US20220149589A1 - Laser element - Google Patents
Laser element Download PDFInfo
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- US20220149589A1 US20220149589A1 US17/585,015 US202217585015A US2022149589A1 US 20220149589 A1 US20220149589 A1 US 20220149589A1 US 202217585015 A US202217585015 A US 202217585015A US 2022149589 A1 US2022149589 A1 US 2022149589A1
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- 239000010410 layer Substances 0.000 claims abstract description 140
- 239000000758 substrate Substances 0.000 claims abstract description 84
- 239000004065 semiconductor Substances 0.000 claims abstract description 79
- 239000012790 adhesive layer Substances 0.000 claims abstract description 43
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- 229910052751 metal Inorganic materials 0.000 description 6
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 4
- 230000001427 coherent effect Effects 0.000 description 4
- 229910021478 group 5 element Inorganic materials 0.000 description 4
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- -1 AlInGaAs Inorganic materials 0.000 description 2
- 229910002601 GaN Inorganic materials 0.000 description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 2
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 2
- UMIVXZPTRXBADB-UHFFFAOYSA-N benzocyclobutene Chemical compound C1=CC=C2CCC2=C1 UMIVXZPTRXBADB-UHFFFAOYSA-N 0.000 description 2
- 229910052733 gallium Inorganic materials 0.000 description 2
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
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- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 2
- YVTHLONGBIQYBO-UHFFFAOYSA-N zinc indium(3+) oxygen(2-) Chemical compound [O--].[Zn++].[In+3] YVTHLONGBIQYBO-UHFFFAOYSA-N 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- UQZIWOQVLUASCR-UHFFFAOYSA-N alumane;titanium Chemical compound [AlH3].[Ti] UQZIWOQVLUASCR-UHFFFAOYSA-N 0.000 description 1
- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical compound [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 description 1
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- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
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- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
- H01S5/0425—Electrodes, e.g. characterised by the structure
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
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- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
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- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
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- H01S5/04256—Electrodes, e.g. characterised by the structure characterised by the configuration
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- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
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- H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
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- H01S2301/00—Functional characteristics
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/0233—Mounting configuration of laser chips
- H01S5/0234—Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings
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- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
- H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
- H01S5/18386—Details of the emission surface for influencing the near- or far-field, e.g. a grating on the surface
- H01S5/18391—Aperiodic structuring to influence the near- or far-field distribution
Definitions
- the present application relates to a laser element, and particularly to a laser element having a flip chip structure.
- 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.
- VCSELs vertical cavity surface emitting lasers
- 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.
- a 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
- 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.
- 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.
- 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.
- 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.
- 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.
- the conductive layer forms a conductive region which is located on a periphery of the adhesive layer.
- the conductive region surrounds the laser unit and is electrically separated from the laser unit.
- the conductive region directly connected to a periphery of the substrate, and the adhesive layer is embraced by the substrate and the conductive region.
- At least two of the first electrode, the second electrode, the third electrode and the fourth electrode are coplanar.
- 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.
- 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.
- 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.
- the laser element further comprises an ohmic contact formed between the back conductive structure and the second type semiconductor stack.
- two of the second conductive channels are respectively disposed on opposite sidewalls of the laser unit.
- At least one of the second conductive channels has an “L” shape.
- the conductive layer, the third electrode and the fourth electrode are integrated into the laser element and provided to connected to a control circuit.
- FIG. 1 is a schematic view of a laser element according to an embodiment of the present application
- FIG. 2 is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application
- FIG. 3 is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application
- FIG. 4 is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application.
- FIG. 5A is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application.
- FIG. 5B is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application.
- FIG. 6 is a schematic view of the laser element according to an embodiment of the present application.
- FIG. 7 is a schematic view of the laser element according to an embodiment of the present application.
- FIG. 8 is a schematic view of the laser element according to an embodiment of the present application.
- FIG. 9 is a schematic view of the laser element according to an embodiment of the present application.
- FIG. 10 is a schematic view of the laser element according to an embodiment of the present application.
- FIG. 11 is a schematic view of the laser element according to an embodiment of the present application.
- FIG. 12 to FIG. 16 are schematic views showing the steps of manufacturing a laser element according to an embodiment of the present application.
- FIG. 17 to FIG. 21 are schematic views showing the steps of manufacturing a laser element according to an embodiment of the present application.
- FIG. 22 to FIG. 24 are schematic views showing the steps of manufacturing a laser element according to an embodiment of the present invention.
- a laser element 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 .
- the transparent substrate 1 includes sapphire, glass, or silicon carbide (SiC).
- 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).
- the conductive layer 10 is disposed between the transparent substrate 1 and the adhesive layer 2 .
- the adhesive layer 2 is attached to the conductive layer 10 , and the other side thereof is attached to a light exiting side 3 S of the laser unit 3 .
- the adhesive layer 2 can be benzocyclobutene (BCB), silicon dioxide or a transparent conductive oxide.
- 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.
- the first type semiconductor stack 31 is an n-type semiconductor stack
- 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.
- the active layer 33 is formed of multiple quantum wells, which has better luminous efficiency than the p-n junction.
- 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.
- 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.
- 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).
- AlGaAs series represents Al x1 Ga (1-x1) As, where 0 ⁇ x1 ⁇ 1; AlInP represents Al x2 In (1-x2) P, where, 0 ⁇ x2 ⁇ 1; AlGaInP represents (Al y1 Ga (1-y1) ) 1-x3 In x3 P, where 0 ⁇ x3 ⁇ 1, and 0 ⁇ y1 ⁇ 1; AlGaN series represents Al x4 Ga (1-x4) N, where 0 ⁇ x4 ⁇ 1; AlAsSb series represents AlAs x5 Sb (1-x5) , where 0 ⁇ x5 ⁇ 1; InGaP series represents In x6 Ga 1-x6 P, where 0 ⁇ x6 ⁇ 1; InGaAsP series represents In x Ga 1-x6 As 1-y2 P y2 , where 0 ⁇ x6 ⁇ 1, and 0 ⁇ y2 ⁇ 1; InGaAsN series represents In x
- the active layer 33 may emit infrared light having a peak wavelength between 700 nm and 1700 nm.
- 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.
- 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.
- the active layer 33 may emit ultraviolet light having a peak wavelength between 250 nm and 400 nm.
- 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.
- DBR distributed Bragg reflector
- the insulating layer 36 is disposed between the back conductive structure 32 and the second type semiconductor stack 35 .
- the material of the insulating layer 36 includes silicon dioxide.
- a contact resistance between the back conductive structure 32 and the second type semiconductor stack 35 is lower than 10 ⁇ 4 ⁇ cm 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.
- 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.
- the III-V compound for example, aluminum gallium nitride
- 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
- the second type semiconductor stack 35 is connected to the second conductive electrode 324 .
- 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 3 S 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 .
- the laser element of the present embodiment has an eye safety monitoring circuit which can monitor abnormal damage of the light exiting side 3 S of the laser unit 3 in real time.
- 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.
- 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 .
- the laser element is adapted to flip chip packaging with no need for a wire bonding process, thereby saving the package volume.
- 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 .
- 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.
- the laser element is damaged by an external impact, especially when the transparent substrate 1 is damaged at the light exiting side 3 S, the conductive layer 10 is also damaged, so the resistance value becomes large, even causing an open circuit.
- 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.
- the laser unit 3 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.
- 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.
- the laser element 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.
- 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.
- the conductive layer 10 in order to expand the monitoring range, 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.
- 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.
- 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.
- 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.
- 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 .
- the first channels 34 further penetrates through the adhesive layer 2 and the transparent substrate 1 .
- 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.
- 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.
- 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.
- 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.
- the laser element 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.
- 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 .
- 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.
- 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.
- the conductive region 10 ′ is directly connected to the transparent substrate 1 , abnormal conditions of the transparent substrate 1 can be acutely monitored.
- 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.
- the laser element includes an optical structure 12 disposed on one side of the transparent substrate 1 opposite to the adhesive layer 2 .
- 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.
- a manufacturing method of a laser element is described below.
- a conductive layer 10 is formed on a transparent substrate 1 .
- the transparent substrate 1 includes a first surface 1 a and a second surface 1 b opposite to each other, the conductive layer 10 is disposed on the first surface 1 a , and the transparent substrate 1 faces a laser unit 3 with the first surface 1 a .
- 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.
- the transparent substrate 1 and a laser unit 3 are bonded by an adhesive layer 2 , as shown in FIG. 13 .
- 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 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.
- 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.
- 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 .
- a patterned insulating layer 36 is formed on the second type semiconductor stack 35 .
- 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.
- 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 .
- 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 .
- 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.
- 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.
- 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 .
- 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.
- the optical structure may be formed by a lithography process or a bonding process.
- the conductive layer 10 is formed on the first surface 1 a of the transparent substrate 1 , and in other embodiment, as shown in FIG. 6 , the second surface 1 b 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 .
- 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 .
- 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.
- 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.
- 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 .
- a patterned insulating layer 36 is formed on the second type semiconductor stack 35 .
- 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.
- 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.
- 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 ′.
- 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 .
- 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.
- 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.
- 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 .
- 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 .
- 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.
- 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
- a plurality of second via holes 320 ′ is formed to expose a portion of the front conductive structure 30 , as shown in FIG. 22 .
- 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.
- 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.
- 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 ′.
- 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 .
- 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.
- 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.
- 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 .
- 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 .
- the optical structure may be formed by a lithography process or a bonding process.
- 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.
- 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.
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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.
Description
- 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.
- The present application relates to a laser element, and particularly to a laser element having a flip chip structure.
- The statements herein merely provide background information related to the present application and do not necessarily constitute the prior art.
- 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.
- In view of this, some embodiments of the present application provide a laser element and a manufacturing method thereof.
- 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.
- According to an embodiment, the first passivation layer contacts the patterned insulating layer on the second type semiconductor stack.
- 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.
- 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.
- 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.
- 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.
- 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.
- According to an embodiment, the conductive layer forms a conductive region which is located on a periphery of the adhesive layer.
- According to an embodiment, the conductive region surrounds the laser unit and is electrically separated from the laser unit.
- 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.
- According to an embodiment, at least two of the first electrode, the second electrode, the third electrode and the fourth electrode are coplanar.
- 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.
- 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.
- 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.
- According to an embodiment, the laser element further comprises an ohmic contact formed between the back conductive structure and the second type semiconductor stack.
- 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.
- According to an embodiment, from a top view of the laser element, at least one of the second conductive channels has an “L” shape.
- 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.
- 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.
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FIG. 1 is a schematic view of a laser element according to an embodiment of the present application; -
FIG. 2 is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application; -
FIG. 3 is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application; -
FIG. 4 is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application; -
FIG. 5A is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application; -
FIG. 5B is a schematic top view of the laser element taken along AA′ according to an embodiment of the present application; -
FIG. 6 is a schematic view of the laser element according to an embodiment of the present application; -
FIG. 7 is a schematic view of the laser element according to an embodiment of the present application; -
FIG. 8 is a schematic view of the laser element according to an embodiment of the present application; -
FIG. 9 is a schematic view of the laser element according to an embodiment of the present application; -
FIG. 10 is a schematic view of the laser element according to an embodiment of the present application; -
FIG. 11 is a schematic view of the laser element according to an embodiment of the present application; -
FIG. 12 toFIG. 16 are schematic views showing the steps of manufacturing a laser element according to an embodiment of the present application; -
FIG. 17 toFIG. 21 are schematic views showing the steps of manufacturing a laser element according to an embodiment of the present application; and -
FIG. 22 toFIG. 24 are schematic views showing the steps of manufacturing a laser element according to an embodiment of the present invention. - 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.
- Referring to
FIG. 1 , a laser element according to an embodiment of the present application includes atransparent substrate 1, anadhesive layer 2, alaser unit 3, a plurality offirst channels 34, and aconductive layer 10 on thetransparent substrate 1. For example, thetransparent substrate 1 includes sapphire, glass, or silicon carbide (SiC). In some embodiments, thetransparent substrate 1 is an optical element, and may be patterned to produce a specific optical effect. Theconductive 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, theconductive layer 10 is disposed between thetransparent substrate 1 and theadhesive layer 2. - One side of the
adhesive layer 2 is attached to theconductive layer 10, and the other side thereof is attached to alight exiting side 3S of thelaser unit 3. For example, theadhesive layer 2 can be benzocyclobutene (BCB), silicon dioxide or a transparent conductive oxide. - The
laser unit 3 includes a frontconductive structure 30, a firsttype semiconductor stack 31, anactive layer 33, a secondtype semiconductor stack 35, aninsulating layer 36, and a backconductive structure 32. The backconductive structure 32 includes a firstconductive electrode 323 and a secondconductive 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 firsttype semiconductor stack 31 is an n-type semiconductor stack, and the secondtype semiconductor stack 35 is a p-type semiconductor stack, and vice versa. Theactive layer 33 is between the firsttype semiconductor stack 31 and the secondtype 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, theactive 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 firsttype semiconductor stack 31, the secondtype semiconductor stack 35, and theactive 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 Alx1Ga(1-x1)As, where 0≤x1≤1; AlInP represents Alx2In(1-x2)P, where, 0≤x2≤1; AlGaInP represents (Aly1Ga(1-y1))1-x3Inx3P, where 0≤x3≤1, and 0≤y1≤1; AlGaN series represents Alx4Ga(1-x4)N, where 0≤x4≤1; AlAsSb series represents AlAsx5Sb(1-x5), where 0≤x5≤1; InGaP series represents Inx6Ga1-x6P, where 0≤x6≤1; InGaAsP series represents InxGa1-x6As1-y2Py2, where 0≤x6≤1, and 0≤y2≤1; InGaAsN series represents InxGa1-x8As1-y3Ny3, where 0≤x8≤1, and 0≤y3≤1; AlGaAsP series represents Alx9Ga1-x9As1-y4Py4, where 0≤x9≤1, and 023 y4≤1; and InGaAs series represents Inx10Ga1-x10As, where 0≤x10≤1. According to the material of theactive layer 33, when the material of the semiconductor stacks 31, 35 is AlGaAs series, theactive 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, theactive 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, theactive 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, theactive layer 33 may emit ultraviolet light having a peak wavelength between 250 nm and 400 nm. - In the present embodiment, the first
type semiconductor stack 31 and the secondtype semiconductor stack 35 include a plurality of overlapping layer structures to form a distributed Bragg reflector (DBR), so that a light emitted from theactive layer 33 can be reflected between two distributed Bragg reflectors to form coherent light, and then the coherent light is emitted from the firsttype semiconductor stack 31 to form a laser light L. - In an embodiment, the insulating
layer 36 is disposed between the backconductive structure 32 and the secondtype semiconductor stack 35. In an embodiment, the material of the insulatinglayer 36 includes silicon dioxide. - In an embodiment, a contact resistance between the back
conductive structure 32 and the secondtype semiconductor stack 35 is lower than 10−4 Ωcm2 and an ohmic contact is formed between the backconductive structure 32 and the secondtype 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 secondconductive electrode 324 of the backconductive 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 secondtype 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. - In an embodiment, the first
type semiconductor stack 31 is connected to the frontconductive structure 30, the frontconductive structure 30 is connected to the firstconductive electrode 323 through asecond channel 320, the secondconductive electrode 324 and the firstconductive electrode 323 are separated from each other to avoid a short circuit, and the secondtype semiconductor stack 35 is connected to the secondconductive electrode 324. With the above conductive structure, thelaser unit 3 receives an external driving voltage/current, and generate the laser light L. The frontconductive structure 30 is disposed on thelight exiting side 3S of thelaser unit 3 and attached to theadhesive layer 2. Therefore, the laser light L from thelaser unit 3 emits to outside through theadhesive layer 2 and thetransparent substrate 1. - 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 thetransparent 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 thelight exiting side 3S of thelaser unit 3 in real time. The following examples illustrate the working principle of the laser element structure of some embodiments. - In the present embodiment, in addition to the above semiconductor structure required for emitting the laser light, the
laser unit 3 further includes a backconductive structure 32. The backconductive structure 32 includes a plurality of detectingelectrodes conductive structure 32 and the frontconductive structure 30 are oppositely disposed on two sides of thelaser unit 3. The plurality offirst channels 34 extend from the backconductive structure 32 and penetrates through the frontconductive structure 30 and theadhesive layer 2, and is connected to theconductive layer 10. Namely, two ends of one of thefirst channels 34 are connected to one of the detectingelectrodes conductive layer 10 respectively. In some embodiments, the backconductive structure 32 includes a plurality of detectingelectrodes conductive electrodes 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 backconductive structure 32 includes a plurality of detectingelectrodes conductive layer 10. - Referring to
FIG. 1 andFIG. 2 together,FIG. 2 is a schematic top view ofFIG. 1 taken along AA′ as viewed from the top. The plurality of detectingelectrodes conductive layer 10 through thefirst channels 34. Therefore, the plurality of detectingelectrodes conductive layer 10 can be monitored in real time. When the laser element is damaged by an external impact, especially when thetransparent substrate 1 is damaged at thelight exiting side 3S, theconductive 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 thelaser unit 3 according to the change in the resistance value of theconductive layer 10 through the monitoring circuit, so as to prevent the laser light L emitted by thelaser unit 3 from being leaked via a rupture of thetransparent substrate 1 and being directly irradiated to the human eyes, thereby achieving the effect of monitoring abnormal conditions in real time. - In another embodiment, in order to prevent a conductive medium (that is the first channels 34) from contacting the front
conductive structure 30, the firsttype semiconductor stack 31 or the secondtype semiconductor stack 35 of thelaser unit 3 to form a short circuit, thelaser unit 3 further includes apassivation layer 340 disposed on an inner wall of thefirst channels 34 to prevent the measured resistance value of thefirst channels 34 from electrical interference of thelaser unit 3 and to reduce the noise during measurement. - 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.
-
FIG. 3 shows the top view of theconductive layer 10 taken along line AA′ shown in the cross-sectional schematic view ofFIG. 1 in another embodiment. In the embodiment, in order to expand the monitoring range, theconductive layer 10 has a larger area that covers most of thetransparent substrate 1.FIG. 4 shows the top view of theconductive layer 10 taken along line AA′ in the cross-sectional schematic view ofFIG. 1 in another embodiment. In the embodiment, theconductive layer 10 surrounds a periphery of thetransparent substrate 1 and has a hollow region corresponding to a light exiting hole (not shown) on the lower side of thelaser unit 3 to prevent the laser light L emitted by thelaser unit 3 from being shielded by theconductive layer 10, and thus, the material of theconductive layer 10 may be an opaque material, such as a metal oxide. In some embodiments, theconductive layer 10 made of metal may have better conductivity to enhance the monitoring sensitivity without shielding the light emitted by thelaser unit 3.FIG. 5A shows the top view of theconductive layer 10 taken along line AA′ in the cross-sectional schematic view ofFIG. 1 in another embodiment. In the embodiment, the plurality of light exiting holes of thelaser unit 3 is arranged as an array, so that theconductive layer 10 form a strip-like structure for avoiding covering the plurality of light exiting holes.FIG. 5B shows the top view of theconductive layer 10 taken along line AA′ in the cross-sectional schematic view ofFIG. 1 in another embodiment. In the embodiment, the plurality of light exiting holes of thelaser unit 3 are staggered, so that theconductive 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. - Referring to
FIG. 6 , in an embodiment, the laser element is structurally different from the abovementioned embodiments in that theconductive layer 10 is disposed on one side of thetransparent substrate 1 opposite to theadhesive layer 2. Therefore, one side of theadhesive layer 2 is attached to thetransparent substrate 1, and the other side thereof is attached to the frontconductive structure 30 of thelaser unit 3. In order to effectively monitor the change of the resistance value of theconductive layer 10, thefirst channels 34 further penetrates through theadhesive layer 2 and thetransparent substrate 1. Thus, the plurality of detectingelectrodes conductive layer 10 through thefirst channels 34 for facilitating monitoring the change of the resistance value of theconductive layer 10. The structural features and connection relationships of other components have been described as above and will not be repeated herein. - Referring to
FIG. 7 , in an embodiment, the laser element is structurally different from the abovementioned embodiments in that the plurality ofconductive layers 10 is simultaneously disposed on two opposite sides of thetransparent substrate 1, and thefirst channels 34 penetrate through theadhesive layer 2, thetransparent substrate 1 and at least oneconductive layer 10, or simultaneously penetrates through theconductive layers 10 on two sides of thetransparent substrate 1. Therefore, when theconductive layer 10 on one or two sides is damaged, resistance values measured by the plurality of detectingelectrodes transparent substrate 1 from being leaked. The structural features and connection relationships of other components have been described as above. - Referring to
FIG. 8 , in an embodiment, the laser element further includes anoptical structure 12 disposed on one side of thetransparent substrate 1 opposite to theadhesive layer 2, that is. For example, theoptical structure 12 is a diffractive optical element and is able to match with thelaser unit 3 to generate tens of thousands of laser spots which are suitable for three-dimensional sensing or face recognition. - Referring to
FIG. 9 , the laser element according to another embodiment of the present application includes atransparent substrate 1, anadhesive layer 2, aconductive region 10′, alaser unit 3, and a plurality offirst channels 34. Theconductive 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). Thelaser unit 3 includes a frontconductive structure 30, a firsttype semiconductor stack 31, anactive layer 33, a secondtype semiconductor stack 35, an insulatinglayer 36, and a backconductive structure 32. The component features, connection relationships and advantages of thetransparent substrate 1, the frontconductive structure 30, the firsttype semiconductor stack 31, theactive layer 33, thefirst channels 34, thepassivation layer 340, the secondtype semiconductor stack 35, the insulatinglayer 36 and the backconductive 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 annularconductive region 10′ is used for replacing the entire conductive layer to simplify the semiconductor manufacturing process and increase the production yield, and namely, theconductive region 10′ is disposed on the periphery of theadhesive layer 2. Theconductive region 10′ surrounds thelaser unit 3 and is electrically separated therefrom to prevent theconductive region 10′ from contacting thelaser unit 3 to form a short circuit or interfere with the monitoring circuit. In the present embodiment, since thefirst channels 34 do not penetrate through theadhesive layer 2 and thetransparent substrate 1, it is easier to control the etching process for forming thefirst channels 34. Further, theconductive region 10′ is formed after the etching process for forming thefirst channels 34, thereby preventing the conductive material for forming theconductive region 10′ from being affected in the etching process. - Referring to
FIG. 10 , in an embodiment, the laser element is structurally different from the embodiment shown inFIG. 9 in that theconductive region 10′ penetrate through theadhesive layer 2, and two sides of theconductive region 10′ are respectively connected to thetransparent substrate 1 and thefirst channels 34. The rest of the component features can be referred to the above description for detailed descriptions. In the present embodiment, since theconductive region 10′ is directly connected to thetransparent substrate 1, abnormal conditions of thetransparent substrate 1 can be acutely monitored. Further, theconductive region 10′ is formed after the etching process for forming thefirst channels 34, thereby preventing the conductive material for forming theconductive region 10′ from being affected in the etching process. - Referring to
FIG. 11 , in an embodiment, the laser element includes anoptical structure 12 disposed on one side of thetransparent substrate 1 opposite to theadhesive layer 2. For example, theoptical structure 12 is an optical element such as a diffractive optical element, a microlens or the like, and is able to match with thelaser unit 3 to generate tens of thousands of laser spots. The related advantages have been described as above. - Referring to
FIG. 12 toFIG. 16 , a manufacturing method of a laser element according to still another embodiment of the present application is described below. Firstly, aconductive layer 10 is formed on atransparent substrate 1. As shown inFIG. 12 , thetransparent substrate 1 includes afirst surface 1 a and asecond surface 1 b opposite to each other, theconductive layer 10 is disposed on thefirst surface 1 a, and thetransparent substrate 1 faces alaser unit 3 with thefirst surface 1 a. The material composition, structural features, the connection relationship between the components of theconductive layer 10 and thetransparent substrate 1, and the related embodiments thereof have been described as above. - The
transparent substrate 1 and alaser unit 3 are bonded by anadhesive layer 2, as shown inFIG. 13 . In an embodiment, thelaser unit 3 includes a frontconductive structure 30, a firsttype semiconductor stack 31, anactive layer 33, and a secondtype semiconductor stack 35 sequentially stacked on asubstrate 38. In another embodiment, thesubstrate 38 is a wafer substrate to grow the plurality oflaser 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. - The
substrate 38 of thelaser unit 3 is removed, as shown inFIG. 14 , to expose the secondtype semiconductor stack 35, which can facilitate the subsequent step of forming a back conductive structure. As shown inFIG. 15 , through an etching process, a plurality of first viaholes 34′ penetrating through thelaser unit 3 and theadhesive layer 2 is formed to expose a portion of theconductive layer 10 and a plurality of second viaholes 320′ is formed to expose a portion of the frontconductive structure 30. Then, a patterned insulatinglayer 36 is formed on the secondtype semiconductor stack 35. - Next, referring to
FIG. 16 , apassivation layer 340 is formed on an inner wall of each of the first viaholes 34′ and the second viaholes 320′. The functions and effects of thepassivation layer 340 have been described as above. Through an evaporation process, the plurality of the first viaholes 34′ is filled with a conductive material and connected to theconductive layer 10 to form the plurality offirst channels 34. Then, a backconductive structure 32 is formed on the surface of the insulatinglayer 36 of thelaser unit 3. The backconductive structure 32 includes a plurality of detectingelectrodes electrodes first channel 34. - In an embodiment, the
laser unit 3 is a flip chip structure. Therefore, in the step of forming the backconductive structure 32, a plurality of first and secondconductive electrodes electrodes FIG. 15 , in the etching process, a plurality of second viaholes 320′ and the plurality of first viaholes 34′ are formed at the same time, and then, the plurality of second viaholes 320′ is filled with thepassivation layer 340 and the conductive material during the evaporation process to form the plurality ofsecond channels 320, so that two ends of each of thesecond channels 320 are respectively connected to the frontconductive structure 30 and the firstconductive electrode 323 of the backconductive 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 thelaser unit 3 and thetransparent substrate 1 to form multiple laser elements, wherein the structure of each of the multiple laser elements is shown inFIG. 1 . - 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.
- Referring to
FIG. 12 , theconductive layer 10 is formed on thefirst surface 1 a of thetransparent substrate 1, and in other embodiment, as shown inFIG. 6 , thesecond surface 1 b of thetransparent substrate 1 can be bonded to thelaser unit 3 with theadhesive layer 2, that is, theconductive layer 10 and theadhesive layer 2 are respectively disposed on two opposite sides of thetransparent substrate 1. In the present embodiment, through the etching process, the first viaholes 34′channel 34 further penetrates through thetransparent substrate 1, and then is filled with thepassivation layer 340 and the conductive medium which is used as thefirst channels 34 during the evaporation process, so that the two ends of each of thefirst channels 34 are respectively connected to the frontconductive structure 30 and the plurality of detectingelectrodes conductive structure 32, as shown inFIG. 6 . - Referring to
FIG. 17 toFIG. 21 , a manufacturing method of a laser element according to another embodiment of the present invention is described below. Firstly, atransparent substrate 1 and alaser unit 3 are bonded through anadhesive layer 2, as shown inFIG. 17 . In an embodiment, thelaser unit 3 includes a frontconductive structure 30, a firsttype semiconductor stack 31, anactive layer 33, and a secondtype semiconductor stack 35 sequentially stacked on asubstrate 38. The structural features, material composition and advantages of the components, and the related embodiments thereof have been described as above. - As shown in
FIG. 18 , thesubstrate 38 of thelaser unit 3 is removed to expose the secondtype semiconductor stack 35, which can facilitate the subsequent step of forming a back conductive structure. As shown inFIG. 19 , through an etching process, a plurality of first viaholes 34′ penetrating through thelaser unit 3 is formed to expose a portion of theadhesive layer 2 and a plurality of second viaholes 320′ is formed to expose a portion of the frontconductive structure 30. Then, a patterned insulatinglayer 36 is formed on the secondtype semiconductor stack 35. - Next, referring to
FIG. 20 , apassivation layer 340 is formed on an inner wall of each of the plurality of first viaholes 34′ and the second viaholes 320′. The functions and effects of thepassivation layer 340 have been described as above. Then, aconductive region 10′ is formed in the plurality of first viaholes 34′ and on thepassivation layer 340. Theconductive region 10′ surrounds the periphery of thelaser unit 3 and connects theadhesive layer 2. Theconductive region 10′ is electrically separated from thelaser unit 3 by thepassivation layer 340 to prevent theconductive region 10′ from being electrically interfered by thelaser unit 3 or from forming short circuit therewith. As shown inFIG. 21 , through an evaporation process, the plurality of first viaholes 34′ is filled with a conductive medium which is used as thefirst channels 34 and is connected to theconductive region 10′. Then, a backconductive structure 32 is formed on the surface of the insulatinglayer 36 of thelaser unit 3. The backconductive structure 32 includes a plurality of detectingelectrodes electrodes first channels 34. - In an embodiment, the
laser unit 3 is a flip chip structure. Therefore, in the step of forming the backconductive structure 32, a plurality ofconductive electrodes electrodes FIG. 19 , in the etching process, a plurality of second viaholes 320′ and the plurality of first viaholes 34′ are formed at the same time. And, as shown in 21, apassivation layer 340 is formed on an inner wall of each of the plurality of second viaholes 320′, and then, the plurality of second viaholes 320′ is filled with the conductive material to form a plurality ofsecond channels 320 through the evaporation process, so that the two ends of each of thesecond channels 320 are respectively connected to the frontconductive structure 30 and the firstconductive electrode 323 of the backconductive 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 thelaser unit 3 and thetransparent substrate 1 to form multiple laser elements, wherein the structure of each of the multiple laser elements is shown inFIG. 11 . - 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 thetransparent substrate 1 opposite to theadhesive 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. - Referring to
FIG. 22 andFIG. 24 , in some embodiments, through the etching process, the plurality of first viaholes 34′ penetrating through thelaser unit 3 and theadhesive layer 2 is formed to expose a portion of thetransparent substrate 1, and a plurality of second viaholes 320′ is formed to expose a portion of the frontconductive structure 30, as shown inFIG. 22 . - Referring to
FIG. 23 , apassivation layer 340 is formed on an inner wall of each of the first viaholes 34′ and the second viaholes 320′. The functions and effects of thepassivation layer 340 have been described as above. Then, aconductive region 10′ is formed in each of the first viaholes 34′ and on thepassivation layer 340. Theconductive region 10′ surrounds the periphery of thelaser unit 3 and is directly disposed on thetransparent substrate 1, thereby monitoring abnormal conditions such as damage of thetransparent substrate 1 more acutely. Theconductive region 10′ is electrically separated from thelaser unit 3 by thepassivation layer 340 to prevent theconductive region 10′ from being electrically interfered by thelaser unit 3 or from forming a short circuit therewith. As shown inFIG. 24 , through an evaporation process, the plurality of viaholes 34′ is filled with a conductive medium which is used as thefirst channels 34 and is connected to theconductive region 10′. Finally, a backconductive structure 32 is formed on the surface of the insulatinglayer 36 of thelaser unit 3. The backconductive structure 32 includes a plurality of detectingelectrodes electrodes first channels 34. - In an embodiment, the
laser unit 3 is a flip chip structure. Therefore, in the step of forming the backconductive structure 32, a plurality ofconductive electrodes electrodes holes 320′ and the plurality of first viaholes 34′ are formed at the same time, and the plurality of second viaholes 320′ is filled with thepassivation layer 340 and the conductive material to form a plurality ofsecond channels 320 through the evaporation process, so that the two ends of each of thesecond channels 320 are respectively connected to the frontconductive structure 30 and the firstconductive electrode 323 of the backconductive 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 thelaser unit 3 and thetransparent substrate 1 to form multiple laser elements, wherein the structure of each of the multiple laser elements is as shown inFIG. 10 . - 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 theadhesive 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. - 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.
- 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.
Claims (18)
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.
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