TWI730151B - Manufacturing method of light-emitting diode chip - Google Patents

Abstract

Provided are a method for manufacturing a light-emitting diode chip capable of obtaining sufficient brightness and a light-emitting diode chip.

A method for manufacturing a light-emitting diode wafer is characterized by having a wafer preparation step, a wafer backside processing step, a transparent substrate processing step, an integration step, and a dividing step. The wafer preparation step is to prepare the wafer. The wafer has a laminate layer in which a plurality of semiconductor layers including a light-emitting layer are formed on a transparent substrate for crystal growth, and is formed on the front surface of the laminate layer in each area divided by a plurality of predetermined dividing lines that intersect each other. There is an LED circuit, the wafer back processing step is to form a plurality of recesses or grooves corresponding to each LED circuit on the back of the wafer, and the transparent substrate processing step is to form a transparent substrate with a plurality of through holes covering the entire surface The front surface corresponds to each LED circuit of the wafer to form a plurality of recesses. The integration step is to attach the front surface of the transparent substrate to the back surface of the wafer after performing the wafer back processing step and the transparent substrate processing step To form an integrated wafer, the dividing step is to cut the wafer and the transparent substrate together along the predetermined dividing line to divide the integrated wafer into individual light-emitting diode wafers.

Description

Manufacturing method of light-emitting diode chip

Field of invention

The 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 crystal growth substrate such as a sapphire substrate, a GaN substrate, and a SiC substrate, there is formed a laminate layer in which a plurality of n-type semiconductor layers, light-emitting layers, and p-type semiconductor layers are laminated, and on this laminate layer A wafer in which a plurality of light-emitting elements such as LEDs (Light Emitting Diode) are formed in the area divided by the plurality of intersecting planned dividing lines is cut along the planned dividing line to be divided into individual wafers. The light-emitting element chip, the divided light-emitting element chip 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 literature Patent literature

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 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 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.

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 the wafer, the wafer being crystallized The transparent substrate for growth has a laminated body layer, and the front side of the laminated body layer is mutually LED circuits are formed in each area divided by a plurality of intersecting predetermined dividing lines, and the laminated body layer is formed with a plurality of semiconductor layers including a light-emitting layer; the wafer back side processing step corresponds to each LED on the back side of the wafer The circuit is used to form a plurality of recesses or grooves; 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 through holes formed on the entire surface; the integration step is implemented After the wafer back 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 the dividing step, the wafer and the transparent substrate are attached along the planned dividing line The transparent substrate is cut together to divide the integrated wafer into individual light-emitting diode chips.

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 or grooves formed in the wafer backside processing step are formed by any method of cutting knife, etching, sandblasting, and laser, and the recesses formed in the transparent substrate processing step are It is 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, it is possible to provide a luminous A diode chip comprising: a light-emitting diode with an LED circuit formed on the front and recesses or grooves on the back, and a plurality of through-holes formed on the back of the light-emitting diode The transparent member of the hole, and a recess is formed on the attachment surface of the transparent member and the light-emitting diode.

Since the light-emitting diode chip 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 a transparent member with a plurality of through holes attached to the back surface, in addition to increasing the surface area of the transparent member In addition, the light irradiated from the light-emitting layer of the LED and incident on the transparent member is complicatedly refracted in the concave portion or the groove portion, and the light emitted from the transparent member is further complicatedly refracted in the concave portion. When the transparent member emits light, the proportion of light whose incident angle is above the critical angle on the interface between the transparent member and the air layer will decrease, and the amount of light emitted from the transparent member will increase and the light emitting diode chip The brightness of the increase.

2: mask

3, 3A, 3B, 7: groove

4: hole

5, 5A, 5B, 9: recess

10: Cutting unit

11: Optical component wafer (wafer)

11a, 21a: front

11b: back

12: Spindle housing

13: Sapphire substrate

13A: LED

14: Cutter

15: Laminated body layer

16: blade cover

17: Divide the planned 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 groove

29: Through hole

31: LED chip

35, 35A, 35B, 39: recessed

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 step of processing the back surface of a wafer by a cutter, and Figs. 2(B) to 2(D) are cross-sectional views showing the shape of the groove formed.

Fig. 3(A) is a perspective view of the back side of a wafer with a plurality of grooves extending in the first direction formed on the back side of the wafer, and Fig. 3(B) is a perspective view of the back side of a wafer having formed grooves on the back side of the wafer. A perspective view of the back side of a wafer with a plurality of grooves extending in the first direction and in the second direction orthogonal to the first direction.

Figure 4(A) is a stand showing the situation where the mask is attached to the backside of the wafer Figure 4(B) is a perspective view of a state where a mask with a plurality of holes has been attached to the back of the wafer. Figures 4(C) ~ 4(E) show that the mask is formed on the back of the wafer A partial perspective view of a wafer in the shape of a recess.

Fig. 5(A) is a perspective view showing a situation where a groove is formed on the backside of the wafer by a laser beam, Fig. 5(B) is a partial cross-sectional view of a wafer showing a groove shape, and Fig. 5(C) is a view of a wafer with a laser beam. A perspective view of a situation in which a circular recess is formed on the back surface of a wafer by an irradiated light beam. FIG. 5(D) is a partial perspective view of a wafer with a circular recess formed thereon.

Fig. 6(A) is a perspective view showing a situation in which a mask is attached to the front surface of a transparent substrate with a plurality of through holes covering the entire surface, and Fig. 6(B) is a perspective view showing that a mask with a plurality of holes has been attached to the transparent substrate. The perspective view of the state of the front surface of the substrate. FIGS. 6(C) to 6(E) are partial perspective views of the transparent substrate showing the shape of a recess 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 shape of the depression formed.

FIG. 8(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. 8(B) is a perspective view of the integration 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 the dividing step of dividing the integrated wafer into light-emitting diode chips.

FIG. 11 is a perspective view of the integrated wafer after the dividing step is completed.

Fig. 12 is a perspective view of a light emitting diode chip according to an embodiment of the present invention.

The form used to implement 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 this 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. In addition, the wafer backside processing steps are implemented, and the wafer backside In the surface processing step, a plurality of grooves 3 are formed corresponding to the LED circuit 19 on the back surface 11b of the wafer 11.

This wafer backside processing step is performed 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 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 wafer back surface processing step in which a plurality of grooves 3 are formed on the back surface 11b of the wafer 11, the front surface 11a of the wafer 11 is sucked and held on a work chuck of a cutting device not shown. Then, by rotating the cutter 14 in the direction of arrow R at a high speed, the back surface 11b of the wafer 11 is cut into a predetermined depth, and the wafer 11 held on the work chuck not shown in the figure is processed in the direction of arrow X1. Here, the groove 3 elongated in the first direction is formed by cutting.

The wafer 11 is indexed in a direction orthogonal to the arrow X1 direction at each pitch of the predetermined dividing line 17 of the wafer 11, and the back side 11b of the wafer 11 is cut, as shown in FIG. 3(A) , A plurality of grooves 3 extending in the first direction are successively formed.

As shown in FIG. 3(A), the plurality of grooves 3 formed on the back surface 11b of the wafer 11 may be elongated in only one direction, or may be formed as shown in FIG. 3(B), in the wafer 11 The back surface 11b of the slab is formed with a plurality of grooves 3 extending in the first direction and in the second direction orthogonal to the first direction.

The groove formed on the back side 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 shown grooves 3B having a semicircular cross section may be used.

It is also possible to replace the embodiment in which a plurality of grooves 3, 3A, 3B are formed by cutting on the back side 11b of the wafer 11, and a plurality of recesses are formed on the back side 11b 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 circuits 19 of the wafer 11 is used.

As shown in FIG. 4(B), the holes 4 of the mask 2 are attached to the back surface 11b of the wafer 11 corresponding to the LED circuits 19 of the wafer 11. Then, 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 as shown in FIG. 4(C) .

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 is formed on the back surface 11b of the wafer 11 as shown in FIG. 4(D), or as shown in FIG. 4 As shown in (E), a circular recess 5B is formed on the back surface 11b of the wafer 11.

As a modified example of this embodiment, it can also be made: by attaching the mask 2 to the back surface 11b of the wafer 11, then performing sandblasting, and On the back side 11b of the wafer 11 is formed a triangular recess 5 as shown in Figure 4(C), or a quadrangular recess 5A as shown in Figure 4(D), or a circular recess as shown in Figure 4(E). Recess 5B.

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 11b of the wafer 11. In the first embodiment performed by laser processing, as shown in FIG. 5(A), a laser beam with a wavelength (for example, 266 nm) that is absorptive to the wafer 11 is removed from a condenser (laser The head) 24 is irradiated on the back side 11b of the wafer 11, while the work chuck, not shown in the figure, holding the wafer 11 is processed and fed in the direction of the arrow X1, thereby ablating the back side of the wafer 11 11b forms a groove 7 extending in the first direction.

The wafer 11 is indexed in a direction orthogonal to the arrow X1 direction at each pitch of the planned dividing line 17 of the wafer 11, and the back surface 11b of the wafer 11 is ablated to sequentially form Plural grooves 7 elongated 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 other shapes.

It can also be made that as an alternative embodiment, as shown in FIG. 5(C), a pulsed laser beam of a wavelength (for example, 266 nm) having an absorptive wavelength to the wafer 11 is intermittently irradiated from the condenser 24 to A plurality of recesses 9 corresponding to the LED circuits 19 are formed on the back surface 11b of the wafer 11. The shape of the recess 9 is usually a circle as shown in FIG. 5(D) corresponding to the spot shape of the laser beam.

After the wafer backside processing step is implemented, or before the implementation, the transparent substrate processing step is performed. The transparent substrate processing step is required The front surface 21a of the transparent substrate 21 having a plurality of through holes 29 formed on the entire surface of the transparent substrate 21 attached to the back surface 11b of the wafer 11 corresponds to the LED circuit 19, and a plurality of recesses are formed.

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 circuits 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 21a 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. 6(C) ( Recess) 35.

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 35A as shown in FIG. 6(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 35B 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 as shown in FIG. 6(C). A triangular recess 35, or a quadrangular recess 35A as shown in Fig. 6(D), or a circular recess 35B as shown in Fig. 6(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 21 a of the transparent substrate 21. In the embodiment performed by laser processing, as shown in FIG. 7(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, that has held the transparent substrate 21 in the direction of the arrow X1, thereby ablation (ablation) on the transparent substrate 21 The front surface 21a is formed with a plurality of recesses 39 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 39. The cross-sectional shape of the recess 39 is usually a circle 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 recesses 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 integrates the wafer 11 and the transparent substrate 21 to form an integrated wafer 25.

After the integration step is implemented, the support step is implemented. As shown in FIG. 9, 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. Frame list The integrated wafer 25 is supported by 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 division step will be explained with reference to FIG. 10.

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, while rotating the cutting blade 14 in the direction of arrow R at a high speed, cut 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. The cutting fluid is supplied at a point to process and feed the integrated wafer 25 in the arrow X1 direction, thereby forming a cutting groove 27 that cuts 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 elongated in the second direction orthogonal to the first direction to form the state shown in FIG. 11 In this way, the integrated wafer 25 is divided into the light-emitting diode wafer 31 as shown in FIG. 12.

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 sexual wavelength irradiates the wafer 11 along the predetermined dividing 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 an external force is applied to the integrated wafer 25 to divide the integrated wafer 25 with the modified layer as the starting point for dividing. The light-emitting diode chips 31 are formed one by one.

The light emitting diode chip 31 shown in FIG. 12 has a transparent member 21A having a plurality of through holes 29 attached to the back surface of an LED 13A having an LED circuit 19 on the front surface. In addition, recesses 35, 35A, 35B or recesses 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 recesses or grooves are formed on the back surface of the light-emitting diode and recesses are 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 chip 31 and incident on the transparent member 21A enters the transparent member 21A after being refracted at the recessed portion.

Therefore, when it is refracted and emitted from the transparent member 21A to the outside, the proportion of light whose incident angle on the interface between the transparent member 21A and the air layer becomes greater than 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.

11: Optical component wafer (wafer)

11a, 21a: front

11b: back

21: Transparent substrate

25: Integrated wafer

29: Through hole

39: sunken

Claims (4)

A method for manufacturing a light-emitting diode wafer, characterized by comprising: a wafer preparation step, preparing a wafer, the wafer having a laminate layer on a first transparent substrate for crystal growth, and placing it on the front surface of the laminate layer LED circuits are formed in each area divided by a plurality of intersecting predetermined dividing 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 the backside of the wafer A plurality of recesses or grooves are formed for each LED circuit; 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 second transparent substrate with a plurality of through holes formed on the entire surface; the integration step , After the wafer back processing step and the transparent substrate processing step are implemented, the front surface of the second transparent substrate is attached to the back surface of the wafer to form an integrated wafer; and the dividing step is along the planned dividing line The wafer and the second transparent substrate 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 the cross-sectional shape of the recess 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 backside processing step, the concave portion or the groove is It is formed by any method of cutting blade, etching, sandblasting, and laser, and in the transparent substrate processing step, the aforementioned recesses are formed by any method of etching, sandblasting, and laser. The method for manufacturing a light-emitting diode wafer according to claim 1, wherein the second transparent substrate is formed of any one of transparent ceramics, optical glass, sapphire, and transparent resin, and in the integration step, the second transparent substrate A transparent adhesive is used to attach to the wafer.

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