CN118040476A - Gallium nitride-based laser tube core structure suitable for flip-chip bonding and manufacturing method thereof - Google Patents
Gallium nitride-based laser tube core structure suitable for flip-chip bonding and manufacturing method thereof Download PDFInfo
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- CN118040476A CN118040476A CN202211420387.7A CN202211420387A CN118040476A CN 118040476 A CN118040476 A CN 118040476A CN 202211420387 A CN202211420387 A CN 202211420387A CN 118040476 A CN118040476 A CN 118040476A
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- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 title claims abstract description 58
- 229910002601 GaN Inorganic materials 0.000 title claims abstract description 55
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 230000003287 optical effect Effects 0.000 claims abstract description 32
- 229910000679 solder Inorganic materials 0.000 claims abstract description 29
- 238000003466 welding Methods 0.000 claims abstract description 21
- 239000000758 substrate Substances 0.000 claims description 47
- 230000007704 transition Effects 0.000 claims description 17
- 238000005530 etching Methods 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 12
- 229910052751 metal Inorganic materials 0.000 claims description 11
- 239000002184 metal Substances 0.000 claims description 11
- 238000005516 engineering process Methods 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- 238000000992 sputter etching Methods 0.000 claims description 7
- 230000005496 eutectics Effects 0.000 claims description 6
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 4
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 4
- 229910002704 AlGaN Inorganic materials 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 238000001704 evaporation Methods 0.000 description 6
- 229920002120 photoresistant polymer Polymers 0.000 description 5
- 238000001755 magnetron sputter deposition Methods 0.000 description 3
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 description 2
- 238000001451 molecular beam epitaxy Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- -1 GaN Chemical class 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
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- 229910052737 gold Inorganic materials 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
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- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000001883 metal evaporation Methods 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000012858 packaging process Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
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Abstract
The application discloses a gallium nitride-based laser tube core structure suitable for flip-chip bonding and a manufacturing method thereof. The gallium nitride-based laser die structure includes an epitaxial structure; the epitaxial structure comprises a first ohmic contact electrode contact layer, a second ohmic contact electrode contact layer, a first optical confinement layer, a second optical confinement layer, a first waveguide layer, a second waveguide layer, an active region and the like; the epitaxial structure also comprises a step structure, a ridge structure and a groove structure, wherein the step structure is distributed at the edge parts of the two sides of the epitaxial structure on the laser resonant cavity; the groove structures are distributed on two sides of the ridge structure along the direction of the laser resonant cavity, and the notch and the groove bottom of the groove structures are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer. The application can effectively solve the problems of short circuit and the like caused by inclination of the tube core and overflow of solder from the side when the laser tube core and the high-heat-conductivity transitional heat sink are in flip-chip welding together, thereby greatly improving the reliability and the yield of the flip-chip welding of the laser tube core.
Description
Technical Field
The application relates to a gallium nitride (GaN) base laser, in particular to a gallium nitride base laser tube core structure suitable for flip-chip bonding and a manufacturing method thereof, belonging to the technical field of semiconductors.
Background
Gallium nitride (GaN) based lasers have important application prospects and wide market demands in the fields of projection display, laser processing, laser illumination, storage and the like.
In the packaging process of the GaN-based laser tube core, in order to better dissipate heat and improve the output power of the laser, a flip-chip welding technology, that is, a technology of welding a P-type electrode surface of the laser tube core and a high-heat-conductivity transition heat sink with a welding material layer such as AuSn on the surface, is the most commonly used and effective method at present. However, since the ridge-type width of the GaN-based laser die is generally narrower than the chip width and the ridge-type has a certain height, the problems such as tilting of the chip or overflow of solder from the side wall of the die often occur during flip-chip bonding, and thus short circuit is caused, resulting in failure of the laser die.
Disclosure of Invention
The present application is directed to a gallium nitride-based laser die and a method for fabricating the same, which are suitable for flip-chip bonding, to overcome the above-mentioned problems of the prior art.
In order to achieve the aim of the application, the application adopts the following scheme:
One aspect of the present application provides a gallium nitride-based laser die structure suitable for flip-chip bonding, comprising an epitaxial structure comprising a first ohmic contact electrode contact layer, a first optical confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second optical confinement layer, and a second ohmic contact electrode contact layer sequentially stacked along a first direction;
the epitaxial structure further comprises a step structure, a ridge structure and a groove structure, wherein the step structure is distributed at two side edge parts of the epitaxial structure in a second direction, the step structure is provided with a first step surface and a second step surface, the first mesa and the second step surface are respectively overlapped with partial surfaces of the first ohmic contact electrode contact layer and the second ohmic contact electrode contact layer, the second direction is a direction parallel to a laser resonant cavity, and the first direction is perpendicular to the second direction;
the ridge structure is formed by matching local areas of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer, and the height of the ridge structure is smaller than the sum of the thicknesses of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer;
the groove structures are distributed on two sides of the ridge structure along the second direction, and the notch and the groove bottom of the groove structures are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer.
Another aspect of the present application provides a method of fabricating a gallium nitride-based laser die structure suitable for flip-chip bonding, comprising:
Sequentially growing a first ohmic contact electrode contact layer, a first optical confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second optical confinement layer and a second ohmic contact electrode contact layer on a second surface of the conductive substrate, thereby forming an epitaxial structure of the gallium nitride-based laser;
removing local areas of the two side edge parts of the epitaxial structure along the direction of the laser resonant cavity to form a step structure, wherein the step structure is provided with a first step surface and a second step surface, and the first mesa and the second step surface are respectively overlapped with local surfaces of the first ohmic contact electrode contact layer and the second ohmic contact electrode contact layer;
And removing the second ohmic contact electrode contact layer, the second optical confinement layer and the local area of the second waveguide layer to form a ridge structure of the laser, and simultaneously forming groove structures on two sides of the ridge structure along the direction of the laser resonant cavity, wherein the height of the ridge structure is smaller than the sum of the thicknesses of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer, and the notch and the groove bottom of the groove structure are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer.
Compared with the prior art, the application has the advantages that the deep step structures are formed at the two side edges of the gallium nitride-based laser tube core, and the two groove structures are etched in the epitaxial structure of the gallium nitride-based laser to form the ridge structure of the laser, so that the height of the ridge structure of the laser tube core is consistent with the heights of other parts except the groove structures, when one end surface of the gallium nitride-based laser tube core far away from a substrate is in flip-chip welding with a high thermal conductivity transition heat sink with a heat conducting material layer, the tube core inclination can not occur, the problem of short circuit caused by overflow of solder from the side edge can be effectively improved, and the reliability and the yield of flip-chip welding of the gallium nitride-based laser tube core can be effectively improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.
FIG. 1 is a schematic diagram of an epitaxial structure of a GaN-based laser according to an embodiment of the invention;
fig. 2 is a schematic view of a step structure formed by processing edge portions on both sides of the epitaxial structure shown in fig. 1;
FIG. 3 is a schematic illustration of the epitaxial structure of FIG. 2 being processed to form a trench structure and a ridge structure;
FIG. 4 is a schematic illustration of the formation of an insulating dielectric layer on the surface of the device shown in FIG. 3;
FIG. 5 is a schematic illustration of forming a first ohmic contact electrode on the insulating dielectric layer of the device structure of FIG. 4;
FIG. 6 is a schematic illustration of the formation of a second ohmic contact electrode on the backside of the conductive substrate of the device structure of FIG. 5;
FIG. 7 is a schematic view of a high thermal conductivity transition heat sink according to embodiment 1;
Fig. 8 is a schematic diagram of the GaN-based laser die of fig. 6 after flip-chip bonding to the high thermal conductivity submount of fig. 7.
Detailed Description
The following description of some embodiments of the present application will be used to describe the technical solution of the present application and its advantageous effects in detail.
Some embodiments of the present application provide a gallium nitride-based laser die structure suitable for flip-chip bonding, comprising an epitaxial structure comprising a first ohmic contact electrode contact layer, a first optical confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second optical confinement layer, and a second ohmic contact electrode contact layer sequentially stacked along a first direction; the epitaxial structure further comprises a step structure, a ridge structure and a groove structure, wherein the step structure is distributed at two side edge parts of the epitaxial structure in a second direction, the step structure is provided with a first step surface and a second step surface, the first mesa and the second step surface are respectively overlapped with partial surfaces of the first ohmic contact electrode contact layer and the second ohmic contact electrode contact layer, the second direction is a direction parallel to a laser resonant cavity, and the first direction is perpendicular to the second direction;
the ridge structure is formed by matching local areas of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer, and the height of the ridge structure is smaller than the sum of the thicknesses of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer;
the groove structures are distributed on two sides of the ridge structure along the second direction, and the notch and the groove bottom of the groove structures are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer.
In one embodiment, the gallium nitride-based laser die structure further comprises:
the insulating medium layer continuously covers the surface of the step structure, the inner wall of the groove structure and the side wall of the ridge structure, but at least a partial area of the top end surface of the ridge structure is exposed from the insulating medium layer;
and the second ohmic contact electrode is arranged on the insulating medium layer, and a local area of the second ohmic contact electrode is combined with the top end surface of the ridge structure to form ohmic contact.
In one embodiment, the second ohmic contact electrode continuously covers at least an inner wall of the groove structure and a surface of the ridge structure.
In one embodiment, the gallium nitride-based laser die structure further includes a first ohmic contact electrode bonded to and forming an ohmic contact with a first side of the conductive substrate, and the epitaxial structure is formed on a second side of the conductive substrate, the first side being disposed opposite the second side.
In one embodiment, an end surface of the epitaxial structure, which is far away from the conductive substrate, is welded and combined with the high thermal conductivity transition heat sink through a heat conducting solder layer, and part of the heat conducting solder layer is filled in the groove structure.
Furthermore, the surface of the second ohmic contact electrode and the high-heat-conductivity transitional heat sink are in eutectic welding connection through the heat-conducting solder layer, and particularly, the surface of the second ohmic contact electrode and the high-heat-conductivity transitional heat sink are in seamless connection, so that a better heat-conducting effect is obtained.
In one embodiment, the step structures are symmetrically distributed on both sides of the ridge structure along the second direction.
In one embodiment, the groove structures are symmetrically distributed on both sides of the ridge structure along the second direction.
Further, the step structures and the groove structures distributed on the same side of the ridge structures are spaced from each other.
In one embodiment, the substrate has a thickness of 70 to 100 μm.
In one embodiment, the insulating dielectric layer has a thickness of 0.02 to 1 μm.
Some embodiments of the present application also provide a method of fabricating a gallium nitride-based laser die structure suitable for flip-chip bonding, comprising:
Sequentially growing a first ohmic contact electrode contact layer, a first optical confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second optical confinement layer and a second ohmic contact electrode contact layer on a second surface of the conductive substrate, thereby forming an epitaxial structure of the gallium nitride-based laser;
removing local areas of the two side edge parts of the epitaxial structure along the direction of the laser resonant cavity to form a step structure, wherein the step structure is provided with a first step surface and a second step surface, and the first mesa and the second step surface are respectively overlapped with local surfaces of the first ohmic contact electrode contact layer and the second ohmic contact electrode contact layer;
And removing the second ohmic contact electrode contact layer, the second optical confinement layer and the local area of the second waveguide layer to form a ridge structure of the laser, and simultaneously forming groove structures on two sides of the ridge structure along the direction of the laser resonant cavity, wherein the height of the ridge structure is smaller than the sum of the thicknesses of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer, and the notch and the groove bottom of the groove structure are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer.
In one embodiment, the epitaxial structure may be processed using dry etching and/or wet etching processes to form the step structure, the recess structure, etc.
In one embodiment, the manufacturing method specifically includes: and arranging a first mask on one end face of the epitaxial structure far away from the conductive substrate, and etching the epitaxial structure at least by utilizing an ion etching technology so as to form the step structure.
In one embodiment, the manufacturing method specifically includes: and setting a second mask on one end face of the epitaxial structure far away from the conductive substrate, and etching the epitaxial structure at least by utilizing an ion etching technology, so as to form the groove structure and the ridge structure.
Further, the first and second masks may be photoresist, dielectric film, or the like, and are not limited thereto.
In one embodiment, the manufacturing method further comprises:
Forming an insulating medium layer on one end surface of the epitaxial structure far away from the conductive substrate, and enabling the insulating medium layer to continuously cover the surface of the step structure, the inner wall of the groove structure and the surface of the ridge structure;
A window is processed on the insulating medium layer so that at least partial area of the top end face of the ridge structure is exposed;
And forming a second ohmic contact electrode on the insulating medium layer, and enabling a local area of the second ohmic contact electrode to form ohmic contact with the top end surface of the ridge structure.
Further, the window may be formed by performing mask etching or the like on the insulating dielectric layer.
Further, the second ohmic contact electrode is in ohmic contact with the second electrode contact layer, and the ohmic contact between the second ohmic contact electrode and the second electrode contact layer is usually performed, for example, annealing or the like may be used.
In one embodiment, the manufacturing method further comprises: and carrying out thinning treatment on the conductive substrate, then forming a first ohmic contact electrode on a first surface of the conductive substrate, and enabling the first ohmic contact electrode to form ohmic contact with the conductive substrate, wherein the first surface and the second surface are arranged opposite to each other.
In one embodiment, the manufacturing method further comprises: and the surface of the second ohmic contact electrode is in eutectic welding connection with the high-heat-conductivity transitional heat sink through the heat-conducting solder layer, and the groove structure is completely filled with the part of the heat-conducting solder layer.
In the present application, the material of the epitaxial structure is selected from group III-V compounds, such as GaN, alGaN, alGaAs, inGaN, inN, alInGaN, but not limited thereto.
In the present application, each semiconductor material layer in the epitaxial structure may be grown by HVPE (hydride vapor phase epitaxy), MOCVD (metal organic chemical vapor deposition), MBE (molecular beam epitaxy), PECVD (plasma enhanced chemical vapor deposition), or the like, without being limited thereto.
In the present application, the first ohmic contact electrode contact layer, the first optical confinement layer, and the first waveguide layer are all of a first conductivity type, and the second ohmic contact electrode contact layer, the second optical confinement layer, and the second waveguide layer are all of a second conductivity type. The first and second conductive types are different, for example, N-type and P-type, respectively, and the first ohmic contact electrode and the second ohmic contact electrode are N-type ohmic contact electrode and P-type ohmic contact electrode, respectively.
In the present application, the first ohmic contact electrode and the second ohmic contact electrode may be formed by metal evaporation, magnetron sputtering, or the like, and the material thereof may be Ti, al, au, ag, cu, ni, or the like, but is not limited thereto.
In the present application, the material of the insulating dielectric layer includes, but is not limited to, one or more of SiO 2, silicon nitride, aluminum oxide, etc.
In the present application, the conductive substrate includes, but is not limited to, gallium nitride, silicon carbide, silicon, gallium arsenide substrate, or the like.
In the application, the high thermal conductivity transition heat sink comprises a substrate, a metal transition layer and a heat conducting solder layer which are sequentially overlapped on the substrate. Wherein the substrate is made of AlN and the like; the material of the metal transition layer comprises Ti, pt, au and the like or alloys thereof; the heat conducting solder layer is made of AuSn solder and the like; and neither is limited thereto.
In a more typical embodiment, a method for fabricating a gallium nitride-based laser die structure suitable for flip-chip bonding includes:
1) Sequentially epitaxially growing an N-type GaN electrode contact layer, an N-type AlGaN light limiting layer, an N-type AlInGaN waveguide layer, a light emitting active region, a P-type AlInGaN waveguide layer, a P-type AlGaN light limiting layer and a P-type GaN electrode contact layer on the front surface of a conductive substrate such as gallium nitride, silicon carbide, silicon or gallium arsenide and the like to obtain an epitaxial structure of the gallium nitride-based laser;
2) Etching the two side edges of the epitaxial structure along the direction of the laser resonant cavity to an N-type GaN electrode contact layer by using photoresist, a dielectric film or the like as a mask through an ion etching technology, so as to form a step structure;
3) Etching two groove structures with preset widths on the epitaxial structure by using photoresist or a dielectric film and the like as masks through an ion etching technology, etching to a P type A1GaN light limiting layer, and etching part of a P type AlInGaN waveguide layer to form a ridge structure of the laser at the same time;
4) Forming an insulating medium layer on the surface of the epitaxial structure by utilizing methods such as evaporation or plasma enhanced chemical deposition (PECVD), and the like, wherein the insulating medium layer continuously covers the surface of the step structure, the inner wall of the groove structure and the surface of the ridge structure;
5) Removing the insulating medium layer at the top of the ridge structure by photoetching, chemical corrosion and other methods to at least expose the top end surface of the ridge structure, and depositing electrode metal on the insulating medium layer and the top end surface of the ridge structure by evaporation, magnetron sputtering or other modes to form a P-type ohmic contact electrode with good ohmic contact characteristics;
6) Thinning the conductive substrate to a thickness of 70-100 micrometers by grinding, chemical mechanical polishing and the like;
7) Depositing electrode metal on the back surface of the conductive substrate by means of evaporation, magnetron sputtering or the like to form N-type ohmic contact electrode metal with good ohmic contact characteristics;
8) And (3) welding the top end face of the device structure manufactured in the step (7), namely the P-type face of the laser tube core and the high-heat-conductivity transition heat sink with AuSn solder together through a eutectic welding method.
The application can ensure the ridge shape of the laser tube core to be consistent with the height of other parts outside the groove by forming the deep step at the edge of the gallium nitride-based laser tube core and forming the groove with the preset width at the two sides of the ridge-shaped structure at the same time, and is suitable for flip-chip welding, especially when the P-shaped surface of the laser tube core and the high-heat conductivity transition heat sink are welded together through the heat conduction solder layer, the problems of tilting of the laser tube core, short circuit caused by overflow of the solder from the side edge and the like are avoided, and the reliability and the yield of the flip-chip welding of the laser tube core are improved.
In order to make the objects, technical solutions and advantages of the present application more apparent, the following detailed description of the embodiments of the present application will be given with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the application shown in the drawings and described in accordance with the drawings are merely exemplary and the application is not limited to these embodiments.
It should be noted here that, in order to avoid obscuring the present application due to unnecessary details, only structures and/or processing steps closely related to the solution according to the present application are shown in the drawings, while other details not greatly related to the present application are omitted.
Referring to fig. 1 to 7, the method for manufacturing a gallium nitride-based laser die suitable for flip-chip bonding according to the present embodiment includes the following steps:
(1) An epitaxial structure of a gallium nitride laser is formed by sequentially epitaxially growing an N-type GaN electrode contact layer 11, an N-type AlGaN light confinement layer 12, an N-type GaN waveguide layer 13, a light emitting active region 14, a P-type GaN waveguide layer 15, a P-type AlGaN light confinement layer 16 and a P-type GaN electrode contact layer 17 on a GaN substrate 10 by using an MOCVD method, as shown in FIG. 1. Wherein the thickness of the N-type GaN electrode contact layer 11 is about 1.6 μm, and the doping concentration of Si is about 1.3X10 18cm-3; the thickness of the N-type AlGaN light confinement layer 12 is about 1.8 μm, and the Si doping concentration is about 1.5X10 18cm-3; the N-type GaN waveguide layer 13 is unintentionally doped and has a thickness of about 0.3 μm; the light emitting active region 14 employs a GaN/InGaN quantum well active region capable of emitting blue light of about 450 nm; the P-type GaN waveguide layer 15 is also unintentionally doped, with a thickness of about 0.2 μm; the thickness of the P-type AlGaN light confinement layer 16 is about 0.7 μm, and the Mg doping concentration is about 1.5X10 19cm-3; the thickness of the P-type GaN electrode contact layer 17 is about 10nm, and the Mg doping concentration is about 1.5X10 20cm-3.
(2) By using photoresist or a dielectric film as a mask, etching the epitaxial structure shown in fig. 1 along the two side edge portions of the laser resonant cavity direction by ion etching technology to form two step structures 20, wherein the etching depth reaches the inside of the N-type GaN electrode contact layer 11, as shown in fig. 2. The two step structures 20 may be symmetrically disposed. The overall width D of the chip is, for example, about 250 μm, the width D of the step structure is about 20 μm, the depth is about 4.5 μm, and the lower step surface is about 0.5 μm from the substrate.
(3) The ion beam technique is used to continue etching the ridge structure 40 in the epitaxial structure of the device structure shown in fig. 2 using the photoresist or dielectric film as a mask, while forming trench structures 30 on both sides of the ridge structure 40, as shown in fig. 3. Illustratively, the width L 1 of the ridge structure is about 10 μm and the width L 2 of the trench structure 30 is about 50 μm.
(4) An insulating dielectric layer 50 is deposited on the surface of the device structure shown in fig. 3 by using an inductively coupled plasma chemical vapor deposition (ICP-CVD) method, as shown in fig. 4, and then the insulating dielectric layer at the top end of the ridge structure 40 may be removed by mask etching or the like, so as to expose the top end of the ridge structure 40. The dielectric layer 50 may be, for example, a SiO 2 film having a thickness of about 0.2 μm.
(5) Palladium/platinum/gold (0.01 μm/0.05 μm/0.5 μm) was vapor-deposited on the surface of the device structure shown in fig. 4 by evaporation or the like, and alloyed in a nitrogen atmosphere at 500 c for about 5 minutes, thereby forming a P-type ohmic contact electrode 60 having good ohmic contact on the surface of the ridge structure 40, as shown in fig. 5.
(6) The gallium nitride substrate 10 is thinned from the back surface to about 80 μm by grinding or the like, and Ti (0.1 μm)/Al (0.4 μm) Ti (0.1 μm)/Al (0.5 μm) metal is vapor-deposited on the back surface of the gallium nitride substrate 10, and then alloying treatment or the like is performed in a conventional manner to form P-type ohmic contact electrodes 70 having good ohmic contact, thereby obtaining a gallium nitride-based laser die, as shown in fig. 6.
(7) A high thermal conductivity transition heat sink is provided, the structure of which may be referred to in fig. 7, comprising an AlN substrate 80, a Ti (0.1 μm)/Pt (0.4 μm)/Au (0.5 μm) metal transition layer 81 deposited on the surface of the substrate 80 by evaporation or the like, and an AuSn conductive solder layer 82 deposited on the metal transition layer 81 by evaporation or the like, the thickness of the conductive solder layer 82 may be about 5 μm. And (3) welding the high-heat-conductivity transitional heat sink and the laser tube core obtained in the step (6) together by a eutectic welding method, wherein the welding temperature can be about 280 ℃, and the finally formed laser tube core welding structure is shown in fig. 8.
According to the embodiment, the deep steps are formed at the edge of the laser tube core, the two groove structures are etched at the two sides of the laser tube core while the ridge structure of the laser tube core is manufactured, so that the ridge structure of the laser tube core is ensured to be consistent with the height of other parts outside the groove, and further, when the P-type surface of the laser tube core is in flip-chip welding with a high-thermal conductivity transition heat sink with AuSn solder, the problems of tube core inclination, short circuit caused by overflow of the solder from the side edge and the like are avoided, and the reliability and the yield of flip-chip welding of the laser tube core can be effectively improved.
It should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to specific embodiments, and that the embodiments may be combined appropriately to form other embodiments that will be understood by those skilled in the art.
Claims (10)
1. The gallium nitride-based laser tube core structure suitable for flip chip bonding comprises an epitaxial structure, wherein the epitaxial structure comprises a first ohmic contact electrode contact layer, a first optical confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second optical confinement layer and a second ohmic contact electrode contact layer which are sequentially laminated along a first direction; the method is characterized in that:
The epitaxial structure further comprises a step structure, a ridge structure and a groove structure, wherein the step structure is distributed at two side edge parts of the epitaxial structure in a second direction, the step structure is provided with a first step surface and a second step surface, the first mesa and the second step surface are respectively overlapped with partial surfaces of the first ohmic contact electrode contact layer and the second ohmic contact electrode contact layer, the second direction is a direction parallel to the laser resonant cavity, and the first direction is perpendicular to the second direction;
the ridge structure is formed by matching local areas of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer, and the height of the ridge structure is smaller than the sum of the thicknesses of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer;
the groove structures are distributed on two sides of the ridge structure along the second direction, and the notch and the groove bottom of the groove structures are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer.
2. A gallium nitride-based laser die structure adapted for flip-chip bonding as recited in claim 1, further comprising:
the insulating medium layer continuously covers the surface of the step structure, the inner wall of the groove structure and the side wall of the ridge structure, but at least a partial area of the top end surface of the ridge structure is exposed from the insulating medium layer;
and the second ohmic contact electrode is arranged on the insulating medium layer, and a local area of the second ohmic contact electrode is combined with the top end surface of the ridge structure to form ohmic contact.
3. A gallium nitride-based laser die structure adapted for flip-chip bonding according to claim 1 or 2, further comprising a first ohmic contact electrode bonded to and forming an ohmic contact with a first face of a conductive substrate, the epitaxial structure being formed on a second face of the conductive substrate, the first face being disposed opposite the second face.
4. A gallium nitride-based laser die structure adapted for flip-chip bonding according to claim 3, wherein: and one end surface of the epitaxial structure, which is far away from the conductive substrate, is welded and combined with the high-heat-conductivity transitional heat sink through a heat-conducting solder layer, and part of the heat-conducting solder layer is filled in the groove structure.
5. A gallium nitride-based laser die structure adapted for flip-chip bonding as defined in claim 4, wherein:
the high-heat-conductivity transition heat sink comprises a substrate, a metal transition layer and a heat-conducting solder layer which are sequentially overlapped on the substrate;
And/or the material of the heat conduction solder layer comprises AuSn solder;
and/or, the surface of the second ohmic contact electrode and the high-heat-conductivity transitional heat sink are in eutectic welding connection through the heat-conducting solder layer;
And/or the first ohmic contact electrode contact layer, the first optical confinement layer and the first waveguide layer are all of a first conductivity type, and the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer are all of a second conductivity type;
and/or the substrate comprises a gallium nitride, silicon carbide, silicon or gallium arsenide substrate;
And/or the thickness of the substrate is 70-100 mu m;
And/or the step structures are symmetrically distributed on two sides of the ridge structure along the second direction;
And/or the groove structures are symmetrically distributed on two sides of the ridge structure along the second direction.
6. A method of fabricating a gallium nitride-based laser die structure suitable for flip-chip bonding, comprising:
Sequentially growing a first ohmic contact electrode contact layer, a first optical confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second optical confinement layer and a second ohmic contact electrode contact layer on a second surface of the conductive substrate, thereby forming an epitaxial structure of the gallium nitride-based laser;
removing local areas of the two side edge parts of the epitaxial structure along the direction of the laser resonant cavity to form a step structure, wherein the step structure is provided with a first step surface and a second step surface, and the first mesa and the second step surface are respectively overlapped with local surfaces of the first ohmic contact electrode contact layer and the second ohmic contact electrode contact layer;
And removing the second ohmic contact electrode contact layer, the second optical confinement layer and the local area of the second waveguide layer to form a ridge structure of the laser, and simultaneously forming groove structures on two sides of the ridge structure along the direction of the laser resonant cavity, wherein the height of the ridge structure is smaller than the sum of the thicknesses of the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer, and the notch and the groove bottom of the groove structure are respectively arranged on the surface of the second ohmic contact electrode contact layer and the inside of the second waveguide layer.
7. The manufacturing method according to claim 6, characterized by comprising the following steps: a first mask is arranged on one end face, far away from the conductive substrate, of the epitaxial structure, and the epitaxial structure is etched at least by utilizing an ion etching technology, so that the step structure is formed;
And/or, setting a second mask on one end face of the epitaxial structure far away from the conductive substrate, and etching the epitaxial structure at least by utilizing an ion etching technology, so as to form the groove structure and the ridge structure.
8. The method of manufacturing according to claim 6, further comprising:
forming an insulating medium layer on one end face of the epitaxial structure far away from the conductive substrate, and enabling the insulating medium layer to continuously cover the surface of the step structure, the inner wall of the groove structure and the surface of the ridge structure,
A window is processed on the insulating medium layer so as to expose at least partial area of the top end face of the ridge structure,
Forming a second ohmic contact electrode on the insulating medium layer, and enabling a local area of the second ohmic contact electrode to form ohmic contact with the top end surface of the ridge structure;
And/or thinning the conductive substrate, and then forming a first ohmic contact electrode on a first surface of the conductive substrate, wherein the first ohmic contact electrode and the conductive substrate form ohmic contact, and the first surface and the second surface are arranged opposite to each other.
9. The method of manufacturing according to claim 8, further comprising: eutectic welding and combining the surface of the second ohmic contact electrode and the high-heat-conductivity transitional heat sink through a heat-conducting solder layer, and enabling part of the heat-conducting solder layer to be completely filled in the groove structure;
And/or the first ohmic contact electrode contact layer, the first optical confinement layer and the first waveguide layer are all of a first conductivity type, and the second ohmic contact electrode contact layer, the second optical confinement layer and the second waveguide layer are all of a second conductivity type;
and/or the substrate comprises a gallium nitride, silicon carbide, silicon or gallium arsenide substrate;
and/or the thickness of the conductive substrate after the thinning treatment is 70-100 mu m;
And/or the step structures are symmetrically distributed on two sides of the ridge structure along the second direction;
And/or the groove structures are symmetrically distributed on two sides of the ridge structure along the second direction.
10. The method of manufacturing according to claim 9, wherein: the high-heat-conductivity transition heat sink comprises a substrate, a metal transition layer and a heat-conducting solder layer which are sequentially overlapped on the substrate;
and/or the material of the heat conduction solder layer comprises AuSn solder.
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| CN202211420387.7A CN118040476A (en) | 2022-11-14 | 2022-11-14 | Gallium nitride-based laser tube core structure suitable for flip-chip bonding and manufacturing method thereof |
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