CN116479400A - Method for improving crystal quality of nitride semiconductor material containing Al - Google Patents
Method for improving crystal quality of nitride semiconductor material containing Al Download PDFInfo
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- CN116479400A CN116479400A CN202210050516.1A CN202210050516A CN116479400A CN 116479400 A CN116479400 A CN 116479400A CN 202210050516 A CN202210050516 A CN 202210050516A CN 116479400 A CN116479400 A CN 116479400A
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- 239000000463 material Substances 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 title claims abstract description 80
- 239000004065 semiconductor Substances 0.000 title claims abstract description 61
- 150000004767 nitrides Chemical class 0.000 title claims abstract description 59
- 239000013078 crystal Substances 0.000 title claims abstract description 34
- 229910017109 AlON Inorganic materials 0.000 claims abstract description 50
- 239000000758 substrate Substances 0.000 claims abstract description 41
- 230000008569 process Effects 0.000 claims abstract description 22
- 230000006911 nucleation Effects 0.000 claims abstract description 9
- 238000010899 nucleation Methods 0.000 claims abstract description 9
- 238000000151 deposition Methods 0.000 claims abstract description 5
- 229910052760 oxygen Inorganic materials 0.000 claims description 38
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 36
- 239000001301 oxygen Substances 0.000 claims description 36
- 239000010408 film Substances 0.000 claims description 31
- 239000012298 atmosphere Substances 0.000 claims description 19
- 239000007789 gas Substances 0.000 claims description 16
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 claims description 16
- 238000004544 sputter deposition Methods 0.000 claims description 15
- 238000001451 molecular beam epitaxy Methods 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000010409 thin film Substances 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 8
- 229910052594 sapphire Inorganic materials 0.000 claims description 8
- 239000010980 sapphire Substances 0.000 claims description 8
- 238000004549 pulsed laser deposition Methods 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 6
- 239000003153 chemical reaction reagent Substances 0.000 claims description 6
- 238000011065 in-situ storage Methods 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 239000013043 chemical agent Substances 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 2
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 claims 5
- 238000000407 epitaxy Methods 0.000 abstract description 8
- 230000000903 blocking effect Effects 0.000 abstract description 3
- 238000011031 large-scale manufacturing process Methods 0.000 abstract description 3
- 229910002704 AlGaN Inorganic materials 0.000 description 19
- 230000000694 effects Effects 0.000 description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 238000000137 annealing Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 230000005693 optoelectronics Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000001259 photo etching Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000003877 atomic layer epitaxy Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- -1 for example Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
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- 238000011112 process operation Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010897 surface acoustic wave method Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/301—AIII BV compounds, where A is Al, Ga, In or Tl and B is N, P, As, Sb or Bi
- C23C16/303—Nitrides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02367—Substrates
- H01L21/0237—Materials
- H01L21/02387—Group 13/15 materials
- H01L21/02389—Nitrides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02436—Intermediate layers between substrates and deposited layers
- H01L21/02439—Materials
- H01L21/02488—Insulating materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02518—Deposited layers
- H01L21/02521—Materials
- H01L21/02538—Group 13/15 materials
- H01L21/0254—Nitrides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02612—Formation types
- H01L21/02617—Deposition types
- H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses a method for improving the crystal quality of an Al-containing nitride semiconductor material. The method comprises the following steps: depositing an Al-containing nitride semiconductor material bottom layer serving as a nucleation layer on a substrate; and forming an AlON layer on the bottom layer of the Al-containing nitride semiconductor material, and then continuously growing the Al-containing nitride semiconductor material layer to prepare the high-quality epitaxial film of the Al-containing nitride semiconductor material. According to the invention, alON is grown on the Al-containing nitride semiconductor material film, and then the formed AlON is used for further blocking and annihilating threading dislocation during the next epitaxial growth, so that the crystal quality is improved, and meanwhile, the problems of difficult merging of AlN lateral epitaxy and the like are avoided. Meanwhile, the method disclosed by the invention is simple in process, can be suitable for various epitaxial growth, and is also completely suitable for large-scale production.
Description
Technical Field
The invention relates to a method for improving the crystal quality of an Al-containing nitride semiconductor material, and belongs to the technical field of semiconductor material growth.
Background
The AlN film material has the excellent characteristics of large forbidden bandwidth, direct band gap structure, stable chemical bond, high breakdown voltage, strong piezoelectric effect and the like, so that the AlN film material has wide application prospect in the fields of photoelectrons, power electronics and communication. AlGaN-based deep ultraviolet light emitting devices and detection devices using AlN as a bottom layer can be widely applied to the fields of disinfection, purification, medical treatment, communication and the like, and have a very large market prospect. Meanwhile, the AlN nucleation layer is also an indispensable buffer layer for epitaxially growing the GaN-based optoelectronic device on the silicon substrate, and the quality of the AlN film material directly influences the performance of the optoelectronic device. AlN is used as an ultra-wide band gap semiconductor, and can be used for preparing a high-voltage power electronic device, wherein the defect density of dislocation and the like can influence the performance of the electronic device. In addition, the performance of the surface acoustic wave and bulk acoustic wave filters based on AlN materials is also closely related to the AlN material quality. Therefore, the method has great value for improving the quality of the AlN film material.
However, since AlN self-supporting substrates are very expensive, and the wafer size is small. Currently, most of commercial AlN film materials are heteroepitaxially grown on substrates such as sapphire, silicon, siC and the like. But because of great lattice mismatch and thermal expansion coefficient mismatch of AlN and substrate materials, the AlN thin film materials which are heteroepitaxially grown often have poor crystal quality, have high-density dislocation defects, and are extremely easy to crack due to large stress. These problems greatly limit the application of AlN thin film materials.
Conventional AlN thin film heteroepitaxial growth is usually performed by growing an AlN nucleation layer and regrowing a high-temperature AlN combined layer. However, the bond energy between AlN is large, and the migration capability of the Al atom surface is low, so that the method for efficiently reducing the dislocation density in GaN growth is not suitable for AlN material growth, and the quality of the hetero-epitaxially grown AlN film material is still poor and the dislocation density is high. In addition, the problem that cracks are easy to generate due to large stress in the AlN growing process cannot be solved by the traditional growing means. In addition, some other methods, such as lateral epitaxy and pulse atomic layer epitaxy, can improve the quality of the AlN epitaxial layer to a certain extent, but tend to be long in time consumption and complex in process, so that the cost in actual production is high. Therefore, it is important to develop a method for improving the quality of AlN epitaxial thin film crystals with high efficiency and low cost.
For the existing scheme for improving the quality of AlN epitaxial thin film crystals, a two-step growth scheme similar to GaN epitaxial growth is generally adopted, as shown in patent CN 109065438A. Firstly, an AlN nucleation layer is grown on a substrate by a Metal Organic Chemical Vapor Deposition (MOCVD), molecular Beam Epitaxy (MBE), hydride Vapor Phase Epitaxy (HVPE) growth or sputtering and the like, and secondly, alN is grown at a high temperature after high-temperature annealing in the MOCVD. Due to the low surface mobility of Al atoms, the effect of growing AlN In a two-step process on the quality of the crystal is limited, so surfactants such as Ga, in, etc. are often added during the growth process, as shown In patents CN 105543969B, CN 103695999B. In addition, the crystal quality of the AlN grown by the two-step method can be improved by continuously introducing an Al source and simultaneously pulse introducing NH3 to increase the surface mobility of Al atoms, as shown in patent CN 106252211A. However, these methods only increase the surface mobility of Al atoms to some extent, and the improvement of AlN crystal quality is still relatively inefficient.
The lateral epitaxial growth method is a growth method for obviously improving the quality of AlN epitaxial thin film crystals, such as patent CN 108155090A. The method firstly makes various rugged patterns on the original substrate or the substrate on which the AlN nucleation layer is grown through photoetching, nano imprinting and the like, then carries out high-temperature growth in MOCVD, and reduces dislocation density and improves crystal quality by utilizing turning and annihilation of dislocation when AlN in different areas is combined in the growth process. Although the method can effectively improve the crystal quality of the AlN film material, the process is complex and the working procedures are numerous. The AlN film product has the advantages of greatly increased cost, low yield and poor uniformity, so that the method is difficult to be practically applied to mass production.
In addition, there are other technical schemes, such as alternately growing AlN (CN 107083539A) at high and low temperatures and alternately growing AlN (CN 104392909A) at a high-low V/III ratio. Such a solution promotes the alternating evolution of the roughening-flattening of the epitaxial surface during the growth process by means of a certain alternation of the growth conditions. Thus, part of dislocation is bent under the action of the mirror force of some inclined growth crystal planes, so that the dislocation is interacted, looped and annihilated, and does not extend upwards any more, and the dislocation density in AlN grown later is reduced. However, since the bond energy between AlN is very large (AlN is 2.88eV and GaN is 2.2 eV), it is difficult to realize high-quality large-size effective three-dimensional growth like GaN growth, and therefore the effect of improving the crystal quality of such methods is very limited.
It can be found that the existing high-quality AlN epitaxial film growth method is not obvious in effect, the grown AlN is still poor in quality, or the process is complex, and a series of problems such as cost and uniformity are caused due to the fact that the process steps such as a patterned substrate and secondary epitaxy are needed, so that the practicability and the effect are not good.
Disclosure of Invention
The invention mainly aims to provide a method for improving the crystal quality of an Al-containing nitride semiconductor material so as to overcome the defects in the prior art.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a method for improving the crystal quality of an Al-containing nitride semiconductor material, which comprises the following steps:
depositing an Al-containing nitride semiconductor material bottom layer serving as a nucleation layer on a substrate;
and forming an AlON layer on the bottom layer of the Al-containing nitride semiconductor material, and then continuously growing the Al-containing nitride semiconductor material layer to prepare the high-quality epitaxial film of the Al-containing nitride semiconductor material.
In some embodiments, the Al-containing nitride semiconductor material includes any one or a combination of two or more of AlN, alGaN, alInN, alInGaN, BAlN.
In some embodiments, the method comprises: an AlON layer is formed on the Al-containing nitride semiconductor material underlayer under an oxygen-containing atmosphere, or under the action of an oxygen-containing chemical agent or an oxygen-containing plasma.
The embodiment of the invention also provides a high-quality Al-containing nitride semiconductor material epitaxial film prepared by the method.
Compared with the prior art, the method for improving the crystal quality of the nitride semiconductor material containing Al has the following advantages:
according to the invention, alON is grown on the Al-containing nitride semiconductor material film, and then the formed AlON is used for further blocking and annihilating threading dislocation during the next epitaxial growth, so that the crystal quality is improved, and meanwhile, the problems of difficult merging of AlN lateral epitaxy and the like are avoided. Meanwhile, the method disclosed by the invention is simple in process, can be suitable for various epitaxial growth, and is also completely suitable for large-scale production.
Drawings
In order to more clearly illustrate the embodiments of the present invention 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 invention, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.
FIG. 1 is a schematic illustration of depositing an AlN underlayer on a substrate in an exemplary embodiment of the invention;
FIG. 2 is a schematic illustration of AlON formation on an AlN surface in an exemplary embodiment of the invention;
FIG. 3 is a schematic representation of an exemplary embodiment of the present invention after continued growth of AlN;
fig. 4 is a schematic diagram of AlON blocking dislocation in an exemplary embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, those skilled in the art will appreciate: the technical scheme of each embodiment can be modified or part of technical features in the technical scheme can be replaced equivalently; such modifications and substitutions do not depart from the spirit and scope of the various embodiments of the invention, and all other embodiments which may be obtained without inventive faculty are intended to fall within the scope of the present invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present invention, directional terms, order terms, etc. are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
The technical scheme, the implementation process, the principle and the like are further explained as follows.
One aspect of the embodiments of the present invention provides a method for improving the crystal quality of an Al-containing nitride semiconductor material, including:
depositing an Al-containing nitride semiconductor material bottom layer serving as a nucleation layer on a substrate;
and forming an AlON layer on the bottom layer of the Al-containing nitride semiconductor material, and then continuously growing the Al-containing nitride semiconductor material layer to prepare the high-quality epitaxial film of the Al-containing nitride semiconductor material.
In some preferred embodiments, the method comprises: the underlayer of Al-containing nitride semiconductor material, or the layer of Al-containing nitride semiconductor material, is formed on the substrate using at least any one of MOCVD, MBE, HVPE, sputtering.
Further, the thickness of the bottom layer of the nitride semiconductor material containing Al is 50 nm-2000 nm.
In some preferred embodiments, the method comprises: an AlON layer is formed on the Al-containing nitride semiconductor material underlayer under an oxygen-containing atmosphere, or under the action of an oxygen-containing chemical agent or an oxygen-containing plasma. Alternatively, the AlON layer is formed by introducing O 2 、N 2 /O 2 Mixture gas, or O 3 The reaction may be carried out by using an oxygen-containing gas, or may be carried out by other methods including an oxygen-containing chemical reagent, an oxygen-containing plasma, and the like.
The invention utilizes the idea that AlON is formed by oxidizing the surface of AlN or AlGaN to improve the quality of AlN or AlGaN crystal, creatively utilizes an AlON layer to block dislocation, and opens up a new idea for improving the quality of the crystal. The AlON layer is formed by introducing O 2 、N 2 /O 2 Mixture gas, H 2 O, or O 3 AlON is formed on the surface of an Al-containing nitride semiconductor material such as AlN or AlGaN, and dislocation can be blocked by forming an AlON layer inside the Al-containing nitride semiconductor material such as AlN or AlGaN by another method. The invention utilizes the characteristic that Al atoms are easy to oxidize, and can protect the underlying material from further oxidation after AlON is formed on the surface, so that only a thin AlON layer is provided, and lateral epitaxy is not required as in the traditional mask technology.
Further, the oxygen-containing atmosphere comprises an oxygen atmosphere, a mixed gas atmosphere composed of nitrogen and oxygen, O 3 An atmosphere, and the like, wherein the volume ratio of oxygen in the mixed gas atmosphere consisting of nitrogen and oxygen is more than 1%.
Further, the oxygen-containing chemical reagent includes a combination of concentrated sulfuric acid and hydrogen peroxide, or hydrogen peroxide, etc., but is not limited thereto.
Further, the AlON layer has a thickness of 5nm or less, preferably 1 to 2nm.
Further, the number of the AlON layers may be one layer or may be multiple layers.
In some preferred schemes, the method for forming the AlON layer can be either a MOCVD, HVPE, MBE, PLD method, a sputtering method or the like in MOCVD, HVPE, MBE, PLD or sputtering or the like in situ for one-time growth, or can be a method for forming the AlON layer by growing outside MOCVD, HVPE, MBE, PLD or sputtering or the like, and then placing the AlON layer in MOCVD, HVPE, MBE, PLD or sputtering or the like for continuous growth.
In some more specific preferred embodiments, the method comprises:
(1) Forming a bottom layer of an Al-containing nitride semiconductor material on a substrate by adopting at least any one of MOCVD, MBE, HVPE and sputtering;
(2) Forming an AlON layer with the thickness of 1-2 nm on the bottom layer of the Al-containing nitride semiconductor material under the action of an oxygen-containing atmosphere or an oxygen-containing chemical reagent or oxygen-containing plasma;
(3) Continuing to grow an Al-containing nitride semiconductor material layer on the structure obtained in the step (2);
(4) Repeating the step (2) and the step (3) for a plurality of times, and finally obtaining the high-quality Al-containing nitride semiconductor material epitaxial film with a flat surface and no cracks.
Further, the material of the substrate may include any one or a combination of two or more of GaN, znO, alN, sapphire, siC, si, etc., but is not limited thereto.
Further, the method further comprises: the substrate is subjected to heat treatment and pre-paving Al treatment, and then the bottom layer of the nitride semiconductor material containing Al is grown on the substrate.
Wherein, specifically, the process conditions of the heat treatment may include: at H 2 Heat treatment is carried out for 5-10 min at 1100-1200 deg.C under atmosphere. The process conditions of the pre-paving Al treatment may include: at H 2 Paving Al for 5-15 s at 1050-1100 deg.C under atmosphere.
In some preferred embodiments, the Al-containing nitride semiconductor material comprises any one or a combination of two or more of AlN, alGaN, alInN, alInGaN, BAlN. Alternatively, the epitaxial material that can be used to enhance the crystal quality by the method of the present invention is not limited to AlN and AlGaN, but can be applied to other Al-containing nitride semiconductor materials, including, for example, alloy combinations such as AlInN, alInGaN, BAlN.
In some embodiments, taking AlN and AlGaN as examples, the method for improving the crystal quality of the Al-containing nitride semiconductor material specifically includes the steps of:
1) An AlN underlying nucleation layer (or grown to AlGaN) is first deposited on a substrate by Metal Organic Chemical Vapor Deposition (MOCVD), molecular Beam Epitaxy (MBE), hydride Vapor Phase Epitaxy (HVPE), sputtering, or the like, as shown in fig. 1.
2) Introducing a mixed gas (N) into the AlN bottom layer (or AlGaN layer) 2 :O 2 =4:1) or O 3 The oxygen-containing gas forms an AlON layer having a thickness of 1 to 2nm on the Al (Ga) N surface of at most 5nm, as shown in FIG. 2.
3) Continuing to grow Al (Ga) N, it can be seen that some dislocations turn or annihilate at AlON cladding sites, as shown in FIG. 3, which is schematically illustrated in FIG. 4.
4) The step 2) and the step 3) can be circularly grown, the effect of AlON on annihilation dislocation for improving the crystal quality is enhanced, and finally the high-quality Al (Ga) N epitaxial film with a flat surface and no cracks is obtained.
By the technical scheme, the preparation method for improving the crystal quality of the AlN and AlGaN film material can effectively reduce dislocation density: the conventional method for improving the quality of the AlN film mainly improves the surface mobility of Al atoms, and is expected to reduce the dislocation density by simulating the growth of GaN in two steps, but the effect is not ideal. The invention innovatively proposes to reduce dislocation density by growing an AlON layer, on the one hand, the AlON layer region can directly block threading dislocation from extending upwards, and the aim of reducing dislocation density can be achieved without the need of thicker thickness for combined growth in the subsequent AlN lateral epitaxial growth process. The technical scheme can be also used in superposition with techniques such as AlN cavity layers and other AlN crystal quality improvement methods.
The method has simple process, can be suitable for various epitaxial growth, and is also completely suitable for large-scale production. Compared with the lateral epitaxy of a patterned substrate with complex process, the method can be completed in a MOCVD, MBE, HVPE cavity through one-time growth, can uniformly perform AlON growth outside a furnace, has no capacity limitation theoretically, can be operated in batches, and does not need procedures of photoetching, cleaning, secondary epitaxy and the like which extremely affect the yield and the cost. In addition, the method of the invention can be applied to AlN epitaxial growth on various substrates, including sapphire substrates, silicon substrates, siC substrates, alN substrates and the like, has wide applicability and is completely suitable for commercial application. But also can effectively reduce dislocation density of AlN or AlGaN film materials, has the advantages of strong compatibility, simple process, wide applicability and the like, and is completely suitable for mass production.
In another aspect of the embodiments of the present invention, there is provided a high quality epitaxial thin film of Al-containing nitride semiconductor material prepared by the method.
In summary, the present invention further uses the formed AlON to further block and annihilate threading dislocation during the next epitaxial growth by growing AlON on the Al-containing nitride semiconductor material film, thereby improving crystal quality, and simultaneously, the problems of difficult merging of AlN lateral epitaxy and the like are not existed. The technical scheme is also compatible with the technical scheme of growth of other AlN film materials, and can further improve the crystal quality of the Al-containing nitride semiconductor material.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be further described in detail with reference to the accompanying drawings and several preferred embodiments. The above-described aspects are further described below in conjunction with specific embodiments. It should be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The reagents and starting materials used in the following examples were all commercially available, and the test methods in which the specific conditions were not specified were generally conducted under conventional conditions or under the conditions recommended by the respective manufacturers. Further, unless otherwise indicated, the experimental methods and detection methods disclosed in the present invention all employ conventional techniques in the relevant arts.
Example 1: preparation of high quality AlN epitaxial thin film on silicon substrate
S1: and (3) heat treatment of a substrate: placing Si (111) substrate in MOCVD in pure H 2 The surface oxide layer was removed by heating to 1150 c under an atmosphere and then heat-treating for 5 minutes.
S2: pre-paving Al: reducing the growth temperature to 1050 ℃ and maintaining pure H 2 Under the condition of introducing an Al source, paving a layer of Al on the surface of the substrate to prevent NH 3 Is in contact with the substrate.
S3: growing an AlN bottom layer: after the Al is spread, through NH 3 An AlN underlayer of 200nm in thickness was grown under growth conditions of 1050℃and V/III of 200.
S4: growing an AlN surface oxide layer: introducing N in MOCVD 2 /O 2 Mixed gas or O 3 And forming AlON on the surface of the sample.
S5: and (5) continuing to grow an AlN layer: the growth temperature is increased to 1150 ℃, the V/III ratio is reduced to 20, and AlN with the thickness of 100nm is grown at high temperature and low V/III.
The AlN epitaxial layer obtained in this embodiment has no cracks when viewed under an optical microscope, and a significant contrast difference in the position of the AlON layer in the epitaxial film can be observed by a cross-sectional Transmission Electron Microscope (TEM), and dislocation has significant turning and annihilation at the AlON layer. The surface of the epitaxial layer is smooth under the observation of an atomic force microscope AFM, the half-width of the (002) plane rocking curve is lower than 1000 arsec by X-ray diffraction (XRD) scanning, the half-width of the (102) plane is lower than 1300 arsec, and the epitaxial layer obtained in the embodiment has a smooth surface and good crystal quality.
Example 2: preparation of high quality AlN epitaxial film on planar sapphire substrate
S1: sputtering an AlN bottom layer: and sputtering a 50nm AlN film on the sapphire substrate as an AlN bottom layer.
S2: placing AlN bottom layer into MOCVD, heating to 1150 deg.C, and introducing H 2 And NH 3 Annealing at high temperature for 10min.
S3: growing an AlN hole forming layer: the growth temperature is reduced to 900 ℃, the V/III ratio is regulated to 5000, and the AlN hole forming layer with the thickness of 300nm is grown at low temperature and high V/III.
S4: growing an AlN merging layer: the growth temperature is increased to 1200 ℃, the V/III ratio is reduced to 50, and the AlN merging layer with the thickness of 450nm is grown at high temperature and low V/III, so that the cavity inside the material is formed.
S5: growing an AlN oxide layer: introducing N in MOCVD 2 /O 2 Mixed gas or O 3 And forming AlON on the surface of the sample.
S6: and (5) continuing to grow an AlN layer: the growth temperature is increased to 1200 ℃, the V/III ratio is increased to 200, and AlN with the thickness of 200nm is grown at high temperature and low V/III.
S7: recycling the steps S3 and S4 for a plurality of times, and finally obtaining the high-quality AlN film with the total thickness of about 3 mu m.
The AlN epitaxial layer obtained in this example has a total thickness of 3 μm and no surface cracks, and has a (002) plane rocking curve half width of less than 150 arsec and a (102) plane half width of less than 300 arsec as measured by XRD, and has an obvious effect of reducing dislocation density.
Example 3: preparation of high quality AlGaN epitaxial film on planar sapphire substrate
S1: high quality AlN layer growth: a high quality AlN epitaxial layer was grown according to the method in example 2.
S2: and (3) growing a transition layer: and on the basis of the high-quality epitaxial layer, the growth temperature is reduced to 1050 ℃, the V/III ratio is increased to 1000, and the AlN/AlGaN superlattice transition layer is grown.
S3: nAlGaN growth: the V/III ratio was adjusted to 2000 and nAlGaN with a thickness of 500nm was grown.
S4: growing an AlGaN oxide layer: introducing N in MOCVD 2 /O 2 Mixed gas or O 3 And forming AlON on the surface of the sample.
S5: and continuing to grow a nAlGaN layer: the V/III ratio was adjusted to 2000 and nAlGaN with a thickness of 500nm was grown.
S6: recycling the steps S3 and S4 for a plurality of times, and finally obtaining the high-quality AlGaN film with the total thickness of about 2 mu m.
The AlGaN epitaxial layer obtained in this example has a total thickness of 2 μm and no surface cracks, and has a (002) plane rocking curve half width of less than 250 arsec and a (102) plane half width of less than 350 arsec as scanned by XRD, and the dislocation density is effectively reduced.
Example 4: alON growth of AlN epitaxial film outside MOCVD chamber
S1: high quality AlN layer growth: a high quality AlN epitaxial layer was grown according to the methods of examples 1, 2.
S2: growing AlON outside the MOCVD chamber: the high-quality AlN epitaxial layer and oxygen in the air naturally and slowly form an AlON layer or N is introduced into an annealing furnace 2 /O 2 Mixed gas or O 3 The oxygen-containing gas rapidly forms an AlON layer.
S3: and (5) placing the substrate in MOCVD to continuously grow an AlN layer: the growth temperature is increased to 1150 ℃, the V/III ratio is reduced to 20, and AlN with the thickness of 100nm is grown at high temperature and low V/III.
The AlN epitaxial layer obtained in this example also had the same effect as that obtained by the oxidation treatment in MOCVD in example 1, and the (002) plane rocking curve half width was less than 1000 arsec and the (102) plane half width was less than 1300 arsec as measured by X-ray diffraction (XRD), which indicated that the same experimental effect could be obtained by AlON layer growth both in MOCVD and outside MOCVD.
By the technical scheme, the crystal quality of the AlN or AlGaN film material can be improved by utilizing in-situ generation or in-furnace growth of an AlON layer. By introducing O 2 、N 2 /O 2 Mixture gas, H 2 O, or O 3 The oxygen-containing gas can be formed in situ or outside the furnace in the AlN or AlGaN epitaxial process, can block threading dislocation, and can be repeatedly used for a plurality of times, so that the crystal quality of AlN and AlGaN films is effectively improved.
Further, the inventors have also made experiments with other materials, process operations, process conditions described in the present specification with reference to the foregoing examples, and have obtained desirable results, such as replacing the substrate with GaN, znO, alN, sapphire, siC, si, etc., and forming AlON layers, etc., with oxygen-containing chemicals or oxygen-containing plasma, for example. As another example, other Al-containing nitride semiconductor materials, such as AlInN, alInGaN, balN, are prepared on a substrate, with desirable results.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. A method of improving the crystal quality of an Al-containing nitride semiconductor material, comprising:
depositing an Al-containing nitride semiconductor material bottom layer serving as a nucleation layer on a substrate;
and forming an AlON layer on the bottom layer of the Al-containing nitride semiconductor material, and then continuously growing the Al-containing nitride semiconductor material layer to prepare the high-quality epitaxial film of the Al-containing nitride semiconductor material.
2. The method according to claim 1, characterized in that: the Al-containing nitride semiconductor material includes any one or a combination of two or more of AlN, alGaN, alInN, alInGaN, BAlN.
3. The method according to claim 1, characterized in that it comprises: forming the bottom layer of the Al-containing nitride semiconductor material or the Al-containing nitride semiconductor material layer on the substrate by at least adopting any one of MOCVD, MBE, HVPE and sputtering; and/or the thickness of the bottom layer of the nitride semiconductor material containing Al is 50 nm-2000 nm.
4. The method according to claim 1, characterized in that it comprises: an AlON layer is formed on the Al-containing nitride semiconductor material underlayer under an oxygen-containing atmosphere, or under the action of an oxygen-containing chemical agent or an oxygen-containing plasma.
5. The method according to claim 4, wherein: the oxygen-containing atmosphere comprises an oxygen atmosphere, a mixed gas atmosphere composed of nitrogen and oxygen, O 3 Any one of the atmospheres, wherein the volume ratio of oxygen in the mixed gas atmosphere consisting of nitrogen and oxygen is more than 1%;
and/or the oxygen-containing chemical reagent comprises a combination of concentrated sulfuric acid and hydrogen peroxide, or hydrogen peroxide.
6. The method according to claim 1 or 4, characterized in that: the AlON layer has a thickness of 5nm or less, preferably 1 to 2nm; and/or the number of AlON layers is one or more.
7. The method according to claim 1 or 4, comprising: forming the AlON layer by adopting at least one of MOCVD, HVPE, MBE, PLD and sputtering methods through in-situ one-time growth; alternatively, the AlON layer is formed by growing outside the MOCVD, HVPE, MBE, PLD or sputtering apparatus, and then the AlON layer is placed in the MOCVD, HVPE, MBE, PLD or sputtering apparatus for further growth.
8. The method according to claim 1, characterized in that it comprises in particular:
(1) Forming a bottom layer of an Al-containing nitride semiconductor material on a substrate by adopting at least any one of MOCVD, MBE, HVPE and sputtering;
(2) Forming an AlON layer with the thickness of 1-2 nm on the bottom layer of the Al-containing nitride semiconductor material under the action of an oxygen-containing atmosphere or an oxygen-containing chemical reagent or oxygen-containing plasma;
(3) Continuing to grow an Al-containing nitride semiconductor material layer on the structure obtained in the step (2);
(4) Repeating the step (2) and the step (3) for a plurality of times, and finally obtaining the high-quality Al-containing nitride semiconductor material epitaxial film with a flat surface and no cracks.
9. The method according to claim 8, wherein: the substrate is made of any one or more than two of GaN, znO, alN, sapphire, siC and Si;
and/or, the method further comprises: firstly, carrying out heat treatment and pre-paving Al treatment on a substrate, and then growing the bottom layer of the nitride semiconductor material containing Al on the substrate;
preferably, the process conditions of the heat treatment include: at H 2 Heat treatment is carried out for 5 to 10 minutes at 1100 to 1200 ℃ under the atmosphere;
preferably, the process conditions of the pre-paving Al treatment include: at H 2 Paving Al for 5-15 s at 1050-1100 deg.C under atmosphere.
10. High quality epitaxial thin films of Al-containing nitride semiconductor material produced by the process of any one of claims 1-9.
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