U.S. patent application number 17/585015 was filed with the patent office on 2022-05-12 for laser element.
The applicant listed for this patent is iReach Corporation. Invention is credited to Shou-Lung CHEN, Hsin-Chan CHUNG.
Application Number | 20220149589 17/585015 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-12 |
United States Patent
Application |
20220149589 |
Kind Code |
A1 |
CHEN; Shou-Lung ; et
al. |
May 12, 2022 |
LASER ELEMENT
Abstract
A laser element comprises a substrate, an adhesive layer, and a
laser unit adhesive to the substrate by the adhesive layer. The
laser unit includes a front conductive structure, a first type
semiconductor stack, an active layer, a second type semiconductor
stack, a patterned insulating layer, a back conductive structure.
The back conductive structure includes a first electrode and a
second electrode, and the first electrode of the back conductive
structure contacts the second type semiconductor stack. A via hole
passing through the patterned insulating layer, the second type
semiconductor stack, the active layer and the first type
semiconductor stack, and a conductive channel located in the via
hole and electrically connected to the second electrode of the back
conductive structure and the front conductive structure. A first
passivation layer formed on a sidewall of the via hole and located
between the conductive channel and the sidewall of the via
hole.
Inventors: |
CHEN; Shou-Lung; (Hsinchu,
TW) ; CHUNG; Hsin-Chan; (Hsinchu, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
iReach Corporation |
Hsinchu |
|
TW |
|
|
Appl. No.: |
17/585015 |
Filed: |
January 26, 2022 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16678805 |
Nov 8, 2019 |
11271365 |
|
|
17585015 |
|
|
|
|
International
Class: |
H01S 5/028 20060101
H01S005/028; H01S 5/02 20060101 H01S005/02; H01S 5/183 20060101
H01S005/183; H01S 5/042 20060101 H01S005/042 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2018 |
TW |
107139739 |
Claims
1. A laser element, comprising: a substrate; an adhesive layer; and
a laser unit adhesive to the substrate by the adhesive layer,
wherein the laser unit comprising: a front conductive structure; a
first type semiconductor stack, and the front conductive structure
located on the first type semiconductor stack; an active layer; a
second type semiconductor stack, and the active layer located
between the first type semiconductor stack and the second type
semiconductor stack; a patterned insulating layer on the second
type semiconductor stack; a back conductive structure on the
patterned insulating layer, and the back conductive structure
includes a first electrode and a second electrode, and wherein the
first electrode of the back conductive structure contacts the
second type semiconductor stack; a first via hole passing through
the patterned insulating layer, the second type semiconductor
stack, the active layer and the first type semiconductor stack; a
first conductive channel located in the first via hole and
electrically connected to the second electrode of the back
conductive structure and the front conductive structure; and a
first passivation layer formed on a sidewall of the first via hole
and located between the first conductive channel and the sidewall
of the first via hole.
2. The laser element according to claim 1, wherein the first
passivation layer contacts the patterned insulating layer on the
second type semiconductor stack.
3. The laser element according to claim 1, wherein the back
conductive structure further comprising a third electrode and a
fourth electrode, and the first electrode, the second electrode,
the third electrode and the fourth electrode are separated from
each other.
4. The laser element according to claim 3, further comprising: a
conductive layer on the substrate; and second conductive channels
on sidewalls of the laser unit and electrically isolated with the
laser unit by a second passivation layer, wherein the conductive
layer, the second conductive channels, the third electrode and the
fourth electrode are electrically connected to each other.
5. The laser element according to claim 4, wherein the conductive
layer is disposed on one side of the substrate opposite to the
adhesive layer, and the second conductive channel extends across
the substrate and is electrically connected to the conductive
layer.
6. The laser element according to claim 4, wherein the conductive
layer is disposed between the substrate and the laser unit, and the
second conductive channel extends across the laser unit and is
electrically connected to the conductive layer.
7. The laser element according to claim 4, wherein the adhesive
layer is disposed between the substrate and the conductive layer,
and the second conductive channel extends across the laser unit and
is electrically connected to the conductive layer.
8. The laser element according to claim 4, wherein the conductive
layer forms a conductive region which is located on a periphery of
the adhesive layer.
9. The laser element according to claim 8, wherein the conductive
region surrounds the laser unit and is electrically separated from
the laser unit.
10. The laser element according to claim 8, wherein the conductive
region directly connected to a periphery of the substrate, and the
adhesive layer is embraced by the substrate and the conductive
region.
11. The laser element according to claim 3, wherein at least two of
the first electrode, the second electrode, the third electrode and
the fourth electrode are coplanar.
12. The laser element according to claim 1, further comprising a
conductive layer on the substrate, and from a top view of the laser
element, the conductive layer surrounds a periphery of the
substrate and has at least one hollow region.
13. The laser element according to claim 1, further comprising a
conductive layer on the substrate, and from a top view of the laser
element, the conductive layer has plural hollow regions arranged as
an array.
14. The laser element according to claim 1, further comprising a
conductive layer on the substrate, from a top view of the laser
element, wherein the conductive layer forms a strip-like structure
or a snakelike geometry structure on the substrate.
15. The laser element according to claim 1, further comprising an
ohmic contact formed between the back conductive structure and the
second type semiconductor stack.
16. The laser element according to claim 4, from a top view of the
laser element, wherein two of the second conductive channels are
respectively disposed on opposite sidewalls of the laser unit.
17. The laser element according to claim 4, from a top view of the
laser element, wherein at least one of the second conductive
channels has an "L" shape.
18. The laser element according to claim 4, wherein the conductive
layer, the third electrode and the fourth electrode are integrated
into the laser element and provided to connected to a control
circuit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
application Ser. No. 16/678,805, which claims the right of priority
of TW Application No. 107139739, filed on Nov. 8, 2018, and the
entire contents of each of which are hereby incorporated by
reference.
TECHNICAL FIELD
[0002] The present application relates to a laser element, and
particularly to a laser element having a flip chip structure.
BACKGROUND
[0003] The statements herein merely provide background information
related to the present application and do not necessarily
constitute the prior art.
[0004] A laser module is an assembly of a laser element, such as
vertical cavity surface emitting lasers (VCSELs), with a
corresponding optical element as a laser source. However, when in
use, if the laser module is subjected to an external force like
collision or falls, the optical element may be ruptured and laser
light emitted by the laser element is leaked from the rupture
without any optical processing, which may be directly irradiated to
human eyes.
SUMMARY
[0005] In view of this, some embodiments of the present application
provide a laser element and a manufacturing method thereof.
[0006] A laser element is provided according to an embodiment. The
laser element comprises a substrate, an adhesive layer, and a laser
unit adhesive to the substrate by the adhesive layer, wherein the
laser unit includes a front conductive structure, a first type
semiconductor stack and the front conductive structure located on
the first type semiconductor stack, an active layer, a second type
semiconductor stack and the active layer located between the first
type semiconductor stack and the second type semiconductor stack, a
patterned insulating layer on the second type semiconductor stack,
a back conductive structure on the patterned insulating layer, and
the back conductive structure includes a first electrode and a
second electrode and wherein the first electrode of the back
conductive structure contacts the second type semiconductor stack,
a first via hole passing through the patterned insulating layer,
the second type semiconductor stack, the active layer and the first
type semiconductor stack, a first conductive channel located in the
first via hole and electrically connected to the second electrode
of the back conductive structure and the front conductive
structure; and a first passivation layer formed on a sidewall of
the first via hole and located between the first conductive channel
and the sidewall of the first via hole.
[0007] According to an embodiment, the first passivation layer
contacts the patterned insulating layer on the second type
semiconductor stack.
[0008] According to an embodiment, the back conductive structure of
the laser unit further comprises a third electrode and a fourth
electrode, and the first electrode, the second electrode, the third
electrode and the fourth electrode are separated from each
other.
[0009] According to an embodiment, the laser element further
comprises a conductive layer on the substrate; and second
conductive channels on sidewalls of the laser unit and electrically
isolated with the laser unit by a second passivation layer, wherein
the conductive layer, the second conductive channels, the third
electrode and the fourth electrode are electrically connected to
each other.
[0010] According to an embodiment, the conductive layer is disposed
on one side of the substrate opposite to the adhesive layer, and
the second conductive channel extends across the substrate and is
electrically connected to the conductive layer.
[0011] According to an embodiment, the conductive layer is disposed
between the substrate and the laser unit, and the second conductive
channel extends across the laser unit and is electrically connected
to the conductive layer.
[0012] According to an embodiment, the adhesive layer is disposed
between the substrate and the conductive layer, and the second
conductive channel extends across the laser unit and is
electrically connected to the conductive layer.
[0013] According to an embodiment, the conductive layer forms a
conductive region which is located on a periphery of the adhesive
layer.
[0014] According to an embodiment, the conductive region surrounds
the laser unit and is electrically separated from the laser
unit.
[0015] According to an embodiment, the conductive region directly
connected to a periphery of the substrate, and the adhesive layer
is embraced by the substrate and the conductive region.
[0016] According to an embodiment, at least two of the first
electrode, the second electrode, the third electrode and the fourth
electrode are coplanar.
[0017] According to an embodiment, the laser element further
comprises a conductive layer on the substrate, and from a top view
of the laser element, the conductive layer surrounds a periphery of
the substrate and has at least one hollow region.
[0018] According to an embodiment, the laser element further
comprises a conductive layer on the substrate, and from a top view
of the laser element, the conductive layer has plural hollow
regions arranged as an array.
[0019] According to an embodiment, the laser element further
comprises a conductive layer on the substrate, from a top view of
the laser element, wherein the conductive layer forms a strip-like
structure or a snakelike geometry structure on the substrate.
[0020] According to an embodiment, the laser element further
comprises an ohmic contact formed between the back conductive
structure and the second type semiconductor stack.
[0021] According to an embodiment, from a top view of the laser
element, two of the second conductive channels are respectively
disposed on opposite sidewalls of the laser unit.
[0022] According to an embodiment, from a top view of the laser
element, at least one of the second conductive channels has an "L"
shape.
[0023] According to an embodiment, the conductive layer, the third
electrode and the fourth electrode are integrated into the laser
element and provided to connected to a control circuit.
[0024] The purposes, technical contents, features, and effects of
the present invention will be more readily understood by the
following specific embodiments in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a schematic view of a laser element according to
an embodiment of the present application;
[0026] FIG. 2 is a schematic top view of the laser element taken
along AA' according to an embodiment of the present
application;
[0027] FIG. 3 is a schematic top view of the laser element taken
along AA' according to an embodiment of the present
application;
[0028] FIG. 4 is a schematic top view of the laser element taken
along AA' according to an embodiment of the present
application;
[0029] FIG. 5A is a schematic top view of the laser element taken
along AA' according to an embodiment of the present
application;
[0030] FIG. 5B is a schematic top view of the laser element taken
along AA' according to an embodiment of the present
application;
[0031] FIG. 6 is a schematic view of the laser element according to
an embodiment of the present application;
[0032] FIG. 7 is a schematic view of the laser element according to
an embodiment of the present application;
[0033] FIG. 8 is a schematic view of the laser element according to
an embodiment of the present application;
[0034] FIG. 9 is a schematic view of the laser element according to
an embodiment of the present application;
[0035] FIG. 10 is a schematic view of the laser element according
to an embodiment of the present application;
[0036] FIG. 11 is a schematic view of the laser element according
to an embodiment of the present application;
[0037] FIG. 12 to FIG. 16 are schematic views showing the steps of
manufacturing a laser element according to an embodiment of the
present application;
[0038] FIG. 17 to FIG. 21 are schematic views showing the steps of
manufacturing a laser element according to an embodiment of the
present application; and
[0039] FIG. 22 to FIG. 24 are schematic views showing the steps of
manufacturing a laser element according to an embodiment of the
present invention.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0040] The various embodiments of the present application will be
described in detail below with reference to the drawings as
examples. In the description of the specification, a number of
specific details are provided for a reader to more completely
understand the present invention. However, the present invention
may be implemented based on the premise of omitting some or all of
the specific details. The same or similar elements in the drawings
will be denoted by the same or similar symbols. It is to be
specially noted that the drawings are for illustrative purposes
only and do not represent the actual dimensions or quantities of
the elements. Some of the details may not be fully drawn in order
to facilitate the simplicity of the drawings.
[0041] Referring to FIG. 1, a laser element according to an
embodiment of the present application includes a transparent
substrate 1, an adhesive layer 2, a laser unit 3, a plurality of
first channels 34, and a conductive layer 10 on the transparent
substrate 1. For example, the transparent substrate 1 includes
sapphire, glass, or silicon carbide (SiC). In some embodiments, the
transparent substrate 1 is an optical element, and may be patterned
to produce a specific optical effect. The conductive layer 10
includes a transparent conductive oxide or a metal. The transparent
conductive oxide may be indium tin oxide (ITO) or indium zinc oxide
(IZO). In the present embodiment, the conductive layer 10 is
disposed between the transparent substrate 1 and the adhesive layer
2.
[0042] One side of the adhesive layer 2 is attached to the
conductive layer 10, and the other side thereof is attached to a
light exiting side 3S of the laser unit 3. For example, the
adhesive layer 2 can be benzocyclobutene (BCB), silicon dioxide or
a transparent conductive oxide.
[0043] The laser unit 3 includes a front conductive structure 30, a
first type semiconductor stack 31, an active layer 33, a second
type semiconductor stack 35, an insulating layer 36, and a back
conductive structure 32. The back conductive structure 32 includes
a first conductive electrode 323 and a second conductive electrode
324 separated from each other. The first type semiconductor and the
second type semiconductor herein respectively refer to
semiconductors with different electrical properties. If a
semiconductor uses holes as a majority carrier, it is a p-type
semiconductor, and if the semiconductor uses electrons as a
majority carrier, it is an n-type semiconductor. For example, the
first type semiconductor stack 31 is an n-type semiconductor stack,
and the second type semiconductor stack 35 is a p-type
semiconductor stack, and vice versa. The active layer 33 is between
the first type semiconductor stack 31 and the second type
semiconductor stack 32, and includes a p-n junction to generate a
depletion region for holes and electrons recombining to emit light.
In some embodiments, the active layer 33 is formed of multiple
quantum wells, which has better luminous efficiency than the p-n
junction. In an embodiment, the materials of the first type
semiconductor stack 31, the second type semiconductor stack 35, and
the active layer 33 include a III-V compound semiconductor, for
example, GaAs, InGaAs, AlGaAs, AlInGaAs, GaP, InGaP, AlInP,
AlGaInP, GaN, InGaN, AlGaN, AlInGaN, AlAsSb, InGaAsP, InGaAsN,
AlGaAsP, and the like. In the embodiments of the present
disclosure, unless otherwise specified, the above chemical
expressions include "stoichiometric compounds" and
"non-stoichiometric compounds". The "stoichiometric compound" has a
total element measurement of the group III element the same as a
total element measurement of the group V element, whereas the
"non-stoichiometric compounds" has a total element measurement of
the group III element different from as a total element measurement
of the group V element. For example, the chemical expression AlGaAs
means that it includes the group III element aluminum (Al) and/or
gallium (Ga) and includes the group V element arsenic (As). The
total element measurement of the group III element (aluminum and/or
gallium) may be the same as or different from the total element
measurement of the group V element (arsenic). In addition, if the
above compounds represented by the chemical expressions are
stoichiometric compounds, AlGaAs series represents
Al.sub.x1Ga.sub.(1-x1)As, where 0.ltoreq.x1.ltoreq.1; AlInP
represents Al.sub.x2In.sub.(1-x2)P, where, 0.ltoreq.x2.ltoreq.1;
AlGaInP represents (Al.sub.y1Ga.sub.(1-y1)).sub.1-x3In.sub.x3P,
where 0.ltoreq.x3.ltoreq.1, and 0.ltoreq.y1.ltoreq.1; AlGaN series
represents Al.sub.x4Ga.sub.(1-x4)N, where 0.ltoreq.x4.ltoreq.1;
AlAsSb series represents AlAs.sub.x5Sb.sub.(1-x5), where
0.ltoreq.x5.ltoreq.1; InGaP series represents
In.sub.x6Ga.sub.1-x6P, where 0.ltoreq.x6.ltoreq.1; InGaAsP series
represents In.sub.xGa.sub.1-x6As.sub.1-y2P.sub.y2, where
0.ltoreq.x6.ltoreq.1, and 0.ltoreq.y2.ltoreq.1; InGaAsN series
represents In.sub.xGa.sub.1-x8As.sub.1-y3N.sub.y3, where
0.ltoreq.x8.ltoreq.1, and 0.ltoreq.y3.ltoreq.1; AlGaAsP series
represents Al.sub.x9Ga.sub.1-x9As.sub.1-y4P.sub.y4, where
0.ltoreq.x9.ltoreq.1, and 023 y4.ltoreq.1; and InGaAs series
represents In.sub.x10Ga.sub.1-x10As, where 0.ltoreq.x10.ltoreq.1.
According to the material of the active layer 33, when the material
of the semiconductor stacks 31, 35 is AlGaAs series, the active
layer 33 may emit infrared light having a peak wavelength between
700 nm and 1700 nm. When the material of the semiconductor stacks
31, 35 is AlGaInP series, the active layer 33 may emit infrared red
light having a peak wavelength between 610 nm and 700 nm, or yellow
light having a peak wavelength between 530 nm and 570 nm. When the
material of the semiconductor stacks 31, 35 is InGaN series, the
active layer 33 may emit blue light or deep blue light having a
peak wavelength between 400 nm and 490 nm, or green light having a
peak wavelength between 490 nm and 550 nm. When the material of the
semiconductor stacks 31, 35 is AlGaN series, the active layer 33
may emit ultraviolet light having a peak wavelength between 250 nm
and 400 nm.
[0044] In the present embodiment, the first type semiconductor
stack 31 and the second type semiconductor stack 35 include a
plurality of overlapping layer structures to form a distributed
Bragg reflector (DBR), so that a light emitted from the active
layer 33 can be reflected between two distributed Bragg reflectors
to form coherent light, and then the coherent light is emitted from
the first type semiconductor stack 31 to form a laser light L.
[0045] In an embodiment, the insulating layer 36 is disposed
between the back conductive structure 32 and the second type
semiconductor stack 35. In an embodiment, the material of the
insulating layer 36 includes silicon dioxide.
[0046] In an embodiment, a contact resistance between the back
conductive structure 32 and the second type semiconductor stack 35
is lower than 10.sup.-4 .OMEGA.cm.sup.2 and an ohmic contact is
formed between the back conductive structure 32 and the second type
semiconductor stack 35. A formation mechanism of the ohmic contact
is that a metal work function must be less than a semiconductor
work function, so that electrons from the semiconductor to the
metal and from the metal to the semiconductor can easily leap over
this energy level, and current can be turned on in two directions.
For example, the metal component of the second conductive electrode
324 of the back conductive structure 32 is mainly titanium aluminum
alloy because titanium can form titanium nitride with the III-V
compound (for example, aluminum gallium nitride) of the second type
semiconductor stack 35, such that nitrogen atoms become an n-type
doped surface on the surface and form a good ohmic contact after
high temperature annealing.
[0047] In an embodiment, the first type semiconductor stack 31 is
connected to the front conductive structure 30, the front
conductive structure 30 is connected to the first conductive
electrode 323 through a second channel 320, the second conductive
electrode 324 and the first conductive electrode 323 are separated
from each other to avoid a short circuit, and the second type
semiconductor stack 35 is connected to the second conductive
electrode 324. With the above conductive structure, the laser unit
3 receives an external driving voltage/current, and generate the
laser light L. The front conductive structure 30 is disposed on the
light exiting side 3S of the laser unit 3 and attached to the
adhesive layer 2. Therefore, the laser light L from the laser unit
3 emits to outside through the adhesive layer 2 and the transparent
substrate 1.
[0048] Since the coherent light emitted by the laser element has a
high energy, a corresponding optical element, such as the
transparent substrate 1, is required for processing the coherent
light to output the laser light L with appropriate intensity. In
order to effectively monitor whether the laser element is damaged
and prevent the laser light L that has not been optically processed
through the transparent substrate 1 from being leaked and directly
irradiated to human eyes, the laser element of the present
embodiment has an eye safety monitoring circuit which can monitor
abnormal damage of the light exiting side 3S of the laser unit 3 in
real time. The following examples illustrate the working principle
of the laser element structure of some embodiments.
[0049] In the present embodiment, in addition to the above
semiconductor structure required for emitting the laser light, the
laser unit 3 further includes a back conductive structure 32. The
back conductive structure 32 includes a plurality of detecting
electrodes 321, 322, and the back conductive structure 32 and the
front conductive structure 30 are oppositely disposed on two sides
of the laser unit 3. The plurality of first channels 34 extend from
the back conductive structure 32 and penetrates through the front
conductive structure 30 and the adhesive layer 2, and is connected
to the conductive layer 10. Namely, two ends of one of the first
channels 34 are connected to one of the detecting electrodes 321,
322 and the conductive layer 10 respectively. In some embodiments,
the back conductive structure 32 includes a plurality of detecting
electrodes 321, 322 and a plurality of first and second conductive
electrodes 323, 324 which are separated from each other and
coplanar with each other, as shown in FIG. 1. Thus, the laser
element is adapted to flip chip packaging with no need for a wire
bonding process, thereby saving the package volume. In another
embodiment, the back conductive structure 32 includes a plurality
of detecting electrodes 321, 322 extending from the back conductive
structure and penetrating through the front conductive structure
and the adhesive layer, and connected to the conductive layer
10.
[0050] Referring to FIG. 1 and FIG. 2 together, FIG. 2 is a
schematic top view of FIG. 1 taken along AA' as viewed from the
top. The plurality of detecting electrodes 321, 322 separated from
each other are electrically connected to the two ends of the
conductive layer 10 through the first channels 34. Therefore, the
plurality of detecting electrodes 321, 322 is externally connected
to a control circuit, so that the change in a resistance value of
the conductive layer 10 can be monitored in real time. When the
laser element is damaged by an external impact, especially when the
transparent substrate 1 is damaged at the light exiting side 3S,
the conductive layer 10 is also damaged, so the resistance value
becomes large, even causing an open circuit. Thus, the control
circuit determines whether to cut off power supply to the laser
unit 3 according to the change in the resistance value of the
conductive layer 10 through the monitoring circuit, so as to
prevent the laser light L emitted by the laser unit 3 from being
leaked via a rupture of the transparent substrate 1 and being
directly irradiated to the human eyes, thereby achieving the effect
of monitoring abnormal conditions in real time.
[0051] In another embodiment, in order to prevent a conductive
medium (that is the first channels 34) from contacting the front
conductive structure 30, the first type semiconductor stack 31 or
the second type semiconductor stack 35 of the laser unit 3 to form
a short circuit, the laser unit 3 further includes a passivation
layer 340 disposed on an inner wall of the first channels 34 to
prevent the measured resistance value of the first channels 34 from
electrical interference of the laser unit 3 and to reduce the noise
during measurement.
[0052] It can be seen from the above description that the laser
element according to some embodiments of the present application
includes the monitoring circuit composed of the conductive layer,
the first channels, and the detecting electrodes , and the laser
element with the built-in monitoring circuit is produced through
wafer-level semiconductor manufacturing process, thereby saving the
package volume at module stage, simplifying a modularization
process, and reducing the production cost.
[0053] FIG. 3 shows the top view of the conductive layer 10 taken
along line AA' shown in the cross-sectional schematic view of FIG.
1 in another embodiment. In the embodiment, in order to expand the
monitoring range, the conductive layer 10 has a larger area that
covers most of the transparent substrate 1. FIG. 4 shows the top
view of the conductive layer 10 taken along line AA' in the
cross-sectional schematic view of FIG. 1 in another embodiment. In
the embodiment, the conductive layer 10 surrounds a periphery of
the transparent substrate 1 and has a hollow region corresponding
to a light exiting hole (not shown) on the lower side of the laser
unit 3 to prevent the laser light L emitted by the laser unit 3
from being shielded by the conductive layer 10, and thus, the
material of the conductive layer 10 may be an opaque material, such
as a metal oxide. In some embodiments, the conductive layer 10 made
of metal may have better conductivity to enhance the monitoring
sensitivity without shielding the light emitted by the laser unit
3. FIG. 5A shows the top view of the conductive layer 10 taken
along line AA' in the cross-sectional schematic view of FIG. 1 in
another embodiment. In the embodiment, the plurality of light
exiting holes of the laser unit 3 is arranged as an array, so that
the conductive layer 10 form a strip-like structure for avoiding
covering the plurality of light exiting holes. FIG. 5B shows the
top view of the conductive layer 10 taken along line AA' in the
cross-sectional schematic view of FIG. 1 in another embodiment. In
the embodiment, the plurality of light exiting holes of the laser
unit 3 are staggered, so that the conductive layer 10 form a
snakelike geometry structure for avoiding covering the plurality of
light exiting holes. Some of the above embodiments are merely
illustrative of the design of a conductive layer and may also be
applied to the laser element structure of other embodiments herein,
but the present application is not limited thereto.
[0054] Referring to FIG. 6, in an embodiment, the laser element is
structurally different from the abovementioned embodiments in that
the conductive layer 10 is disposed on one side of the transparent
substrate 1 opposite to the adhesive layer 2. Therefore, one side
of the adhesive layer 2 is attached to the transparent substrate 1,
and the other side thereof is attached to the front conductive
structure 30 of the laser unit 3. In order to effectively monitor
the change of the resistance value of the conductive layer 10, the
first channels 34 further penetrates through the adhesive layer 2
and the transparent substrate 1. Thus, the plurality of detecting
electrodes 321, 322 is separated from each other are electrically
connected to the two ends of the conductive layer 10 through the
first channels 34 for facilitating monitoring the change of the
resistance value of the conductive layer 10. The structural
features and connection relationships of other components have been
described as above and will not be repeated herein.
[0055] Referring to FIG. 7, in an embodiment, the laser element is
structurally different from the abovementioned embodiments in that
the plurality of conductive layers 10 is simultaneously disposed on
two opposite sides of the transparent substrate 1, and the first
channels 34 penetrate through the adhesive layer 2, the transparent
substrate 1 and at least one conductive layer 10, or simultaneously
penetrates through the conductive layers 10 on two sides of the
transparent substrate 1. Therefore, when the conductive layer 10 on
one or two sides is damaged, resistance values measured by the
plurality of detecting electrodes 321, 322 are changed for ensuring
that the two sides of the transparent substrate 1 (i.e., the
optical element) are not damaged, and preventing the laser light
not processed by the transparent substrate 1 from being leaked. The
structural features and connection relationships of other
components have been described as above.
[0056] Referring to FIG. 8, in an embodiment, the laser element
further includes an optical structure 12 disposed on one side of
the transparent substrate 1 opposite to the adhesive layer 2, that
is. For example, the optical structure 12 is a diffractive optical
element and is able to match with the laser unit 3 to generate tens
of thousands of laser spots which are suitable for
three-dimensional sensing or face recognition.
[0057] Referring to FIG. 9, the laser element according to another
embodiment of the present application includes a transparent
substrate 1, an adhesive layer 2, a conductive region 10', a laser
unit 3, and a plurality of first channels 34. The conductive region
10' includes a transparent conductive oxide, a metal, or silicon
monoxide. The transparent conductive oxide may be indium tin oxide
(ITO) or indium zinc oxide (IZO). The laser unit 3 includes a front
conductive structure 30, a first type semiconductor stack 31, an
active layer 33, a second type semiconductor stack 35, an
insulating layer 36, and a back conductive structure 32. The
component features, connection relationships and advantages of the
transparent substrate 1, the front conductive structure 30, the
first type semiconductor stack 31, the active layer 33, the first
channels 34, the passivation layer 340, the second type
semiconductor stack 35, the insulating layer 36 and the back
conductive structure 32 of the laser element, and the related
embodiments thereof have been described as above. The present
embodiment is different from the abovementioned embodiments in that
an annular conductive region 10' is used for replacing the entire
conductive layer to simplify the semiconductor manufacturing
process and increase the production yield, and namely, the
conductive region 10' is disposed on the periphery of the adhesive
layer 2. The conductive region 10' surrounds the laser unit 3 and
is electrically separated therefrom to prevent the conductive
region 10' from contacting the laser unit 3 to form a short circuit
or interfere with the monitoring circuit. In the present
embodiment, since the first channels 34 do not penetrate through
the adhesive layer 2 and the transparent substrate 1, it is easier
to control the etching process for forming the first channels 34.
Further, the conductive region 10' is formed after the etching
process for forming the first channels 34, thereby preventing the
conductive material for forming the conductive region 10' from
being affected in the etching process.
[0058] Referring to FIG. 10, in an embodiment, the laser element is
structurally different from the embodiment shown in FIG. 9 in that
the conductive region 10' penetrate through the adhesive layer 2,
and two sides of the conductive region 10' are respectively
connected to the transparent substrate 1 and the first channels 34.
The rest of the component features can be referred to the above
description for detailed descriptions. In the present embodiment,
since the conductive region 10' is directly connected to the
transparent substrate 1, abnormal conditions of the transparent
substrate 1 can be acutely monitored. Further, the conductive
region 10' is formed after the etching process for forming the
first channels 34, thereby preventing the conductive material for
forming the conductive region 10' from being affected in the
etching process.
[0059] Referring to FIG. 11, in an embodiment, the laser element
includes an optical structure 12 disposed on one side of the
transparent substrate 1 opposite to the adhesive layer 2. For
example, the optical structure 12 is an optical element such as a
diffractive optical element, a microlens or the like, and is able
to match with the laser unit 3 to generate tens of thousands of
laser spots. The related advantages have been described as
above.
[0060] Referring to FIG. 12 to FIG. 16, a manufacturing method of a
laser element according to still another embodiment of the present
application is described below. Firstly, a conductive layer 10 is
formed on a transparent substrate 1. As shown in FIG. 12, the
transparent substrate 1 includes a first surface 1a and a second
surface 1b opposite to each other, the conductive layer 10 is
disposed on the first surface 1a, and the transparent substrate 1
faces a laser unit 3 with the first surface 1a. The material
composition, structural features, the connection relationship
between the components of the conductive layer 10 and the
transparent substrate 1, and the related embodiments thereof have
been described as above.
[0061] The transparent substrate 1 and a laser unit 3 are bonded by
an adhesive layer 2, as shown in FIG. 13. In an embodiment, the
laser unit 3 includes a front conductive structure 30, a first type
semiconductor stack 31, an active layer 33, and a second type
semiconductor stack 35 sequentially stacked on a substrate 38. In
another embodiment, the substrate 38 is a wafer substrate to grow
the plurality of laser units 3. Therefore, in the present
embodiment, the following monitoring circuit growth steps and
subsequent miniaturized packaging application may be performed on a
wafer level.
[0062] The substrate 38 of the laser unit 3 is removed, as shown in
FIG. 14, to expose the second type semiconductor stack 35, which
can facilitate the subsequent step of forming a back conductive
structure. As shown in FIG. 15, through an etching process, a
plurality of first via holes 34' penetrating through the laser unit
3 and the adhesive layer 2 is formed to expose a portion of the
conductive layer 10 and a plurality of second via holes 320' is
formed to expose a portion of the front conductive structure 30.
Then, a patterned insulating layer 36 is formed on the second type
semiconductor stack 35.
[0063] Next, referring to FIG. 16, a passivation layer 340 is
formed on an inner wall of each of the first via holes 34' and the
second via holes 320'. The functions and effects of the passivation
layer 340 have been described as above. Through an evaporation
process, the plurality of the first via holes 34' is filled with a
conductive material and connected to the conductive layer 10 to
form the plurality of first channels 34. Then, a back conductive
structure 32 is formed on the surface of the insulating layer 36 of
the laser unit 3. The back conductive structure 32 includes a
plurality of detecting electrodes 321, 322 separated from each
other, and the plurality of detecting electrodes 321, 322 is
respectively connected to the first channel 34.
[0064] In an embodiment, the laser unit 3 is a flip chip structure.
Therefore, in the step of forming the back conductive structure 32,
a plurality of first and second conductive electrodes 323, 324,
which is separated from and coplanar with the plurality of
detecting electrodes 321, 322, are formed at the same time.
Further, as shown in FIG. 15, in the etching process, a plurality
of second via holes 320' and the plurality of first via holes 34'
are formed at the same time, and then, the plurality of second via
holes 320' is filled with the passivation layer 340 and the
conductive material during the evaporation process to form the
plurality of second channels 320, so that two ends of each of the
second channels 320 are respectively connected to the front
conductive structure 30 and the first conductive electrode 323 of
the back conductive structure 32. The structural features,
connection relationships and advantages of the components, and the
related embodiments thereof have been described as above. Finally,
a cutting process is performed along the dot-line BB' to separate
the laser unit 3 and the transparent substrate 1 to form multiple
laser elements, wherein the structure of each of the multiple laser
elements is shown in FIG. 1.
[0065] In an embodiment, the manufacturing method of the laser
device further includes forming an optical structure on one side of
the transparent substrate opposite to the adhesive layer. For
example, the optical structure may be formed by a lithography
process or a bonding process. The component features of the optical
structure and the related embodiments thereof have been described
as above.
[0066] Referring to FIG. 12, the conductive layer 10 is formed on
the first surface 1a of the transparent substrate 1, and in other
embodiment, as shown in FIG. 6, the second surface 1b of the
transparent substrate 1 can be bonded to the laser unit 3 with the
adhesive layer 2, that is, the conductive layer 10 and the adhesive
layer 2 are respectively disposed on two opposite sides of the
transparent substrate 1. In the present embodiment, through the
etching process, the first via holes 34' channel 34 further
penetrates through the transparent substrate 1, and then is filled
with the passivation layer 340 and the conductive medium which is
used as the first channels 34 during the evaporation process, so
that the two ends of each of the first channels 34 are respectively
connected to the front conductive structure 30 and the plurality of
detecting electrodes 321, 322 of the back conductive structure 32,
as shown in FIG. 6.
[0067] Referring to FIG. 17 to FIG. 21, a manufacturing method of a
laser element according to another embodiment of the present
invention is described below. Firstly, a transparent substrate 1
and a laser unit 3 are bonded through an adhesive layer 2, as shown
in FIG. 17. In an embodiment, the laser unit 3 includes a front
conductive structure 30, a first type semiconductor stack 31, an
active layer 33, and a second type semiconductor stack 35
sequentially stacked on a substrate 38. The structural features,
material composition and advantages of the components, and the
related embodiments thereof have been described as above.
[0068] As shown in FIG. 18, the substrate 38 of the laser unit 3 is
removed to expose the second type semiconductor stack 35, which can
facilitate the subsequent step of forming a back conductive
structure. As shown in FIG. 19, through an etching process, a
plurality of first via holes 34' penetrating through the laser unit
3 is formed to expose a portion of the adhesive layer 2 and a
plurality of second via holes 320' is formed to expose a portion of
the front conductive structure 30. Then, a patterned insulating
layer 36 is formed on the second type semiconductor stack 35.
[0069] Next, referring to FIG. 20, a passivation layer 340 is
formed on an inner wall of each of the plurality of first via holes
34' and the second via holes 320'. The functions and effects of the
passivation layer 340 have been described as above. Then, a
conductive region 10' is formed in the plurality of first via holes
34' and on the passivation layer 340. The conductive region 10'
surrounds the periphery of the laser unit 3 and connects the
adhesive layer 2. The conductive region 10' is electrically
separated from the laser unit 3 by the passivation layer 340 to
prevent the conductive region 10' from being electrically
interfered by the laser unit 3 or from forming short circuit
therewith. As shown in FIG. 21, through an evaporation process, the
plurality of first via holes 34' is filled with a conductive medium
which is used as the first channels 34 and is connected to the
conductive region 10'. Then, a back conductive structure 32 is
formed on the surface of the insulating layer 36 of the laser unit
3. The back conductive structure 32 includes a plurality of
detecting electrodes 321, 322 separated from each other, and the
detecting electrodes 321, 322 are respectively connected to the
plurality of first channels 34.
[0070] In an embodiment, the laser unit 3 is a flip chip structure.
Therefore, in the step of forming the back conductive structure 32,
a plurality of conductive electrodes 323, 324, which is separated
from and coplanar with the plurality of detecting electrodes 321,
322, is formed at the same time. Further, as shown in FIG. 19, in
the etching process, a plurality of second via holes 320' and the
plurality of first via holes 34' are formed at the same time. And,
as shown in 21, a passivation layer 340 is formed on an inner wall
of each of the plurality of second via holes 320', and then, the
plurality of second via holes 320' is filled with the conductive
material to form a plurality of second channels 320 through the
evaporation process, so that the two ends of each of the second
channels 320 are respectively connected to the front conductive
structure 30 and the first conductive electrode 323 of the back
conductive structure 32. The structural features, connection
relationships and advantages of the components, and the related
embodiments thereof have been described as above. Finally, a
cutting process is performed along the dot-line BB' to separate the
laser unit 3 and the transparent substrate 1 to form multiple laser
elements, wherein the structure of each of the multiple laser
elements is shown in FIG. 11.
[0071] Referring to FIG. 21, in an embodiment, the manufacturing
method of the laser device further includes forming an optical
structure (not shown) on one side of the transparent substrate 1
opposite to the adhesive layer 2. For example, the optical
structure may be formed by a lithography process or a bonding
process. The component features of the optical structure and the
related embodiments thereof have been described as above.
[0072] Referring to FIG. 22 and FIG. 24, in some embodiments,
through the etching process, the plurality of first via holes 34'
penetrating through the laser unit 3 and the adhesive layer 2 is
formed to expose a portion of the transparent substrate 1, and a
plurality of second via holes 320' is formed to expose a portion of
the front conductive structure 30, as shown in FIG. 22.
[0073] Referring to FIG. 23, a passivation layer 340 is formed on
an inner wall of each of the first via holes 34' and the second via
holes 320'. The functions and effects of the passivation layer 340
have been described as above. Then, a conductive region 10' is
formed in each of the first via holes 34' and on the passivation
layer 340. The conductive region 10' surrounds the periphery of the
laser unit 3 and is directly disposed on the transparent substrate
1, thereby monitoring abnormal conditions such as damage of the
transparent substrate 1 more acutely. The conductive region 10' is
electrically separated from the laser unit 3 by the passivation
layer 340 to prevent the conductive region 10' from being
electrically interfered by the laser unit 3 or from forming a short
circuit therewith. As shown in FIG. 24, through an evaporation
process, the plurality of via holes 34' is filled with a conductive
medium which is used as the first channels 34 and is connected to
the conductive region 10'. Finally, a back conductive structure 32
is formed on the surface of the insulating layer 36 of the laser
unit 3. The back conductive structure 32 includes a plurality of
detecting electrodes 321, 322 separated from each other, and the
detecting electrodes 321, 322 are respectively connected to the
first channels 34.
[0074] In an embodiment, the laser unit 3 is a flip chip structure.
Therefore, in the step of forming the back conductive structure 32,
a plurality of conductive electrodes 323, 324, which are separated
from and coplanar with the plurality of detecting electrodes 321,
322, is formed at the same time. Further, in the etching process, a
plurality of second via holes 320' and the plurality of first via
holes 34' are formed at the same time, and the plurality of second
via holes 320' is filled with the passivation layer 340 and the
conductive material to form a plurality of second channels 320
through the evaporation process, so that the two ends of each of
the second channels 320 are respectively connected to the front
conductive structure 30 and the first conductive electrode 323 of
the back conductive structure 32. The structural features,
connection relationships and advantages of the components, and the
related embodiments thereof have been described as above. Finally,
a cutting process is performed along the dot-line BB' to separate
the laser unit 3 and the transparent substrate 1 to form multiple
laser elements, wherein the structure of each of the multiple laser
elements is as shown in FIG. 10.
[0075] In an embodiment, the manufacturing method of the laser
device further includes forming an optical structure (not shown) on
one side of the transparent substrate 1 opposite to the adhesive
layer 2. For example, the optical structure may be formed by a
lithography process or a bonding process. The component features of
the optical structure and the related embodiments thereof have been
described as above.
[0076] Based on the above, some embodiments of the present
application provide a laser element and a manufacturing method
thereof. The laser element includes the monitoring circuit composed
of the conductive layer/conductive region, the first channels and
the detecting electrodes, the external control circuit is connected
with the monitoring circuit in the laser element, and whether to
cut off the power supply to the laser unit is determined according
to the change of the resistance value of the conductive
layer/conductive region, so as to prevent the laser light emitted
by the laser unit from being leaked via the damaged region(s) of
the transparent substrate and being directly irradiated to the
human eyes, thereby achieving the effect of eye safety monitoring
and protection. At the same time, the manufacturing process of
forming an integrally formed element can reduce the package size of
the module, simplify the module packaging process and reduce the
production cost. For example, through a wafer level semiconductor
process, the laser element with the built-in monitoring circuit can
be produced in flip chip package without a wire bonding for saving
the package volume and facilitating subsequent miniaturized
applications.
[0077] The embodiments described above are only for explaining the
technical idea and characteristics of the present invention with
the purpose of enabling those skilled in the art to understand the
contents of the present application and implement them accordingly,
and are not intended to limit the patent scope of the present
application. That is, any equivalent change or modification made by
the spirit of the present invention shall fall within the patent
scope of the present application.
* * * * *