CN117747418A - Preparation method of high-purity high-transmittance AlN wafer and deep ultraviolet device - Google Patents
Preparation method of high-purity high-transmittance AlN wafer and deep ultraviolet device Download PDFInfo
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- CN117747418A CN117747418A CN202311790936.4A CN202311790936A CN117747418A CN 117747418 A CN117747418 A CN 117747418A CN 202311790936 A CN202311790936 A CN 202311790936A CN 117747418 A CN117747418 A CN 117747418A
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- 238000002834 transmittance Methods 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 229910052582 BN Inorganic materials 0.000 claims abstract description 53
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims abstract description 53
- 230000005496 eutectics Effects 0.000 claims abstract description 51
- 239000000758 substrate Substances 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 20
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 claims abstract 12
- 239000010410 layer Substances 0.000 claims description 88
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 11
- 229910052739 hydrogen Inorganic materials 0.000 claims description 11
- 239000001257 hydrogen Substances 0.000 claims description 11
- 239000002346 layers by function Substances 0.000 claims description 10
- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical compound [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 claims description 8
- 229910002601 GaN Inorganic materials 0.000 claims description 7
- 239000012159 carrier gas Substances 0.000 claims description 7
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000005498 polishing Methods 0.000 claims description 3
- 238000000227 grinding Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 abstract description 138
- 239000012535 impurity Substances 0.000 abstract description 30
- 239000000463 material Substances 0.000 abstract description 16
- 238000010521 absorption reaction Methods 0.000 abstract description 6
- 239000004065 semiconductor Substances 0.000 abstract description 3
- 235000012431 wafers Nutrition 0.000 description 59
- 238000012360 testing method Methods 0.000 description 16
- 229910002704 AlGaN Inorganic materials 0.000 description 11
- 239000013078 crystal Substances 0.000 description 9
- 230000007547 defect Effects 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 238000007605 air drying Methods 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910052594 sapphire Inorganic materials 0.000 description 2
- 239000010980 sapphire Substances 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
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- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention relates to the technical field of semiconductor materials, in particular to a preparation method of a high-purity high-transmittance AlN wafer and a deep ultraviolet device. The preparation method comprises the following steps: growing a boron nitride eutectic pseudo-lattice layer on a first surface of the PVT AlN substrate; epitaxially growing an HVPE AlN layer on the boron nitride eutectic pseudo-lattice layer; and stripping the PVT AlN substrate and the boron nitride eutectic pseudo-lattice layer to obtain the HVPE AlN wafer. The method obviously reduces the introduction of foreign impurities in the high-purity aluminum nitride wafer and solves the problem of deep ultraviolet band absorption of the aluminum nitride wafer caused by the impurities.
Description
Technical Field
The invention relates to the technical field of semiconductor materials, in particular to a preparation method of a high-purity high-transmittance AlN crystal plate and a deep ultraviolet device.
Background
Aluminum nitride (AlN) material has wide application prospect in the fields of visible ultraviolet band light-emitting diodes, high-frequency and high-power electronic devices, ultraviolet detectors and other optoelectronic devices due to the special band gap width and excellent photoelectric characteristics, so that the aluminum nitride (AlN) material is also an attractive material in wide band gap semiconductor materials.
The template commonly used by the ultraviolet device at the present stage is a sapphire-aluminum nitride substrate, and because of the thermal mismatch and lattice mismatch of the two materials during heterogeneous growth, aluminum nitride grown on the sapphire is subjected to larger tensile stress, so that the lattice is stretched, the growth of a subsequent aluminum gallium nitride epitaxial layer is affected, and the high matching property of the aluminum nitride material and the aluminum gallium nitride material cannot be effectively exerted. Mainly because various impurities are easily introduced in the growth process of the aluminum nitride single crystal, an ultraviolet absorption band is generated, so that the aluminum nitride wafer cannot penetrate through a deep ultraviolet band, and the optical, electrical and other performances of the aluminum nitride wafer are seriously affected.
To solve the above problems, doping compensation is generally required to compensate the defect energy level, so that an aluminum nitride wafer with high transmittance in the ultraviolet band can be obtained.
Disclosure of Invention
In view of the above, the present invention provides a method for preparing an AlN wafer with high purity and high transmittance, which significantly reduces the introduction of foreign impurities in a high purity aluminum nitride (AlN) wafer, and solves the problem that impurities cause absorption of the aluminum nitride wafer in the deep ultraviolet band (light with a wavelength of 200nm to 350nm in ultraviolet is called deep ultraviolet).
In order to solve the technical problems, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a high purity high transmittance AlN wafer, including:
growing a boron nitride eutectic pseudo-lattice layer on a first surface of the PVT AlN substrate;
epitaxially growing an HVPE AlN layer on the boron nitride eutectic pseudo-lattice layer;
and stripping the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer to obtain the HVPE AlN wafer.
With reference to the first aspect, in some possible implementations, before the growing of the boron nitride eutectic pseudo lattice layer on the first surface of the PVT AlN substrate, a pretreatment step of the PVT AlN substrate is further included, specifically, deionized water, alcohol and acetone are sequentially used to clean the PVT AlN substrate in inert gas, and after air drying, the first surface of the PVT AlN substrate is bombarded with hydrogen plasma of a plasma enhanced chemical vapor deposition system for 1-2 hours.
According to the invention, the first surface of the PVT AlN substrate is bombarded by hydrogen plasma to etch away C, O and other impurity elements adsorbed on the surface of the PVT AlN substrate, the surface of the seed crystal is not damaged, and the interface order degree of the subsequent eutectic pseudo-lattice layer growth is improved, so that the lattice arrangement height of the PVT AlN substrate and the eutectic pseudo-lattice layer is consistent. The actual etching temperature of the hydrogen plasma is 1000-1500 ℃, the pressure in the cavity is 400mbar, and the atmosphere is H with the flow ratio of 5:1 2 And N 2 。
With reference to the first aspect, in some possible implementations, the boron nitride eutectic pseudo-lattice layer is grown using a hydrogen plasma of a plasma enhanced chemical vapor deposition system, wherein a thickness of the boron nitride eutectic pseudo-lattice layer is 0.8-1nm.
On one hand, boron nitride can exist stably in the growth atmosphere of an HVPE (hydrogen phase epitaxy) AlN layer, on the other hand, the difference of lattice constants of III-V group nitride and aluminum nitride is not large, and the boron nitride is adopted as a eutectic pseudo-lattice layer to prevent PVT AlN substrate defects, especially impurity defects, from spreading into the HVPE AlN layer; the thickness of the boron nitride eutectic pseudo-lattice layer is 0.8-1nm, so that the aim of blocking impurities can be fulfilled; too thick (greater than 1 nm) boron nitride eutectic pseudolattice layers can lead to relatively severe lattice distortions that affect the growth of HVPE AlN layers.
With reference to the first aspect, in some possible implementations, the growth temperature of the boron nitride eutectic pseudo-lattice layer is 500-600 ℃, which is a temperature that is suitable for boron nitride deposition as verified by experiments, and at which the AlN wafer in the PVT AlN substrate is not damaged.
With reference to the first aspect, in some possible implementations, the step of epitaxially growing the HVPE AlN layer on the boron nitride eutectic pseudo lattice layer includes: placing PVT AlN substrate growing with boron nitride eutectic pseudo-lattice layer into HVPE growing equipment, and at carrier gas partial pressure P H2 :P N2 And (3) epitaxially growing at least 15h at 1400-1550 ℃ at a raw material flow ratio of Al to N of 7:3 to obtain the HVPE AlN layer.
Although Al is solid, HCl gas flows into a reaction boat filled with metallic Al in the step of epitaxially growing the HVPE AlN layer, so that HCl and Al react to generate AlCl 3 The gas, therefore, the ratio of Al to N raw material flow is 1:3.
The invention finds that when the partial pressure P of the carrier gas H2 :P N At 7:3, the impurity content of the prepared HVPE AlN wafer is lower, the C, si impurity content is 16 times, and the O impurity content is 17 times. The ultraviolet test result shows that the cut-off edge of the HVPE AlN wafer is positioned at 207nm, the ultraviolet transmittance at 280nm is more than 60%, and the 265nm wave band has no obvious absorption, which shows that the HVPE AlN wafer prepared by the invention has the high transmittance performance of the deep ultraviolet wave band.
With reference to the first aspect, in some possible implementations, the HVPE AlN layer has a thickness of 300-500 μm.
When the HVPE AlN layer is too thin (less than 300 mu m), the prior art cannot be processed into slices and the processing process is easy to crack; when the HVPE AlN layer is too thick (more than 500 μm), the HVPE AlN layer is cracked by stress accumulation during growth, and therefore, the thickness of the HVPE AlN layer is preferably 300 to 500 μm.
With reference to the first aspect, in some possible implementations, the step of stripping the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer is: and (3) stripping the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer by adopting wire cutting to obtain an HVPE AlN layer, and then polishing and cleaning the HVPE AlN layer to obtain the HVPE AlN wafer.
In a second aspect, the present invention also provides a deep ultraviolet device, comprising: epitaxially growing an AlGaN functional layer on the HVPE AlN wafer obtained by the preparation method, wherein the parameters of epitaxial growth are as follows: growth temperature1000-1200 ℃, growth pressure of 400-500mbar, NH 3 The flow rate is 200-800sccm, the Al source flow rate is 50-100sccm, and the Ga source flow rate is 5-10sccm.
The embodiment of the invention has the beneficial effects that:
according to the method, the PVT AlN substrate is pretreated by a cleaning and hydrogen plasma high-temperature etching method to remove C, O impurities adsorbed on the surface of the PVT AlN substrate, so that the growth order of the interface of the subsequent boron nitride eutectic pseudo-lattice layer is improved, and the lattice arrangement heights of the PVT AlN substrate and the boron nitride eutectic pseudo-lattice layer are consistent; growing a boron nitride eutectic pseudo-lattice layer on the PVT AlN substrate, wherein the existence of the boron nitride eutectic pseudo-lattice layer does not influence the lattice arrangement of PVT AlN on one hand, and can inhibit the untreated depth C, O impurities in the PVT AlN substrate from being transported upwards from the PVT AlN layer to the HVPE AlN layer under the high-temperature HVPE condition when the AlN layer is grown at a high temperature by the HVPE method, so that the growth of an aluminum gallium nitrogen functional layer is influenced; on the other hand, the existence of the boron nitride eutectic pseudo-lattice layer is beneficial to stripping the PVT AlN substrate and the boron nitride eutectic pseudo-lattice layer from the HVPE AlN layer; and finally, carrying out homoepitaxial growth (the growth epitaxial layer and the substrate are the same materials) on the surface of the boron nitride crystal pseudo-lattice layer by adopting an HVPE method, peeling off the PVT AlN substrate and the boron nitride crystal pseudo-lattice layer to obtain HVPE AlN, grinding and polishing the HVPE AlN layer, and cleaning to obtain the high-purity HVPE AlN wafer. The high-purity HVPE AlN wafer can greatly improve the growth quality of a subsequent AlGaN functional layer, further improve the deep ultraviolet band transmittance performance of the aluminum nitride substrate, and solve the problems that the aluminum nitride lattice is stretched due to thermal mismatch and lattice mismatch of a heterogeneous sapphire-aluminum nitride template, so that the aluminum nitride material and the AlGaN material cannot effectively exert high matching performance.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
FIG. 1 is a schematic flow chart of an HVPE AlN wafer prepared in accordance with the present invention;
FIG. 2 is a schematic diagram of a boron nitride eutectic pseudo-lattice layer prepared in accordance with the present invention;
FIG. 3 is a pictorial view of a prior art high impurity level AlN wafer;
FIG. 4 is a schematic view of HVPE AlN wafer prepared in accordance with the present invention;
FIG. 5 is a graph showing the results of impurity testing of HVPE AlN wafers prepared in accordance with the present invention;
FIG. 6 is a graph showing the transmittance test results of HVPE AlN wafers prepared in accordance with the present invention;
FIG. 7 shows the XRD rocking curve test results of 002 face of HVPE AlN wafer prepared in the present invention;
FIG. 8 is a graph showing the results of a 102-plane XRD rocking curve test of an HVPE AlN wafer prepared in accordance with the present invention;
FIG. 9 is a graph showing AFM test results of epitaxial AlGaN on HVPE AlN wafers prepared in accordance with the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should also be understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the invention. Thus, the appearances of the phrases "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more, but not all, embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.
FIG. 1 is a schematic flow chart of an HVPE AlN wafer prepared in accordance with the present invention;
the specific preparation method comprises the following steps:
and step 101, preprocessing the PVT AlN substrate.
Exemplary, placing PVT AlN substrate (PVT AlN seed crystal) into an operation box in inert atmosphere, cleaning the PVT AlN substrate by adopting deionized water, alcohol and acetone in turn, air-drying by adopting nitrogen, and then adopting hydrogen plasma of a plasma enhanced chemical vapor deposition system, wherein the etching temperature is 1500 ℃, the pressure in the cavity is 400mbar, and the atmosphere is H with the flow ratio of 5:1 2 And N 2 And bombarding the wafer for 1h to obtain the pretreated PVT AlN substrate. According to the invention, the wafer is bombarded by hydrogen plasma to etch away C, O and other impurity elements adsorbed on the surface of the PVT AlN substrate, and the surface of the seed crystal is not damaged, so that the interface order of the subsequent eutectic pseudo-lattice layer growth is improved, and the lattice arrangement height of the PVT AlN substrate and the eutectic pseudo-lattice layer is consistent.
Step 102, a hydrogen plasma enhanced chemical vapor deposition system is adopted on the pretreated PVT AlN substrate, and a reaction gas source is adopted: n (N) 2 ，H 2 ，B 2 H 6 ，N 2 /B 2 H 6 The flow ratio is (10-5) 1, the base temperature: 500-600 ℃, pressure: 200-300pa, radio frequency power: and growing a boron nitride eutectic pseudo-lattice layer under 125-225W. Wherein H is 2 On the one hand as a system carrier gas and on the other hand also as B 2 H 6 Is used as a carrier gas for transportation.
Illustratively, the boron nitride eutectic pseudo-lattice layer has a thickness of 0.8-1nm. Preferably, the thickness of the boron nitride eutectic pseudo-lattice layer is 1nm.
On one hand, boron nitride can exist stably in an HVPE aluminum nitride growth atmosphere, on the other hand, the difference of lattice constants of III-V group nitride and aluminum nitride is not large, and the boron nitride is adopted as a eutectic pseudo-lattice layer to prevent PVT AlN substrate defects, especially impurity defects, from spreading into the HVPE AlN layer; the thickness of the boron nitride eutectic pseudo-lattice layer is 0.8-1nm, so that the aim of blocking impurities can be fulfilled; too thick (greater than 1 nm) boron nitride eutectic pseudolattice layers can lead to relatively severe lattice distortions that affect the growth of HVPE AlN layers.
The growth temperature of the boron nitride eutectic pseudo-lattice layer is 500-600 ℃, which is the temperature suitable for boron nitride deposition through test verification, and the AlN wafer in the PVT AlN substrate is not damaged at the temperature.
FIG. 2 is a schematic diagram of a boron nitride eutectic pseudo-lattice layer prepared in accordance with the present invention.
And 103, epitaxially growing an HVPE AlN layer on the boron nitride eutectic pseudo lattice layer by adopting an HVPE method.
Illustratively, the PVT AlN substrate with the boron nitride eutectic pseudo-lattice layer is immediately placed in an HVPE growth device at a carrier gas partial pressure P H2: P N2 And (3) epitaxially growing for 15 hours at 1400-1500 ℃ with the flow ratio of Al to N being 1:3 to obtain the HVPE AlN layer.
In the present invention, in the growth carrier gas partial pressure P H2 :P N2 When the ratio is 7:3, the impurity content of the prepared AlN single crystal wafer is lower, wherein the impurity content of C, si is 16 times, the impurity content of O is 17 times, and an ultraviolet test result shows that the ultraviolet transmittance of the cut-off edge at the position of 207nm and 280nm is more than 60%, and the 265nm wave band is not obviously absorbed.
The HVPE AlN layer is illustratively 300-500 μm thick. When the HVPE AlN layer is too thin (less than 300 mu m), the prior art cannot be processed into slices and the processing process is easy to crack; when the HVPE AlN layer is too thick (more than 500 μm), the HVPE AlN layer is cracked by stress accumulation during growth, and therefore, the thickness of the HVPE AlN layer is preferably 300 to 500 μm.
In some embodiments, the Al feedstock is 6N grade metallic aluminum particles, the high purity ammonia gas of the N feedstock having a purity of 99.999%.
And 104, stripping the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer to obtain the HVPE AlN wafer.
Illustratively, the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer are peeled off by cutting, and then the HVPE AlN layer is polished and cleaned to obtain the HVPE AlN wafer.
Illustratively, FIG. 3 is a pictorial view of a prior art high impurity level AlN wafer; as can be seen from fig. 3, the high impurity level wafers were amber to yellow in the visible region (i.e., macroscopic range). FIG. 4 is a schematic view of HVPE AlN wafer prepared in accordance with the present invention; as can be seen from fig. 4, the HVPE AlN wafer in the physical image of the present invention is transparent in the visual state, and has a clear appearance and good quality.
The HVPE AlN wafer prepared in the above example was subjected to impurity and transmittance tests, and the results are shown in fig. 5 and 6. FIG. 5 is a graph showing the results of impurity testing of HVPE AlN wafers prepared in accordance with the present invention; as can be seen from fig. 5, the HVPE AlN wafer contains O, si, and C as impurity elements, wherein C, si has an impurity content of 16 times and an O impurity content of 17 times. FIG. 6 is a graph showing the transmittance test results of HVPE AlN wafers prepared in accordance with the present invention; in fig. 6, one sample was tested three times to obtain three corresponding curves. As can be seen from FIG. 6, the transmittance of the HVPE AlN wafer at 280nm or more was more than 65%, and the cut-off edge was 207nm. This shows that the HVPE AlN wafer prepared by the invention has high transmittance in the deep ultraviolet band.
Fig. 7 shows the 002 face XRD rocking curve test results of HVPE AlN wafer prepared in accordance with the present invention. Fig. 8 shows the 102-plane XRD rocking curve test results of HVPE AlN wafer prepared in accordance with the present invention.
While the FWHM of aluminum nitride XRD on sapphire in the prior art is between 100-300arcsec, as can be seen from fig. 7 and 8, both FWHM (002) and (102) of XRD of HVPE AlN wafer prepared in accordance with the present invention are within 50 arcsec. (FWHM is the half width of the measurement standard of the rocking curve, and the smaller the half width is, the better the crystallization quality is), so that the crystal quality of the HVPE AlN wafer obtained by the invention is obviously improved, the ultraviolet band is good, and the growth quality of the aluminum gallium nitride epitaxial layer with a later high Al component can be improved. The invention also solves the problems that the aluminum nitride lattice is stretched due to thermal mismatch and lattice mismatch of the heterogeneous sapphire-aluminum nitride template, so that the aluminum nitride material and the aluminum gallium nitride material cannot effectively exert high matching property.
Corresponding to the preparation method of the HVPE AlN wafer in the embodiment, the invention also provides a deep ultraviolet device, which comprises: the HVPE AlN wafer prepared by any one of the embodiments is used for epitaxially growing an AlGaN functional layer, and has the beneficial effects when the HVPE AlN wafer preparation method of any one of the embodiments is operated.
Step 105, epitaxially growing an AlGaN functional layer on the HVPE AlN wafer.
Illustratively, the resulting HVPE AlN wafer prepared using any of the examples described above, is specifically: epitaxially growing an AlGaN functional layer on the HVPE AlN wafer, wherein the parameters of epitaxial growth are as follows: the growth temperature is 1000-1200 ℃, the growth pressure is 400-500mbar, and the NH is 3 The flow rate is 200-800sccm, the Al source flow rate is 50-100sccm, and the Ga source flow rate is 5-10sccm.
The resulting HVPE AlN wafer was subjected to AFM testing for an epitaxial aluminum gallium nitride functional layer, as shown in fig. 9, for example. FIG. 9 is a graph showing AFM test results of epitaxial AlGaN on an HVPE AlN wafer in the present invention. As can be seen from fig. 9, the AlGaN epitaxial layer is flat and has a good morphology.
In conclusion, the HVPE AlN wafer prepared by the invention obviously reduces the introduction of foreign impurities in the high-purity aluminum nitride (AlN) wafer, and solves the problem that the impurities cause the absorption of deep ultraviolet bands (light with the wavelength of 200-350 nm in ultraviolet rays is called deep ultraviolet rays) of the aluminum nitride wafer. The ultraviolet test result shows that the cut-off edge of the HVPE AlN wafer is positioned at 207nm, the ultraviolet transmittance at 280nm is more than 60%, and the 265nm wave band has no obvious absorption, so that the HVPE AlN wafer prepared by the invention has the high transmittance performance of the deep ultraviolet wave band; the HVPE AlN prepared by the method can also improve the growth quality of a subsequent AlGaN functional layer to a greater extent, further improve the deep ultraviolet band transmittance performance of the aluminum nitride substrate, and solve the problems that the aluminum nitride lattice is stretched and the aluminum nitride material and the AlGaN material cannot effectively exert high matching performance due to thermal mismatch and lattice mismatch of a heterogeneous sapphire-aluminum nitride template.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (9)
1. A preparation method of a high-purity high-transmittance AlN wafer is characterized by comprising the following steps:
growing a boron nitride eutectic pseudo-lattice layer on a first surface of the PVT AlN substrate;
epitaxially growing an HVPE AlN layer on the boron nitride eutectic pseudo-lattice layer;
and stripping the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer to obtain the HVPE AlN wafer.
2. The method according to claim 1, further comprising a step of pre-treating the PVT AlN substrate, in particular, before said growing the boron nitride eutectic pseudo-lattice layer on the first surface of the PVT AlN substrate: and bombarding the first surface of the PVT AlN substrate by hydrogen plasma of a plasma enhanced chemical vapor deposition system for 1-2h.
3. The method of claim 1 or 2, wherein the boron nitride eutectic pseudo-lattice layer is grown using a hydrogen plasma of a plasma enhanced chemical vapor deposition system, wherein the thickness of the boron nitride eutectic pseudo-lattice layer is 0.8-1nm.
4. A method of manufacturing according to claim 3, wherein the boron nitride eutectic pseudo-lattice layer has a growth temperature of 500-600 ℃.
5. The method of claim 1, wherein the step of epitaxially growing an HVPE AlN layer on the boron nitride eutectic pseudolattice layer comprises:
placing PVT AlN substrate growing with boron nitride eutectic pseudo-lattice layer into HVPE growing equipment, and at carrier gas partial pressure P H2 :P N2 And (5-7) epitaxially growing at 1400-1550 ℃ for at least 15h to obtain the HVPE AlN layer, wherein the flow ratio of the Al to the N is 1:3.
6. The method according to claim 5, wherein the HVPE AlN layer has a thickness of 300-500 μm.
7. The method of claim 1, wherein the step of stripping the PVT AlN substrate and boron nitride eutectic pseudo-lattice layer comprises: and stripping the PVT AlN substrate and the boron nitride eutectic pseudo lattice layer by adopting wire cutting, grinding and polishing the HVPE AlN layer, and cleaning to obtain the HVPE AlN wafer.
8. A deep ultraviolet device, comprising: an aluminum gallium nitride functional layer is epitaxially grown on the HVPE AlN wafer obtained by the method of any one of claims 1-7.
9. The deep ultraviolet device of claim 8, wherein an aluminum gallium nitride functional layer is epitaxially grown on the HVPE AlN wafer, wherein parameters of epitaxial growth are: the growth temperature is 1000-1200 ℃, the growth pressure is 400-500mbar, and the NH is 3 The flow rate is 200-800sccm, the Al source flow rate is 50-100sccm, and the Ga source flow rate is 5-10sccm.
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| CN202311790936.4A CN117747418A (en) | 2023-12-22 | 2023-12-22 | Preparation method of high-purity high-transmittance AlN wafer and deep ultraviolet device |
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