TWI789375B - Manufacturing method of light emitting diode wafer - Google Patents

Abstract

Provided are a method of manufacturing a light emitting diode wafer capable of obtaining sufficient luminance, and a light emitting diode wafer.

A method for manufacturing a light-emitting diode chip, characterized in that it includes: a wafer preparation step, preparing a wafer, the wafer has a laminated body layer on a transparent substrate for crystal growth, and the front side of the laminated body layer is connected to each other LED circuits are formed in each area demarcated by the plurality of intersecting dividing lines, and the laminate layer is formed with a plurality of semiconductor layers including a light-emitting layer; a transparent substrate processing step, forming a first transparent substrate with a plurality of air bubbles inside. On the front or back of at least any one of the substrate or the second transparent substrate with a plurality of air bubbles formed therein, a plurality of grooves are formed corresponding to the LED circuit; the step of attaching the transparent substrate is carried out after the step of processing the transparent substrate. The front of the first transparent substrate is attached to the back of the wafer, and the front of the second transparent substrate is attached to the back of the first transparent substrate to form an integrated wafer; After the additional step, the wafer is cut together with the first and second transparent substrates along the planned dividing line to divide the integrated wafer into individual light emitting diode chips.

Description

Manufacturing method of light emitting diode wafer field of invention

The invention relates to a manufacturing method of a light emitting diode wafer and the 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, or a SiC substrate, a laminate layer in which an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer are laminated is formed. Wafers on which light-emitting elements such as LEDs (Light Emitting Diodes) are formed in the area demarcated by a plurality of intersecting planned dividing lines are cut along the planned dividing lines and divided into individual wafers. Divided light-emitting element wafers 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 into the inside of the substrate for crystal growth, the light is emitted from the back surface and the side surface of the substrate. However, since the light irradiated to the inside of the substrate has an incident angle above the critical angle on the interface with the air layer, it is totally reflected on the interface and is enclosed inside the substrate, and there is no Since the light is emitted from the substrate to the outside, there is a problem that the brightness of the light-emitting element wafer is lowered.

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 to improve the brightness.

prior art literature patent documents

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

Summary of the invention

However, in the light emitting diode disclosed in Patent Document 1, although the luminance can be slightly improved by attaching the transparent member on the back surface of the substrate, there is still a problem that sufficient luminance cannot be obtained.

The present invention was made in view of such points, and an object of the present invention is to provide a method of manufacturing a light emitting diode wafer and a light emitting diode wafer capable of obtaining sufficient luminance.

According to the invention described in Claim 1, a method of manufacturing a light emitting diode wafer can be provided, which is characterized in that it has: a wafer preparation step, preparing a wafer, and the wafer is crystallized There is a laminated body layer on the transparent substrate for growth, and the front side of the laminated body layer is mutually LED circuits are formed in each area demarcated by the plurality of intersecting dividing lines, and the laminate layer is formed with a plurality of semiconductor layers including a light-emitting layer; a transparent substrate processing step, forming a first transparent substrate with a plurality of air bubbles inside. On the front or back of at least any one of the substrate or the second transparent substrate with a plurality of air bubbles formed therein, a plurality of grooves are formed corresponding to the LED circuit; the step of attaching the transparent substrate is carried out after the step of processing the transparent substrate. The front of the first transparent substrate is attached to the back of the wafer, and the front of the second transparent substrate is attached to the back of the first transparent substrate to form an integrated wafer; After the additional step, the wafer is cut together with the first and second transparent substrates along the planned dividing line to divide the integrated wafer into individual light emitting diode chips.

Preferably, the cross-sectional shape of the groove formed in the transparent substrate processing step is any one of triangular, quadrangular, or semicircular. Preferably, the groove formed in the transparent substrate processing step is formed by cutting knife, etching, sand blasting, or laser.

The first and second transparent substrates are formed of any one of transparent ceramics, optical glass, sapphire, and transparent resin, and in the step of attaching the transparent substrate, the first transparent substrate is bonded to the crystal by using a transparent adhesive. Circle, the second transparent substrate is bonded to the first transparent substrate with a transparent adhesive.

According to the invention described in Claim 5, a light-emitting A diode chip, the light emitting diode chip is equipped with a light emitting diode with an LED circuit formed on the front surface, a first transparent member with a plurality of air bubbles attached to the back of the light emitting diode, and an attached A second transparent member having a plurality of air cells is formed inside the back of the first transparent member, and a groove is formed on the front or back of at least one of the first transparent member or the second transparent member.

The light-emitting diode chip of the present invention reduces the light enclosed in the first and second transparent members by complexly refracting light through the plurality of air bubbles and grooves formed in at least two transparent members, and The amount of light emitted from the first and second transparent members is increased and the brightness of the light-emitting diode chip is improved.

10: Cutting unit

11: Optical component wafer (wafer)

11a, 21a: front

11b, 21b: back

12: Spindle housing

13: Sapphire substrate

13A:LED

14: Cutter

15: laminated body layer

16: Blade cover

17: Split scheduled line

18: Cooling nozzle

19: LED circuit

20: Work clamp table

21: The first transparent substrate

21A: Second transparent substrate

21': The first transparent member

21A': the second transparent member

23, 23A, 23B: ditch

25: The first integrated wafer

25A: The second integrated wafer

27: cut groove

29, 29A: Bubbles

31, 31A, 31B, 31C: light emitting diode 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 the processing steps of the transparent substrate, and FIG. 2(B) to FIG. 2(D) are cross-sectional views showing the shape of the groove formed.

Fig. 3 (A) is a perspective view showing the transparent substrate attaching step of forming the first integrated wafer by attaching the first transparent substrate having a plurality of grooves extending toward the first direction on the front surface to the back of the wafer. 3(B) is a perspective view of the first integrated wafer.

Fig. 4 is a diagram showing steps of integrating a first transparent substrate having a plurality of grooves extending in the first direction and in the second direction perpendicular to the first direction on the back surface of the wafer. stereogram.

Fig. 5 (A) shows that the front side of the second transparent substrate is attached to the first body 5(B) is a perspective view of the second integrated wafer.

6 is a perspective view showing a supporting step of supporting a second integrated wafer with a ring frame through a dicing tape.

Fig. 7 is a perspective view showing a step of dividing the second integrated wafer into light emitting diode chips.

FIG. 8 is a perspective view of the second integrated wafer after the dividing step is completed.

9(A) to 9(D) are perspective views of a light emitting diode wafer according to an embodiment of the present invention.

form for carrying out the invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 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 (laminate layer) 15 such as gallium nitride (GaN) on a sapphire substrate 13 . The optical element wafer 11 has a front surface 11a on which the crystal film layer 15 is laminated, and a back surface 11b on which the sapphire substrate 13 is exposed.

Here, in the optical element wafer 11 of this embodiment, the sapphire substrate 13 is used as the substrate for crystal growth, but 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 formed by sequentially making electrons a majority carrier (carrier) n-type semiconductor layer (such as an n-type GaN layer), a semiconductor layer that becomes a light-emitting layer (such as an InGaN layer), and holes that become a majority. Carrier p -type semiconductor layer (for example, p-type GaN layer) is formed by crystal film growth.

Sapphire substrate 13 has a thickness of, for example, 100 μm, and laminate layer 15 has a thickness of, for example, 5 μm. A plurality of LED circuits 19 are formed on the laminated body layer 15 by dividing by a plurality of dividing lines 17 formed in a lattice. Wafer 11 has front surface 11 a on which LED circuit 19 is formed, and back surface 11 b on which sapphire substrate 13 is exposed.

According to the manufacturing method of the light emitting diode wafer according to the embodiment of the present invention, the wafer preparation step of preparing the optical element wafer 11 as shown in FIG. 1 will be implemented first. 2 (A) and FIG. 5, the first transparent substrate 21 with a plurality of air bubbles formed therein and the second transparent substrate 21A with a plurality of air bubbles 29A formed therein are also prepared.

After the preparation steps of the wafer and the transparent substrate have been implemented, the transparent substrate processing step is carried out. A plurality of grooves are formed corresponding to the LED circuits 19 on the front or back surface of the second transparent substrate 21A on the back surface of the first transparent substrate 21 . The transparent substrate processing step is implemented using, for example, a well-known cutting device.

As shown in FIG. 2(A), 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 blade 14 mounted on the front end of the spindle.

The cutting edge of the cutting blade 14 is formed by, for example, an electroformed grindstone with diamond abrasive grains fixed by nickel plating, and its front end is triangular, square, or semicircular.

The roughly upper half of the cutting knife 14 is covered by the blade (blade cover) (wheel cover (wheel cover)) 16 is covered, and on the blade cover 16, a pair of (only one is shown in the figure) cooling nozzles 18 extending horizontally on the back side and near front side of the cutting blade 14 is arranged. .

In the transparent substrate processing step of forming the plurality of grooves 23 on the front surface 21a of the first transparent substrate 21, the first transparent substrate 21 is sucked and held by a chuck of a cutting device not shown. Then, by rotating the cutting blade 14 at a high speed in the direction of the arrow R, the front surface 21a of the first transparent substrate 21 is cut to a predetermined depth, and the first transparent substrate 21 held on the work holder (not shown) is moved toward the arrow R direction. Machining feed in the X1 direction forms the groove 23 elongated in the first direction by cutting.

The first transparent substrate 21 is indexed and fed in a direction perpendicular to the direction of the arrow X1 according to each pitch of the planned dividing line 17 of the wafer 11, and the front surface 21a of the first transparent substrate 21 is cut, so that as shown in FIG. 3 As shown, a plurality of grooves 23 extending in the first direction are sequentially formed.

As shown in FIG. 3(A), the plurality of grooves 23 formed on the front surface 21a of the first transparent substrate 21 may be elongated in only one direction, or may be set as shown in FIG. On the front surface 21a of the substrate 21, a plurality of grooves 23 extending in a first direction and a second direction perpendicular to the first direction are formed.

The groove formed on the front side 21a of the first transparent substrate 21 is a groove 23 with a triangular cross-section as shown in FIG. 2 (B), or a quadrangular groove 23A with a cross-section as shown in FIG. Any of the semicircular cross-sectional grooves 23B shown in D) may be used.

The first transparent substrate 21 and the second transparent substrate 21A are made of transparent Any one of bright resin, optical glass, sapphire, and transparent ceramics. In this embodiment, the first transparent substrate 21 and the second transparent substrate 21A are formed of a transparent resin such as polycarbonate or acrylic, which is more durable than optical glass. In addition, as a method of forming the groove, sandblasting (sandblast), etching, or laser can also be used.

In the above-mentioned embodiment, the plurality of grooves 23, 23A, and 23B are formed on the front surface 21a of the first transparent substrate 21, but instead of this embodiment, it may be formed on the back surface 21b of the first transparent substrate 21. A plurality of grooves 23, 23A, 23B.

Alternatively, it is also possible to form a plurality of grooves corresponding to the LED circuits 19 of the wafer 11 on the front surface 21a or the back surface 21b of the second transparent substrate 21A without performing any processing on the front and back surfaces of the first transparent substrate 21. 23, 23A, 23B.

After the transparent substrate processing step has been implemented, a transparent substrate attaching step is implemented. The transparent substrate attaching step is to attach the front surface 21a of the first transparent substrate 21 to the back surface 11b of the wafer 11, and attach the front surface of the second transparent substrate 21A to the back surface 11b of the wafer 11. 21a is attached to the back surface 21b of the first transparent substrate 21 .

In this transparent substrate attaching step, as shown in FIG. 3(A), the back side 11b of the wafer 11 is attached to the front side 21a where the plurality of grooves 23 elongated in the first direction are formed with a transparent adhesive. On the front side of the first transparent substrate 21 , as shown in FIG. 3(B) , the wafer 11 and the first transparent substrate 21 are integrated to form a first integrated wafer 25 .

As an alternative embodiment, it can also be set as that the back surface 11b of the wafer 11 is bonded to the first transparent substrate as shown in FIG. The front side 21a of 21 has the front side 21a of the first transparent substrate 21 of a plurality of grooves 23 extending toward the first direction and the second direction perpendicular to the first direction, so that the wafer 11 and the first transparent substrate 21 are integrated. change. Here, the pitch of the grooves 23 formed on the front surface 21 a of the first transparent substrate 21 corresponds to the pitch of the planned dividing lines 17 of the wafer 11 .

Next, as shown in FIG. 5(A), the front surface 21a of the second transparent substrate 21A with a plurality of bubbles 29A formed therein is attached to the back surface 21b of the first transparent substrate 21 of the first integrated wafer 25 to form The second integrated wafer 25A is shown in FIG. 5(B).

This transparent substrate attaching step is not limited to the steps of the above-mentioned order, and may also be set as follows: after attaching the front surface 21a of the second transparent substrate 21A to the back surface 21b of the first transparent substrate 21, the first transparent substrate 21 The front side 21a of the wafer 11 is attached to the back side 11b of the wafer 11 to form a second integrated wafer 25A.

After the step of attaching the transparent substrate is carried out, the step of supporting is carried out. As shown in FIG. The dicing tape T is used to form a frame unit, and the second integrated wafer 25A is supported by the ring frame F through the dicing tape T.

After the supporting step is carried out, the dividing step is carried out. In the dividing step, the frame unit is put into the cutting device, and the integrated wafer 25 is cut by the cutting device to be divided into individual LED chips. This dividing step will be described with reference to FIG. 7 .

During the segmentation step, it is the dicing tape that separates the frame unit T, the second integrated wafer 25A is sucked and held on the chuck table 20 of the cutting device, and the ring frame F is clamped and fixed by a jig not shown in the figure.

Then, the cutting blade 14 is rotated at high speed in the arrow R direction while cutting into the planned dividing line 17 of the wafer 11 until the front end 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 the cutting fluid at the processing point, the second integrated wafer 25A is processed and fed in the direction of the arrow X1, whereby the cut wafer 11 and the first and second transparent substrates 21, Cutting groove 27 of 21A.

The cutting unit 10 is index-feeded in the Y-axis direction, and the same cutting grooves 27 are sequentially formed along the planned dividing line 17 extending in the first direction. Next, after rotating the work clamp table 20 by 90°, the same cutting groove 27 is formed along all the planned dividing lines 17 extending in the second direction perpendicular to the first direction, so as to form the state shown in FIG. 8 , thereby dividing the second integrated wafer 25A into light emitting diode chips 31 as shown in FIG. 9 .

In the above-mentioned embodiment, although the cutting device is used on the light-emitting diode chips 31 that divide the second integrated wafer 25A into individual pieces, it may also be set so that the counter wafer 11 and the transparent substrate 21, 21A, a laser beam with a penetrating wavelength is irradiated toward the wafer 11 along the planned dividing line 13, and a plurality of modified layers are formed in the thickness direction inside the wafer 11 and the transparent substrates 21 and 21A, and then, External force is applied to the second integrated wafer 25A, and the second integrated wafer 25A is divided into individual light-emitting diode chips 31 with the modified layer as the starting point for dividing.

The light-emitting diode chip 31 shown in Fig. 9 (A) is on the front side A first transparent member 21' is attached to the back of the LED 13A having the LED circuit 19, and a plurality of air bubbles 29 are formed inside the first transparent member 21'. Also, a groove 23B is formed on the front surface of the first transparent member 21'. In addition, a second transparent member 21A' in which a plurality of air cells are formed is attached to the back surface of the first transparent member 21'.

The light emitting diode chip 31A shown in FIG. 9(B) has a first transparent member 21' attached to the back of the LED 13A with the LED circuit 19 on the front, and a plurality of air bubbles are formed inside the first transparent member 21'. . Also, a groove 23B is formed on the back surface of the first transparent member 21'. In addition, the front surface of the second transparent member 21A' is attached to the back surface of the first transparent member 21'.

The light emitting diode chip 31B shown in FIG. 9(C) has a first transparent member 21' attached to the back of the LED 13A with the LED circuit 19 on the front, and a plurality of air bubbles are formed inside the first transparent member 21'. . In addition, a second transparent member 21A' is attached to the back surface of the first transparent member 21'. Moreover, a groove 23B is formed on the front surface of the second transparent member 21A'.

In the light emitting diode chip 31C shown in FIG. 9(D), the first transparent member 21' is attached to the back of the LED 13A with the LED circuit 19 on the front, and a plurality of air bubbles are formed inside the first transparent member 21'. . In addition, the front surface of the second transparent member 21A' is attached to the back surface of the first transparent member 21'. Moreover, a groove 23B is formed on the back surface of the second transparent member 21A'.

Therefore, in the light emitting diode chip 31 shown in FIG. 9(A), since the groove 23B is formed on the front surface of the first transparent member 21', the surface area of the first transparent member 21' is increased. In addition, the light emitted from the LED circuit 19 of the light emitting diode chip 31 and incident on the first transparent member 21' Part of it enters the first transparent member 21' after being refracted in the groove 23B.

Accordingly, when the light is refracted and emitted from the first transparent member 21' and the second transparent member 21A' toward the outside, the incident light on the interface between the first and second transparent members 21', 21A' and the air layer The ratio of light having an angle equal to or greater than the critical angle decreases, thereby increasing the amount of light emitted from the first and second transparent members 21 ′, 21A′, and improving the brightness of the light emitting diode chip 31 .

The light emitting diode chips 31A, 31B, and 31C shown in FIG. 9(B) to FIG. 9(D) also have the same effect as the light emitting diode chip 31 shown in FIG. 9(A).

13A:LED

19: LED circuit

21': The first transparent member

21A': the second transparent member

23B: ditch

31, 31A, 31B, 31C: light emitting diode chip

Claims (4)

A method for manufacturing a light-emitting diode chip, characterized in that the method for manufacturing a light-emitting diode chip includes: a wafer preparation step, preparing a wafer, the wafer having a laminate layer on a transparent substrate for crystal growth, In addition, LED circuits are respectively formed in the areas demarcated by a plurality of predetermined division lines crossing each other on the front side of the laminate layer. The laminate layer is formed with a plurality of semiconductor layers including a light-emitting layer; the transparent substrate processing step, in the internal On the front or back of at least any one of the first transparent substrate with a plurality of air bubbles or the second transparent substrate with a plurality of air bubbles inside, a plurality of grooves are formed corresponding to the LED circuit; the step of attaching the transparent substrate, after implementing the transparent After the substrate processing step, attaching the front of the first transparent substrate to the back of the wafer, and attaching the front of the second transparent substrate to the back of the first transparent substrate to form an integrated wafer; and dividing step , after implementing the step of attaching the transparent substrate, cutting the wafer together with the first and second transparent substrates along the planned dividing line so as to divide the integrated wafer into individual light-emitting diode chips . The method of manufacturing a light-emitting diode wafer according to claim 1, wherein the cross-sectional shape of the groove formed in the transparent substrate processing step is any one of a triangle, a square, and a semicircle. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein in the transparent substrate processing step, the aforementioned grooves are formed by any means of cutting knife, etching, sandblasting, and laser. The method of manufacturing a light-emitting diode chip according to claim 1, wherein the first and second transparent substrates are formed of any one of transparent ceramics, optical glass, sapphire, and transparent resin, and in the step of attaching the transparent substrates The first transparent substrate is attached to the wafer using a transparent adhesive, and the second transparent substrate is attached to the first transparent substrate using a transparent adhesive.

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