U.S. patent application number 12/981776 was filed with the patent office on 2011-06-30 for method of forming light-emitting diode.
Invention is credited to Chi-Hsing Chen, Yi-Ming Chen, Tzu-Chieh Hsu, Hsin-Ying Wang.
Application Number | 20110159624 12/981776 |
Document ID | / |
Family ID | 44188040 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110159624 |
Kind Code |
A1 |
Chen; Yi-Ming ; et
al. |
June 30, 2011 |
METHOD OF FORMING LIGHT-EMITTING DIODE
Abstract
A method of forming a light emitting diode is provided. The
method includes providing a growth substrate; sequentially forming
a sacrificial layer and an epitaxial layer on the growing
substrate; forming one or more epitaxial layer openings penetrating
the epitaxial layer and exposing the sacrificial layer; forming a
supporting layer on the epitaxial layer, the supporting layer
having one or more supporting layer openings penetrating the
supporting layer and joining the epitaxial layer openings; and
selectively etching the sacrificial layer to separate the growth
substrate from the epitaxial layer.
Inventors: |
Chen; Yi-Ming; (Hsinchu,
TW) ; Hsu; Tzu-Chieh; (Hsinchu, TW) ; Chen;
Chi-Hsing; (Hsinchu, TW) ; Wang; Hsin-Ying;
(Hsinchu, TW) |
Family ID: |
44188040 |
Appl. No.: |
12/981776 |
Filed: |
December 30, 2010 |
Current U.S.
Class: |
438/42 ;
257/E33.055 |
Current CPC
Class: |
H01L 33/0093 20200501;
H01L 33/005 20130101; H01L 21/02436 20130101; H01L 21/02664
20130101 |
Class at
Publication: |
438/42 ;
257/E33.055 |
International
Class: |
H01L 33/00 20100101
H01L033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 31, 2009 |
TW |
098146467 |
Claims
1. A method of forming light-emitting diode, comprising: providing
a growth substrate on which a sacrificial layer and an epitaxial
layer are sequentially formed; forming one or more epitaxial layer
openings passing through the epitaxial layer and exposing the
sacrificial layer; providing a supporting layer having one or more
supporting layer openings; connecting at least one epitaxial layer
opening with at least one supporting layer opening; and decreasing
a volume of the sacrificial layer to separate the growth substrate
from the epitaxial layer.
2. The method of claim 1, wherein the step of connecting the at
least one epitaxial layer opening with the at least one supporting
layer opening comprises: penetrating the supporting layer.
3. The method of claim 1, wherein the step of decreasing the volume
of the sacrificial layer comprises: providing an etchant to contact
the sacrificial layer through the epitaxial layer opening and the
supporting layer opening.
4. The method of claim 3, wherein the growth substrate comprises a
material selected from the group consisting of nitrogen, aluminum,
gallium, arsenic, zinc, silicon, and oxygen; the sacrificial layer
comprises a material selected from the group consisting of aluminum
and arsenic; the supporting layer comprises a material selected
from the group consisting of photo resister, metal, and plating
metal; and the etchant comprises citric acid.
5. A method of forming light-emitting diode, includes: providing a
growth substrate having one or more substrate openings passing
through the growth substrate; forming a sacrificial layer on the
growth substrate; forming a epitaxial layer on the sacrificial
layer, the epitaxial layer having one or more epitaxial layer
openings passing through the epitaxial layer; providing a
supporting substrate to connect with the epitaxial layer; and
selectively etching the sacrificial layer to separate the growth
substrate from epitaxial layer.
6. The method of claim 5, wherein the growth substrate surrounds
the substrate opening.
7. The method of claim 5, wherein the step of forming the
sacrificial layer comprises: forming one or more sacrificial layer
openings, passing through the sacrificial layer, to connect the one
or more substrate openings.
8. The method of claim 7, wherein the sacrificial layer surrounds
the sacrificial layer opening.
9. The method of claim 7, wherein at least one epitaxial layer
opening is connected with at least one sacrificial layer
opening.
10. The method of claim 7, wherein the step of selectively etching
the sacrificial layer comprises: providing an etchant to contact
the sacrificial layer through the one or more substrate openings
and the one ore more sacrificial layer openings.
11. The method of claim 10, wherein the growth substrate comprises
a material selected fro the group consisting of nitrogen, aluminum,
gallium, arsenic, zinc, silicon, and oxygen; the sacrificial layer
comprises a material selected from the group consisting of aluminum
and arsenic; the supporting substrate comprises a material selected
from the group consisting of glass, metal, semiconductor, plastics,
and ceramics; and the etchant comprises citric acid.
12. A method of forming light-emitting diode, includes: providing a
growth substrate on which a sacrificial layer and an epitaxial
layer are sequentially formed; providing a supporting substrate
having an upper surface and a lower surface, the lower surface
having one or more recesses; connecting the lower surface with the
epitaxial layer; removing a portion of the supporting substrate
from the upper surface to expose at least one recess; etching the
epitaxial layer by using the supporting substrate as a mask to form
one or more epitaxial layer openings passing through the epitaxial
layer and exposing the sacrificial layer; and selectively etching
the sacrificial layer to separate the growth substrate from the
epitaxial layer.
13. The method of claim 12, wherein the step of selectively etching
the sacrificial layer comprises: providing an etchant to contact
the sacrificial layer through the recess and the sacrificial layer
opening.
14. The method of claim 13, wherein the growth substrate comprises
a material selected fro the group consisting of nitrogen, aluminum,
gallium, arsenic, zinc, silicon, and oxygen; the sacrificial layer
comprises a material selected from the group consisting of aluminum
and arsenic; the supporting substrate comprises a material selected
from the group consisting of Si. A.sub.2lO.sub.3, metal,
semiconductor, plastics, and ceramics; and the etchant comprises
citric acid.
15. A method of forming light-emitting diode, includes: providing a
growth substrate on which a sacrificial layer and an epitaxial
layer are sequentially formed; providing a supporting substrate;
forming one or more supporting substrate openings through the
supporting substrate; connecting the supporting substrate with the
epitaxial layer; etching the epitaxial layer by using the
supporting substrate as a mask to form one or more epitaxial layer
openings passing through the epitaxial layer and exposing the
sacrificial layer; and selectively etching the sacrificial layer to
separate the growth substrate from the epitaxial layer.
16. The method of claim 15, wherein the supporting substrate
surrounds the supporting substrate opening.
17. The method of claim 15, wherein the step of selectively etching
the sacrificial layer comprises: providing an etchant to contact
the sacrificial layer through the supporting substrate opening and
the epitaxial layer opening.
18. The method of claim 17, wherein the growth substrate comprises
a material selected fro the group consisting of nitrogen, aluminum,
gallium, arsenic, zinc, silicon, and oxygen; the sacrificial layer
comprises a material selected from the group consisting of aluminum
and arsenic; the supporting substrate comprises a material selected
from the group consisting of Si. A.sub.2lO.sub.3, metal,
semiconductor, plastics, and ceramics; and the etchant comprises
citric acid.
19. The method of claim 15, wherein the step of providing the
supporting substrate comprises: connecting the supporting substrate
with a temporary substrate; and removing the temporary substrate
after connecting the supporting substrate with the epitaxial layer
and before etching the epitaxial layer.
20. The method of claim 15, wherein the temporary substrate
comprises a material selected from the group consisting of glass,
metal, semiconductor, plastics, and ceramics.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the right of priorities based on
Taiwan applications Ser. No. 098146467, filed Dec. 31, 2009, the
content of which is hereby incorporated by reference.
TECHNICAL FIELD
[0002] The application relates to a method of making a
light-emitting diode, and more particularly to a method of
replacing a substrate of the light-emitting diode with the help of
a sacrificial layer.
DESCRIPTION OF BACKGROUND ART
[0003] A Light-emitting diode epitaxial thin film is usually grown
on a GaAs substrate which absorbs light. To improve the
light-emitting efficiency, the GaAs substrate is etched away after
the grown epitaxial layer is bonded to another suitable substrate.
However, it is not cost effective to dissolve the recyclable GaAs
substrate. Moreover, the As residue can easily cause the
environmental pollution.
SUMMARY OF THE DISCLOSURE
[0004] The present application provides a method of recycling a
growth substrate of a light-emitting diode.
[0005] A method of forming light-emitting diode in accordance with
an embodiment of the present application includes steps of
providing a growth substrate on which a sacrificial layer and an
epitaxial layer are sequentially formed; forming one or more
epitaxial layer openings passing through the growth substrate and
exposing the sacrificial layer; forming a supporting layer on the
epitaxial layer, the supporting layer having one or more supporting
layer openings passing through the supporting layer and connecting
with the one or more epitaxial layer openings; and selectively
etching the sacrificial layer to separate the growth substrate from
the epitaxial layer.
[0006] A method of forming light-emitting diode in accordance with
another embodiment of present application includes steps of
providing a growth substrate having one or more substrate openings
passing through the growth substrate; forming a sacrificial layer
on the growth substrate; forming an epitaxial layer on the
sacrificial layer, the epitaxial layer having one or more epitaxial
layer openings passing through the epitaxial layer; providing a
supporting substrate to connect with the epitaxial layer; and
selectively etching the sacrificial layer to separate the growth
substrate from the epitaxial layer.
[0007] A method of forming light-emitting diode in accordance with
further embodiment of present application includes steps of
providing a growth substrate on which a sacrificial layer and an
epitaxial layer are sequentially formed; providing a supporting
substrate having an upper surface and a lower surface, the lower
surface having one or more recesses; connecting the lower surface
with the epitaxial layer; removing a portion of the supporting
substrate from the upper surface to expose at least one recess and
form one or more supporting substrate openings passing through the
supporting substrate; etching the epitaxial layer by using the
supporting substrate as a mask to form one or more epitaxial layer
openings passing through the epitaxial layer and exposing the
sacrificial layer; and selectively etching the sacrificial layer to
separate the growth substrate from the epitaxial layer.
[0008] A method of forming light-emitting diode in accordance with
one embodiment of present application includes steps of providing a
growth substrate on which a sacrificial layer and an epitaxial
layer are sequentially formed; providing a supporting substrate to
connect with a temporary substrate; forming one or more supporting
substrate openings passing through the supporting substrate;
connecting the supporting substrate with the epitaxial layer;
removing the temporary substrate; etching the epitaxial layer by
using the supporting substrate as a mask to form one or more
epitaxial layer openings passing through the epitaxial layer and
exposing the sacrificial layer; and selectively etching the
sacrificial layer to separate the growth substrate from the
epitaxial layer.
[0009] A method of forming light-emitting diode in accordance with
another embodiment of present application includes steps of
providing a growth substrate on which a sacrificial layer and an
epitaxial layer are sequentially formed; providing a supporting
substrate; forming one or more supporting substrate openings
through the supporting substrate; connecting the supporting
substrate with the epitaxial layer; etching the epitaxial layer by
using the supporting substrate as a mask to form one or more
epitaxial layer openings passing through the epitaxial layer and
exposing the sacrificial layer; and selectively etching the
sacrificial layer to separate the growth substrate from the
epitaxial layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1A.about.1E and FIGS. 1A'.about.1E' illustrate cross
sectional views and top views of steps of forming a light-emitting
diode 190 in accordance with an embodiment of the present
application.
[0011] FIGS. 2A.about.2D and FIGS. 2A'.about.2D' illustrate cross
sectional views and top views of steps of forming a light-emitting
diode 290 in accordance with an embodiment of the present
application.
[0012] FIGS. 3A.about.3E and FIGS. 3A'.about.3E' illustrate cross
sectional views and top views of steps of forming a light-emitting
diode 290 in accordance with an embodiment of the present
application.
[0013] FIGS. 4A.about.4E and FIGS. 4A'.about.4E' illustrate cross
sectional views and top views of steps of forming a light-emitting
diode 290 in accordance with an embodiment of the present
application.
[0014] FIGS. 5A.about.5E and FIGS. 5A'.about.5E' illustrate cross
sectional views and top views of steps of forming a light-emitting
diode 290 in accordance with an embodiment of the present
application.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0015] The embodiments are described hereinafter in accompany with
drawings. The similar part is designated by the same reference
numeral. It is noted that the dimensions of the various elements
illustrated in the various figures are not to scale. Moreover, some
conventional parts, materials, and processing techniques are
omitted in the description for simplification.
[0016] Referring to FIGS. 1A and 1A', a sacrificial layer 120 and
an epitaxial layer 140 are sequentially formed on a growth
substrate 100. The growth substrate 100 is composed of at least one
element of nitrogen, aluminum, gallium, arsenic, zinc, silicon, and
oxygen, for example, the growth substrate 100 is an n-type GaAs.
The epitaxial layer 140 is a multi-layer structure and can be
composed of at least one element of nitrogen, aluminum, gallium,
indium, arsenic, phosphorus, silicon, and oxygen. However, each
layer of the multi-layer structure can have different composition
element, for example, the multi-layer structure includes an n-type
GaAs lower contact layer, an n-type Al.sub.xGa.sub.1-xAs lower
cladding layer, a Al.sub.yGa.sub.1-yAs active layer, a p-type
Al.sub.zGa.sub.1-zAs upper cladding layer, and a p-type GaAs upper
contact layer, herein x, y, and z are between 0 and 1. The
epitaxial layer 140 has a thickness of between 1 .mu.m and 100
.mu.m. In the present embodiment, the sacrificial layer 120 and the
epitaxial layer 140 are formed by epitaxial growth. The sacrificial
layer 120 can be composed of at least one element of aluminum and
arsenic. For example, an AlAs sacrificial layer can be
selectively-etched away by an etchant having a lower etching rate
to the growth substrate 100, the epitaxial layer 140, and the
following supporting layer. The sacrificial layer 120 preferably
has a thickness of between 3000 .ANG. and 5000 .ANG.. In addition,
the growth substrate 100 can have p-type conductivity.
[0017] Referring to FIGS. 1B and 1B', the epitaxial layer 140 is
patterned to form one or more epitaxial layer openings 141 which
pass through the epitaxial layer 140 in order to expose the
sacrificial layer 120 under thereof. The objectives of forming the
several epitaxial layer openings are, for example, for positioning
the light-emitting diode chips, or making an etchant flow to the
sacrificial layer 120. As the objective described above, the
opening or recess in other embodiment is not limited to forming on
the epitaxial layer. The opening can be formed by photolithography
and etching process. As shown in FIG. 1B, the several epitaxial
layer openings 141 are formed on the surface of the epitaxial layer
140 in a matrix or random configuration. The epitaxial layer
opening 141 can have a shape of circle, rectangle, polygon, or
other suitable geometry. The size of the epitaxial 1 layer opening
141 can be adjusted according to the requirement. In one
embodiment, after being patterned, the epitaxial layer region 142
(i.e. the patterned epitaxial layer 140) still surrounds the
epitaxial layer openings 141. For example, FIG. 1B' illustrates the
epitaxial layer region 142a surrounding the openings 141a, the
epitaxial layer region 142b surrounding the opening 141b, and the
epitaxial layer region 142c surrounding the opening 141c. As shown
in the drawing, the epitaxial layer regions 142a, 142b, and 142c
are integrated with each other. In other words, the patterned
epitaxial layer 142 is a continuous structure. No isolated island
appears in the patterned epitaxial layer 142 after forming the
epitaxial layer opening 141. In the present embodiment, the
epitaxial layer opening 141 is illustrated to penetrate the
epitaxial layer 140. However, the epitaxial layer opening 141 can
also penetrate the sacrificial layer 120 partially or thoroughly.
In another embodiment, besides the epitaxial layer opening 141, a
sacrificial recess (not shown) corresponding to at least one
epitaxial layer opening 141 is formed on the sacrificial layer 120.
In a further embodiment, besides the epitaxial layer opening 141, a
sacrificial opening (not shown) penetrating the sacrificial layer
120 and corresponding to at least one epitaxial layer opening 141
is formed on the sacrificial layer 120.
[0018] Referring to FIGS. 1C and 1C', a supporting layer 150 is
formed on the epitaxial layer 140 which has epitaxial layer
openings 141. The supporting layer 150 has supporting layer
openings 151 penetrating the supporting layer 150 and connecting to
the corresponding epitaxial layer openings 141. In other words, the
supporting layer 150 is formed on the upper surface of the
epitaxial layer 140 exclusive of the epitaxial layer openings 141.
In one embodiment, the supporting layer 150 has a pattern similar
to the patterned epitaxial layer 140, and therefore continuously
surrounds the supporting layer openings. However, in another
embodiment, the supporting layer 150 has a pattern different to the
patterned epitaxial layer 140. In other words, the epitaxial layer
openings 141 are different to the supporting layer openings 151 in
at least one of the layout, opening geometry, and quantity. The
supporting layer 150 can be used to replace the growth substrate
100 so as to support the epitaxial layer 140; the growth substrate
therefore can be removed in following steps. If there is no
supporting layer 150, the epitaxial layer 140 is too thin to carry
out. In the present embodiment, the supporting layer 150 can be
selected from but not limited to a photo resistor, metal, or
electroplating metal, which has a thickness of between 50 .mu.m and
300 .mu.m.
[0019] Referring to FIGS. 1C and 1C', after forming the supporting
layer 150, the sacrificial layer 120 is selectively etched away
such that the growth substrate 100 can be separated from the
epitaxial layer 140. In detail, the sacrificial layer 120 can be
selectively etched away using an etchant having a lower etching
rate to the growth substrate 100, the epitaxial layer 140, and the
supporting layer 150. The etchant can remove the sacrificial layer
120 via the epitaxial layer openings 140 and the supporting layer
openings 150 such that the growth substrate 100 is separated from
the epitaxial layer 140. However, the sacrificial layer 120 is not
necessary to be completely removed; the volume or the area
contacting its upper and lower layers can be shrunk such that the
growth substrate 100 can be separated from the epitaxial layer 140.
In the present embodiment, citric acid as the etchant is applied.
However, other suitable wet etching or dry etching method can be
also introduced into the present invention.
[0020] FIGS. 1D and 1D' illustrate the structures after removing
the sacrificial layer 120 and separating the growth substrate 100.
It is also noted that the epitaxial layer 140 and the supporting
layer 150 are connected with each other; the epitaxial layer 142 is
formed to continuously surround the epitaxial layer openings; and
the supporting layer 152 is formed to continuously surround the
supporting layer openings 151. Because no or few discrete islands
exist within the structure, as long as the supporting layer 150 has
a sufficient thickness, the following process can further carry
on.
[0021] FIGS. 1E and 1E' illustrate an optional step in accordance
with an embodiment of the present application. The step includes
providing a supporting substrate 160 to join to the supporting
layer 150 of FIGS. 1D and 1D'. The object of the present step is,
such as, to reinforce the supporting layer 150. The material of the
supporting substrate 160 is glass, metal, semiconductor, plastic,
ceramic, or other suitable material.
[0022] FIGS. 2A and 2A'.about.2D and 2D' illustrate processes of
making a light-emitting diode 290 in accordance with an embodiment
of the present invention FIGS. 2A'.about.2D' are top views, and
FIGS. 2A.about.2D are cross-sectional views along I-I' lines in
FIGS. 2A'.about.2D'. Comparing with the above embodiments, the
present embodiment is characterized by the openings of the growth
substrate and the replacement of the supporting layer by the
supporting substrate. The similar part is designated by the same
reference numeral, uses similar material, and has similar thickness
without additional explanation.
[0023] As shown in FIGS. 2A and 2A', a growth substrate 200 is
provided to have one or more substrate openings 201 penetrating the
growth substrate 200. The growth substrate 202 is formed to
continuously surround the substrate openings 201. In other words,
the remaining part of the growth substrate 202, after forming the
substrate openings 201, is an integral structure and does not
include a discrete island. The substrate openings 201 can be formed
by mechanical machining, laser, dry etching, or wet etching.
[0024] As shown in FIGS. 2B and 2B', a sacrificial layer 220 is
formed on the growth substrate 200. The sacrificial layer 220 has
sacrificial layer openings 221 penetrating the sacrificial layer
220 so as to reach the substrate openings 201. The sacrificial
layer region 222 is formed to continuously surround the sacrificial
layer openings 221. The sacrificial layer 220 can be epitaxially
formed.
[0025] Referring to FIGS. 2B and 2B', a supporting substrate 260 is
provided to connect to the epitaxial layer 240 formed in FIGS. 2B
and 2B'. The material of the supporting substrate 260 is such as
glass, metal, semiconductor, plastic, ceramic, or other suitable
material. In the present embodiment, the growth substrate 200 is
replaced by the supporting substrate 260. Also referring to FIGS.
2C and 2C', after connecting the supporting substrate 260 and the
epitaxial layer 240, the sacrificial layer 220 is selectively
etched away so as to separate the growth substrate 200 from the
epitaxial layer 240. In detail, the sacrificial layer 220 can be
selectively etched away using an etchant having a lower etching
rate to the growth substrate 200, the epitaxial layer 240, and the
supporting substrate 260. The etchant can remove the sacrificial
layer 220 via the substrate openings 201 and the sacrificial layer
openings 221 such that the growth substrate 200 is separated from
the epitaxial layer 240. However, the sacrificial layer 220 is not
necessary to be completely removed; the volume or the area
contacting its upper and lower layers can be shrunk such that the
growth substrate 200 can be separated from the epitaxial layer 240.
In the present embodiment, citric acid as the etchant is applied.
However, other suitable wet etching or dry etching method can be
also introduced into the present invention.
[0026] FIGS. 2D and 2D' illustrate the structures after removing
the sacrificial layer 220 and separating the growth substrate 200.
It is noted that only the epitaxial layer 240 and the supporting
substrate 260 are connected with each other. Therefore, as long as
the supporting substrate 260 has a sufficient thickness, the
following process can carry on.
[0027] FIGS. 3A and 3A'.about.3D and 3D' illustrate processes of
making a light-emitting diode 390 in accordance with an embodiment
of the present invention. FIGS. 3A'.about.3F' are top views, and
FIGS. 3A.about.3F are cross-sectional views along I-I' lines in
FIGS. 3A'.about.3F'. Comparing with the description of FIG. 1, the
present embodiment is characterized by providing a patterned
supporting substrate as a mask to form a pattern on the epitaxial
layer such that the sacrificial layer is exposed for further
etching process. The similar part is designated by the same
reference numeral, uses similar material, and has similar thickness
without additional explanation.
[0028] As shown in FIGS. 3A and 3A', a growth substrate 300 is
provided, and a sacrificial layer 320 and an epitaxial layer 340
are sequentially formed on the growth substrate 300. Referring to
FIGS. 3B and 3B', a supporting substrate 350, having an upper
surface 350a and a lower surface 350b, is provided. The supporting
substrate 350 has a sufficient thickness for handling. The material
of the supporting substrate 350 can include at least one of Si,
Al.sub.2O.sub.3, metal, semiconductor, plastic, and ceramic. One or
more recesses are formed on the lower surface 350b by laser, dry
etching, or wt etching, for example. In the present status, the
recess is not formed to penetrate the supporting substrate 350.
[0029] FIGS. 3D and 3D' illustrate structures exposing the recesses
(openings) 351 by removing part of the supporting substrate 350. In
the structures, the supporting substrate region 352 is formed to
continuously surround the recesses 351. The supporting substrate
350 is then used as a mask such that the epitaxial layer 340 is
etched away to form the epitaxial layer openings 341 penetrating
the epitaxial layer 340 and exposing the sacrificial layer 320.
FIGS. 3E and 3E' illustrate the structures after etching the
epitaxial layer 340. The epitaxial layer region 342 is formed to
continuously surround the epitaxial layer openings 341.
[0030] Referring to FIGS. 3E and 3E', the sacrificial layer 320 is
selectively etched away so as to separate the growth substrate 300
from the epitaxial layer 340. In detail, the sacrificial layer 320
can be selectively etched away using an etchant having a lower
etching rate to the growth substrate 300, the epitaxial layer 340,
and the supporting substrate 350. The etchant can remove the
sacrificial layer 320 via the supporting substrate recesses
(openings) 351 and the epitaxial layer openings 341 such that the
growth substrate 300 is separated from the epitaxial layer 340.
However, the sacrificial layer 320 is not necessary to be
completely removed; the volume or the area contacting its upper and
lower layers can be shrunk such that the growth substrate 300 can
be separated from the epitaxial layer 340. In the present
embodiment, citric acid as the etchant is applied. However, other
suitable wet etching or dry etching method can be also introduced
into the present invention.
[0031] FIGS. 3F and 3F' illustrate the structures after removing
the sacrificial layer 320 and separating the growth substrate 300.
It is noted that only the epitaxial layer 340 and the supporting
substrate 350 are connected with each other. No or few discrete
island regions exist in this structure. Therefore, as long as the
supporting substrate 350 has a sufficient thickness, the following
process can carry on
[0032] FIGS. 4A and 4A'.about.4E and 4E' illustrate processes of
making a light-emitting diode 490 in accordance with an embodiment
of the present invention. FIGS. 4A'.about.4E' are top views, and
FIGS. 4A.about.4E are cross-sectional views along I-I' lines in
FIGS. 4A'.about.4E'. Comparing with the description of FIG. 3, the
present embodiment is characterized by patterning a supporting
substrate formed on a temporary substrate; and the patterned
supporting substrate has openings penetrating the supporting
substrate. The similar part is designated by the same reference
numeral, uses similar material, and has similar thickness without
additional explanation.
[0033] As shown in FIGS. 4A and 4A', a growth substrate 400 is
provided, and a sacrificial layer 420 and an epitaxial layer 440
are sequentially formed on the growth substrate 400. Referring to
FIGS. 4B and 4B', a temporary substrate 470 is provided to connect
to a supporting substrate 450. The material of the temporary
substrate 470 can include at least one of glass, metal,
semiconductor, plastic, ceramic, and other suitable material. The
supporting substrate 450 is patterned to form one or more
supporting substrate openings 451 penetrating the supporting
substrate 450. The supporting substrate region 452 is formed to
continuously surround the supporting substrate openings 451. The
supporting substrate 450 can be patterned by laser, dry etching,
wet etching, or cutting. The supporting substrate 450 has an upper
surface 450a connecting to the temporary substrate 470, and a lower
surface 450b opposite to the upper surface 450a.
[0034] As shown in FIGS. 4C and 4C', the supporting substrate 450
is connected to the epitaxial layer 440 by lower surface 450b. The
temporary substrate 470 is then removed to expose the upper surface
450a inside the supporting substrate openings 451. The supporting
substrate 450 is used as a mask such that the epitaxial layer 440
is etched away to form one or more epitaxial layer openings 441
penetrating the epitaxial layer 440 and exposing the sacrificial
layer 420. The etched epitaxial layer 440 has a pattern similar to
or different from the patterned supporting substrate 450. The
epitaxial layer 440 can be also patterned by defining the masked
area. The etched epitaxial layer 440 has a structure as shown in
FIGS. 4D and 4D'.
[0035] Referring to FIGS. 4D and 4D', the sacrificial layer 320 is
selectively etched away so as to separate the growth substrate 400
from the epitaxial layer 440. In detail, the sacrificial layer 420
can be selectively etched away using an etchant having a lower
etching rate to the growth substrate 400, the epitaxial layer 440,
and the supporting substrate 450. The etchant can remove the
sacrificial layer 420 via the supporting substrate openings 451 and
the epitaxial layer openings 441 such that the growth substrate 400
is separated from the epitaxial layer 440. However, the sacrificial
layer 420 is not necessary to be completely removed; the volume or
the area contacting its upper and lower layers can be shrunk such
that the growth substrate 400 can be separated from the epitaxial
layer 440. In the present embodiment, citric acid as the etchant is
applied. However, other suitable wet etching or dry etching method
can be also introduced into the present application.
[0036] FIGS. 4E and 4E' illustrate the structures after removing
the sacrificial layer 420 and separating the growth substrate 400.
It is noted that only the epitaxial layer 440 and the supporting
substrate 450 are connected with each other. No or few discrete
island regions exist in this structure. Therefore, as long as the
supporting substrate 450 has a sufficient thickness, the following
process can carry on.
[0037] FIGS. 5A and 5A'.about.5E and 5E' illustrate processes of
making a light-emitting diode 590 in accordance with an embodiment
of the present invention. FIGS. 5A'.about.5E' are top views, and
FIGS. 5A.about.5E are cross-sectional views along I-I' lines in
FIGS. 5A'.about.5E'. Comparing with above embodiments, the present
embodiment is characterized by not introducing a temporary
substrate. The similar part is designated by the same reference
numeral, uses similar material, and has similar thickness without
additional explanation.
[0038] As shown in FIGS. 5A and 5A', a growth substrate 500 is
provided, and a sacrificial layer 520 and an epitaxial layer 540
are sequentially formed on the growth substrate 500. Referring to
FIGS. 5B and 5B', a supporting substrate 550 is provided. The
supporting substrate 550 needs a sufficient thickness for following
process. The supporting substrate 550 is patterned to form one or
more supporting substrate openings 551 penetrating the supporting
substrate 550. The supporting substrate region 552 is formed to
continuously surround the supporting substrate openings 551. The
supporting substrate 550 can be patterned by laser, dry etching, or
wet etching.
[0039] As shown in FIGS. 5C and 5C', the supporting substrate 550
is connected to the epitaxial layer 540. The supporting substrate
550 is used as a mask such that the epitaxial layer 540 is etched
away to from one or more epitaxial layer openings 541 penetrating
the epitaxial layer 540 and exposing the sacrificial layer 520. The
etched epitaxial layer 540 has a pattern similar to or different
from the patterned supporting substrate 550. The epitaxial layer
540 can be also patterned by defining the masked area. The etched
epitaxial layer 540 has a structure as shown in FIGS. 5D and
5D'.
[0040] Referring to FIGS. 5D and 5D', the sacrificial layer 520 is
selectively etched away so as to separate the growth substrate 500
from the epitaxial layer 540. In detail, the sacrificial layer 520
can be selectively etched away using an etchant having a lower
etching rate to the growth substrate 500, the epitaxial layer 540,
and the supporting substrate 550. The etchant can remove the
sacrificial layer 520 via the supporting substrate openings 551 and
the epitaxial layer openings 541 such that the growth substrate 500
is separated from the epitaxial layer 540. However, the sacrificial
layer 520 is not necessary to be completely removed; the volume or
the area contacting its upper and lower layers can be shrunk such
that the growth substrate 500 can be separated from the epitaxial
layer 540. In the present embodiment, citric acid as the etchant is
applied. However, other suitable wet etching or dry etching method
can be also introduced into the present invention.
[0041] FIGS. 5E and 5E' illustrate the structures after removing
the sacrificial layer 520 and separating the growth substrate 500.
It is noted that only the epitaxial layer 540 and the supporting
substrate 550 are connected with each other. No or few discrete
island regions exist in this structure. Therefore, as long as the
supporting substrate 550 has a sufficient thickness, the following
process can carry on
[0042] Although the invention is explained above, it is not limited
the range, the sequence in practice, the material in practice, or
the method in practice. Any modification or decoration for this
invention is not away from the spirit and the range of this
invention.
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