U.S. patent application number 14/919693 was filed with the patent office on 2016-02-11 for method of fabricating a light emitting diode device.
The applicant listed for this patent is Genesis Photonics Inc.. Invention is credited to Yi-Ru Huang, Yun-Li Li, Tzu-Yang Lin, Yu-Yun Lo, Chih-Ling Wu.
Application Number | 20160043281 14/919693 |
Document ID | / |
Family ID | 48466021 |
Filed Date | 2016-02-11 |
United States Patent
Application |
20160043281 |
Kind Code |
A1 |
Lo; Yu-Yun ; et al. |
February 11, 2016 |
METHOD OF FABRICATING A LIGHT EMITTING DIODE DEVICE
Abstract
The present invention relates to a light emitting diode (LED)
and a flip-chip packaged LED device. The present invention provides
an LED device. The LED device is flipped on and connected
electrically with a packaging substrate and thus forming the
flip-chip packaged LED device. The LED device mainly has an
Ohmic-contact layer and a planarized buffer layer between a
second-type doping layer and a reflection layer. The Ohmic-contact
layer improves the Ohmic-contact characteristics between the
second-type doping layer and the reflection layer without affecting
the light emitting efficiency of the LED device and the flip-chip
packaged LED device. The planarized buffer layer id disposed
between the Ohmic-contact layer and the reflection layer for
smoothening the Ohmic-contact layer and hence enabling the
reflection layer to adhere to the planarized buffer layer smoothly.
Thereby, the reflection layer can have the effect of mirror
reflection and the scattering phenomenon on the reflected light can
be reduced as well.
Inventors: |
Lo; Yu-Yun; (Tainan City,
TW) ; Huang; Yi-Ru; (Tainan City, TW) ; Wu;
Chih-Ling; (New Taipei City, TW) ; Lin; Tzu-Yang;
(Kaohsiung City, TW) ; Li; Yun-Li; (Taipei City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Genesis Photonics Inc. |
Tainan City |
|
TW |
|
|
Family ID: |
48466021 |
Appl. No.: |
14/919693 |
Filed: |
October 21, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13661272 |
Oct 26, 2012 |
9196797 |
|
|
14919693 |
|
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|
|
Current U.S.
Class: |
438/29 |
Current CPC
Class: |
H01L 2224/14 20130101;
H01L 33/38 20130101; H01L 2933/0016 20130101; H01L 33/46 20130101;
H01L 33/42 20130101; H01L 33/405 20130101 |
International
Class: |
H01L 33/40 20060101
H01L033/40; H01L 33/42 20060101 H01L033/42 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2011 |
TW |
100143830 |
Claims
1. A method of fabricating a light emitting diode device,
comprising: sequentially forming a first-type doping layer, a light
emitting layer and a second-type doping layer on a substrate;
forming an Ohmic-contact layer on the second-type doping layer;
forming a material layer and a metal layer on the Ohmic-contact
layer, wherein the material layer at least comprises a metal oxide
layer; and forming a first electrode and a second electrode the
first-type doping layer and the metal layer respectively, wherein
the first electrode is electrically connected to the first-type
doping layer and the second electrode is electrically connected to
the Ohmic-contact layer through the metal layer.
2. The method of claim 1, wherein a light transmittance of the
Ohmic-contact layer is greater than 90%.
3. The method of claim 1, wherein a light transmittance of the
material layer is greater than 95%.
4. The method of claim 1 further comprising: forming a cover layer,
wherein the cover layer is disposed on the metal layer and extends
to a sidewall of the metal layer.
5. The method of claim 1, wherein a portion of the light emitted
from the light emitting layer passes through the Ohmic-contact
layer as well as the material layer and is reflected by the metal
layer.
6. A method of fabricating a light emitting diode device,
comprising: sequentially forming a first-type doping layer, a light
emitting layer and a second-type doping layer on a substrate;
forming an Ohmic-contact layer on the second-type doping layer;
forming an oxide stacking layer and a metal reflection layer on the
Ohmic-contact layer, wherein the oxide stacking layer comprises a
plurality of stacked oxide layers; and forming a first electrode
and a second electrode the first-type doping layer and the metal
reflection layer respectively, wherein the first electrode is
electrically connected to the first-type doping layer, the second
electrode is electrically connected to the Ohmic-contact layer, and
the oxide stacking layer and the metal reflection layer are
disposed between the second electrode and the Ohmic-contact
layer.
7. The method of claim 6, wherein a light transmittance of the
Ohmic-contact layer is greater than 90%.
8. The method of claim 6 further comprising: forming a cover layer,
wherein the cover layer is disposed between the metal reflection
layer and the second electrode.
9. The method of claim 6, wherein a portion of the light emitted
from the light emitting layer passes through the Ohmic-contact
layer and is reflected by the metal reflection layer.
10. A method of fabricating a light emitting diode device,
comprising: sequentially forming a first-type doping layer, a light
emitting layer and a second-type doping layer on a substrate;
forming an Ohmic-contact layer on the second-type doping layer;
forming an oxide stacking layer and a metal reflection layer on the
Ohmic-contact layer, wherein the oxide stacking layer comprises a
plurality of stacked oxide layers; and forming a first electrode
and a second electrode the first-type doping layer and the metal
reflection layer respectively, wherein the first electrode is
electrically connected to the first-type doping layer, the oxide
stacking layer and the metal reflection layer are disposed between
the second electrode and the Ohmic-contact layer, and the second
electrode is electrically connected to the Ohmic-contact layer
through the metal reflection layer.
11. The method of claim 10, wherein a light transmittance of the
Ohmic-contact layer is greater than 90%.
12. The method of claim 10 further comprising: forming a cover
layer, wherein the cover layer is disposed between the metal
reflection layer and the second electrode.
13. The method of claim 10, wherein a portion of the light emitted
from the light emitting layer passes through the Ohmic-contact
layer and is reflected by the metal reflection layer.
14. A method of fabricating a light emitting diode device,
comprising: sequentially forming a first-type doping layer, a light
emitting layer and a second-type doping layer on a substrate;
forming an Ohmic-contact layer on the second-type doping layer;
forming a metal reflection layer and at least one oxide layer on
the Ohmic-contact layer, wherein the at least one oxide layer is
disposed between the Ohmic-contact layer and the metal reflection
layer; and forming a first electrode and a second electrode the
first-type doping layer and the metal reflection layer
respectively, wherein the first electrode is electrically connected
to the first-type doping layer, the second electrode is
electrically connected to the Ohmic-contact layer, and the metal
reflection layer disposed between the second electrode and the
Ohmic-contact layer.
15. The method of claim 14, wherein a light transmittance of the
Ohmic-contact layer is greater than 90%.
16. The method of claim 14, wherein a light transmittance of the
oxide layer is greater than 95%.
17. The method of claim 14 further comprising: forming a cover
layer, wherein the cover layer is disposed between the metal
reflection layer and the second electrode.
18. The method of claim 14, wherein a portion of the light emitted
from the light emitting layer passes through the Ohmic-contact
layer as well as the oxide layer and is reflected by the metal
reflection layer.
19. A method of fabricating a light emitting diode device,
comprising: sequentially forming a first-type doping layer, a light
emitting layer and a second-type doping layer on a substrate;
forming an Ohmic-contact layer on the second-type doping layer;
forming a metal reflection layer and at least one oxide layer on
the Ohmic-contact layer; and forming a first electrode and a second
electrode the first-type doping layer and the metal reflection
layer respectively, wherein the first electrode is electrically
connected to the first-type doping layer, the metal reflection
layer and the at least one oxide layer are disposed between the
second electrode and the Ohmic-contact layer, and the second
electrode is electrically connected the Ohmic-contact layer through
the metal reflection layer.
20. The method of claim 19, wherein a light transmittance of the
Ohmic-contact layer is greater than 90%.
21. The method of claim 19, wherein a light transmittance of the
oxide layer is greater than 95%.
22. The method of claim 19 further comprising: forming a cover
layer, wherein the cover layer is disposed between the metal
reflection layer and the second electrode.
23. The method of claim 19, wherein a portion of the light emitted
from the light emitting layer passes through the Ohmic-contact
layer and is reflected by the metal reflection layer.
24. A method of fabricating a light emitting diode device,
comprising: sequentially forming a first-type doping layer, a light
emitting layer and a second-type doping layer on a substrate;
forming an Ohmic-contact layer on the second-type doping layer;
forming a material stacking layer on the Ohmic-contact layer,
wherein the material stacking layer comprises a plurality of first
material layers and a plurality of second material layers
alternately stacked, and light transmittance of the first material
layers differs from light transmittance of the second material
layers; and forming a first electrode and a second electrode the
first-type doping layer and the material stacking layer
respectively, wherein the first electrode is electrically connected
to the first-type doping layer, the second electrode is
electrically connected to the Ohmic-contact layer, and the material
stacking layer is disposed between the second electrode and the
Ohmic-contact layer.
25. The method of claim 24, wherein a light transmittance of the
Ohmic-contact layer is greater than 90%.
26. The method of claim 24 further comprising: forming a metal
layer disposed between the second electrode and the Ohmic-contact
layer.
27. The method of claim 26, wherein a portion of the light emitted
from the light emitting layer passes through the Ohmic-contact
layer and is reflected by the metal layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S.
application Ser. No. 13/661,272, filed on Oct. 26, 2012, now
allowed. The prior U.S. application Ser. No. 13/661,272 claims the
priority benefit of Taiwan application serial no. 100143830, filed
on Nov. 29, 2011. The entirety of each of the above-mentioned
patent applications is hereby incorporated by reference herein and
made a part of this specification.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a method of
fabricating a light emitting diode (LED) device, and particularly
to a method of fabricating an LED device having excellent
Ohmic-contact characteristics and light emitting efficiency.
BACKGROUND OF THE INVENTION
[0003] Electricity is an indispensable energy nowadays. No matter
lighting devices, home appliances, communication apparatuses,
transportation, or industrial equipment, without electricity, none
can operate. Current global energy mainly comes from burning
petroleum or coal. However, the supply of petroleum or coal is not
inexhaustible. If people don't search actively for alternative
energy, when petroleum or coal is exhausted, the world will
encounter energy crisis. For solving the problem of energy crisis,
in addition to developing positively various kinds of renewable
energy, it is required to save energy and use energy efficiently
for improving the usage efficiency of energy.
[0004] Take lighting equipment as an example. Light equipment is
indispensable in human lives. As technologies develop, lighting
tools having better luminance and more power saving are gradually
provided. Currently, an emerging light source is LED. In comparison
with light sources according to prior art, LEDs have the advantage
of small size, power saving, good light emitting efficiency, long
lifetime, fast response time, no thermal radiation, and no
pollution of poisonous materials such as mercury. Thereby, in
recent years, the applications of LEDs are wide-spreading. In the
past, the brightness of LEDs still cannot replace the light sources
according to the prior art. As the technologies advance,
high-luminance LEDs (high-power LEDs) are developed recently and
sufficient to replace the light sources according to the prior
art.
[0005] The epitaxial structure of LED is composed of semiconductor
layers of p-type and n-type gallium-nitride family and light
emitting layers. The light emitting efficiency of LED is determined
by the quantum efficiency of the light emitting layer as well as
the extraction efficiency of the LED. The method for increasing the
quantum efficiency is mainly to improve the epitaxial quality and
the structure of the light emitting layer; the key to increasing
the extraction efficiency is to reduce the energy loss caused by
reflection of the light emitted by the light emitting layer within
the LED.
[0006] Depending on the property of the material of the p-type
semiconductor layer and the work function of the metal used as the
reflection layer, an Ohmic-contact or a Schottky contact is formed
between the p-type semiconductor layer and the reflection layer of
a general LED. When the resistance of an Ohmic-contact is too high,
the operating characteristics of LED will be affected. It is
thereby required to lower the resistance of the Ohmic-contact. The
Ohmic-contact characteristics between the p-type semiconductor
layer and the reflection layer can be improved by disposing an
Ohmic-contact layer therebetween. The Ohmic-contact layer according
to the prior art adopts a Ni/Au Ohmic-contact layer and heat
treatment is performed on the Ohmic-contact layer for forming a
good Ohmic-contact. Nonetheless, the light absorption rate of the
Ni/Au Ohmic-contact layer is higher. Besides, the interface between
the p-type semiconductor layer and the Ni--Au Ohmic-contact layer
is roughened due to the heat treatment and leading to inability in
reflecting light. Consequently, the reflection efficiency of the
LED will be reduced.
[0007] For solving the problems described above, please refer to
FIG. 1, which shows a structure diagram of the LED device according
to the prior art. As shown in the figure, an Ohmic-contact layer
11' is disposed between the p-type semiconductor layer 10' and the
reflection layer 12'. The Ohmic-contact layer 11' uses a
single-layer metal-oxide layer and has high electrical
conductivity. Although the Ohmic-contact layer 11' has high
electrical conductivity, it lowers the light transmittance, and
hence leading to lowering of the light emitting efficiency of the
LED. If the Ohmic-contact layer 11' has high light transmittance,
its electrical conductivity will be reduced, making the
Ohmic-contact characteristics of the Ohmic-contact layer 11'
inferior. Thereby, the Ohmic-contact layer 11' according to the
prior art, which adopts a single-layer metal-oxide layer, cannot
have good Ohmic-contact characteristics while maintaining superior
light emitting efficiency.
[0008] Accordingly, the present invention provides an LED device
and a flip-chip packaged LED device having excellent Ohmic-contact
characteristics as well as superior light emitting efficiency.
SUMMARY
[0009] An objective of the present invention is to provide an LED
device. The LED device can enhance its Ohmic-contact
characteristics effectively while maintaining superior light
emitting efficiency.
[0010] A method of fabricating an LED device according to an
embodiment of the present invention comprises: sequentially forming
a first-type doping layer, a light emitting layer and a second-type
doping layer on a substrate; forming an Ohmic-contact layer on the
second-type doping layer; forming a material layer and a metal
layer on the Ohmic-contact layer, wherein the material layer at
least comprises a metal oxide layer; and forming a first electrode
and a second electrode the first-type doping layer and the metal
layer respectively, wherein the first electrode is electrically
connected to the first-type doping layer and the second electrode
is electrically connected to the Ohmic-contact layer through the
metal layer.
[0011] A method of fabricating an LED device according to an
embodiment of the present invention comprises: sequentially forming
a first-type doping layer, a light emitting layer and a second-type
doping layer on a substrate; forming an Ohmic-contact layer on the
second-type doping layer; forming an oxide stacking layer and a
metal reflection layer on the Ohmic-contact layer, wherein the
oxide stacking layer comprises a plurality of stacked oxide layers;
and forming a first electrode and a second electrode the first-type
doping layer and the metal reflection layer respectively, wherein
the first electrode is electrically connected to the first-type
doping layer, the second electrode is electrically connected to the
Ohmic-contact layer, and the oxide stacking layer and the metal
reflection layer are disposed between the second electrode and the
Ohmic-contact layer.
[0012] A method of fabricating an LED device according to an
embodiment of the present invention comprises: sequentially forming
a first-type doping layer, a light emitting layer and a second-type
doping layer on a substrate; forming an Ohmic-contact layer on the
second-type doping layer; forming an oxide stacking layer and a
metal reflection layer on the Ohmic-contact layer, wherein the
oxide stacking layer comprises a plurality of stacked oxide layers;
and forming a first electrode and a second electrode the first-type
doping layer and the metal reflection layer respectively, wherein
the first electrode is electrically connected to the first-type
doping layer, the oxide stacking layer and the metal reflection
layer are disposed between the second electrode and the
Ohmic-contact layer, and the second electrode is electrically
connected to the Ohmic-contact layer through the metal reflection
layer.
[0013] A method of fabricating an LED device according to an
embodiment of the present invention comprises: sequentially forming
a first-type doping layer, a light emitting layer and a second-type
doping layer on a substrate; forming an Ohmic-contact layer on the
second-type doping layer; forming a metal reflection layer and at
least one oxide layer on the Ohmic-contact layer, wherein the at
least one oxide layer is disposed between the Ohmic-contact layer
and the metal reflection layer; and forming a first electrode and a
second electrode the first-type doping layer and the metal
reflection layer respectively, wherein the first electrode is
electrically connected to the first-type doping layer, the second
electrode is electrically connected to the Ohmic-contact layer, and
the metal reflection layer disposed between the second electrode
and the Ohmic-contact layer.
[0014] A method of fabricating an LED device according to an
embodiment of the present invention comprises: sequentially forming
a first-type doping layer, a light emitting layer and a second-type
doping layer on a substrate; forming an Ohmic-contact layer on the
second-type doping layer; forming a metal reflection layer and at
least one oxide layer on the Ohmic-contact layer; and forming a
first electrode and a second electrode the first-type doping layer
and the metal reflection layer respectively, wherein the first
electrode is electrically connected to the first-type doping layer,
the metal reflection layer and the at least one oxide layer are
disposed between the second electrode and the Ohmic-contact layer,
and the second electrode is electrically connected the
Ohmic-contact layer through the metal reflection layer.
[0015] A method of fabricating an LED device according to an
embodiment of the present invention comprises: sequentially forming
a first-type doping layer, a light emitting layer and a second-type
doping layer on a substrate; forming an Ohmic-contact layer on the
second-type doping layer; forming a material stacking layer on the
Ohmic-contact layer, wherein the material stacking layer comprises
a plurality of first material layers and a plurality of second
material layers alternately stacked, and light transmittance of the
first material layers differs from light transmittance of the
second material layers; and forming a first electrode and a second
electrode the first-type doping layer and the material stacking
layer respectively, wherein the first electrode is electrically
connected to the first-type doping layer, the second electrode is
electrically connected to the Ohmic-contact layer, and the material
stacking layer is disposed between the second electrode and the
Ohmic-contact layer.
[0016] According to the present invention, the highly conductive
Ohmic-contact layer is used for giving good current conduction
between the second-type doping layer and the reflection layer of
the LED device and thus improving the Ohmic-contact characteristics
of the LED device. In addition, the present invention further uses
the planarized buffer layer disposed between the Ohmic-contact
layer and the reflection layer for making the surface of the
Ohmic-contact layer smooth, which facilitates smooth adhesion of
the reflection layer to the planarized buffer layer as well as
reducing the scattering phenomenon of the reflected light. Thereby,
superior light emitting efficiency can be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows a structure diagram of the LED device according
to the prior art;
[0018] FIG. 2 shows a structure diagram according to a preferred
embodiment of the present invention;
[0019] FIG. 3 shows a structure diagram according to another
preferred embodiment of the present invention;
[0020] FIG. 4 shows a structure diagram according to another
preferred embodiment of the present invention; and
[0021] FIG. 5 shows a structure diagram according to another
preferred embodiment of the present invention.
DETAILED DESCRIPTION
[0022] In order to make the structure and characteristics as well
as the effectiveness of the present invention to be further
understood and recognized, the detailed description of the present
invention is provided as follows along with embodiments and
accompanying figures.
[0023] FIG. 2 shows a structure diagram according to a preferred
embodiment of the present invention. As shown in the figure, the
present embodiment provides an LED device 22, which comprises a
device substrate 221, a first-type doping layer 222, a light
emitting layer 223, a second-type doping layer 224, an
Ohmic-contact layer 225, a planarized buffer layer 226, a
reflection layer 227, and two electrodes 228, 229. The first-type
doping layer 222 is disposed on the device substrate 221; the light
emitting layer 223 is disposed on the first-type doping layer 222;
and the second-type doping layer 224 is disposed on the light
emitting layer 223. According to the present embodiment, the
first-type doping layer 222 is an n-type semiconductor layer, and
the second-type doping layer 224 is a p-type semiconductor layer.
Besides, the Ohmic-contact layer 225 is a metal thin film or a
metal-oxide layer with light transmittance higher than 90% and
thickness less than 5000 angstroms (.ANG.). The metal thin film can
be composed by gold, nickel, platinum, aluminum, chrome, tin,
indium, and their mixtures or alloys. The metal-oxide layer is
chosen from the group consisting of indium-tin oxide, cerium-tin
oxide, antimony-tin oxide, indium-zinc oxide, and zinc oxide.
[0024] Besides, the planarized buffer layer 226 is disposed on the
Ohmic-contact layer 225. The planarized buffer layer 226 is a
metal-oxide layer with light transmittance greater than 95%; the
metal-oxide layer is chosen from the group consisting of indium-tin
oxide, cerium-tin oxide, antimony-tin oxide, indium-zinc oxide, and
zinc oxide. The reflection layer 227 is disposed on the planarized
buffer layer 226. The root-mean-square roughness of the surface
between the planarized buffer layer 226 and the reflection layer
227 is less than 20 .ANG.. The reflection layer 227 is chosen from
the group consisting of silver, gold, aluminum, and copper.
Finally, the two electrodes 228, 229 are disposed on the first-type
doping layer 222 and the reflection layer 227, respectively.
[0025] FIG. 3 shows a structure diagram according to another
preferred embodiment of the present invention. As shown in the
figure, the LED device 22 according to the above embodiment is used
in a flip-chip packaged LED device 2, which comprises a packaging
substrate 20 and the LED device 22. The LED device 22 is flipped on
and connected electrically with the packaging substrate 20. The LED
device 22 is connected electrically with the packaging substrate 20
by a eutectic structure 24.
[0026] The Ohmic-contact characteristics between the second-type
doping layer 224 and the reflection layer 227 in the above
embodiment is enhanced mainly by means of the Ohmic-contact layer
225. Because the Ohmic-contact layer 225 has high electrical
conductivity, the current conduction between the second-type doping
layer 224 and the reflection layer 227 can be improved effectively,
and thus enhancing the Ohmic-contact characteristics between the
second-type doping layer 224 and the reflection layer 227.
[0027] Because the Ohmic-contact layer 225 has high electrical
conductivity, its light transmittance is lowered. In order to
maintain the light transmittance of the Ohmic-contact layer 225,
its thickness is less than 5000 .ANG.. Thereby, the light emitted
by the light emitting layer 223 will not be absorbed too much by
the Ohmic-contact layer 225, and hence enabling the light emitting
efficiency of the LED device unaffected.
[0028] Because the thickness of the Ohmic-contact layer 225 is very
thin, its surface is relatively rougher. For avoiding the
scattering phenomenon on the reflected light produced by the
surface of the Ohmic-contact layer 225, according to the present
embodiment, the planarized buffer layer 226 is used for mending the
surface of the Ohmic-contact layer 225. The thickness of the
planarized buffer layer 226 is between 500 to 5000 .ANG. for
reducing effectively the scattering phenomenon on the reflected
light produced by the surface of the Ohmic-contact layer 225. The
root-mean-square roughness of the surface between the planarized
buffer layer 226 and the reflection layer 227 is less than 20A for
adhering the reflection layer 227 smoothly to the planarized buffer
layer 226. In addition, the reflection layer 227 can have the
effect of mirror reflection by means if the planarized buffer layer
226.
[0029] The thickness of the Ohmic-contact layer 225 according to
the present embodiment is thinner with light transmittance greater
than 90%. Thereby, the light emitted by the light emitting layer
223 will not be absorbed too much by the Ohmic-contact layer 225;
most of the light can transmit the Ohmic-contact layer 225.
Besides, the light transmittance of the planarized buffer layer 226
is higher than 95%. Most of the light can transmit the planarized
buffer layer 226 and reach the reflection layer 227. Hence, the
light emitting efficiency of the LED device 22 will not be
affected.
[0030] By comparing the present invention with the prior art, it is
known that according to the prior art, only the Ohmic-contact
layer, which is a single-layer metal-oxide layer, is disposed
between the reflection layer and the second-type doping layer. By
making the Ohmic-contact layer highly electrically conductive, its
light transmittance will be lowered, leading to reduction in the
light emitting efficiency of the LED device, which, in turn, lowers
the light emitting efficiency of the flip-chip packaged LED device.
If the Ohmic-contact layer is thinned, its surface will be rough,
resulting in scattering of the reflected light. The LED device 22
according to the present invention adopts the planarized buffer
layer 226 disposed on the thin Ohmic-contact layer 225 for reducing
the scattering phenomenon on the reflected light owing to the
surface of the Ohmic-contact layer 225. In addition, the
Ohmic-contact layer 225 according to the present embodiment can
make the Ohmic-contact characteristics between the second-type
doping layer 224 and the reflection layer 227 superior without
affecting the light emitting efficiency of the LED device 22.
Accordingly, the light emitting efficiency of the flip-chip
packaged LED device 2 will not be affected either.
[0031] FIG. 4 shows a structure diagram according to another
preferred embodiment of the present invention. As shown in the
figure, in addition to the embodiment shown in FIG. 2, the LED
device 22 further comprises a cover layer 230 disposed between the
reflection layer 227 and the electrode 229 and extending to the
sidewall of the reflection layer 227. The cover layer 230 is used
for prevent the migration phenomenon of the metal ions in the
reflection layer 227.
[0032] FIG. 5 shows a structure diagram according to another
preferred embodiment of the present invention. As shown in the
figure, the present embodiment provides another LED device 22. The
difference between the LED device 22 and the one in FIG. 2 is that
the LED device 22 according to the present embodiment has a
plurality of Ohmic-contact layers 225a and a plurality of
planarized buffer layers 226a stacked together. Each Ohmic-contact
layer 225a has the characteristics of high electrical conductivity
and high refractivity. Thereby, before part of the light emitted by
the light emitting layer 223 reaches the reflection layer 227, the
light has already been refracted by the plurality of Ohmic-contact
layers 225a for enhancing the light emitting efficiency of the
flip-chip packages LED device 2. Besides, the plurality of
planarized buffer layers 226a have the effect of smoothening each
Ohmic-contact layer 225a. Hence, the scattering phenomenon on the
reflected light caused by the surface of each Ohmic-contact layer
225a can be avoided.
[0033] To sum up, the present invention provides an LED device and
a flip-chip packages LED device. The LED device is flipped on and
connected electrically with the packaging substrate and thus
forming the flip-chip packaged LED device. The LED device has the
Ohmic-contact layer and the planarized buffer layer. The
Ohmic-contact layer enhances the current conduction between the
second-type doping layer and the reflection layer and thus
improving the Ohmic-contact characteristics of the LED device. The
planarized buffer layer smoothens the surface of the Ohmic-contact
layer, which enables the reflection layer to attach to the
planarized buffer layer smoothly and achieving the effect of mirror
reflection as well as reducing the scattering phenomenon of the
reflected light. By disposing the Ohmic-contact layer and the
planarized buffer layer, the LED device and the flip-chip packages
LED device according to the present invention can have superior
Ohmic-contact characteristics without affecting the light emitting
efficiency thereof.
[0034] Accordingly, the present invention conforms to the legal
requirements owing to its novelty, nonobviousness, and utility.
However, the foregoing description is only embodiments of the
present invention, not used to limit the scope and range of the
present invention. Those equivalent changes or modifications made
according to the shape, structure, feature, or spirit described in
the claims of the present invention are included in the appended
claims of the present invention.
* * * * *