CN117894830A - Diamond aluminum nitride heterojunction field effect transistor and preparation method thereof - Google Patents
Diamond aluminum nitride heterojunction field effect transistor and preparation method thereof Download PDFInfo
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- 229910003460 diamond Inorganic materials 0.000 title claims abstract description 149
- 239000010432 diamond Substances 0.000 title claims abstract description 149
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 title claims abstract description 130
- 238000002360 preparation method Methods 0.000 title abstract description 22
- 238000002353 field-effect transistor method Methods 0.000 title description 2
- 239000011241 protective layer Substances 0.000 claims abstract description 66
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 56
- 239000001257 hydrogen Substances 0.000 claims abstract description 56
- 239000000758 substrate Substances 0.000 claims abstract description 55
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 53
- 230000005669 field effect Effects 0.000 claims abstract description 52
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 39
- 239000001301 oxygen Substances 0.000 claims abstract description 39
- 238000009832 plasma treatment Methods 0.000 claims abstract description 23
- 238000005530 etching Methods 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims description 17
- 239000010410 layer Substances 0.000 claims description 11
- 229910052751 metal Inorganic materials 0.000 claims description 11
- 239000002184 metal Substances 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 239000013078 crystal Substances 0.000 claims description 9
- 238000001259 photo etching Methods 0.000 claims description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 239000010931 gold Substances 0.000 claims description 5
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052737 gold Inorganic materials 0.000 claims description 4
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- 238000005229 chemical vapour deposition Methods 0.000 claims description 3
- 229910000449 hafnium oxide Inorganic materials 0.000 claims description 3
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 claims description 3
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 3
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 150000002902 organometallic compounds Chemical class 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 11
- 230000006911 nucleation Effects 0.000 description 6
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- 238000000231 atomic layer deposition Methods 0.000 description 4
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- 238000000151 deposition Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
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- 230000004913 activation Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
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- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- DKNPRRRKHAEUMW-UHFFFAOYSA-N Iodine aqueous Chemical compound [K+].I[I-]I DKNPRRRKHAEUMW-UHFFFAOYSA-N 0.000 description 1
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- 125000004432 carbon atom Chemical group C* 0.000 description 1
- RZVXOCDCIIFGGH-UHFFFAOYSA-N chromium gold Chemical compound [Cr].[Au] RZVXOCDCIIFGGH-UHFFFAOYSA-N 0.000 description 1
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- 239000003989 dielectric material Substances 0.000 description 1
- 238000005566 electron beam evaporation Methods 0.000 description 1
- FHUGMWWUMCDXBC-UHFFFAOYSA-N gold platinum titanium Chemical compound [Ti][Pt][Au] FHUGMWWUMCDXBC-UHFFFAOYSA-N 0.000 description 1
- ZNKMCMOJCDFGFT-UHFFFAOYSA-N gold titanium Chemical compound [Ti].[Au] ZNKMCMOJCDFGFT-UHFFFAOYSA-N 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
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- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000002207 thermal evaporation Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910001258 titanium gold Inorganic materials 0.000 description 1
- -1 titanium tungsten platinum gold Chemical compound 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
Abstract
The invention provides a diamond aluminum nitride heterojunction field effect transistor and a preparation method thereof, wherein the method comprises the following steps: a protective layer is prepared on a target area of the upper surface of the diamond substrate. And carrying out oxygen plasma treatment on the surface of the diamond substrate outside the target area to obtain an oxygen terminal. And removing the protective layer of the target area, and epitaxially growing aluminum nitride in the target area under the shielding of the oxygen terminal to prepare the conductive channel of the diamond aluminum nitride heterojunction. And carrying out hydrogen plasma treatment on the oxygen terminal outside the target area under the shielding of aluminum nitride in the target area to obtain a hydrogen terminal conducting channel. And preparing a source electrode and a drain electrode on a conducting channel of the hydrogen terminal, and preparing a gate electrode on aluminum nitride to obtain the field effect transistor. The method and the device solve the problem that the etching depth is difficult to control and difficult to etch to the heterojunction conductive channel in the existing mode, and reduce the preparation difficulty of the device.
Description
Technical Field
The invention relates to the technical field of diamond semiconductor materials, in particular to a diamond aluminum nitride heterojunction field effect transistor and a preparation method thereof.
Background
The diamond material has the advantages of wide band gap, high carrier mobility, high carrier saturation drift velocity, low dielectric constant, radiation resistance, corrosion resistance and the like, and can be used for preparing high-frequency power devices. However, due to the wide band gap of diamond, when the conventional doping technology realizes the conductive characteristic, the activation energy of doping elements (B, P, S and the like) is high, the activation rate of the doping elements is low, and the problems of low carrier concentration, low mobility, high sheet resistance and the like of the diamond semiconductor material are caused. The aluminum nitride grows on the diamond to form a heterojunction, so that a high-performance two-dimensional carrier conducting channel can be obtained in the diamond, and the diamond material with high conductivity can be obtained.
The existing preparation method of the diamond aluminum nitride heterojunction field effect transistor device etches an aluminum nitride layer to a heterojunction, namely a combination interface of diamond and aluminum nitride, so that a source electrode and a drain electrode are prepared on the heterojunction serving as a conducting channel to form ohmic contact. The thickness of the diamond aluminum nitride heterojunction is typically thin, for example around 10nm. The existing etching mode is difficult to accurately control the etching depth just above the diamond aluminum nitride heterojunction. When the etching depth is too shallow, only the aluminum nitride layer is etched, and ohmic contact is difficult to form on the aluminum nitride layer by the source electrode and the drain electrode; when the etching depth is too deep, the diamond layer is etched, the diamond aluminum nitride heterojunction serving as the conducting channel is removed, and the conducting channel is not arranged below the source electrode and the drain electrode, so that the function of the device cannot be realized.
Disclosure of Invention
The invention provides a diamond aluminum nitride heterojunction field effect transistor and a preparation method thereof, which are used for solving the problems that the etching depth is difficult to control and the preparation difficulty of a diamond aluminum nitride heterojunction field effect transistor device is high in the existing etching mode.
In a first aspect, the present invention provides a method for preparing a diamond aluminum nitride heterojunction field effect transistor, comprising: and preparing a protective layer in a target area on the upper surface of the diamond substrate, wherein the target area corresponds to an area between a source electrode and a drain electrode of the field effect transistor. And carrying out oxygen plasma treatment on the surface of the diamond substrate outside the target area to obtain an oxygen terminal. And removing the protective layer of the target area, and epitaxially growing aluminum nitride in the target area under the shielding of the oxygen terminal to prepare the conductive channel of the diamond aluminum nitride heterojunction. And under the shielding of aluminum nitride of the target area, performing hydrogen plasma treatment on the oxygen terminal outside the target area to obtain a hydrogen terminal conducting channel. And preparing a source electrode and a drain electrode on a conducting channel of the hydrogen terminal, and preparing a gate electrode on the aluminum nitride to obtain the field effect transistor.
In one possible implementation, the preparing a protective layer on the target area of the upper surface of the diamond substrate includes: and growing a protective layer on the upper surface of the diamond substrate. And photoetching on the protective layer to prepare a photoetching mask for covering the target area. Etching under the shielding of the photoetching mask, and removing the protective layer outside the target area to prepare the protective layer covering the target area so as to expose the surface of the diamond substrate outside the target area.
In one possible implementation, before the preparation of the protective layer in the target region on the upper surface of the diamond substrate, the method further includes: and carrying out hydrogen plasma treatment on the upper surface of the diamond substrate. Accordingly, oxygen plasma treating the surface of the diamond substrate outside the target region comprises: and carrying out oxygen plasma treatment on the surface of the diamond substrate outside the target area, and replacing the hydrogen terminal outside the target area with an oxygen terminal. Accordingly, after the protective layer of the target region is removed, the surface of the diamond substrate of the target region is a hydrogen termination.
In one possible implementation, the diamond substrate is a 001 crystal orientation, cubic structure. Correspondingly, epitaxially growing aluminum nitride in the target area, and preparing the conducting channel of the diamond aluminum nitride heterojunction comprises the following steps: and growing cubic-structure aluminum nitride on the hydrogen terminal of the surface of the diamond substrate in the target area to prepare the conductive channel of the cubic-structure diamond aluminum nitride heterojunction.
In one possible implementation, epitaxially growing aluminum nitride in the target region includes: and placing the diamond substrate after the protective layer is removed in metal organic compound chemical vapor deposition equipment, and heating to a preset epitaxial temperature. Introducing hydrogen, trimethylaluminum and ammonia gas at a preset epitaxial temperature, and epitaxially growing aluminum nitride.
In one possible implementation, the protective layer is a dielectric protective layer or a metal protective layer.
In one possible implementation, the material of the dielectric protective layer includes aluminum oxide, hafnium oxide, zirconium oxide, or silicon oxide.
In one possible implementation, the material of the metal protection layer includes gold or aluminum.
In one possible implementation, the aluminum nitride has a thickness in the range of 1nm to 500nm.
In a second aspect, the present invention provides a diamond aluminum nitride heterojunction field effect transistor, which is prepared based on the preparation method of the diamond aluminum nitride heterojunction field effect transistor provided in any one of the possible implementation manners.
The invention provides a diamond aluminum nitride heterojunction field effect transistor and a preparation method thereof, wherein the method comprises the following steps: and preparing a protective layer in a target area on the upper surface of the diamond substrate, wherein the target area corresponds to an area between a source electrode and a drain electrode of the field effect transistor. And carrying out oxygen plasma treatment on the surface of the diamond substrate outside the target area to obtain an oxygen terminal. And removing the protective layer of the target area, and epitaxially growing aluminum nitride in the target area under the shielding of the oxygen terminal to prepare the conductive channel of the diamond aluminum nitride heterojunction. And carrying out hydrogen plasma treatment on the oxygen terminal outside the target area under the shielding of aluminum nitride in the target area to obtain a hydrogen terminal conducting channel. And preparing a source electrode and a drain electrode on a conducting channel of the hydrogen terminal, and preparing a gate electrode on aluminum nitride to obtain the field effect transistor. According to the invention, aluminum nitride is epitaxially grown on a diamond in a selected area, and a conductive channel of the diamond aluminum nitride heterojunction is prepared in a target area. And then preparing a conductive channel of the hydrogen terminal outside the target area. The conducting channels inside and outside the prepared target area are positioned on the same horizontal plane and are mutually communicated to form an integral conducting channel, and then the source-drain grid is prepared on the basis of the integral conducting channel to obtain the field effect transistor. The method and the device solve the problem that the etching depth is difficult to control and difficult to etch to the heterojunction conductive channel in the existing mode, and reduce the preparation difficulty of the device.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a prior art diamond aluminum nitride heterojunction field effect transistor;
fig. 2 is a flowchart of a method for manufacturing a diamond aluminum nitride heterojunction field effect transistor according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a structure after a protective layer is prepared according to an embodiment of the present invention;
FIG. 4 is a schematic view of the structure after oxygen plasma treatment according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of the structure of an embodiment of the present invention after aluminum nitride is prepared;
FIG. 6 is a schematic diagram of a structure after preparing a hydrogen conduction channel according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a diamond aluminum nitride heterojunction field effect transistor according to an embodiment of the present invention.
Detailed Description
In order to make the present solution better understood by those skilled in the art, the technical solution in the present solution embodiment will be clearly described below with reference to the accompanying drawings in the present solution embodiment, and it is obvious that the described embodiment is an embodiment of a part of the present solution, but not all embodiments. All other embodiments, based on the embodiments in this solution, which a person of ordinary skill in the art would obtain without inventive faculty, shall fall within the scope of protection of this solution.
The term "comprising" in the description of the present solution and the claims and in the above-mentioned figures, as well as any other variants, means "including but not limited to", intended to cover a non-exclusive inclusion, and not limited to only the examples listed herein. Furthermore, the terms "first" and "second," etc. are used for distinguishing between different objects and not for describing a particular sequential order.
The implementation of the invention is described in detail below with reference to the specific drawings:
fig. 1 is a schematic diagram of a prior art diamond aluminum nitride heterojunction field effect transistor. Fig. 1 is a schematic cross-sectional structure of a field effect transistor. Referring to fig. 1, an aluminum nitride diamond heterojunction is arranged below a source electrode and a drain electrode of a field effect transistor. The preparation method comprises etching aluminum nitride onto the diamond aluminum nitride heterojunction, and preparing source electrode and drain electrode on the heterojunction. When the etching depth is too shallow, only the aluminum nitride layer is etched, and ohmic contact is difficult to form on the aluminum nitride layer by the source electrode and the drain electrode. When the etching depth is too deep, the diamond layer is etched, the diamond aluminum nitride heterojunction serving as the conducting channel is removed, and the conducting channel is not arranged below the source electrode and the drain electrode, so that the function of the device cannot be realized.
According to the preparation method of the diamond aluminum nitride heterojunction field effect transistor, provided by the embodiment of the invention, the conducting channel of the diamond aluminum nitride heterojunction is epitaxially grown through the selected area, and the conducting channel of the hydrogen terminal is prepared on the same horizontal plane, so that the problems that the etching depth is difficult to control and the preparation difficulty of the diamond aluminum nitride heterojunction field effect transistor device is high in the existing etching mode are solved.
Fig. 2 is a flowchart of a method for manufacturing a diamond aluminum nitride heterojunction field effect transistor according to an embodiment of the present invention. Referring to fig. 2, the method includes:
in step 201, a protective layer is prepared on a target region of the upper surface of the diamond substrate, wherein the target region corresponds to a region between a source electrode and a drain electrode of the field effect transistor.
Illustratively, the diamond substrate is a single crystal. Further exemplary, the diamond substrate is a single crystal of cubic structure.
Illustratively, the target area is a rectangular area. For example, the region between the strip-shaped source electrode and the strip-shaped drain electrode constitutes a rectangular target region, or so-called mesa region. The target region is used for growing aluminum nitride in a subsequent step.
It should be noted that the prepared protective layer is distributed in the target area and is used for protecting the target area. No protective layer is present outside the target area or the protective layer outside the target area has been removed. An example is given below to illustrate a specific preparation process of the protective layer in the target region.
Fig. 3 is a schematic structural diagram of a protective layer according to an embodiment of the present invention. Referring to fig. 3, in one possible implementation, preparing a protective layer on a target area of an upper surface of a diamond substrate includes:
in step 2011, a protective layer is grown on the upper surface of the diamond substrate.
The protective layer has a thickness in the range of 10 to 100nm, for example.
Illustratively, the protective layer is a dielectric protective layer or a metal protective layer. For example, the material of the dielectric protective layer includes aluminum oxide, hafnium oxide, zirconium oxide, or silicon oxide. For another example, the material of the metal protective layer includes gold or aluminum.
In some embodiments, the growth method of the dielectric protective layer may be atomic layer deposition, thermal evaporation, or the like.
In some embodiments, the deposition method of the metal protection layer may be electron beam evaporation, atomic layer deposition, or the like.
In step 2012, photolithography is performed on the protective layer to prepare a photolithographic mask covering the target area.
In some embodiments, photoresist is coated on the protective layer, and photolithography and development are performed to prepare a photolithography mask covering the target area.
In step 2013, etching is performed under the shielding of the photolithography mask, and the protective layer outside the target area is removed, so as to prepare a protective layer covering the target area, so as to expose the surface of the diamond substrate outside the target area.
In some embodiments, the etching to remove the protective layer outside the target region includes: dry etching or wet etching.
Illustratively, the dry etching may be ICP or RIE or the like. Still another exemplary etchant for wet etching may be iodine and potassium iodide solution, hydrofluoric acid, etc. The etchant can be selected correspondingly according to different etching materials.
In step 202, an oxygen plasma treatment is performed on the surface of the diamond substrate outside the target region to obtain an oxygen termination.
Fig. 4 is a schematic structural diagram of an oxygen plasma treated structure according to an embodiment of the present invention. Referring to fig. 4: after oxygen plasma treatment, the carbon atoms and oxygen atoms on the surface of the diamond substrate outside the target area are combined into C-O bonds to form an oxygen terminal.
In step 203, the protective layer of the target area is removed, and aluminum nitride is epitaxially grown in the target area under the shielding of the oxygen terminal, so as to prepare a conductive channel of the diamond aluminum nitride heterojunction.
In some embodiments, the protective layer of the target region is removed by wet etching.
The surface outside the target area is an oxygen terminal, the nucleation energy requirement is high during epitaxial growth, and aluminum nitride cannot be grown. After the protective layer of the target region is removed, the diamond substrate surface of the target region is exposed, and aluminum nitride can be epitaxially grown in the target region.
Fig. 5 is a schematic structural diagram of an embodiment of the present invention after aluminum nitride is prepared. Referring to fig. 5, aluminum nitride is epitaxially grown in a target region, and a portion of the aluminum nitride in contact with the diamond substrate forms a diamond aluminum nitride heterojunction. The diamond aluminum nitride heterojunction forms a conductive channel with high conductivity efficiency. Meanwhile, aluminum nitride is not grown outside the target region.
The thickness of aluminum nitride is illustratively in the range of 1nm to 500nm.
In step 204, hydrogen plasma treatment is performed on the oxygen termination outside the target area under the shielding of aluminum nitride in the target area to obtain a hydrogen termination conductive channel.
Fig. 6 is a schematic structural diagram of a hydrogen conducting channel according to an embodiment of the present invention. Referring to fig. 6, in some embodiments, the oxygen termination outside the target region is subjected to a hydrogen plasma treatment to remove carbon-oxygen bonds, replaced with hydrocarbon bonds, and a hydrogen termination is formed, resulting in a hydrogen conduction channel.
The aluminum nitride in the target region serves as a masking layer so that only the surface of the diamond substrate outside the target region is treated during oxygen treatment. It should be further noted that the surfaces of the diamond substrate inside and outside the target region are on the same plane, the heterojunction is formed on the upper surface of the diamond substrate, and the hydrogen termination is also formed on the upper surface of the diamond substrate. The heterojunction and the hydrogen terminal are on the same plane and are communicated with each other to form an integral conductive channel.
In step 205, a source electrode and a drain electrode are prepared on a conductive channel of a hydrogen terminal, and a gate electrode is prepared on aluminum nitride, thereby obtaining a field effect transistor.
In some embodiments, source and drain electrodes are fabricated on the conductive channel of the hydrogen termination.
Exemplary materials for the source and drain electrodes include titanium gold, titanium platinum gold, titanium tungsten platinum gold, palladium gold, or chromium gold.
The alloy temperature ranges from 500 to 1000 c when preparing the source and drain electrodes, for example. For example, it may be 800 ℃.
In some embodiments, a gate electrode is fabricated on aluminum nitride by a metal strip process.
Illustratively, the material of the gate electrode is aluminum, lead, or copper.
The gate electrode has a gate morphology of straight gate, T-gate, TT-gate, U-gate or Y-gate, for example. Further exemplary, the gate electrode has a gate topography that is a combination of the various gate morphologies described above.
Illustratively, the method further comprises, prior to preparing the gate electrode: a gate dielectric is prepared over the aluminum nitride. Further exemplary, the gate dielectric material may be SiO x 、TiO x 、AlO x 、CuO x 、NiO x Or ZnO x . Further exemplary, the gate dielectric has a thickness in the range of 1 to 100nm.
According to the embodiment of the invention, the aluminum nitride is epitaxially grown on the diamond in a selected area, and the conductive channel of the diamond aluminum nitride heterojunction is prepared in the target area. And then preparing a conductive channel of the hydrogen terminal outside the target area. The conducting channels inside and outside the prepared target area are positioned on the same horizontal plane and are mutually communicated to form an integral conducting channel, and then the source-drain grid is prepared on the basis of the integral conducting channel to obtain the field effect transistor. The method and the device solve the problem that the etching depth is difficult to control and difficult to etch to the heterojunction conductive channel in the existing mode, and reduce the preparation difficulty of the device. The embodiment of the invention can realize a high-performance diamond/aluminum nitride heterojunction field effect transistor device.
In one possible implementation, before the preparation of the protective layer in the target region on the upper surface of the diamond substrate, the method further includes: a hydrogen plasma treatment is performed on the upper surface of the diamond substrate. Accordingly, oxygen plasma treatment of the surface of the diamond substrate outside the target region includes: oxygen plasma treatment is performed on the surface of the diamond substrate outside the target area, and hydrogen terminals outside the target area are replaced by oxygen terminals. Accordingly, after the protective layer of the target region is removed, the diamond substrate surface of the target region is hydrogen terminated.
After the surface of the diamond was subjected to hydrogen plasma treatment, the surface of the diamond was terminated with hydrogen. The hydrogen termination outside the target area is replaced with an oxygen termination after oxygen plasma treatment. The diamond substrate surface within the target area remains hydrogen terminated under the protection of the protective layer. Accordingly, after the protective layer of the target region is removed, the diamond substrate surface of the target region is hydrogen terminated. Further, in step 203, when epitaxially growing aluminum nitride in the target area, growing aluminum nitride on a hydrogen terminated basis reduces the energy required for nucleation, facilitates nucleation of aluminum nitride, and facilitates growth of aluminum nitride.
According to the embodiment of the invention, the protective layer is grown after hydrogen treatment, so that the target area after the protective layer is removed in the step 203 is a hydrogen terminal, aluminum nitride grows on the basis of the hydrogen terminal, the energy required by nucleation is reduced, aluminum nitride nucleation is easy, aluminum nitride growth is easy, and the quality of a conductive channel of the diamond aluminum nitride heterojunction is high.
In one possible implementation, the diamond substrate is a 001 crystal orientation, cubic structure. Correspondingly, epitaxially growing aluminum nitride in a target area, and preparing the conducting channel of the diamond aluminum nitride heterojunction comprises the following steps: growing cubic structure aluminum nitride on the hydrogen terminal of the surface of the diamond substrate in the target area to prepare the conductive channel of the cubic structure diamond aluminum nitride heterojunction.
According to the embodiment of the invention, on one hand, the 001 crystal orientation cubic structure diamond substrate is adopted for epitaxial growth, so that the cubic structure aluminum nitride can be prepared, and the diamond aluminum nitride heterojunction is formed. On the other hand, by first carrying out hydrogen treatment on the cubic structure diamond and then growing aluminum nitride, the nucleation energy of the aluminum nitride is reduced, and the cubic structure aluminum nitride is easy to grow. The prepared cubic diamond/cubic aluminum nitride heterojunction epitaxial material has high matching degree of heterogeneous crystal lattices and few heterojunction interface epitaxial defects, and the conductivity of the diamond aluminum nitride heterojunction epitaxial material is improved.
The diamond is in a cubic structure, an aluminum nitride material with the cubic structure is epitaxially grown on the diamond to form a lattice matched heterostructure, a high-performance two-dimensional carrier conducting channel is obtained, the conducting channel has excellent characteristics of high mobility, low sheet resistance and the like, and the saturation current, transconductance and breakdown voltage of a diamond field effect transistor device can be improved by using the diamond/aluminum nitride heterojunction as the conducting channel, so that the diamond field effect transistor with high frequency, high gain, high output power density and high efficiency is realized, the performance of the diamond field effect transistor device is greatly improved, and the diamond device is promoted to advance towards application.
In one possible implementation, epitaxially growing aluminum nitride in the target region includes:
in step 2031, the diamond substrate after removal of the protective layer is placed in a metal organic chemical vapor deposition apparatus and heated to a preset epitaxy temperature.
In step 2032, hydrogen, trimethylaluminum and ammonia are introduced at a preset epitaxy temperature to epitaxially grow aluminum nitride.
The preset epitaxy temperature is, for example, in the range of 900 to 1200 ℃.
Illustratively, the temperature is raised to a preset epitaxial temperature under a hydrogen atmosphere.
In connection with the above examples of the preparation method, a specific embodiment is given below to further illustrate the present scheme: and (3) carrying out hydrogenation treatment on a target area on the surface of the single crystal diamond, growing cubic aluminum nitride on the target area by an MOCVD method, preparing a hydrogen conducting channel and a source-drain electrode at the edge of the target area, and preparing a gate electrode on the aluminum nitride to realize the preparation of the diamond/aluminum nitride heterojunction field effect transistor device. The specific technical scheme comprises the following steps:
the first step, high quality single crystal diamond is processed under hydrogen plasma to form C-H bond on the diamond surface, the atomic layer deposition technology is utilized to grow medium as a protective layer on the diamond surface, a target area is photoetched, the protective layer of the area outside the target area is removed through wet etching, then the C-H bond is removed through oxygen plasma processing to form C-O bond, the C-H bond is reserved in the target area, and the protective layer of the target area is removed through wet etching.
And secondly, placing the diamond with the target area being C-H bond in an MOCVD system, and growing aluminum nitride to 15nm by taking trimethylaluminum as an aluminum source and ammonia as a nitrogen source under the conditions of 1050 ℃ and hydrogen atmosphere.
And thirdly, hydrogen plasma treatment. Photoetching source and drain, depositing source and drain ohmic contact metal Ti/Au, and alloying at 800 ℃ to obtain a source and drain electrode.
And fourthly, growing an alumina medium by utilizing an atomic layer deposition technology to serve as a gate medium, wherein the thickness of the alumina is 10nm.
Fifth, photoetching the gate, depositing gate metal Al, and stripping to form the gate.
The embodiment of the invention provides a preparation method of a diamond/aluminum nitride heterojunction field effect transistor device with a cubic structure, which is characterized in that an aluminum nitride material with the cubic structure epitaxially grows on diamond to form a lattice-matched heterostructure to obtain a high-performance two-dimensional carrier conducting channel, the conducting channel has excellent characteristics of high mobility, low sheet resistance and the like, and the saturation current, transconductance and breakdown voltage of the diamond field effect transistor device can be improved by using the diamond/aluminum nitride heterojunction as the conducting channel, so that the diamond field effect transistor with high frequency, high gain, high output power density and high efficiency is realized, the performance of the diamond field effect transistor device is greatly improved, and the diamond device is promoted to be applied.
Fig. 7 is a schematic structural diagram of a diamond aluminum nitride heterojunction field effect transistor according to an embodiment of the present invention. Referring to fig. 7: the invention provides a diamond aluminum nitride heterojunction field effect transistor, which is prepared based on the preparation method of the diamond aluminum nitride heterojunction field effect transistor provided in any one of the possible implementation modes.
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 of the 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.
Claims (10)
1. A method for fabricating a diamond aluminum nitride heterojunction field effect transistor, comprising:
preparing a protective layer in a target area on the upper surface of the diamond substrate, wherein the target area corresponds to an area between a source electrode and a drain electrode of the field effect transistor;
performing oxygen plasma treatment on the surface of the diamond substrate outside the target area to obtain an oxygen terminal;
removing the protective layer of the target area, and epitaxially growing aluminum nitride in the target area under the shielding of the oxygen terminal to prepare a conductive channel of the diamond aluminum nitride heterojunction;
under the shielding of aluminum nitride of the target area, performing hydrogen plasma treatment on the oxygen terminal outside the target area to obtain a conductive channel of the hydrogen terminal;
and preparing a source electrode and a drain electrode on a conducting channel of the hydrogen terminal, and preparing a gate electrode on the aluminum nitride to obtain the field effect transistor.
2. The method of fabricating a diamond aluminum nitride heterojunction field effect transistor of claim 1, wherein fabricating a protective layer on the target region of the upper surface of the diamond substrate comprises:
growing a protective layer on the upper surface of the diamond substrate;
photoetching is carried out on the protective layer, and a photoetching mask covering a target area is prepared;
etching under the shielding of the photoetching mask, and removing the protective layer outside the target area to prepare the protective layer covering the target area so as to expose the surface of the diamond substrate outside the target area.
3. The method of fabricating a diamond aluminum nitride heterojunction field effect transistor of claim 1, further comprising, prior to fabricating the protective layer in the target region on the upper surface of the diamond substrate:
performing hydrogen plasma treatment on the upper surface of the diamond substrate;
accordingly, oxygen plasma treating the surface of the diamond substrate outside the target region comprises:
oxygen plasma treatment is carried out on the surface of the diamond substrate outside the target area, and the hydrogen terminal outside the target area is replaced by an oxygen terminal;
accordingly, after the protective layer of the target region is removed, the surface of the diamond substrate of the target region is a hydrogen termination.
4. The method of fabricating a diamond aluminum nitride heterojunction field effect transistor of claim 3, wherein the diamond substrate has a 001 crystal orientation, cubic structure;
correspondingly, epitaxially growing aluminum nitride in the target area, and preparing the conducting channel of the diamond aluminum nitride heterojunction comprises the following steps:
and growing cubic-structure aluminum nitride on the hydrogen terminal of the surface of the diamond substrate in the target area to prepare the conductive channel of the cubic-structure diamond aluminum nitride heterojunction.
5. The method of fabricating a diamond aluminum nitride heterojunction field effect transistor of claim 1, wherein epitaxially growing aluminum nitride in the target region comprises:
placing the diamond substrate after the protective layer is removed in metal organic compound chemical vapor deposition equipment, and heating to a preset epitaxial temperature;
introducing hydrogen, trimethylaluminum and ammonia gas at a preset epitaxial temperature, and epitaxially growing aluminum nitride.
6. The method of manufacturing a diamond aluminum nitride heterojunction field effect transistor of claim 1, wherein the protective layer is a dielectric protective layer or a metal protective layer.
7. The method of manufacturing a diamond aluminum nitride heterojunction field effect transistor of claim 6, wherein the material of the dielectric protective layer comprises aluminum oxide, hafnium oxide, zirconium oxide or silicon oxide.
8. The method of manufacturing a diamond aluminum nitride heterojunction field effect transistor of claim 6, wherein the material of the metal protection layer comprises gold or aluminum.
9. The method of fabricating a diamond aluminum nitride heterojunction field effect transistor of claim 1, wherein the thickness of the aluminum nitride is in the range of 1nm to 500nm.
10. A diamond aluminum nitride heterojunction field effect transistor prepared based on the method of preparing a diamond aluminum nitride heterojunction field effect transistor as claimed in any one of claims 1 to 9.
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