TWI525853B - Light emitting diode device, manufacturing method thereof, and flip-chip light emitting diode device - Google Patents

Description

Light-emitting diode element, method of manufacturing the same, and flip-chip light-emitting diode element Piece

The present invention relates to a photovoltaic element and a method of fabricating the same, and more particularly to a light emitting diode element and a method of fabricating the same.

Since Thomas. Since Edison invented the incandescent lamp, the world has widely used electric lighting, and has developed a high-brightness and durable lighting device such as a fluorescent lamp. Fluorescent lamps have the advantages of high efficiency and low operating temperature compared to incandescent bulbs. However, fluorescent lamps contain heavy metals (mercury), which can cause environmental damage when discarded. With the development of lighting technology, a more energy-saving and environmentally friendly light source, namely a light emitting diode, has been developed. The light-emitting diode emits light by recombining electrons and holes in the P-N junction. Compared to incandescent or fluorescent lamps, light-emitting diodes have the advantages of low power consumption and long life. In addition, the light-emitting diodes are more environmentally friendly without the use of mercury.

The basic structure of the light-emitting diode element includes a P-type semiconductor epitaxial layer, an N-type semiconductor epitaxial layer, and a light-emitting layer therebetween. The luminous efficiency of the light-emitting diode element depends on the quantum efficiency of the light-emitting layer and the light extraction efficiency of the light-emitting diode element. The method of increasing the quantum efficiency mainly improves the epitaxial quality of the luminescent layer and its structural design, and the key to increasing the light extraction efficiency is to reduce the energy loss caused by the reflection of the light emitted by the luminescent layer inside the luminescent diode element. In order to improve the luminous efficiency of the light-emitting diode element, there have been conventional techniques in the light-emitting diode element. An optical microstructure is fabricated and it is desirable to increase the light extraction efficiency of the light emitting diode element by the optical microstructure. Although such a structure can increase the diffusion effect of light, it still cannot achieve a good anti-reflection effect.

The present invention provides a light emitting diode element having high light extraction efficiency.

The present invention provides a flip chip type light emitting diode element which also has high light extraction efficiency.

The present invention provides a method of manufacturing a light-emitting diode element which can produce a light-emitting diode element having high light extraction efficiency.

An embodiment of the present invention provides a light emitting diode element including a substrate, an undoped semiconductor layer, a first type doped semiconductor layer, a second type doped semiconductor layer, a light emitting layer, a first electrode, and a second electrode. The substrate has opposing first and second surfaces and includes a plurality of optical microstructures. A plurality of voids are disposed between the optical microstructures, and the optical microstructures are disposed on the second surface. The undoped semiconductor layer is disposed on the first surface of the substrate. The first type doped semiconductor layer is disposed on the undoped semiconductor layer. The second type doped semiconductor layer is disposed on the first type doped semiconductor layer. The light emitting layer is disposed between the first type doped semiconductor layer and the second type doped semiconductor layer. The first electrode is disposed on the first type doped semiconductor layer and electrically connected to the first type doped semiconductor layer. The second electrode is disposed on the second type doped semiconductor layer and electrically connected to the second type doped semiconductor layer. The height h of each optical microstructure satisfies the following formula:

n _eff = n _a . (1- x )+ n _s . x where λ is the center wavelength of the light beam emitted by the light-emitting layer, n _a is the refractive index of the medium outside the substrate and adjacent to the second surface, n _s is the refractive index of the substrate, and x is the optical microstructure on the second surface The ratio of the area occupied.

Another embodiment of the present invention provides a flip-chip light emitting diode device including a package substrate and a light emitting diode element. The light emitting diode element includes a substrate, an undoped semiconductor layer, a first type doped semiconductor layer, a second type doped semiconductor layer, a light emitting layer, a first electrode, and a second electrode. The substrate has opposing first and second surfaces and includes a plurality of optical microstructures. A plurality of voids are disposed between the optical microstructures, and the optical microstructures are disposed on the second surface. The undoped semiconductor layer is disposed on the first surface of the substrate. The first type doped semiconductor layer is disposed on the undoped semiconductor layer. The second type doped semiconductor layer is disposed on the first type doped semiconductor layer. The light emitting layer is disposed between the first type doped semiconductor layer and the second type doped semiconductor layer. The first electrode is disposed on the first type doped semiconductor layer and electrically connected to the first type doped semiconductor layer. The second electrode is disposed on the second type doped semiconductor layer and electrically connected to the second type doped semiconductor layer. The height h of each optical microstructure satisfies the following formula:

n _eff = n _a . (1- x )+ n _s . x where λ is the center wavelength of the light beam emitted by the light-emitting layer, n _a is the refractive index of the medium outside the substrate and adjacent to the second surface, n _s is the refractive index of the substrate, and x is the optical microstructure on the second surface The ratio of the area occupied.

Yet another embodiment of the present invention provides a method of fabricating a light emitting diode device comprising the following steps. A substrate is provided, the substrate having opposing first and second surfaces. An undoped semiconductor layer is formed on the first surface of the substrate. A first type doped semiconductor layer is formed on the undoped semiconductor layer. A light emitting layer is formed on the first type doped semiconductor layer. A second type doped semiconductor layer is formed on the light emitting layer. A first electrode and a second electrode are formed on the first type doped semiconductor layer and the second type doped semiconductor layer, respectively. The second surface of the substrate is patterned to form a plurality of optical microstructures, wherein a plurality of voids are provided between the optical microstructures.

Based on the above, the method of fabricating a light-emitting diode element according to an embodiment of the present invention can form optical microstructures having voids between each other on the second surface of the substrate, and the optical microstructures can reduce light reflection by the second surface. It is limited to the inside of the light-emitting diode element, thereby improving the light extraction efficiency of the light-emitting diode element. In the light-emitting diode element and the flip-chip light-emitting diode element of the embodiment of the invention, since the optical microstructure is provided on the second surface of the substrate, and a plurality of voids are provided between the optical microstructures, The optical microstructure can reduce the light being reflected by the second surface and is limited to the inside of the light-emitting diode element and the flip-chip light-emitting diode element, thereby improving the light extraction efficiency of the light-emitting diode element.

The above described features and advantages of the present invention will be more apparent from the following description.

1A is a cross-sectional view showing a light emitting diode device according to an embodiment of the present invention; intention. Referring to FIG. 1A, the LED component 100 of the present embodiment includes a substrate 110, an undoped semiconductor layer 190, a first type doped semiconductor layer 120, a second type doped semiconductor layer 130, a light emitting layer 140, and a first Electrode 150 and second electrode 160. In the present embodiment, the substrate 110 may be a sapphire substrate, but the invention is not limited thereto.

The substrate 110 of this embodiment has opposite surfaces 110a, 110b. The undoped semiconductor layer 190 of the present embodiment is disposed on the surface 110a of the substrate 110. The first type doped semiconductor layer 120 is disposed on the undoped semiconductor layer 190. The second type doped semiconductor layer 130 of the present embodiment is disposed on the first type doped semiconductor layer 120. The light emitting layer 140 of the present embodiment is disposed between the first type doped semiconductor layer 120 and the second type doped semiconductor layer 130. The first electrode 150 is disposed on the first type doped semiconductor layer 120 and electrically connected to the first type doped semiconductor layer 120 . The second electrode 160 is disposed on the second type doped semiconductor layer 130 and electrically connected to the second type doped semiconductor layer 130 .

In detail, the first type doped semiconductor layer 120 of the present embodiment has the connected land portion 122 and the depressed portion 124. The thickness D1 of the platform portion 122 is greater than the thickness D2 of the depressed portion 124. The light emitting layer 140 and the second type doped semiconductor layer 130 are disposed on the land portion 122. The first electrode 150 is disposed on the depressed portion 124. The second electrode 160 is disposed on the platform portion 122. In the present embodiment, the first type doped semiconductor layer 120 is, for example, an N type semiconductor layer, and the second type doped 130 semiconductor layer is, for example, a P type semiconductor layer. The luminescent layer 140 is, for example, a multiple quantum well structure in which a gallium nitride (GaN) layer and an indium gallium nitride (InGaN) layer are alternately stacked. (Multiple Quantum Well, MQW). However, in other embodiments, the luminescent layer 140 can also be a quantum well structure. The material of the first electrode 150 and the second electrode 160 is a conductive material including titanium, aluminum, chromium, platinum, gold, other conductive materials or a combination of these materials. However, the invention is not limited to the above.

FIG. 1B shows a light-emitting diode element 100 according to another embodiment of the present invention, which may be a flip-chip light-emitting diode element. In other words, the light emitting diode element 100 is overlaid on the package substrate 180 and electrically connected to the package substrate 180 . Furthermore, the LED component 100 can be electrically connected to the package substrate 180 by the conductive bumps 170. The two conductive bumps 170 are respectively disposed on the first electrode 150 and the second electrode 160 and electrically connected to the first electrode 150 and the second electrode 160 respectively. The conductive bump 170 is located between the substrate 110 and the package substrate 180. In this embodiment, the package substrate can be a circuit board, and the conductive bumps are eutectic materials, and the first electrode 150 and the second electrode 160 can be connected to the circuit board through the eutectic material. However, the present invention is not limited thereto. In other embodiments, the LED component 100 may not include the conductive bump 170, but the bonding wire is used to bond the first electrode 150 with the package substrate 180 and the second electrode 160 and the package substrate. 180, while the first electrode 150 and the second electrode 160 face away from the package substrate 180.

It is worth noting that the substrate 110 of the present embodiment includes a plurality of optical microstructures 112. Optical microstructures 112 may form an anti-reflective layer. These optical microstructures 112 are disposed on the surface 110b, and a plurality of voids H are disposed between the optical microstructures 112. Optical microstructures 112 are raised structures. Each optical microstructure 112 can have a diameter of less than 300 nanometers. Furthermore, the height h of each optical microstructure of the embodiment satisfies the following formula:

n _eff = n _a . (1- x )+ n _s . x where λ is the center wavelength of the light beam L emitted by the light-emitting layer 140, n _a is the refractive index of the medium outside the substrate 110 and adjacent to the surface 110b, n _s is the refractive index of the substrate 110, and x is all optical microstructures The ratio of the area occupied by 112 on the second surface 110b. For example, it is preferably 0.35 ≦ x ≦ 0.5, and the diameter d of the optical microstructure 112 of the present embodiment may be between 25 nm and 250 nm.

The optical microstructure 112 of the present embodiment can form an anti-reflection layer. By using an anti-reflection layer between the substrate 110 and the external medium, sudden changes in the refractive index can be avoided, thus reducing the inner boundary between the substrate 110 and the external medium. The amount of light is reflected so that the light beam emitted from the light-emitting layer 140 is effectively passed out from the surface 110b. In other words, the optical microstructure 112 of the present embodiment can reduce the probability that the light beam is reflected back into the light-emitting diode element 100 by the surface 110b, thereby effectively improving the light extraction efficiency of the light-emitting diode element 100.

2A to 2K are schematic views showing a manufacturing process of a light emitting diode element according to an embodiment of the present invention. Referring to FIG. 2A, first, a substrate 110 having an opposite surface 110a and a surface 110b is provided. In the present embodiment, the substrate 110 may be a sapphire substrate, but the invention is not limited to the above.

Referring to FIG. 2B to FIG. 2G in sequence, an undoped semiconductor layer 190 is formed on the first surface 110a of the substrate 110. Then, in the undoped half A first type doped semiconductor layer 120 is formed on the conductor layer 190. Next, a light-emitting layer 140 is formed on the first-type doped semiconductor layer 120. Next, a second type doped semiconductor layer 130 is formed on the light emitting layer 140. Then, a portion of the second type doped semiconductor layer 130, a portion of the light emitting layer 140, and a portion of the first type doped semiconductor layer 120 are etched to form the land region 122 and the depressed portion of the first type doped semiconductor layer 120. A region 124 in which a portion of the light-emitting layer 140 that is not etched and a portion of the second-type doped-state semiconductor layer 130 are disposed on the land region 122. Thereafter, the first electrode 150 and the second electrode 160 are formed on the first type doped semiconductor layer 120 and the second type doped semiconductor layer 130, respectively. In the present embodiment, the first electrode 150 is formed, for example, on the depressed region 124. Next, the substrate 110 is thinned. The method of thinning the substrate 110 includes grinding the second surface 110b of the substrate 110 in a mechanical polish manner. In the present embodiment, the first type doped semiconductor layer 120 is, for example, an N type semiconductor layer, and the second type doped 130 semiconductor layer is, for example, a P type semiconductor layer. The light-emitting layer 140 is, for example, a multiple quantum well structure (MQW) in which a gallium nitride (GaN) layer and an indium gallium nitride (InGaN) layer are alternately stacked. However, in other embodiments, the luminescent layer 140 can also be a quantum well structure. The material of the first electrode 150 and the second electrode 160 is a conductive material including titanium, aluminum, chromium, platinum, gold, other conductive materials or a combination of these materials. However, the invention is not limited to the above.

Next, the surface 110b of the substrate 110 is patterned to form a plurality of optical microstructures 112. A plurality of voids H are provided between the optical microstructures 112. The details will be described below in conjunction with FIGS. 2H to 2K.

The method of forming optical microstructures 112 described in the previous paragraph includes the following steps. Referring to FIG. 2H, first, a metal layer 200 is formed on the surface 110b of the substrate 110. In this embodiment, the material of the metal layer 200 includes silver, nickel, aluminum or gold. Referring to FIG. 2I, the metal layer 200 is annealed to form the metal layer 200 to form a plurality of metal microspheres 210, wherein the metal microspheres 210 are fixed on the surface 110b of the substrate 110. In this embodiment, the annealing treatment includes laser anneal or thermal anneal. The annealing process temperature can range from 200 ° C to 600 ° C. Referring to FIG. 2J, the metal microspheres 210 are etched to etch the surface 110b of the substrate 110 to form the optical microstructures 112. A plurality of voids are provided between the optical microstructures 112. The height h of each of the optical microstructures satisfies the following formula:

n _eff = n _a . (1- x )+ n _s . x where λ is the center wavelength of a beam emitted by the luminescent layer, n _a is the refractive index of the medium outside the substrate and adjacent to the second surface, n _{s is} the refractive index of the substrate, x is the The ratio of the area occupied by the optical microstructure on the second surface. In the present embodiment, it is preferably 0.35 ≦ x ≦ 0.5. The etching of the substrate 110 may be wet etching or dry etching. The etching solution for wet etching includes: sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), and combinations thereof, and dry etching is inductively coupled plasma etching. (ICP). Referring to FIG. 2K, finally, the metal microspheres 210 are removed. Next, the substrate 110 is cleaved, and the light-emitting diode element 100 of the present embodiment is initially completed.

It should be particularly noted that the optical microstructure 112 is formed as described in the above paragraph. In the method, the size of the metal microspheres 210 can be precisely controlled, and the ratio of the area occupied by all the optical microstructures 112 on the second surface 110b can be easily controlled, so that the optical microstructures 112 have good anti-reflection effects. .

In addition, the light-emitting diode element 100 of the present embodiment can be packaged by means of a flip chip. As shown in FIG. 2L , the first bump 150 and the package substrate 180 and the second electrode 160 and the package substrate 180 are bonded by the conductive bumps 170 . In this way, the user can operate the light emitting diode element 100 of the embodiment through the package substrate 180.

In summary, the method for fabricating a light-emitting diode element according to an embodiment of the present invention can form optical microstructures having voids on each other on the second surface of the substrate, and the optical microstructures can reduce light by the second surface. The reflection is limited to the inside of the light-emitting diode element, thereby improving the light extraction efficiency of the light-emitting diode element. In the light-emitting diode element and the flip-chip light-emitting diode element of the embodiment of the invention, since the optical microstructure is provided on the second surface of the substrate, and a plurality of voids are provided between the optical microstructures, The optical microstructure can reduce the light being reflected by the second surface and is limited to the inside of the light-emitting diode element and the flip-chip light-emitting diode element, thereby improving the light extraction efficiency of the light-emitting diode element.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧Lighting diode components

110‧‧‧Substrate

110a, 110b‧‧‧ surface

112‧‧‧Optical microstructure

120‧‧‧First type doped semiconductor layer

122‧‧‧ Platform Department

124‧‧‧Sag

130‧‧‧Second type doped semiconductor layer

140‧‧‧Lighting layer

150‧‧‧first electrode

160‧‧‧second electrode

170‧‧‧Electrical bumps

180‧‧‧Base

190‧‧‧Undoped semiconductor layer

200‧‧‧ metal layer

210‧‧‧Metal Microspheres

D1, D2‧‧‧ thickness

d‧‧‧Optical microstructure diameter

G‧‧‧ spacing

H‧‧‧Void

h‧‧‧Optical microstructure height

1A and 1B are schematic cross-sectional views showing a light emitting diode device according to an embodiment of the present invention.

2A to 2L are schematic diagrams showing a manufacturing process of a light-emitting diode element according to an embodiment of the present invention.

110‧‧‧Substrate

110a, 110b‧‧‧ surface

112‧‧‧Optical microstructure

120‧‧‧First type doped semiconductor layer

130‧‧‧Second type doped semiconductor layer

140‧‧‧Lighting layer

150‧‧‧first electrode

160‧‧‧second electrode

190‧‧‧Undoped semiconductor layer

210‧‧‧Metal Microspheres

Claims (16)

A light emitting diode device comprising: a substrate having a first surface and a second surface, and comprising a plurality of optical microstructures, wherein the plurality of optical structures are provided with a plurality of spaces, and the optical The microstructure is disposed on the second surface; an undoped semiconductor layer is disposed on the first surface of the substrate; a first type doped semiconductor layer is disposed on the undoped semiconductor layer; a doped semiconductor layer disposed on the first type doped semiconductor layer; a light emitting layer disposed between the first type doped semiconductor layer and the second type doped semiconductor layer; a first electrode disposed on The first type doped semiconductor layer is electrically connected to the first type doped semiconductor layer; and a second electrode is disposed on the second type doped semiconductor layer and doped with the second type The semiconductor layer is electrically connected, wherein the height h of each of the optical microstructures satisfies the following formula: n _eff = n _a . (1- x )+ n _s . x where λ is the center wavelength of a beam emitted by the luminescent layer, n _a is the refractive index of the medium outside the substrate and adjacent to the second surface, n _{s is} the refractive index of the substrate, x is the The ratio of the area occupied by the optical microstructure on the second surface. The light-emitting diode element according to claim 1, wherein 0.35≦x≦0.5. The luminescent diode component of claim 1, wherein the optical microstructures form an anti-reflective layer. The luminescent diode component of claim 1, wherein each of the optical microstructures has a diameter of less than 300 nm. The light-emitting diode element according to claim 1, wherein the first-type doped semiconductor layer has a platform portion and a lower trap portion, and the thickness of the land portion is greater than a thickness of the depressed portion. The light emitting layer and the second type doped semiconductor layer are disposed on the land portion, and the first electrode is disposed on the depressed portion. A flip-chip light-emitting diode component, comprising: a package substrate; a light-emitting diode component electrically connected to the package substrate and electrically connected to the package substrate, the light-emitting diode component comprising: a substrate having a first surface and a second surface, and comprising a plurality of optical microstructures, wherein the plurality of optical structures are disposed between the optical microstructures, and the optical microstructures are disposed on the second surface; a semiconductor layer disposed on the first surface of the substrate; a first type doped semiconductor layer disposed on the undoped semiconductor layer; and a second type doped semiconductor layer disposed on the first type doping On the semiconductor layer, a light-emitting layer is disposed between the first-type doped semiconductor layer and the second-type doped semiconductor layer; a first electrode is disposed on the first-type doped semiconductor layer, and The first type of doped semiconductor layer is electrically connected; and a second electrode is disposed on the second type doped semiconductor layer and electrically connected to the second type doped semiconductor layer; wherein each of the optical microstructures The height h satisfies the following formula: n _eff = n _a . (1- x )+ n _s . x where λ is the center wavelength of a beam emitted by the luminescent layer, n _a is the refractive index of the medium outside the substrate and adjacent to the second surface, n _{s is} the refractive index of the substrate, x is the The ratio of the area occupied by the optical microstructure on the second surface. The light-emitting diode element according to claim 6, wherein 0.35 ≦ x ≦ 0.5. The flip-chip light-emitting diode element of claim 6, wherein the optical microstructures form an anti-reflection layer. The flip-chip light emitting diode device of claim 6, wherein the light emitting diode device is electrically connected to the package substrate by a conductive bump. The flip-chip light-emitting diode element according to claim 9, wherein the conductive bump is a eutectic material. A method of fabricating a light emitting diode device, comprising: providing a substrate having a first surface and a second a surface; an undoped semiconductor layer is formed on the first surface of the substrate; a first type doped semiconductor layer is formed on the undoped semiconductor layer; and a light is formed on the first type doped semiconductor layer Forming a second type doped semiconductor layer on the light emitting layer; forming a first electrode and a second electrode on the first type doped semiconductor layer and the second type doped semiconductor layer; Patterning a second surface of the substrate to form a plurality of optical microstructures, wherein the plurality of optical microstructures are provided with a plurality of voids, wherein the method of forming the optical microstructures comprises: the second surface of the substrate Forming a metal layer thereon; annealing the metal layer to form the metal layer to form a plurality of metal microspheres, wherein the metal microspheres are fixed on the second surface of the substrate; and the metal microspheres The second surface of the substrate is etched for masking to form the optical microstructures; and the metal microspheres are removed. The method for manufacturing a light-emitting diode element according to claim 11, wherein the material of the metal layer comprises silver, nickel, aluminum or gold. The method of fabricating a light-emitting diode element according to claim 11, wherein the annealing treatment comprises laser anneal or thermal anneal. The method of manufacturing a light-emitting diode element according to claim 11, wherein the annealing process has a process temperature of from 200 ° C to 600 ° C. The method for fabricating a light-emitting diode element according to claim 11, further comprising: thinning the substrate before patterning the second surface of the substrate. The method of manufacturing a light-emitting diode element according to claim 15, wherein the method of thinning the substrate comprises: grinding the second surface of the substrate by mechanical grinding.