CN108922946B - LED structure and manufacturing method thereof - Google Patents
LED structure and manufacturing method thereof Download PDFInfo
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- CN108922946B CN108922946B CN201810777949.0A CN201810777949A CN108922946B CN 108922946 B CN108922946 B CN 108922946B CN 201810777949 A CN201810777949 A CN 201810777949A CN 108922946 B CN108922946 B CN 108922946B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims abstract description 117
- 239000000758 substrate Substances 0.000 claims abstract description 101
- 239000001257 hydrogen Substances 0.000 claims abstract description 70
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 70
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 49
- 230000008569 process Effects 0.000 claims abstract description 30
- 238000006243 chemical reaction Methods 0.000 claims abstract description 28
- 238000005240 physical vapour deposition Methods 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 22
- 238000005137 deposition process Methods 0.000 claims description 11
- 238000000151 deposition Methods 0.000 claims description 6
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 3
- 229910001882 dioxygen Inorganic materials 0.000 claims description 3
- 239000013078 crystal Substances 0.000 abstract description 17
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052594 sapphire Inorganic materials 0.000 description 36
- 239000010980 sapphire Substances 0.000 description 36
- 238000010586 diagram Methods 0.000 description 14
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 11
- 229910052782 aluminium Inorganic materials 0.000 description 11
- 238000005229 chemical vapour deposition Methods 0.000 description 7
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- 230000005699 Stark effect Effects 0.000 description 5
- 238000001312 dry etching Methods 0.000 description 5
- 238000005530 etching Methods 0.000 description 5
- 150000002431 hydrogen Chemical class 0.000 description 5
- 238000001039 wet etching Methods 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000013077 target material Substances 0.000 description 3
- FOXXZZGDIAQPQI-XKNYDFJKSA-N Asp-Pro-Ser-Ser Chemical compound OC(=O)C[C@H](N)C(=O)N1CCC[C@H]1C(=O)N[C@@H](CO)C(=O)N[C@@H](CO)C(O)=O FOXXZZGDIAQPQI-XKNYDFJKSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 238000002834 transmittance Methods 0.000 description 2
- 229910002704 AlGaN Inorganic materials 0.000 description 1
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
- H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/12—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a stress relaxation structure, e.g. buffer layer
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Led Devices (AREA)
Abstract
The embodiment of the invention discloses an LED structure and a manufacturing method thereof, wherein the method comprises the following steps: providing a patterned substrate; a buffer layer formed on the surface of the substrate by utilizing a physical vapor deposition process, wherein the buffer layer comprises an aluminum nitride buffer layer containing hydrogen; the epitaxial structure is formed on one side, away from the substrate, of the buffer layer, so that the problem that after the aluminum nitride buffer layer is formed, more aluminum residues still exist in the reaction chamber, the crystal quality of the epitaxial structure formed subsequently is influenced, and the photoelectric performance of the LED device is reduced is solved.
Description
Technical Field
The invention relates to the technical field of LED manufacturing, in particular to an LED structure and a manufacturing method thereof.
Background
The LED is called as a fourth generation illumination light source or a green light source, has the characteristics of energy conservation, environmental protection, long service life, small volume and the like, and is widely applied to the fields of various indications, display, decoration, backlight sources, common illumination, urban night scenes and the like.
In the existing LED manufacturing process, before an epitaxial structure is formed on a substrate, an aluminum nitride buffer layer is formed on the surface of the substrate, so that the photoelectric performance of an LED device is improved, the productivity of the LED device is improved, and the cost is reduced.
The existing method for forming an aluminum nitride buffer layer on a substrate generally utilizes an organic chemical vapor deposition process, and utilizes ammonia gas and aluminum-containing organic metal gas to generate the aluminum nitride buffer layer through a chemical reaction under a high-temperature and low-pressure environment.
However, in the above method for forming the aluminum nitride buffer layer, ammonia gas is used to react with an aluminum-containing organic metal gas, so that a large amount of aluminum-containing residues exist in the reaction chamber, and after the aluminum nitride buffer layer is formed, a large amount of aluminum residues still exist in the reaction chamber, which affects the crystal quality of the epitaxial structure formed subsequently, and reduces the photoelectric performance of the LED device.
Disclosure of Invention
In order to solve the above technical problems, embodiments of the present invention provide an LED structure and a manufacturing method thereof, so as to solve the problem that in the existing LED manufacturing method, after the aluminum nitride buffer layer is formed, a large amount of aluminum remains still exist in the reaction chamber, which affects the quality of a subsequently formed crystal of the epitaxial structure, and thus the photoelectric performance of the LED device is reduced.
In order to solve the above problems, the embodiments of the present invention provide the following technical solutions:
a method for manufacturing an LED structure comprises the following steps:
providing a patterned substrate comprising a planar region and a raised structure raised relative to the planar region;
a buffer layer formed on the surface of the substrate, the buffer layer comprising an aluminum nitride buffer layer containing hydrogen;
and forming an epitaxial structure on one side of the buffer layer, which is far away from the substrate.
Optionally, the forming a buffer layer on the surface of the substrate includes:
depositing aluminum nitride on the surface of the substrate by using a physical chemical vapor deposition process, and introducing hydrogen-containing gas into the reaction chamber within a preset time period in the deposition process to form an aluminum nitride buffer layer on the surface of the substrate, wherein the aluminum nitride buffer layer comprises the hydrogen-containing aluminum nitride buffer layer.
Optionally, the forming a buffer layer on the surface of the substrate includes:
depositing aluminum nitride on the surface of the substrate by using a magnetron sputtering process, and introducing hydrogen-containing gas into the reaction chamber within a preset time period in the deposition process to form an aluminum nitride buffer layer on the surface of the substrate, wherein the aluminum nitride buffer layer comprises the hydrogen-containing aluminum nitride buffer layer.
Optionally, the hydrogen-containing gas is H2、NH3、H2O。
Optionally, the preset time period is a part of the time period or the whole time period in the deposition process.
Optionally, the method further includes: during the deposition process, oxygen is introduced into the reaction chamber.
Optionally, the flow ratio of the oxygen gas and the hydrogen-containing gas introduced into the reaction chamber ranges from 0 to 1:20, excluding the left end value and the right end value.
An LED structure, comprising:
a patterned substrate comprising a planar region and a raised structure raised relative to the planar region;
a buffer layer on the surface of the substrate, the buffer layer comprising a hydrogen-containing aluminum nitride buffer layer;
and the epitaxial structure is positioned on one side of the buffer layer, which faces away from the substrate.
Optionally, the buffer layer further comprises an aluminum nitride buffer layer containing no hydrogen.
Optionally, the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer ranges from 60% to 100%, including a right endpoint value.
Compared with the prior art, the technical scheme has the following advantages:
according to the technical scheme provided by the embodiment of the invention, the buffer layer is formed on the surface of the substrate by utilizing a physical vapor deposition process instead of a chemical vapor deposition process, so that an Al-containing organic metal gas is prevented from being introduced into the reaction chamber, and the problem that the photoelectric performance of the LED device is reduced due to the influence on the crystal quality of a subsequent epitaxial structure caused by more aluminum residues still existing in the reaction chamber after the aluminum nitride buffer layer is formed is solved.
In addition, according to the technical scheme provided by the embodiment of the invention, the buffer layer comprises the hydrogen-containing aluminum nitride buffer layer, so that the lattice stress between the substrate and the epitaxial structure can be improved, the lattice stress is greatly released and the warping is reduced in the process of forming the epitaxial structure after the buffer layer, the surface temperature field of the epitaxial structure of the LED is uniform, and the wavelength uniformity of the emergent light of the LED structure is greatly improved.
Meanwhile, according to the technical scheme provided by the embodiment of the invention, in the process of forming the epitaxial structure after the buffer layer, the lattice stress is smaller, and the quantum confinement Stark effect on the quantum well is smaller, so that the luminous performance of the finally formed LED is improved, and the leakage current is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for fabricating an LED structure according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a patterned substrate in a method for manufacturing an LED structure according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a buffer layer formed on a patterned substrate in a method for manufacturing an LED structure according to an embodiment of the present invention;
fig. 4 is a schematic diagram of an LED structure manufactured by the method for manufacturing an LED structure according to an embodiment of the present invention;
fig. 5 is a schematic diagram of the warpage deformation of the LED structure when all of the buffer layers are composed of the aluminum nitride buffer layer containing hydrogen and all of the buffer layers are composed of the aluminum nitride buffer layer containing no hydrogen, where a is a schematic diagram of the warpage deformation of the LED structure when all of the buffer layers are composed of the aluminum nitride buffer layer containing no hydrogen, and b is a schematic diagram of the warpage deformation of the LED structure when all of the buffer layers are composed of the aluminum nitride buffer layer containing hydrogen;
fig. 6 is a schematic diagram of the warp deformation of the LED when the hydrogen-containing aluminum nitride buffer layer and the buffer layer have different thickness ratios in the buffer layer, where c is the hydrogen-containing aluminum nitride buffer layer and the buffer layer has a thickness ratio of 1/3, d is the hydrogen-containing aluminum nitride buffer layer and the buffer layer has a thickness ratio of 2/3, and b is the hydrogen-containing aluminum nitride buffer layer and the buffer layer has a thickness ratio of 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
As described in the background section, in the existing method for forming an aluminum nitride buffer layer, after the aluminum nitride buffer layer is formed, a large amount of aluminum remains in a reaction chamber, which affects the crystal quality of a subsequently formed epitaxial structure, and causes the decrease of the photoelectric performance of the LED device.
In order to solve the above problems, the inventors have studied and found that an aluminum nitride (AlN) buffer layer may be formed on the surface of the substrate using physical chemical vapor deposition. According to the test results of SEM (Scanning Electron Microscope), XRD (X-ray Diffraction) and AFM (Atomic Force Microscope), the AlN buffer layer produced by the process is columnar growth along the C axis, has high crystalline quality and smooth and flat surface. Moreover, after the GaN and other structures are epitaxially grown on the AlN surface, the surface of the grown GaN is very smooth, and the crystal quality can be improved.
However, the better the crystal quality of GaN formed on the surface of the AlN buffer layer, the greater the stress between the AlN buffer layer and the substrate, the greater the thermal mismatch, so that the LED epitaxial structure may generate a very large warping deformation during the growth process, resulting in a large difference between the internal and external temperatures of the LED epitaxial structure at high temperature, and poor uniformity, and the larger lattice stress may also result in a deterioration in the performance of the entire LED epitaxial structure, resulting in a reduction in the LED brightness and an increase in leakage current.
In view of this, an embodiment of the present invention provides a method for manufacturing an LED structure, as shown in fig. 1, the method includes:
s1: a patterned substrate 1 is provided, said patterned substrate 1 comprising a planar area 11 and a raised structure 12 raised with respect to said planar area 11, as shown in fig. 2.
It should be noted that, in this embodiment, a specific material of the patterned substrate is not limited, and optionally, the sapphire substrate has high light transmittance, and a crystal with good crystal quality can be obtained when a crystal is epitaxially grown on the patterned sapphire substrate, so that the patterned substrate that is optional in this embodiment is the patterned sapphire substrate. The specific process for providing the patterned substrate comprises the following steps: providing a sapphire substrate, and etching the surface of the sapphire substrate through dry etching or wet etching to form a patterned sapphire substrate.
Sapphire is usually applied with a cut surface having a plane a, a plane C, and a plane R. The lattice constant adaptation rate between the C-plane of the sapphire and the III-V and II-VI deposited films is small, and the requirement of high temperature resistance in the GaN barrier process is met, so that the substrate is an optional C-plane sapphire substrate in this embodiment. Optionally, in this embodiment, the patterned sapphire substrate is a C-plane sapphire substrate. In this embodiment, a specific manufacturing process of the patterned sapphire substrate is not limited, and the patterned sapphire substrate may be formed by dry etching, that is, the patterned sapphire substrate is a DPSS sapphire substrate, or may be formed by wet etching, that is, the patterned sapphire substrate is a WPSS sapphire substrate. Whichever way the sapphire substrate is formed, the patterned sapphire substrate includes a planar region and a raised structure raised relative to the planar region.
In this embodiment, the specific shape of the protruding structure is not limited, and the protruding structure may be a conical protruding structure, a triangular conical protruding structure, or a truncated cone protruding structure, and the shape of the protruding structure is specifically set according to the manufacturing process of the patterned substrate.
Specifically, on the basis of any of the above embodiments, in an embodiment of the present invention, the substrate has a period of 3um, the width a of the planar region 11 is 0.3um ± 0.1um, and the width of the contact region b between the protruding structure 12 and the planar region 11 is 2.7um ± 0.1 um. However, the present invention is not limited thereto, as the case may be.
In this embodiment, the height of the protrusion structure relative to the planar region is not limited, and the height of the protrusion structure relative to the planar region is set according to the etching rate and the etching time of the dry etching or the wet etching, which is not limited in this embodiment.
S2: as shown in fig. 3, a buffer layer 2 including an aluminum nitride buffer layer containing hydrogen is formed on the surface of the substrate 1 by a physical chemical vapor deposition process.
Specifically, on the basis of the above embodiment, in an embodiment of the present invention, forming a buffer layer on a surface of the substrate, the buffer layer including a hydrogen-containing aluminum nitride buffer layer includes: depositing aluminum nitride on the surface of the substrate by using a physical chemical vapor deposition process, and introducing hydrogen-containing gas into the reaction chamber within a preset time period in the deposition process to form an aluminum nitride buffer layer on the surface of the substrate, wherein the aluminum nitride buffer layer comprises the hydrogen-containing aluminum nitride buffer layer.
On the basis of the above embodiment, in an optional embodiment of the present invention, forming a buffer layer on a surface of the substrate by using a physical chemical vapor deposition process, where the buffer layer includes a hydrogen-containing aluminum nitride buffer layer, includes: depositing aluminum nitride on the surface of the substrate by using a magnetron sputtering process, and introducing hydrogen-containing gas into the reaction chamber within a preset time period in the deposition process to form an aluminum nitride buffer layer on the surface of the substrate, wherein the aluminum nitride buffer layer comprises the hydrogen-containing aluminum nitride buffer layer to improve the uniformity of the aluminum nitride buffer layer.
Specifically, on the basis of any one of the above embodiments, in an embodiment of the present invention, depositing aluminum nitride on the surface of the substrate by using a magnetron sputtering process includes:
and placing an aluminum target material in the reaction chamber, and introducing bombardment gas and nitrogen into the reaction chamber to excite aluminum atoms on the aluminum target material, so that the aluminum atoms can react with nitrogen atoms formed by nitrogen ionization to form an aluminum nitride buffer layer.
In particular, in one embodiment of the present invention, based on the above-described embodiments, the bombardment gas is argon. Optionally, in the embodiment of the present invention, a gas flow ratio of the argon gas to the nitrogen gas introduced into the reaction chamber ranges from 1:6 to 1:3, inclusive.
Therefore, according to the method for forming the LED epitaxial structure provided by the embodiment of the invention, when the aluminum nitride buffer layer is formed, the aluminum atoms in the reaction chamber are derived from the excitation of bombardment gas on the aluminum target material, but not from the organic metal gas containing aluminum, so that the problem that after the aluminum nitride buffer layer is formed, more aluminum residues still exist in the reaction chamber, the crystal quality of the subsequent epitaxial structure is influenced, and the photoelectric performance of the LED device is reduced is solved.
It should be noted that, in the embodiment of the present invention, the preset time period may be a partial time period in the deposition process, so that a part of the thickness of the buffer layer is an aluminum nitride buffer layer containing hydrogen, and a part of the thickness of the buffer layer is an aluminum nitride buffer layer containing no hydrogen; in other embodiments of the present invention, the predetermined time period may also be the whole time period in the deposition process, so that the hydrogen-containing aluminum nitride buffer layer is formed at each thickness of the buffer layer. However, the present invention is not limited thereto, as the case may be.
It should be noted that, when part of the buffer layer is composed of the hydrogen-containing aluminum nitride buffer layer and part is composed of the hydrogen-free aluminum nitride buffer layer, the formation sequence of the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer is not limited in the present invention, the hydrogen-containing aluminum nitride buffer layer may be formed first, then the hydrogen-free aluminum nitride buffer layer may be formed, or the hydrogen-free aluminum nitride buffer layer may be formed first, then the hydrogen-containing aluminum nitride buffer layer may be formed, or the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer may be formed alternately, as the case may be.
Specifically, on the basis of any one of the above embodiments, in an embodiment of the present invention, the hydrogen-containing gas is H2、NH3、H2O, preferably H2However, the present invention is not limited thereto, as the case may be.
On the basis of any of the above embodiments, in one embodiment of the present invention, the method further includes: in the deposition process, oxygen is introduced into the reaction chamber to improve the appearance of plasma, adjust the sputtering rate and the quality of a film layer, improve the subsequent lattice stress to a certain extent and improve the quality and the uniformity of lattices.
Optionally, on the basis of the above embodiment, in an embodiment of the present invention, a gas flow ratio of the oxygen gas and the hydrogen-containing gas introduced into the reaction chamber is in a range of 0-1:20, excluding a left end value and including a right end value, so as to prevent excessive hydrogen in the aluminum nitride buffer layer on the surface of the substrate from affecting crystal quality on the basis of ensuring that the aluminum nitride buffer layer includes the hydrogen-containing aluminum nitride buffer layer.
S3: as shown in fig. 4, an epitaxial structure 3 is formed on the side of the buffer layer 2 facing away from the substrate 1.
Specifically, in an embodiment of the present invention, forming the epitaxial structure 3 on the side of the buffer layer 2 away from the substrate 1 includes:
and taking the position of the plane area 11 of the substrate 1 as a nucleation area, and sequentially epitaxially growing a first type conductive layer, an active area structure, a second type conductive layer and an ohmic contact layer on one side of the buffer layer 2 departing from the substrate 1 to form a complete LED epitaxial structure.
In the embodiment of the present invention, specific types of the first type conductive layer and the second type conductive layer are not limited, and optionally, the first type conductive layer is an N type conductive layer, and the second type conductive layer is a P type conductive layer. In this embodiment, specific materials of each layer of the LED epitaxial structure after the subsequent epitaxial growth are not limited, and the LED may be configured differently according to actual needs, for example, the first type conductive layer of the LED epitaxial structure may be N-type GaN or N-type AlGaN, which is not limited in this embodiment.
In this embodiment, the first conductive layer is N-type GaN, and the epitaxial structure 3 includes an undoped GaN layer 31, an N-type GaN layer 32, a Multiple Quantum Well (MQW) layer 33, an electron blocking layer 34, a P-type GaN layer 35, and an ohmic contact layer 36. In other embodiments of the present invention, the subsequent LED epitaxial structure may further include other layer structures, such as a superlattice structure layer, which is not limited in this embodiment. As the case may be.
By observing and analyzing the TEM (Transmission electron microscope) of the LED structure manufactured by the manufacturing method provided by the embodiment of the present invention, it can be found that the atomic combination arrangement at the interface between GaN and AlN is more regular in the LED structure formed by the manufacturing method provided by the embodiment of the present invention, the dislocations are less in the growth processes of GaN epitaxy and MQW, the atomic arrangement is orderly, and these are all favorable for reducing the leakage current of the LED structure and prolonging the life of the LED structure.
As shown in fig. 5, fig. 5 is a schematic diagram illustrating the warpage deformation of the LED structure when all of the buffer layers on the surface of the substrate are made of the aluminum nitride buffer layer containing hydrogen and all of the buffer layers are made of the aluminum nitride buffer layer containing no hydrogen, where a is a schematic diagram illustrating the warpage deformation of the LED structure when all of the buffer layers on the surface of the substrate are made of the aluminum nitride buffer layer containing no hydrogen, and b is a schematic diagram illustrating the warpage deformation of the LED structure when all of the buffer layers on the surface of the substrate are made of the aluminum nitride buffer layer containing hydrogen. As can be seen from the figure, the LED manufacturing method provided in the embodiment of the present invention can improve lattice stress, so that the lattice stress is greatly released and the warpage is reduced in the epitaxial structure forming process after the buffer layer, so that the surface temperature field of the epitaxial structure of the LED is uniform, and the wavelength uniformity of the light emitted from the LED structure is greatly improved.
Meanwhile, in the LED manufacturing method provided by the embodiment of the invention, in the process of forming the epitaxial structure after the aluminum nitride buffer layer, the lattice stress is smaller, and the quantum confinement Stark effect on quantum hydrazine is smaller, so that the luminous performance of the finally formed LED is improved, and the leakage current is reduced.
Correspondingly, the embodiment of the invention also provides an LED structure, and the LED structure is manufactured by using the manufacturing method provided by any one of the embodiments. Continuing with fig. 4, the LED structure includes:
a patterned substrate 1, the patterned substrate 1 comprising a planar region 11 and a raised structure 12 raised with respect to the planar region 11;
a buffer layer 2 positioned on the surface of the substrate 1, wherein the buffer layer 2 comprises an aluminum nitride buffer layer containing hydrogen;
an epitaxial structure 3 on the side of the buffer layer 2 facing away from the substrate 1.
Optionally, the sapphire substrate has high light transmittance, and a crystal with good crystal quality can be obtained when a crystal is epitaxially grown on the patterned sapphire substrate, so that the patterned sapphire substrate is selected as the patterned sapphire substrate in this embodiment.
The cut surfaces of sapphire that are often used include a-plane, C-plane, and R-plane. The lattice constant adaptation rate between the C-plane of the sapphire and the III-V and II-VI deposited films is small, and the requirement of high temperature resistance in the GaN barrier process is met, so that the substrate is an optional C-plane sapphire substrate in this embodiment. Optionally, in this embodiment, the patterned sapphire substrate is a C-plane sapphire substrate. In this embodiment, a specific manufacturing process of the patterned sapphire substrate is not limited, and the patterned sapphire substrate may be formed by dry etching, that is, the patterned sapphire substrate is a DPSS sapphire substrate, or may be formed by wet etching, that is, the patterned sapphire substrate is a WPSS sapphire substrate. Whichever way the sapphire substrate is formed, the patterned sapphire substrate includes a planar region and a raised structure raised relative to the planar region.
In this embodiment, the specific shape of the protruding structure is not limited, and the protruding structure may be a conical protruding structure, a triangular conical protruding structure, or a truncated cone protruding structure, and the shape of the protruding structure is specifically set according to the manufacturing process of the patterned substrate.
Specifically, on the basis of any of the above embodiments, in an embodiment of the present invention, the substrate has a period of 3um, the width a of the planar region 11 is 0.3um ± 0.1um, and the width of the contact region b between the protruding structure 12 and the planar region 11 is 2.7um ± 0.1 um. However, the present invention is not limited thereto, as the case may be.
In this embodiment, the height of the protrusion structure relative to the planar region is not limited, and the height of the protrusion structure relative to the planar region is set according to the etching rate and the etching time of the dry etching or the wet etching, which is not limited in this embodiment.
Specifically, on the basis of the above embodiment, in an embodiment of the present invention, a forming process of the buffer layer is a physical vapor deposition process or a magnetron sputtering process, so as to solve a problem that after the aluminum nitride buffer layer is formed, a large amount of aluminum remains still exist in a reaction chamber, which affects the crystal quality of a subsequent epitaxial structure, and thus the photoelectric performance of the LED device is reduced.
Specifically, on the basis of the above embodiments, in an embodiment of the present invention, the thickness of the buffer layer ranges from 5nm to 100nm, inclusive, but the present invention is not limited thereto, as the case may be.
On the basis of any of the above embodiments, in an embodiment of the present invention, the buffer layer may only include the hydrogen-containing aluminum nitride buffer layer, or may include both the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer, which is not limited in this respect, that is, the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the aluminum nitride buffer layer ranges from 0 to 100%, including the right endpoint value, excluding the left endpoint value. Specifically, in an embodiment of the present invention, when the buffer layer includes both the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer, the hydrogen-containing aluminum nitride buffer layer may be located on a side of the hydrogen-free aluminum nitride buffer layer facing away from the substrate; in another embodiment of the present invention, when the buffer layer includes both the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer, the hydrogen-containing aluminum nitride buffer layer may also be located on a side of the hydrogen-free aluminum nitride buffer layer facing the substrate; in another embodiment of the present invention, when the buffer layer includes both the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer, the buffer layer may also be a stacked structure in which the hydrogen-containing aluminum nitride buffer layer and the hydrogen-free aluminum nitride buffer layer are crossed, and the present invention is not limited thereto, as the case may be.
As shown in fig. 6, fig. 6 shows a schematic diagram of the warping deformation of the LED when the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer is different from that of the buffer layer in the buffer layer on the surface of the substrate, where c is a schematic diagram of the warping deformation of the LED when the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer is 1/3, d is a schematic diagram of the warping deformation of the LED when the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer is 2/3, and b is a schematic diagram of the warping deformation of the LED when the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer is 1. It can be seen from the figure that, in the buffer layer on the surface of the substrate, the larger the thickness ratio of the hydrogen-containing aluminum nitride buffer layer is, the smaller the warping deformation of the LED is, the better the effect of releasing the lattice stress is in the process of forming the epitaxial structure on the surface of the buffer layer, the more uniform the temperature field on the surface of the epitaxial structure of the LED is, and the better the uniformity of the wavelength of the light emitted from the LED structure is, and accordingly, in the process of forming the epitaxial structure after the aluminum nitride buffer layer, the smaller the lattice stress is, the smaller the quantum confinement stark effect on the quantum well is, so that the better the light emitting performance of the finally formed LED is, and the.
Optionally, the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer is 60% -100%, including a right end value, and more optionally, the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the aluminum nitride buffer layer is 100%, so that the lattice stress is improved to the greatest extent, and the lattice stress is greatly released and the warpage is reduced in the formation process of the epitaxial structure after the aluminum nitride buffer layer, so that the surface temperature field of the epitaxial structure of the LED is uniform, the wavelength uniformity of the light emitted by the LED structure is greatly improved, and meanwhile, the quantum confinement stark effect suffered by quantum hydrazine is reduced, so that the luminous performance of the finally formed LED structure is improved, and the leakage current is reduced.
In summary, the LED structure and the manufacturing method thereof provided by the embodiments of the present invention can solve the problem that in the existing LED manufacturing method, after the aluminum nitride buffer layer is formed, more aluminum remains still exist in the reaction chamber, which affects the crystal quality of the subsequently formed epitaxial structure, and reduces the photoelectric performance of the LED device, and can also improve the lattice stress between the substrate and the epitaxial structure, so that in the process of forming the epitaxial structure on the surface of the buffer layer, the lattice stress is greatly released, and the warpage is reduced, thereby making the surface temperature field of the epitaxial structure of the LED uniform, and the wavelength uniformity of the light emitted from the LED structure greatly improved, and at the same time, reducing the quantum confinement stark effect suffered by the quantum hydrazine, so that the light emitting performance of the finally formed LED is improved, the brightness is increased, and the leakage current is reduced.
In the description, each part is described in a progressive manner, each part is emphasized to be different from other parts, and the same and similar parts among the parts are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A method for manufacturing an LED structure is characterized by comprising the following steps:
providing a patterned substrate comprising a planar region and a raised structure raised relative to the planar region;
depositing aluminum nitride on the surface of the substrate by using a physical vapor deposition process, and introducing hydrogen-containing gas into the reaction chamber and oxygen into the reaction chamber in a part of a preset time period in the deposition process; forming an aluminum nitride buffer layer on the surface of the substrate, wherein the aluminum nitride buffer layer comprises an aluminum nitride buffer layer containing hydrogen partially and an aluminum nitride buffer layer containing no hydrogen partially;
and forming an epitaxial structure on one side of the buffer layer, which is far away from the substrate.
2. The method according to claim 1, wherein aluminum nitride is deposited on the surface of the substrate by a magnetron sputtering process, and during a part of a preset time period during the deposition process, hydrogen-containing gas is introduced into the reaction chamber, and oxygen is introduced into the reaction chamber to form an aluminum nitride buffer layer on the surface of the substrate, wherein the aluminum nitride buffer layer comprises a part of the hydrogen-containing aluminum nitride buffer layer and a part of hydrogen-free aluminum nitride buffer layer.
3. The method of claim 1, wherein the hydrogen-containing gas is H2、NH3、H2O。
4. The method according to claim 1, wherein the flow ratio of the oxygen gas and the hydrogen-containing gas introduced into the reaction chamber is in the range of 0-1:20, excluding the left end value and the right end value.
5. An LED structure using the method of any one of claims 1-4, comprising:
a patterned substrate comprising a planar region and a raised structure raised relative to the planar region;
the buffer layer is positioned on the surface of the substrate and comprises an aluminum nitride buffer layer containing hydrogen and an aluminum nitride buffer layer partially not containing hydrogen;
and the epitaxial structure is positioned on one side of the buffer layer, which faces away from the substrate.
6. The LED structure of claim 5, wherein the thickness ratio of the hydrogen-containing aluminum nitride buffer layer to the buffer layer ranges from 60% to 100%, inclusive.
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