CN114420753A - HEMT device, HEMT epitaxial structure based on GaN substrate and manufacturing method - Google Patents

HEMT device, HEMT epitaxial structure based on GaN substrate and manufacturing method Download PDF

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CN114420753A
CN114420753A CN202011174655.2A CN202011174655A CN114420753A CN 114420753 A CN114420753 A CN 114420753A CN 202011174655 A CN202011174655 A CN 202011174655A CN 114420753 A CN114420753 A CN 114420753A
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hemt
epitaxial structure
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gan substrate
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王国斌
王建峰
徐科
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Jiangsu Third Generation Semiconductor Research Institute Co Ltd
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Jiangsu Third Generation Semiconductor Research Institute Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007—Multistep manufacturing processes
    • H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
    • H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
    • H01L29/66409—Unipolar field-effect transistors
    • H01L29/66446—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET]
    • H01L29/66462—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET] with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/10—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions with semiconductor regions connected to an electrode not carrying current to be rectified, amplified or switched and such electrode being part of a semiconductor device which comprises three or more electrodes
    • H01L29/107—Substrate region of field-effect devices
    • H01L29/1075—Substrate region of field-effect devices of field-effect transistors
    • H01L29/1079—Substrate region of field-effect devices of field-effect transistors with insulated gate
    • H01L29/1083—Substrate region of field-effect devices of field-effect transistors with insulated gate with an inactive supplementary region, e.g. for preventing punch-through, improving capacity effect or leakage current
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/778—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface
    • H01L29/7782—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with confinement of carriers by at least two heterojunctions, e.g. DHHEMT, quantum well HEMT, DHMODFET
    • H01L29/7783—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with confinement of carriers by at least two heterojunctions, e.g. DHHEMT, quantum well HEMT, DHMODFET using III-V semiconductor material

Abstract

The invention discloses an HEMT device, an HEMT epitaxial structure based on a GaN substrate and a manufacturing method. The HEMT epitaxial structure based on the GaN substrate comprises an interface processing layer, a barrier layer, an isolation layer, a channel layer and a contact layer which are sequentially formed on a semi-insulating GaN substrate with N-surface polarity. The HEMT device with the new epitaxial structure is provided based on the characteristics of the N-face GaN substrate, and has higher frequency characteristics compared with the traditional structure; the GaN substrate and the semi-insulating property can be prepared in the early stage, so that adverse effects caused by the growth of a high-resistance epitaxial layer in the later stage can be avoided; and homoepitaxy does not have the problem of a high-density dislocation buffer layer on a heterogeneous substrate, and proper interface treatment is carried out before epitaxy, so that the generation of a leakage channel can be completely blocked.

Description

HEMT device, HEMT epitaxial structure based on GaN substrate and manufacturing method
Technical Field
The invention relates to a HEMT device, in particular to a HEMT device, a HEMT epitaxial structure based on a GaN substrate and a manufacturing method, and belongs to the technical field of semiconductors.
Background
Most of the current GaN-based HEMT devices are prepared on SiC/Si and other heterogeneous substrates, as shown in FIG. 1, an HEMT epitaxial structure based on a SiC heterogeneous substrate needs to deposit an AlN buffer layer in advance in the manufacturing process, so that the lattice mismatch with GaN is reduced; after the buffer layer is transited, continuously growing an iron-or carbon-doped high-resistance GaN layer, wherein a GaN channel layer, an AlN isolating layer, an AlGaN barrier layer and a GaN cap layer structure are sequentially stacked on the high-resistance GaN layer; wherein, a very big potential well can be formed at the interface of the GaN channel layer and the AlGaN barrier layer, electrons are limited in the thin layer, high-density two-dimensional electron gas (2DEG) is formed in the channel layer, and the AlN isolating layer is very thin, so that the interface quality can be improved, the scattering can be reduced, the electron mobility can be improved, meanwhile, the discontinuity of a conduction band can be improved, and the density of the 2DEG can be increased; the purpose of the GaN cap layer is to reduce a gate electric field, inhibit gate current and reduce the generation of surface oxides, and the whole GaN-based HEMT device has Ga-face polarity.
Although the crystal quality is improved by the progress of the epitaxial technology, the requirement on the output efficiency of the device is further improved along with the new application of the high-frequency field such as microwave heating, 5G system communication and the like, and as the buffer layer on the heterogeneous substrate has high-density dislocation and an electric leakage channel with electron loss is formed at the interface between the GaN cap layer and the passivation layer (usually SiN), current collapse is caused, and the improvement of the performance of the GaN-based HEMT is restricted; meanwhile, the heterogeneous substrate needs to grow a high-resistance GaN layer of about 2-4 microns above the buffer layer, and the high-resistance GaN layer usually needs to be doped with iron or carbon, so that the risk of doped memory effect exists in subsequent growth, and the quality of the device is also adversely affected.
Disclosure of Invention
The invention mainly aims to provide an HEMT device, an HEMT epitaxial structure based on a GaN substrate and a manufacturing method, so as to overcome the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a HEMT epitaxial structure based on a GaN substrate, which comprises an interface processing layer, a barrier layer, an isolation layer and a channel layer which are sequentially formed on a semi-insulating GaN substrate with N-surface polarity.
The embodiment of the invention also provides a manufacturing method of the HEMT epitaxial structure, which comprises the following steps:
providing a semi-insulating GaN substrate with N-face polarity;
an interface processing layer is grown and formed on a semi-insulating GaN substrate with N-face polarity, and the growth conditions of the interface processing layer comprise: taking 50-80% of hydrogen and 20-50% of ammonia as raw materials, reacting for 5-10 minutes at 1050-1100 ℃ under 400-700 mbar, and then introducing an Al source at a flow rate of 0-50 umol/min;
and growing a barrier layer, an isolation layer and a channel layer on the interface treatment layer in sequence.
An embodiment of the present invention further provides an HEMT device, including:
the HEMT epitaxial structure;
and the source electrode, the drain electrode and the grid electrode are matched with the HEMT epitaxial structure, and the grid electrode is distributed between the source electrode and the drain electrode.
Compared with the prior art, the invention has the advantages that:
1) according to the HEMT epitaxial structure based on the GaN substrate, the GaN substrate and the semi-insulating property can be prepared in the early stage, so that adverse effects caused by the growth of a high-resistance epitaxial layer in the later stage can be avoided;
2) in the HEMT epitaxial structure based on the GaN substrate provided by the embodiment of the invention, homoepitaxy does not have the problem of a high-density dislocation buffer layer on a heterogeneous substrate, and proper interface treatment is carried out in epitaxial growth, so that the generation of a leakage channel can be completely blocked;
3) GaN is a polar material, the contact resistance of the N-surface polar GaN material is lower, and the surface state density between the N-surface polar GaN material and the passivation layer can be improved, so that the leakage problem is avoided;
4) the N-face polar GaN material has higher transconductance and can support higher working frequency.
Drawings
FIG. 1 is a schematic diagram of a HEMT epitaxial structure based on a SiC heterogeneous substrate in the prior art;
fig. 2 is a schematic structural diagram of an HEMT epitaxial structure based on a GaN substrate according to an exemplary embodiment of the present invention;
FIG. 3 is a diagram of the effect of a HEMT epitaxial structure based on a SiC hetero-substrate in the prior art;
fig. 4 is a diagram illustrating an effect of an HEMT epitaxial structure based on a GaN substrate according to an exemplary embodiment of the present invention;
fig. 5 is an I-V test curve of the HEMT device based on the GaN substrate obtained in example 1 of the present invention and the HEMT device based on the SiC foreign substrate obtained in comparative example 1.
Detailed Description
In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide technical solutions of the present invention. The technical solution, its implementation and principles, etc. will be further explained as follows.
Hemt (high Electron Mobility transistor), a high Electron Mobility transistor, is a heterojunction field effect transistor, also known as a modulation doped field effect transistor (MODFET), a two-dimensional Electron gas field effect transistor (2-DEGFET), a Selective Doped Heterojunction Transistor (SDHT), and the like.
Both the HEMT device and the integrated circuit thereof can work in the fields of ultrahigh frequency (millimeter wave) and ultrahigh speed, because the HEMT device works by utilizing the so-called two-dimensional electron gas with very high mobility, the basic structure of the HEMT is a modulation doping heterojunction, the two-dimensional electron gas (2-DEG) with high mobility exists in the modulation doping heterojunction, the 2-DEG has very high mobility and can not be frozen at very low temperature, and the HEMT has very good low-temperature performance and can be used for low-temperature research work (such as fractional quantum Hall effect).
The HEMT device is a voltage control device, and the grid voltage Vg can control the depth of a heterojunction potential well and the area density of 2-DEG in the potential well, thereby controlling the working current of the device. For HEMTs of the GaAs system, n-Al is usually used thereinxGa1-xThe As control layer should be depleted (typically several hundred nanometers thick with a doping concentration of 10)7～108/cm3) (ii) a If n-AlxGa1-xThe As layer has a large thickness and a high doping concentration, so that when Vg is equal to 0, 2-DEG exists, and the device is a depletion device, otherwise, the device is an enhancement device (when Vg is equal to 0, the Schottky depletion layer extends into the i-GaAs layer); however, if the layer is too thick and the doping concentration is too high, it will not be depleted during operation and will also exhibit leakage resistance in parallel with S-D.
Silicon carbide (SiC) is prepared by smelting quartz sand, petroleum coke (or coal coke), wood chips (salt is required when green silicon carbide is produced) and other raw materials at high temperature in a resistance furnace, and among modern C, N, B and other non-oxide high-technology refractory raw materials, the silicon carbide is the most widely and economically applied one and can be called as corundum or refractory sand. The silicon carbide produced at present is divided into black silicon carbide and green silicon carbide, both of which are hexagonal crystals, the specific gravity of the silicon carbide is 3.20-3.25, and the microhardness of the silicon carbide is 2840-3320 kg.
Silicon carbide has stable chemical properties, high thermal conductivity, small thermal expansion coefficient and good wear resistance, and has other purposes besides being used as an abrasive, for example, silicon carbide powder is coated on the inner wall of a water turbine impeller or a cylinder body by a special process, so that the wear resistance of the silicon carbide powder can be improved, and the service life of the silicon carbide powder is prolonged by 1-2 times; the high-grade refractory material prepared by the method has the advantages of thermal shock resistance, small volume, light weight, high strength and good energy-saving effect; the low-grade silicon carbide (containing SiC about 85%) is an excellent deoxidizer, and can be used for speeding up steel-making, easily controlling chemical composition and raising steel quality. In addition, silicon carbide is also used in great quantity to make silicon carbide rod for electric heating element.
In addition, silicon carbide has a high hardness, on the mohs scale of 9.5, next to the hardest diamond in the world (10), has excellent thermal conductivity, is a semiconductor, and is resistant to oxidation at high temperatures.
GaN is an extremely stable compound, yet a hard, high melting point material, with a melting point of about 1700 ℃, GaN has a high degree of ionization, the highest of group iii-v compounds (0.5 or 0.43); at atmospheric pressure, the GaN crystal is generally of hexagonal wurtzite structure(ii) a It has 4 atoms in one cell and an atomic volume of about half of GaAs. The electrical properties of GaN are the main factors affecting the device, and GaN not intentionally doped is n-type in each case, the best sample has an electron concentration of about 4 × 1016/cm3(ii) a The P-type samples prepared in general are highly compensated, and the GaN material series has low heat generation rate and high breakdown electric field, and is an important material for developing high-temperature high-power electronic devices and high-frequency microwave devices.
At present, with the progress of the MBE technology in GaN material application and the breakthrough of the key thin film growth technology, various GaN heterostructures are successfully grown, and novel devices such as metal field effect transistors (MESFETs), Heterojunction Field Effect Transistors (HFETs), modulation-doped field effect transistors (MODFETs) and the like are prepared by using GaN materials. The modulation doped AlGaN/GaN structure has high electron mobility (2000 cm)2S), high saturation velocity (1X 10)7cm/s) and low dielectric constant, which are the preferred materials for manufacturing microwave devices; the wide forbidden band width (3.4eV) of GaN and sapphire are used as the substrate, so that the heat dissipation performance is good, and the device can work under the condition of high power.
The forbidden band width of GaN is large (3.4eV), the thermal conductivity is high (1.3W/cm-K), the working temperature is high, the breakdown voltage is high, and the radiation resistance is strong; the bottom of the guide band of the GaN is at the point gamma, and the energy difference between the guide band and other energy valleys of the guide band is large, so that the valley scattering is not easy to generate, and a high strong field drift velocity (the electron drift velocity is not easy to saturate) can be obtained; GaN is easy to form mixed crystal with AlN, InN, etc., can be made into various heterostructures, and has mobility of 10 at low temperature5cm22-DEG of/Vs (because the 2-DEG surface density is higher, factors such as optical phonon scattering, ionized impurity scattering and piezoelectric scattering are effectively shielded); GaN has relatively low lattice symmetry (hexagonal wurtzite structure or tetragonal metastable zincblende structure), strong piezoelectricity (due to non-centrosymmetry) and ferroelectricity (spontaneous polarization along the hexagonal c-axis): strong piezoelectric polarization (the polarization electric field reaches 2MV/cm) and spontaneous polarization (the polarization electric field reaches 3MV/cm) are generated near the heterojunction interface, extremely high-density interface charges are induced, and the energy of the heterojunction is strongly modulatedA band structure to strengthen the two-dimensional spatial limitation of the 2-DEG, thereby increasing the areal density of the 2-DEG (up to 10 in AlGaN/GaN heterojunction)13/cm2Which is an order of magnitude higher than in AlGaAs/GaAs heterojunctions), which is significant for device operation.
The embodiment of the invention provides a HEMT epitaxial structure based on a GaN substrate, which comprises an interface processing layer, a barrier layer, an isolation layer and a channel layer which are sequentially formed on a semi-insulating GaN substrate with N-surface polarity.
Further, the growth conditions of the interface treatment layer comprise: taking 50-80% of hydrogen and 20-50% of ammonia as raw materials, reacting for 5-10 minutes at 1050-1100 ℃ under 400-700 mbar, and then introducing an Al source at a flow rate of 0-50 umol/min; wherein the ratio of hydrogen gas and ammonia gas may be a volume ratio or a mass ratio.
Further, the material of the interface treatment layer comprises AlN.
Further, the thickness of the interface treatment layer is 2-5 nm.
Further, the barrier layer comprises AlGaN or InGaN, wherein the content of Al or In component is 15-100%, and the thickness of the barrier layer is 15-25 nm.
Furthermore, the isolation layer is made of AlN and has a thickness of 0.5-1 nm.
Furthermore, the channel layer is made of GaN, InN, In GaN or AlGaN and has a thickness of 100-300 nm, wherein the Al component content of AlGaN is 0-15%, and the In component content of InGaN is 0-15%.
Further, a contact layer is formed on the channel layer, and the contact layer is made of InN and is 1-3nm thick.
The embodiment of the invention also provides a manufacturing method of the HEMT epitaxial structure, which comprises the following steps:
providing a semi-insulating GaN substrate with N-face polarity;
an interface processing layer is grown and formed on a semi-insulating GaN substrate with N-face polarity, and the growth conditions of the interface processing layer comprise: reacting 50-80% of hydrogen and 20-50% of ammonia gas serving as raw materials at 1050-1100 ℃ under 400-700 mbar for 5-10 minutes, and then introducing an Al source at a flow rate of 0-50 umol/min, wherein the ratio of the hydrogen to the ammonia gas can be volume ratio or mass ratio;
and growing an insertion layer, a barrier layer and a channel layer on the interface processing layer in sequence.
It should be noted that, when the HEMT epitaxial structure is manufactured, only a small amount of Al source needs to be introduced, and the specific introduction amount of the Al source may be determined according to specific production needs, and is not particularly limited herein.
Further, the manufacturing method further comprises the following steps: growing a contact layer on the channel layer.
An embodiment of the present invention further provides an HEMT device, including:
the HEMT epitaxial structure; and the source electrode, the drain electrode and the grid electrode are matched with the HEMT epitaxial structure, and the grid electrode is distributed between the source electrode and the drain electrode.
Further, the source and the drain are electrically connected to the contact layer, for example, the source and the drain form an ohmic contact with the contact layer.
Further, a gate dielectric layer is further disposed between the gate and the contact layer, and the gate dielectric layer may be made of a material known to those skilled in the art, and the thickness is not particularly limited.
The technical solution, the implementation process and the principle thereof will be further explained with reference to the drawings and the specific embodiments.
Example 1
Referring to fig. 2, a HEMT epitaxial structure based on a GaN substrate includes an interface treatment layer, an AlGaN barrier layer, an AlN isolation layer, a GaN channel layer, and an InN contact layer sequentially formed on a semi-insulating GaN substrate with N-face polarity, the AlGaN barrier layer and the GaN channel layer cooperate to form a heterojunction, and a two-dimensional electron gas is provided between the AlGaN barrier layer and the GaN channel layer; the thickness of the interface treatment layer is 5nm of an AlN layer, the thickness of the AlGaN barrier layer is 20nm, the content of Al component is 25% (mass fraction, the same below), the thickness of the AlN isolating layer is 1nm, the thickness of the GaN channel layer is 300nm, and the thickness of the InN contact layer is 2 nm.
The manufacturing method of the HEMT epitaxial structure based on the GaN substrate specifically comprises the following steps:
1) providing a semi-insulating GaN substrate with N-face polarity;
2) placing the semi-insulating GaN substrate with N-face polarity in a reaction vessel or a reaction system, introducing 70% of hydrogen and 30% of ammonia gas into the reaction vessel or the reaction system at 1100 ℃ and 600mbar, and baking for 10 minutes (aiming at removing impurity elements such as O in high-activity N-face GaN on the surface of the semi-insulating GaN substrate on the premise of ensuring flatness);
3) then, the temperature of the reaction container or the reaction system is reduced to 1000 ℃, and a small amount of Al is introduced under the condition of 100mbar pressure, so that a smooth AlN layer with the thickness of about 5nm is formed by deposition, the flatness of the epitaxial layer can be improved again because the Al has the effect of filling holes, and meanwhile, the Al-containing barrier layer can be used for laying and transition to improve the flatness and the crystal quality of a subsequent AlGaN/GaN heterojunction;
4) keeping the growth condition of the AlN interface treatment layer, and sequentially growing a 20nm AlGaN (Al component 25%) barrier layer, a 1nm AlN isolating layer and a 300nm GaN channel layer on the AlN interface treatment layer, wherein the AlGaN barrier layer and the GaN channel layer are arranged in a different order from that of the traditional Ga-surface HEMT because the built-in electric field of the N-surface GaN is opposite and the position of the generated two-dimensional electron gas (2DEG) is different;
5) and cooling the reaction container or the reaction system to 700 ℃, and growing an InN contact layer on the GaN channel layer under the pressure condition of 300 mbar.
Comparative example 1
As shown in fig. 1, a HEMT epitaxial structure based on a SiC hetero-substrate includes a SiC hetero-substrate and an AlN buffer layer (about 200nm), a high-resistance GaN layer (about 2um), a GaN channel layer (about 300nm), an AlN spacer layer (about 1nm), an AlGaN barrier layer (about 20nm), and a GaN cap layer (about 2nm) sequentially disposed on the SiC hetero-substrate.
The GaN substrate-based HEMT device obtained in example 1 of the present invention (defined as HEMT-1) and the SiC hetero-substrate-based HEMT device obtained in comparative example 1 (defined as HEMT-2) were subjected to I-V tests (the test methods may be performed using methods and equipment known to those skilled in the art), respectively, and the test results are shown in fig. 5, from which it can be seen that the GaN substrate-based HEMT device obtained in example 1 of the present invention has a higher breakdown voltage and a lower buffer leakage current.
Specifically, referring to fig. 3 and 4, when the HEMT device is under a severer working condition, compared with the HEMT epitaxial structure based on the SiC hetero-substrate in the comparative example 1, the HEMT epitaxial structure based on the GaN substrate provided in the embodiment 1 of the present invention adopts the semi-insulating GaN self-supporting substrate with N-plane polarity, which can avoid the defects caused by lattice mismatch and thermal mismatch due to hetero-epitaxy, thereby causing a channel of electric leakage at the buffer layer; meanwhile, in the embodiment 1 of the invention, the high-frequency response is improved by adopting the semi-insulating GaN substrate with N-surface polarity, the surface state density of the device is reduced by adopting the InN contact layer, and a leakage channel between the epitaxial layer and the passivation layer is inhibited; and the leakage channel is cut off from the two aspects, the current collapse effect is eliminated and reduced, the high performance of the GaN-based HEMT device is improved, and the application of the GaN-based HEMT device in high-temperature, high-frequency and high-power occasions is widened.
Specifically, according to the method for manufacturing the HEMT epitaxial structure based on the GaN substrate provided by the embodiment of the invention, the low-resistance connection of the source/drain terminal can be realized only by penetrating through the GaN channel layer with a small forbidden bandwidth, which is different from the conventional HEMT epitaxial structure which needs to penetrate through the AlGaN barrier layer with a large forbidden bandwidth, so that the low-surface-state contact resistance can be obtained.
The semi-insulating property of the GaN substrate in the HEMT epitaxial structure based on the GaN substrate can be completed through early preparation, so that adverse effects caused by later growth of a high-resistance epitaxial layer can be avoided; the semi-insulating property of the GaN substrate can be obtained by: after the fabrication in the HVPE reactor is completed, the GaN substrate is formed by stripping, grinding and polishing, and then the HEMT structure is grown in the MOCVD reactor, and the specific parameters and processes can be implemented using existing techniques known to those skilled in the art.
Specifically, homoepitaxy does not have the problem of a high-density dislocation buffer layer on a heterogeneous substrate, and proper interface treatment and growth are carried out in epitaxy, so that the generation of a leakage channel can be completely blocked; moreover, the GaN is a polar material, the contact resistance of the N-surface polar GaN material is lower, and the surface state density between the GaN and the passivation layer can be improved, so that the leakage problem is avoided; the N-face polar GaN material also has higher transconductance and can work at higher frequency; in addition, high quality single polarity N-face polar GaN materials can only be obtained by homoepitaxy compared to heteroepitaxy.
It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and therefore, the protection scope of the present invention is not limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. An HEMT epitaxial structure based on a GaN substrate is characterized by comprising an interface processing layer, a barrier layer, an isolation layer and a channel layer which are sequentially formed on a semi-insulating GaN substrate with N-surface polarity.
2. The HEMT epitaxial structure of claim 1, wherein said interface treatment layer growth conditions comprise: taking 50-80% of hydrogen and 20-50% of ammonia as raw materials, reacting for 5-10 minutes at 1050-1100 ℃ under 400-700 mbar, and then introducing an Al source at a flow rate of 0-50 umol/min;
preferably, the material of the interface treatment layer comprises AlN, and the thickness of the interface treatment layer is 2-5 nm.
3. The HEMT epitaxial structure of claim 1, wherein said barrier layer comprises AlGaN or InGaN, wherein the Al or In component is present In an amount of 15-100%, and the thickness of said barrier layer is 15-25 nm.
4. The HEMT epitaxial structure of claim 1, wherein the spacer layer comprises AlN with a thickness of 0.5-1 nm;
preferably, the channel layer is made of GaN, InN, In GaN or AlGaN and has a thickness of 100-300 nm, wherein the Al component content of AlGaN is 0-15%, and the In component content of InGaN is 0-15%.
5. The HEMT epitaxial structure of claim 1, wherein a contact layer is further formed on the channel layer, the contact layer being made of InN and having a thickness of 1-3 nm.
6. A method of fabricating a HEMT epitaxial structure according to any one of claims 1 to 5, comprising:
providing a semi-insulating GaN substrate with N-face polarity;
an interface processing layer is grown and formed on a semi-insulating GaN substrate with N-face polarity, and the growth conditions of the interface processing layer comprise: taking 50-80% of hydrogen and 20-50% of ammonia as raw materials, reacting for 5-10 minutes at 1050-1100 ℃ under 400-700 mbar, and then introducing an Al source at a flow rate of 0-50 umol/min;
and growing a barrier layer, an isolation layer and a channel layer on the interface treatment layer in sequence.
7. The method of manufacturing according to claim 6, further comprising: growing a contact layer on the channel layer.
8. A HEMT device, comprising:
a HEMT epitaxial structure according to any one of claims 1-5;
and the source electrode, the drain electrode and the grid electrode are matched with the HEMT epitaxial structure, and the grid electrode is distributed between the source electrode and the drain electrode.
9. The HEMT device of claim 8, wherein said source and drain are electrically coupled to a contact layer.
10. The HEMT device of claim 8, wherein a gate dielectric layer is further disposed between said gate and said contact layer.
CN202011174655.2A 2020-10-28 2020-10-28 HEMT device, HEMT epitaxial structure based on GaN substrate and manufacturing method Pending CN114420753A (en)

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