U.S. patent application number 14/939463 was filed with the patent office on 2016-06-09 for light emitting diode structure.
The applicant listed for this patent is Lextar Electronics Corporation. Invention is credited to Shiou-Yi Kuo, Shih-Huan Lai.
Application Number | 20160163923 14/939463 |
Document ID | / |
Family ID | 56095090 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160163923 |
Kind Code |
A1 |
Kuo; Shiou-Yi ; et
al. |
June 9, 2016 |
Light Emitting Diode Structure
Abstract
A light emitting diode structure includes a first type
semiconductor layer, a second type semiconductor layer, an active
layer disposed therebetween, and a reflective stacked layer. The
reflective stacked layer includes a first reflective layer and a
second reflective layer. The first reflective layer is disposed at
a side of the second type semiconductor layer opposing the active
layer. The second reflective layer is disposed at a side of the
first reflective layer opposing the second type semiconductor
layer, and extends along a side surface of the first reflective
layer to a surface of the second type semiconductor layer. A
vertical projection area of the second reflective layer on the
second-type semiconductor layer is greater than that of the first
reflective layer thereon. The second reflective layer has a better
resistance to migration than the first reflective layer.
Inventors: |
Kuo; Shiou-Yi; (Kaohsiung
City, TW) ; Lai; Shih-Huan; (Changhua County,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lextar Electronics Corporation |
Hsinchu |
|
TW |
|
|
Family ID: |
56095090 |
Appl. No.: |
14/939463 |
Filed: |
November 12, 2015 |
Current U.S.
Class: |
257/98 |
Current CPC
Class: |
H01L 33/20 20130101;
H01L 33/145 20130101; H01L 33/10 20130101; H01L 33/42 20130101;
H01L 33/405 20130101 |
International
Class: |
H01L 33/10 20060101
H01L033/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2014 |
TW |
103142040 |
Jun 11, 2015 |
TW |
104118969 |
Claims
1. A light emitting diode structure, comprising: a first type
semiconductor layer; an active layer; a second type semiconductor
layer, wherein the active layer is disposed between the first type
semiconductor layer and the second type semiconductor layer; and a
reflective stacked layer, comprising: a first reflective layer
disposed at a side of the second type semiconductor layer opposing
the active layer; and a second reflective layer which is disposed
at a side of the first reflective layer opposing the second type
semiconductor layer, and extends along a side surface of the first
reflective layer to a surface of the second type semiconductor
layer, wherein the first reflective layer has a first surface
proximate to the second type semiconductor layer, and the second
reflective layer has a second surface proximate to the second type
semiconductor layer, and a vertical projection area of the second
reflective layer on the second type semiconductor layer is greater
than a vertical projection area of the first reflective layer on
the second type semiconductor layer, and the second reflective
layer has a better resistance to migration than the first
reflective layer.
2. The light emitting diode structure of claim 1, wherein a
reflectance of the first reflective layer is greater than a
reflectance of the second reflective layer.
3. The light emitting diode structure of claim 2, wherein the
reflectance of the first reflective layer is in a range
substantially from 90% to 100%, and the reflectance of the second
reflective layer is substantially greater than 80% but smaller than
the reflectance of the first reflective layer.
4. The light emitting diode structure of claim 1, wherein the first
surface and the second surface form a reflective surface of the
reflective stacked layer.
5. The light emitting diode structure of claim 4, wherein the first
surface substantially occupies 80% to 99% of an area of the
reflective surface, and the second surface substantially occupies
1% to 20% of the area of the reflective surface.
6. The light emitting diode structure of claim 4, wherein the first
surface substantially occupies 90% to 95% of an area of the
reflective surface, and the second surface substantially occupies
5% to 10% of the area of the reflective surface.
7. The light emitting diode structure of claim 4, wherein the
reflective stacked layer comprises a first blocking layer disposed
between the first reflective layer and the second reflective
layer.
8. The light emitting diode structure of claim 7, wherein the
reflective stacked layer comprises a second blocking layer disposed
at a side of the second reflective layer opposing the first
reflective layer.
9. The light emitting diode structure of claim 8, further
comprising a current blocking layer, wherein the second reflective
layer further comprises a recess disposed at a side of the second
reflective layer facing the second type semiconductor layer, and
the current blocking layer is disposed in the recess and adjoins
the second type semiconductor layer.
10. The light emitting diode structure of claim 1, wherein a
projection of the first reflective layer on the second type
semiconductor layer is located in a projection of the second
reflective layer on the second type semiconductor layer.
11. The light emitting diode structure of claim 1, wherein the
first reflective layer is formed from silver, and the second
reflective layer is formed from aluminum, rhodium, a silver alloy,
or a combination thereof.
12. The light emitting diode structure of claim 1, wherein the
first reflective layer is formed from silver or a silver alloy, and
the second reflective layer is formed from aluminum, rhodium, or a
combination thereof.
13. The light emitting diode structure of claim 1, further
comprising a transparent conductive layer disposed between the
second type semiconductor layer and the reflective stacked
layer.
14. The light emitting diode structure of claim 1, wherein the
reflective stacked layer further comprises a transparent conductive
layer disposed between the first reflective layer and the second
type semiconductor layer, and a surface of the transparent
conductive layer facing the second type semiconductor layer and the
second surface are coplanar to form a reflective surface of the
reflective stacked layer.
15. The light emitting diode structure of claim 14, wherein a
reflectance of the first reflective layer is greater than a
reflectance of the second reflective layer.
16. The light emitting diode structure of claim 15, wherein the
reflectance of the first reflective layer is in a range
substantially from 90% to 100%, and the reflectance of the second
reflective layer is substantially greater than 80% but smaller than
the reflectance of the first reflective layer.
17. The light emitting diode structure of claim 15, wherein the
surface of the transparent conductive layer facing the second type
semiconductor layer substantially occupies 80% to 99% of an area of
the reflective surface, and the second surface substantially
occupies 1% to 20% of the area of the reflective surface.
18. The light emitting diode structure of claim 13, wherein the
reflective stacked layer comprises a first blocking layer disposed
between the first reflective layer and the second reflective
layer.
19. The light emitting diode structure of claim 18, wherein the
reflective stacked layer comprises a second blocking layer disposed
at a side of the second reflective layer opposing the first
reflective layer.
20. The light emitting diode structure of claim 19, further
comprising a current blocking layer, wherein the second reflective
layer further comprises a recess disposed at a side of the second
reflective layer facing the second type semiconductor layer, and
the current blocking layer is disposed in the recess and adjoins
the second type semiconductor layer.
Description
RELATED APPLICATIONS
[0001] This application claims priority to Taiwanese Application
Serial Number 103142040, filed Dec. 3, 2014 and 104118969, filed
Jun. 11, 2015, which are herein incorporated by reference.
BACKGROUND
[0002] 1. Field of Invention
[0003] The present invention relates to a light emitting diode
structure.
[0004] 2. Description of Related Art
[0005] In recent years, with the merits of high-directivity, energy
saving, etc., light-emitting diodes (LEDs) have been applied in
various illumination devices and display devices. A complete light
emitting diode should be accompanied with a suitable packaging
structure for providing light output with desired intensity and
uniformity. Therefore, in the LED industry, in addition to the
disposition of the light-emitting layer itself, such as
semiconductor layers in the light emitting diode, the packaging
structure accompanying the light emitting diode also plays a
role.
[0006] Generally, for increasing light output intensity, in the
packaging structure of the light emitting diode, a reflective layer
is often disposed for reflecting the light emitted by the light
emitting diode. Therefore, the light emitting diode can emit light
in one single direction. This packaging facilitates the application
of LED in various illumination devices and display devices.
However, the packaging structure with the reflective layer may be
affected by an ambient vapor, temperature, acid, etc., thus causing
the problems such as migration, peeling, and corrosion.
SUMMARY
[0007] The invention provides a light emitting diode structure. Two
reflective layers formed from different materials are collectively
used to form a reflective surface of the light emitting diode
structure, thereby increasing the area of the reflective surface,
further protecting the reflective layers from being affected by an
ambient vapor, temperature, acid, etc. without lowering light
output intensity.
[0008] One aspect of this invention is to provide a light emitting
diode structure includes a first type semiconductor layer, an
active layer, a second type semiconductor layer, and a reflective
stacked layer. The active layer is disposed between the first type
semiconductor layer and the second type semiconductor layer. The
reflective stacked layer includes a first reflective layer and a
second reflective layer. The first reflective layer is disposed at
a side of the second type semiconductor layer opposing the active
layer. The second reflective layer is disposed at a side of the
first reflective layer opposing to the second type semiconductor
layer, and extends along a side surface of the first reflective
layer to a surface of the second type semiconductor layer. The
first reflective layer has a first surface proximate to the second
type semiconductor layer, and the second reflective layer has a
second surface proximate to the second type semiconductor layer. A
vertical projection area of the second reflective layer on the
second-type semiconductor layer is greater than that of the first
reflective layer on the second-type semiconductor layer. The second
reflective layer has a better resistance to migration than the
first reflective layer.
[0009] In one or more embodiments of the present invention, a
reflectance of the first reflective layer is greater than a
reflectance of the second reflective layer.
[0010] In one or more embodiments of the present invention, the
reflectance of the first reflective layer is in a range
substantially from 90% to 100%, and the reflectance of the second
reflective layer is substantially greater than 80% but smaller than
the reflectance of the first reflective layer.
[0011] In one or more embodiments of the present invention, the
first surface and the second surface form a reflective surface of
the reflective stacked layer.
[0012] In one or more embodiments of the present invention, the
first surface substantially occupies 80% to 99% of an area of the
reflective surface, and the second surface substantially occupies
1% to 20% of the area of the reflective surface.
[0013] In one or more embodiments of the present invention, the
first surface substantially occupies 90% to 95% of an area of the
reflective surface, and the second surface substantially occupies
5% to 10% of the area of the reflective surface.
[0014] In one or more embodiments of the present invention, the
reflective stacked layer comprises a first blocking layer disposed
between the first reflective layer and the second reflective
layer.
[0015] In one or more embodiments of the present invention, the
reflective stacked layer includes a second blocking layer disposed
at a side of the second reflective layer opposing the first
reflective layer.
[0016] In one or more embodiments of the present invention, the
light emitting diode structure further includes a current blocking
layer, wherein the second reflective layer further includes a
recess disposed at a side of the second reflective layer facing the
second type semiconductor layer, and the current blocking layer is
disposed in the recess and adjoins the second type semiconductor
layer.
[0017] In one or more embodiments of the present invention, a
projection of the first reflective layer on the second type
semiconductor layer is located in a projection of the second
reflective layer on the second type semiconductor layer.
[0018] In one or more embodiments of the present invention, the
first reflective layer is formed from silver, and the second
reflective layer is formed from aluminum, rhodium, a silver alloy,
or a combination thereof.
[0019] In one or more embodiments of the present invention, the
first reflective layer is formed from silver or a silver alloy, and
the second reflective layer is formed from aluminum, rhodium, or a
combination thereof.
[0020] In one or more embodiments of the present invention, the
light emitting diode structure further includes a transparent
conductive layer disposed between the second type semiconductor
layer and the reflective stacked layer.
[0021] In one or more embodiments of the present invention, the
reflective stacked layer further includes a transparent conductive
layer disposed between the first reflective layer and the second
type semiconductor layer, and a surface of the transparent
conductive layer facing the second type semiconductor layer and the
second surface are coplanar to form a reflective surface of the
reflective stacked layer.
[0022] In one or more embodiments of the present invention, a
reflectance of the first reflective layer is greater than a
reflectance of the second reflective layer.
[0023] In one or more embodiments of the present invention, the
reflectance of the first reflective layer is in a range
substantially from 90% to 100%, and the reflectance of the second
reflective layer is substantially greater than 80% but smaller than
the reflectance of the first reflective layer.
[0024] In one or more embodiments of the present invention, the
surface of the transparent conductive layer facing the second type
semiconductor layer substantially occupies 80% to 99% of an area of
the reflective surface, and the second surface substantially
occupies 1% to 20% of the area of the reflective surface.
[0025] In one or more embodiments of the present invention, the
reflective stacked layer includes a first blocking layer disposed
between the first reflective layer and the second reflective
layer.
[0026] In one or more embodiments of the present invention, the
reflective stacked layer includes a second blocking layer disposed
at a side of the second reflective layer opposing the first
reflective layer.
[0027] In one or more embodiments of the present invention, the
light emitting diode structure further includes a current blocking
layer, wherein the second reflective layer further includes a
recess disposed at a side of the second reflective layer facing the
second type semiconductor layer, and the current blocking layer is
disposed in the recess and adjoins the second type semiconductor
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention can be more fully understood by reading the
following detailed description of the embodiment, with reference
made to the accompanying drawings as follows:
[0029] FIG. 1 is a schematic cross-sectional view of a light
emitting diode structure according to one embodiment of this
invention;
[0030] FIG. 2 is a schematic view showing areas of the light
emitting diode structure of FIG. 1;
[0031] FIG. 3 is a schematic cross-sectional view of a light
emitting diode structure according to another embodiment of this
invention;
[0032] FIG. 4 is a schematic cross-sectional view of a light
emitting diode structure according to another embodiment of this
invention;
[0033] FIG. 5 is a schematic cross-sectional view of a light
emitting diode structure according to another embodiment of this
invention; and
[0034] FIG. 6 is a schematic cross-sectional view of a light
emitting diode structure according to another embodiment of this
invention.
DETAILED DESCRIPTION
[0035] The following embodiments are disclosed with accompanying
diagrams for detailed description. For illustration clarity, many
details of practice are explained in the following descriptions.
However, it should be understood that these details of practice do
not intend to limit the present invention. That is, these details
of practice are not necessary in parts of embodiments of the
present invention. Furthermore, for simplifying the drawings, some
of the conventional structures and elements are shown with
schematic illustrations.
[0036] It will be understood that when an element is referred to as
being "on" another element, it can be directly on the other element
or intervening elements may be present therebetween. In contrast,
when an element is referred to as being "directly on" another
element, there are no intervening elements present.
[0037] FIG. 1 is a schematic cross-sectional view of a light
emitting diode structure 100 according to one embodiment of this
invention. The light emitting diode structure 100 includes a first
type semiconductor layer 110, an active layer 120, a second type
semiconductor layer 130, and a reflective stacked layer 140. The
active layer 120 is disposed between the first type semiconductor
layer 110 and the second type semiconductor layer 130, such that
the first type semiconductor layer 110 and the second type
semiconductor layer 130 can be operated to emit light. The
reflective stacked layer 140 includes a first reflective layer 150,
a second reflective layer 160, a first blocking layer 170, and a
second blocking layer 180. The first reflective layer 150 is
disposed at a side of the second type semiconductor layer 130
opposing the active layer 120. The second reflective layer 160 is
disposed at a side of the first reflective layer 150 opposing the
second type semiconductor layer 130 and extends along a side
surface 151 of the first reflective layer 150 to a surface 132 of
the second type semiconductor layer 130. The first blocking layer
170 is disposed between the first reflective layer 150 and the
second reflective layer 160. The second blocking layer 180 is
disposed at a side of the second reflective layer 160 opposing the
first reflective layer 150.
[0038] In one or more embodiments of the present invention, a
vertical projection area of the second reflective layer 160 on the
second type semiconductor layer 130 is greater than that of the
first reflective layer 150 on the second type semiconductor layer
130. To be specific, a projection of the first reflective layer 150
on the second type semiconductor layer 130 is located in a
projection of the second reflective layer 160 on the second type
semiconductor layer 130. Therefore, the second reflective layer 160
covers the first reflective layer 150 and prevents the first
reflective layer 150 from being exposed.
[0039] Furthermore, the first reflective layer 150 has a first
surface 152 proximate to the second type semiconductor layer 130,
and the second reflective layer 160 has a second surface 162
proximate to the second type semiconductor layer 130. Herein, the
first surface 152 is referred to as a contact surface between the
first reflective layer 150 and the second type semiconductor layer
130, and the second surface 162 is referred to as a contact surface
between the second reflective layer 160 and the second type
semiconductor layer 130. The second surface 162 is disposed at a
periphery of the first surface 152.
[0040] As a result, the reflective stacked layer 140 is disposed on
the second type semiconductor layer 130 with a sequence of the
first reflective layer 150, the first blocking layer 170, the
second reflective layer 160 and the second blocking layer 180
stacked on the second type semiconductor layer 130, and the second
reflective layer 160 covers the first reflective layer 150 and
prevents the first reflective layer 150 from being exposed.
[0041] In one or more embodiments of the present invention, in the
configuration of the reflective stacked layer 140, a reflectance of
the first reflective layer 150 is greater than that of the second
reflective layer 160, and the second reflective layer 160 has a
better stability than the first reflective layer 150. In other
words, the second reflective layer 160 has a better resistance to
migration than the first reflective layer 150, and thereby the
second reflective layer 160 suffers less migration, peeling,
corrosion, etc. than the first reflective layer 150.
[0042] Herein, only four materials, silver, aluminum, silver alloy,
and rhodium, are used as examples for explanation, but they do not
intend to limit the scope of the present invention. The reflectance
of these four materials is descending in the sequence of silver
(about 95%), silver alloy (about 90%), aluminum (about 85%), and
rhodium (about 80%). Resistances to migration of these four
materials, ranging from bad to good are, silver, aluminum, silver
alloy, and rhodium. In the configuration of the first reflective
layer 150 and the second reflective layer 160, appropriate
materials are chosen for enhancing the reflectance and improving
the resistance to migration of a combination of the first
reflective layer 150 and the second reflective layer 160. Ideally,
for achieving the light output intensity effectively, in the
selection of the materials of the reflective layers, the
reflectance of the first reflective layer 150 is in a range
substantially from 90% to 100%, and the reflectance of the second
reflective layer 160 is substantially greater than 80% but smaller
than the reflectance of the first reflective layer 150.
[0043] For example, in one embodiment, the first reflective layer
150 can be formed from silver, and the second reflective layer 160
can be formed from aluminum, rhodium, silver alloy, or a
combination thereof. In another embodiment, the first reflective
layer 150 can be formed from aluminum, and the second reflective
layer 160 is formed from rhodium. In this way, the reflectance and
the resistance to migration of the first reflective layer 150 and
those of the second reflective layer 160 can be taken into
consideration. Of course, the materials listed herein do not intend
to limit the scope of the present invention, and any material with
high reflectance and good resistance to migration can also be
applicable to the first reflective layer 150 and the second
reflective layer 160.
[0044] In one or more embodiments of the present invention, the
first blocking layer 170 and the second blocking layer 180 can be
formed from materials having good stability, adhesion, and other
properties. The first blocking layer 170 and the second blocking
layer 180 are configured to prevent the migration, peeling,
corrosion, etc. of metal layers or reflective layers. However,
these materials may have low reflectance, which may be
substantially lower than 60%, for example. The first blocking layer
170 and the second blocking layer 180 can be formed from titanium,
platinum, gold, nickel, wolfram, titanium tungsten alloy, or a
combination thereof, for example.
[0045] In one or more embodiments of the present invention, the
second reflective layer 160 extends along the side surface 151 of
the first reflective layer 150 to the surface 132 of the second
type semiconductor layer 130, thereby preventing either the first
blocking layer 170 or the second blocking layer 180 from directly
adjoining the second type semiconductor layer 130. That is, neither
the first blocking layer 170 nor the second blocking layer 180
constitutes a portion of the reflective surface 142 of the
reflective stacked layer 140 in contact with the second type
semiconductor layer 130. To be specific, the first blocking layer
170 is utilized for preventing the first reflective layer 150 from
peeling off. The second reflective layer 160 covers the first
blocking layer 170 and constitutes a portion of the reflective
surface 142 for increasing the area with the reflective function.
The second blocking layer 180 is utilized for protecting both the
first reflective layer 150 and the second reflective layer 160 from
peeling off. The configuration ensures the protection to the first
reflective layer 150 and the second refection layer 160 against
migration, corrosion, etc. without decreasing the reflective
function of the reflective surface 142, and thereby enhances the
reliability of the first reflective layer 150 and the second
reflective layer 160.
[0046] In one or more embodiments of the present invention, the
first surface 152 and the second surface 162 together form the
reflective surface 142 of the reflective stacked layer 140. Since
the first reflective layer 150 and the second reflective layer 160
are both formed from reflective materials, the reflective surface
has a high reflectance, and therefore can reflect the light emitted
from the active layer 120.
[0047] In one or more embodiments of the present invention, the
first type semiconductor layer 110 can be an n-type semiconductor
layer, and the second type semiconductor layer 130 can be a p-type
semiconductor layer. Instead, the first type semiconductor layer
110 can also be a p-type semiconductor layer, and the second type
semiconductor layer 130 can be an n-type semiconductor layer.
[0048] Reference is now made to both FIG. 1 and FIG. 2. FIG. 2 is a
schematic view showing areas of the light emitting diode structure
100 of FIG. 1. FIG. 2 depicts a distribution of projections of the
first reflective layer 150 and the second reflective layer 160 on
the surface 132 of the second type semiconductor layer 130 in the
light emitting diode structure 100. The projection area of the
first reflective layer 150 on the second type semiconductor layer
130 is substantially equal to an area of the first surface 152. The
projection area of the second reflective layer 160 on the second
type semiconductor layer 130 is substantially equivalent to a sum
of areas of the first surface 152 and the second surface 162. As
previous illustration, the projection area of the second reflective
layer 160 on the second type semiconductor layer 130 is greater
than the projection area of the first reflective layer 150 on the
second type semiconductor layer 130. For example, in an embodiment,
the first surface 152 substantially occupies 80% to 99% of an area
of the reflective surface 142, and the second surface 162
substantially occupies 1% to 20% of the area of the reflective
surface 142. Moreover, the first surface 152 may substantially
occupy 90% to 95% of the area of the reflective surface 142, and
the second surface 162 substantially occupies 5% to 10% of the area
of the reflective surface 142.
[0049] Herein, two sets of experimental results are shown for
reference. The semiconductor layers in the first set of
experimental results and the second set of experimental results are
obtained from different batches and thus should not be discussed
together. Also, to compare the advantages or disadvantages between
the sets of experimental results, another two light emitting diode
structures with the semiconductor layers formed at the same batch
with the semiconductor layers in the two sets of experimental
results are also provided as reference structures, and each of the
reference structures has no second reflective layer 160 but has a
second blocking layer 180 covering the second type semiconductor
layer 130 directly. In other words, in the configuration of each
reference structure, the second blocking layer 180 constitutes a
portion of the reflective surface 142 of the reflective stacked
layer 140 adjoining the second type semiconductor layer 130.
[0050] The first set of experimental results shows that the light
emitting diode structure designed according to the configuration of
FIG. 1 has a light output intensity value of about 425 microwatts,
while the corresponding reference structure has a light output
intensity value of only 390 microwatts. The second set of
experimental results shows that the light emitting diode structure
designed according to the configuration of FIG. 1 has a light
output intensity value of about 450 microwatts, while the
corresponding reference structure has a light output intensity
value of only 410 microwatts. As a result, it can be known that,
with the configuration of FIG. 1, the light output intensity of the
light emitting diode structure can be enhanced.
[0051] Consequently, with the configuration of the second
reflective layer 160, an area of the reflective surface 142 can be
increased, thereby enhancing the light output intensity of the
light emitting diode structure 100.
[0052] FIG. 3 is a schematic cross-sectional view of a light
emitting diode structure 100 according to another embodiment of
this invention. The present embodiment is similar to the embodiment
of FIG. 1, but is different therefrom in that the light emitting
diode structure 100 of the present embodiment includes a
transparent conductive layer 190. The transparent conductive layer
190 is disposed between the second type semiconductor layer 130 and
the reflective stacked layer 140. Herein, the second reflective
layer 160 extends along a side surface 151 of the first reflective
layer 150 to the transparent conductive layer 190 and the second
type semiconductor layer 130, and the second reflective layer 160
is in contact with the surface 192 of the transparent conductive
layer 190. The transparent conductive layer 190 has the properties
of low resistivity and high transmittance, and can be formed from
indium tin oxide. Therefore, the transparent conductive layer 190
can improve the current distribution of the light emitting diode
structure 100 without influencing the light output effect.
[0053] The light emitting diode structures 100 of the embodiments
shown in FIG. 1 and FIG. 3 are applicable to a partial structure of
a flip chip light emitting diode device 200. Referring to FIG. 4,
FIG. 4 shows a configuration of the light emitting diode structure
100 of FIG. 3 applied on the flip chip light emitting diode device
200. Herein, the flip chip light emitting diode device 200 further
includes a passivation layer 220, metal layers 230a and 230b, and a
metal column 240 in addition to the light emitting diode structure
100. The metal column 240 is disposed at a side of the first type
semiconductor layer 110 facing the second type semiconductor layer
130. The passivation layer 220 covers the light emitting diode
structure 100 and the metal column 240 for stopping invasion of
vapor and providing isolation. The passivation layer 220 has an
opening 222 configured to expose the second blocking layer 180 and
an opening 224 configured to expose the metal column 240. The metal
layers 230a and 230b are disposed at a side of the passivation
layer 220 opposing the first type semiconductor layer 110, in which
the metal layer 230a is in contact with the second blocking layer
180 through the opening 222, and the metal layer 230b is
electrically connected with the first type semiconductor layer 110
through the metal column 240 filling the opening 224.
[0054] Thus, by connecting the metal layers 230a and 230b, the flip
chip light emitting diode device 200 can operate and generate
light. Also, due to the configuration of the first reflective layer
150 and the second reflective layer 160 inside the flip chip light
emitting diode device 200, the reliability of the reflective
stacked layer 140 can be improved and the light output intensity
can be enhanced.
[0055] FIG. 5 is a schematic cross-sectional view of a light
emitting diode structure 300 according to another embodiment of
this invention. The present embodiment is similar to the embodiment
of FIG. 1, but is different therefrom in that a vertical light
emitting diode structure is adopted in the present embodiment. To
be specific, the difference between the present embodiment and the
embodiment of FIG. 1 lies in that the light emitting diode
structure 300 includes a configuration of a recess 364.
[0056] As illustrated above, in one or more embodiments of the
present invention, the light emitting diode structure 300 includes
a first type semiconductor layer 310, an active layer 320, a second
type semiconductor layer 330, and a reflective stacked layer 340.
The active layer 320 is disposed between the first type
semiconductor layer 310 and the second type semiconductor layer
330. The reflective stacked layer 340 includes a first reflective
layer 350, a second reflective layer 360, a first blocking layer
344, and a second blocking layer 346. The first reflective layer
350 is disposed at a side of the second type semiconductor layer
330 opposing the active layer 320. The second reflective layer 360
is disposed at a side of the first reflective layer 350 opposing
the second type semiconductor layer 330. The first blocking layer
344 is disposed between the first reflective layer 350 and the
second reflective layer 360. The second blocking layer 346 is
disposed at a side of the second reflective layer 360 opposing the
first reflective layer 350.
[0057] It is noted that, in the present embodiment, the second
reflective layer 360 may include a recess 364. The recess 364 is
disposed at a side of the second reflective layer 360 facing the
second type semiconductor layer 330, and the first reflective layer
350 and the first blocking layer 344 are disposed in the recess
364.
[0058] Herein, since the first reflective layer 350, the second
reflective layer 360, the first blocking layer 344, and the second
blocking layer 346 are similar to the elements in the embodiment of
FIG. 1, the details thereof are not repeated herein.
[0059] In one or more embodiments of the present invention, the
first reflective layer 350 has a first surface 352 proximate to the
second type semiconductor layer 330, and the second reflective
layer 360 has a second surface 362 proximate to the second type
semiconductor layer 330. The first surface 352 and the second
surface 362 are coplanar to form a reflective surface 342 of the
reflective stacked layer 340. Herein, the first surface 352 is
referred to as a contact surface between the first reflective layer
350 and the second type semiconductor layer 330, and the second
surface 362 is referred to as a contact surface between the second
reflective layer 360 and the second type semiconductor layer
330.
[0060] In one or more embodiments of the present invention, the
light emitting diode structure 300 further includes a current
blocking layer 370, and the number of the recess 364 can be plural,
and the current blocking layer 370 can be disposed in the recess
364 in which none of the first reflective layer 350 and the first
blocking layer 344 are disposed, and the current blocking layer 370
adjoins the second type semiconductor layer 330 for improving the
current distribution of the light emitting diode structure 300.
Certainly, the recess 364 with the first reflective layer 350 and
the first blocking layer 344 disposed therein may be different from
the recess 364 with the current blocking layer 370 disposed therein
in size, depth or other configuration features.
[0061] As described the embodiment of FIG. 1, with the
configuration of the second reflective layer 360, neither the first
blocking layer 344 nor the second blocking layer 346 constitutes a
portion of the reflective surface 342. Consequently, the first
reflective layer 350 and the second reflective layer 360 are
protected from having problems such as migration, peeling and
corrosion, and the light output intensity can be increased.
[0062] FIG. 6 is a schematic cross-sectional view of a light
emitting diode structure 400 according to another embodiment of
this invention. The present embodiment is similar to the embodiment
of FIG. 5, but is different therefrom in that the reflective
stacked layer 440 of the light emitting diode structure 400 of the
present embodiment further includes a transparent conductive layer
480.
[0063] As described above, the light emitting diode structure 400
includes a first type semiconductor layer 410, an active layer 420,
a second type semiconductor layer 430, and a reflective stacked
layer 440. The active layer 420 is disposed between the first type
semiconductor layer 410 and the second type semiconductor layer
430.
[0064] Herein, different from the embodiment of FIG. 5, the
reflective stacked layer 440 includes a first reflective layer 450,
a second reflective layer 460, a first blocking layer 444, a second
blocking layer 446, and a transparent conductive layer 480. The
second reflective layer 460 may include a recess 464 disposed at a
side of the second reflective layer 460 facing the second type
semiconductor layer 430. In the present embodiment, the first
reflective layer 450, the first blocking layer 444, and the
transparent conductive layer 480 are all disposed in the recess
464.
[0065] To be specific, the transparent conductive layer 480 is
disposed between the first reflective layer 450 and the second type
semiconductor layer 430. The second reflective layer 460 has a
second surface 465 proximate to the second type semiconductor layer
430. A surface 482 of the transparent conductive layer 480 facing
the second type semiconductor layer 430 is coplanar with the second
surface 462 to form a reflective surface 442 of the reflective
stacked layer 440. Herein, the surface 482 is referred to as a
contact surface between the transparent conductive layer 480 and
the second type semiconductor layer 430, and the second surface 462
is referred to as a contact surface between the second reflective
layer 460 and the second type semiconductor layer 430.
[0066] In one or more embodiments of the present invention, the
surface 482 of the transparent conductive layer 480 facing the
second type semiconductor layer 430 substantially occupies 80% to
99% of an area of the reflective surface 442, and the second
surface 462 substantially occupies 1% to 20% of the area of the
reflective surface 442. Furthermore, the surface 482 of the
transparent conductive layer 480 facing the second type
semiconductor layer 430 substantially occupies 90% to 95% of an
area of the reflective surface 442, and the second surface 462
substantially occupies 5% to 10% of the area of the reflective
surface 442.
[0067] As shown in FIG. 6, the light emitting diode structure 400
further includes a current blocking layer 470, and the number of
the recess 464 can be plural, and the current blocking layer 470
can be disposed in the recess 464 in which none of the first
reflective layer 450, the first blocking layer 444, and the
transparent conductive layer 480 are disposed, and the current
blocking layer 470 adjoins the second type semiconductor layer 430
for improving the current distribution of the light emitting diode
structure 300. Certainly, the recess 464 with the first reflective
layer 450, the first blocking layer 444, and the transparent
conductive layer 480 disposed therein may be different from the
recess 464 with the current blocking layer 470 disposed therein in
size, depth or other configuration features.
[0068] Among the aforementioned light emitting diode structures,
the first blocking layer, the second blocking layer, the
transparent conductive layer, the current blocking layer are not
necessary configuration, and can be optionally disposed based on
the actual package structures. Certainly, preferably, the first
blocking layer and the second blocking layer can be disposed for
achieving better protection.
[0069] The invention provides a light emitting diode structure. Two
reflective layers formed from different materials are collectively
used to form a reflective surface of the light emitting diode
structure, thereby increasing the area of the reflective surface,
further protecting the reflective layers from being affected by an
ambient vapor, temperature, acid, etc. without lowering the
intensity of light output.
[0070] Although the present invention has been described in
considerable detail with reference to certain embodiments thereof,
other embodiments are possible. Therefore, the spirit and scope of
the appended claims should not be limited to the description of the
embodiments contained herein. It will be apparent to those skilled
in the art that various modifications and variations can be made to
the structure of the present invention without departing from the
scope or spirit of the invention. In view of the foregoing, it is
intended that the present invention fall within the scope of the
following claims.
* * * * *