached to a front surface of a transparent substrate having a plurality of through holes on the entire surface, and FIG. 6 (B) is a mask having a plurality of holes attached to a transparent surface. FIG. 6 (C) to FIG. 6 (E) are perspective views of the state of the front surface of the substrate, and are partial perspective views of a transparent substrate showing a depressed shape formed on the front surface of the transparent substrate. FIG. 7 (A) is a perspective view showing the processing steps of the transparent substrate, and FIG. 7 (B) is a partial perspective view showing the formed depression shape. FIG. 8 (A) is a perspective view showing an integration step of attaching a transparent substrate having a plurality of recesses on the front surface to the back surface of the wafer to form an integration, and FIG. 8 (B) is a perspective view of the integrated wafer. FIG. 9 is a perspective view showing a supporting step of supporting an integrated wafer with a ring frame through a dicing tape. FIG. 10 is a perspective view showing a step of dividing an integrated wafer into light-emitting diode wafers. FIG. 11 is a perspective view of the integrated wafer after the dividing step. FIG. 12 is a perspective view of a light emitting diode wafer according to an embodiment of the present invention.

Claims (5)

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. The wafer backside processing step corresponds to each LED on the backside of the wafer. Circuit to form a plurality of recesses or grooves; a transparent substrate processing step, forming a plurality of depressions on the front surface of the transparent substrate covering the entire surface with a plurality of through-holes corresponding to the LED circuits of the wafer; an integration step, in which After the wafer back surface processing step and the transparent substrate processing step, the front surface of the transparent substrate is attached to the back surface of the wafer to form an integrated wafer; and a slicing step, the wafer and the The transparent substrates are cut together to divide the integrated wafer into individual light-emitting diode wafers. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein a 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 wafer back surface processing step, the recess or the groove is formed by any one of a cutter, etching, sandblasting, and laser, and In the transparent substrate processing step, the depression is formed by any 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. A light-emitting diode wafer includes: a light-emitting diode in which an LED circuit is formed on a front surface and a recess or a groove is formed in a back surface; and a transparent member having a plurality of through holes formed on the back surface of the light-emitting diode. A depression is formed on an attachment surface of the transparent member and the light emitting diode.