CN210429824U - Enhanced AlN/AlGaN/GaN HEMT device - Google Patents

Enhanced AlN/AlGaN/GaN HEMT device Download PDF

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CN210429824U
CN210429824U CN201921418007.XU CN201921418007U CN210429824U CN 210429824 U CN210429824 U CN 210429824U CN 201921418007 U CN201921418007 U CN 201921418007U CN 210429824 U CN210429824 U CN 210429824U
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algan
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李国强
孙佩椰
陈丁波
万利军
阙显沣
姚书南
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South China University of Technology SCUT
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Abstract

The utility model belongs to the semiconductor device field discloses a reinforcingAnd the AlN/AlGaN/GaN HEMT device is of a type. The device comprises a substrate, a GaN channel layer, an AlGaN ultrathin barrier layer and an amorphous SiO2A layer, a single crystal AlN layer, a drain metal electrode, a source metal electrode and a gate metal electrode. The utility model discloses an enhancement mode device is on the basis of gaN and ultra-thin AlGaN heterojunction, and regional amorphous SiO inserts under the bars2After the layer, a single crystal AlN layer was epitaxially grown on the heterojunction. Amorphous SiO under grid2The layer can isolate the polarization enhancement effect of the strong-polarity monocrystal AlN layer on the AlGaN ultrathin barrier layer, deplete the two-dimensional electron gas under the gate, turn off the device and realize the enhancement device. Amorphous SiO under the same gate2And the monocrystalline AlN can be used as a gate lower dielectric layer, so that the gate leakage current is reduced, and the breakdown voltage of the device is improved.

Description

Enhanced AlN/AlGaN/GaN HEMT device
Technical Field
The utility model belongs to the semiconductor device field, concretely relates to enhancement mode AlN/AlGaN/GaN HEMT device.
Background
Among compound semiconductor electronic devices, a High Electron Mobility Transistor (HEMT) is the most important electronic device applied to high-frequency high-power applications. The device relies on spontaneous polarization and piezoelectric polarization effects of the III group nitride semiconductor to form a two-dimensional electron gas (2DEG) conducting channel with quantum effect at a heterojunction interface, and the density, mobility, saturation rate and the like of the 2DEG determine the current handling capacity of the device. Among them, HEMT devices based on GaN and related iii-v nitride materials (AlN, InN) are the hot research spots for current compound semiconductor electronic devices. Compared with the second generation semiconductor GaAs, the GaN has the advantages of wide forbidden band, high critical breakdown electric field, high electronic saturation velocity, high thermal conductivity, strong radiation resistance and the like, so the GaN HEMT has the characteristics of excellent high frequency, pressure resistance, high temperature resistance and severe environment resistance, and is widely applied to the fields of radio frequency microwave, power switches and the like.
Spontaneous polarization and piezoelectric polarization at the AlGaN/GaN heterojunction interface can generate the concentration of about 10 between the common AlGaN/GaN heterojunction13cm-2And thus the GaN HEMT device is a natural depletion mode device. The depletion mode device uses negative turn-on voltage in RF microwave application to make the circuit structureThe circuit is complicated, the protection function of preventing the false start of the circuit is influenced, and the safety of the circuit is reduced, so that the research of an enhanced GaN HEMT device is needed to be carried out, the circuit design is simplified, the preparation cost is reduced, and the method has great significance for the application of a large-scale microwave radio frequency circuit. Meanwhile, in a digital circuit, enhancement type and depletion type GaN HEMTs are combined and can be integrated into a direct coupling type field effect transistor logic (DCFL) circuit, and the single-chip integrated enhancement type/depletion type (E/D Mode) GaN HEMTs logic unit can be used in a mixed signal circuit and a direct current-direct current (DC-DC) conversion circuit, so that the circuit design is simpler in the design of an inverter and a ring oscillator.
Common methods for implementing enhancement devices include fluorine ion implantation, trench gate, and p-type gate.
Fluorine ion implantation is to inject fluorine ions into the barrier layer under the gate by Reactive Ion Etching (RIE) or inductively coupled plasma etching (ICP) before the deposition of the gate metal, the injected F ions are usually stabilized at the gap position by the repulsive force from the adjacent atoms (Al, Ga or N), and since fluorine has the strongest electronegativity among all elements, a single fluorine ion at the gap position will trap free electrons and form a negative fixed charge, forming an additional potential barrier, increasing the barrier height, producing a large positive shift of the threshold voltage. However, the inevitable fluorine ion implantation can cause a small amount of fluorine ions in the 2DEG channel, which leads to the reduction of the channel carrier mobility and the damage of the crystal lattice to the barrier layer.
The groove grid structure is formed by etching a barrier layer under a grid, only the polarization charge density under the grid is reduced, channel charges are not influenced as much as possible, and enhancement is realized under the condition of ensuring higher output current. However, in actual preparation, it is difficult to etch the barrier layer precisely in terms of process, and meanwhile, lattice damage is introduced in the etching process, so that the electron mobility of the etched region is reduced, the gate current is increased, the power characteristics of the device are affected, and the device fails in severe cases.
The p-type gate technology is characterized in that a p-type doped GaN or AlGaN epitaxial layer is introduced between an artificially undoped AlGaN barrier layer and gate metal, and a conduction band of the whole heterojunction is lifted so as to deplete 2DEG in a channel below a gate, so that a device is converted from depletion mode to enhancement mode. Because the p-type epitaxial layer has great difficulty in selective growth, a common method for realizing the p-type gate technology at present is to grow a layer of p-AlGaN or p-GaN on the barrier layer and etch the p-type epitaxial layer between the gate source and the gate drain by using ICP. Therefore, the p-type gate technology also has the problem that the etching precision is difficult to control, and the two-dimensional electron gas concentration under the channel is reduced and the output current is reduced due to insufficient etching or excessive etching.
It can be seen that although the enhancement devices can be realized by the above methods, the devices are damaged more or less, which causes a decrease in output current density, an increase in gate leakage current, a decrease in device stability, and even device failure, which is a main reason for the difficulty in realizing the enhancement devices with high threshold voltage and high saturation current. Therefore, a technology for preparing an enhancement mode device in a lossless, controllable and stable mode is developed, the threshold voltage can be improved, and meanwhile, high output current density is kept, so that the technology has great significance for application of a GaN HEMT device in the field of electronic power.
SUMMERY OF THE UTILITY MODEL
Aiming at the defects and shortcomings existing in the prior art, the utility model aims to provide an enhanced AlN/AlGaN/GaN HEMT device.
The utility model discloses the purpose is realized through following technical scheme:
an enhanced AlN/AlGaN/GaN HEMT device comprising: substrate, GaN channel layer, AlGaN ultrathin barrier layer and amorphous SiO2Layer, monocrystalline AlN layer, leak metal electrode, source metal electrode and gate metal electrode, wherein:
the substrate, the GaN channel layer and the AlGaN ultrathin barrier layer are sequentially laminated from bottom to top;
the amorphous SiO2The layer covers a partial area of the upper surface of the AlGaN ultrathin barrier layer;
the drain metal electrode and the source metal electrode are respectively positioned on the upper surface of the AlGaN ultrathin barrier layer and are not coated with amorphous SiO2Two side regions covered by the layer, the drain metal electrode and the source metal electrode and AlOhmic contact is formed between the GaN ultrathin barrier layers;
the monocrystalline AlN layer covers the area of the upper surface of the AlGaN ultrathin barrier layer which is not covered by the source drain metal electrode and covers the amorphous SiO2A layer;
the gate metal electrode is positioned on the amorphous SiO2And Schottky contact is formed between the gate metal electrode and the AlGaN ultrathin barrier layer on the upper surface of the monocrystal AlN layer above the layer.
Preferably, the substrate is a silicon substrate.
Preferably, the thickness of the GaN channel layer is 1-5 μm.
Preferably, the AlGaN ultrathin barrier layer has a thickness of 5-7 nm and a molar content of Al element of 25-30%.
Preferably, the amorphous SiO2The thickness of the layer is 5 to 15 nm.
Preferably, the thickness of the single crystal AlN layer is 15-25 nm.
Preferably, the material of the drain metal electrode and the source metal electrode is composed of four layers of metals of Ti, Al, Ni and Au.
Preferably, the gate metal electrode is located at a side close to the source metal electrode (i.e., the gate metal electrode is located at a distance from the source metal electrode that is less than the distance from the drain metal electrode).
Preferably, the material of the gate metal electrode is composed of two layers of Ni and Au.
The enhanced AlN/AlGaN/GaN HEMT device can be prepared by the following method:
step 1, sequentially extending a GaN channel layer and an AlGaN ultrathin barrier layer on a substrate;
step 2, growing amorphous SiO on the AlGaN ultrathin barrier layer2A layer;
step 3, in the amorphous SiO2Photoetching and wet etching are carried out on the layer, and SiO below the gate is reserved2Layer (i.e. SiO of the region under the gate metal electrode)2A layer);
step 4, depositing a single crystal AlN layer on the surface of the substrate obtained in the step 3;
step 5, photoetching and etching are carried out on the monocrystal AlN layer to form mesa isolation;
step 6, photoetching is carried out on the monocrystal AlN layer again to expose the drain metal electrode and the source metal electrode area, and the monocrystal AlN layer under the drain metal electrode and the source metal electrode area is removed through etching;
step 7, forming a drain metal electrode and a source metal electrode through evaporation, stripping and annealing;
step 8, performing photoetching, evaporation and stripping on the amorphous SiO2And forming a gate metal electrode on the upper surface of the monocrystal AlN layer above the layer.
Further, in the step 1, the epitaxial GaN channel layer and the AlGaN ultrathin barrier layer are grown and prepared by Metal Organic Chemical Vapor Deposition (MOCVD), and the growth temperature is 850-950 ℃.
Further, the amorphous SiO in step 22The layer is prepared by adopting Plasma Enhanced Chemical Vapor Deposition (PECVD) growth, and the growth temperature is 230-320 ℃.
Further, in the step 3, the wet etching adopts HF to HN in mass fraction ratio4And soaking the F-1: 7-1:5 solution of a Buffered Oxide Etchant (BOE) for 10-20 s for wet etching.
Further, in the step 4, the single crystal AlN layer is grown and prepared by adopting Pulsed Laser Deposition (PLD), and the growth temperature is 800-900 ℃.
Further, in the step 5, the etching is performed by using Inductively Coupled Plasma (ICP), and the etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 5-7 mTorr, the upper radio frequency power is 200-300W, the lower radio frequency power is 50-100W, and the etching time is 100-150 s.
Further, in the step 6, the etching is performed by using Inductively Coupled Plasma (ICP), and the etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 5-7 mTorr, the upper radio frequency power is 200-300W, the lower radio frequency power is 50-100W, and the etching time is 10-20 s.
Further, the annealing atmosphere in the step 7 is N2The annealing temperature is 800-900 ℃, the heat preservation time is 20-40 s, and the heating rate is 15-20 ℃/s.
The principle of the utility model is that: the utility model discloses an enhancement mode device is on the basis of gaN and ultra-thin AlGaN heterojunction, and regional amorphous SiO inserts under the bars2After the layer, a single crystal AlN layer was epitaxially grown on the heterojunction. The thickness of the AlGaN barrier layer extending on the GaN channel layer is only 5-7 nm, the spontaneous polarization effect generated by the ultrathin AlGaN barrier layer is very weak, the lattice constant of AlGaN is smaller than that of GaN, the extending ultrathin barrier layer is in a stress relaxation state, piezoelectric polarization is not generated, and therefore two-dimensional electron gas (2DEG) is hardly generated at the interface of GaN and the ultrathin AlGaN heterojunction. After a monocrystal AlN layer is deposited on the GaN and ultrathin AlGaN heterojunction, on one hand, the deposited AlN has a strong spontaneous polarization effect; on the other hand, the lattice constant of AlN is smaller than that of AlGaN, and the AlGaN is subjected to the action of compressive stress to generate piezoelectric polarization, so that the GaN after the single crystal AlN is deposited and the ultrathin AlGaN heterojunction generate high-concentration two-dimensional electron gas under the combined action of spontaneous polarization and piezoelectric polarization. While amorphous SiO is inserted under the gate2The layer can not affect the piezoelectric polarization of the ultrathin AlGaN barrier layer, and simultaneously blocks the action of the spontaneous polarization of single-crystal AlN on a heterojunction, so that two-dimensional electron gas is hardly generated in a region under a gate, and a device is in an off state under zero gate bias, thereby realizing an enhanced device. In addition, deposited single crystal AlN layer and SiO2The layer can also be used as a high-quality gate dielectric layer, which is beneficial to reducing gate leakage current and improving breakdown voltage of the device.
The device and the preparation method of the utility model have the following advantages and beneficial effects:
(1) the utility model discloses amorphous SiO under bars of device2The layer can isolate the polarization enhancement effect of the strong-polarity monocrystal AlN layer on the AlGaN ultrathin barrier layer, deplete the two-dimensional electron gas under the gate, turn off the device and realize the enhancement device.
(2) The utility model discloses amorphous SiO under device bars2The layer and the single crystal AlN layer can be simultaneously used as a gate dielectric layer of the device, thereby being beneficial to reducing gate leakage current and improving breakdown voltage of the device.
(3) The utility model discloses a device need not to carry out the processing that is difficult to accurate control such as dry etching, ion implantation to barrier layer under the gate in the preparation process, and the device output saturation current density that has avoided the crystal lattice damage to bring is little, the device unstability scheduling problem, and the controllability is high, good reproducibility, is favorable to realizing the big saturation current enhancement device of high threshold voltage.
Drawings
Fig. 1 is a schematic structural diagram of an enhanced AlN/AlGaN/GaN HEMT device in an embodiment of the present invention;
FIGS. 2 to 9 are flow charts of the manufacturing process of the enhanced AlN/AlGaN/GaN HEMT device in the embodiment of the present invention; wherein, 1 is substrate, 2 is GaN channel layer, 3 is AlGaN ultrathin barrier layer, and 4 is amorphous SiO2Layer 5 is a monocrystalline AlN layer, 6 is a drain metal electrode, 7 is a source metal electrode, and 8 is a gate metal electrode.
Fig. 10 is a graph of device transfer characteristics measured by the enhanced AlN/AlGaN/GaN HEMT device in embodiment 1 of the present invention;
fig. 11 is a graph of device output characteristics measured by the enhancement type AlN/AlGaN/GaN HEMT device in embodiment 1 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples and drawings, but the present invention is not limited thereto.
Example 1
The structure of the enhanced AlN/AlGaN/GaN HEMT device of this embodiment is schematically shown in fig. 1. The method comprises the following steps: substrate 1, GaN channel layer 2, AlGaN ultrathin barrier layer 3 and amorphous SiO2Layer 4, monocrystalline AlN layer 5, drain metal electrode 6, source metal electrode 7 and gate metal electrode 8, wherein:
the substrate 1, the GaN channel layer 2 and the AlGaN ultrathin barrier layer 3 are sequentially laminated from bottom to top;
the amorphous SiO2The layer 4 covers partial area of the upper surface of the AlGaN ultrathin barrier layer 3;
the drain metal electrode 6 and the source metal electrode 7 are respectively positioned on the upper surface of the AlGaN ultrathin barrier layer 3 and are not coated with amorphous SiO2Ohmic contact is formed between the drain metal electrode 6, the source metal electrode 7 and the AlGaN ultrathin barrier layer 3 in the areas at two sides covered by the layer 4;
the monocrystalline AlN layer 5 covers the area which is not covered by the source drain metal electrode on the upper surface of the AlGaN ultrathin barrier layer 3 and covers the amorphous SiO2A layer 4;
the gate metal electrode 8 is positioned on the amorphous SiO2On the upper surface of the monocrystalline AlN layer 5 above the layer 4, Schottky contact is formed between the gate metal electrode 8 and the AlGaN ultrathin barrier layer 3.
The enhanced AlN/AlGaN/GaN HEMT device of the embodiment is prepared by the following method:
step 1, extending a GaN channel layer with the thickness of 5 microns and an AlGaN ultrathin barrier layer with the thickness of 6nm on a silicon substrate by utilizing a Metal Organic Chemical Vapor Deposition (MOCVD) process, wherein the molar content of Al element is 25%, the growth temperature is 850 ℃, and the result is shown in figure 2;
step 2, growing amorphous SiO with the thickness of 5nm on the AlGaN ultrathin barrier layer by utilizing a plasma enhanced chemical vapor deposition process2Layer, growth temperature 230 ℃, results are shown in fig. 3;
step 3, in the amorphous SiO2Coating positive glue, hardening, exposing and developing on the layer, exposing the area except the gate metal electrode, and then putting HF HN with the mass fraction ratio4Soaking the F-1: 7 buffer oxide etching agent for 10s to remove SiO in the region outside the gate2Layer, retention of SiO under gate2Layer, results are shown in fig. 4;
step 4, depositing a single crystal AlN layer with the thickness of 15nm on the surface of the substrate obtained in the step 3 by using a pulse laser deposition technology, wherein the growth temperature is 800 ℃, and the result is shown in figure 5;
step 5, performing photolithography and Inductively Coupled Plasma (ICP) etching on the single crystal AlN layer to form mesa isolation, the result is shown in FIG. 6, wherein the etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 5mTorr, the upper radio frequency power is 200W, the lower radio frequency power is 50W, and the etching time is 150 s;
step 6, photoetching is carried out on the single crystal AlN layer again to expose the source and drain metal electrode area, and the single crystal AlN layer under the source and drain metal electrode area is removed through ICP etching, wherein etching reaction gas is Cl2And BCl3Mixed gasThe pressure is 5mTorr, the upper RF power is 200W, the lower RF power is 50W, the etching time is 40s, and the result is shown in FIG. 7;
7, forming the drain metal electrode and the source metal electrode by evaporating a Ti/Al/Ni/Au metal material, stripping and rapid thermal annealing, wherein the annealing atmosphere is N2The annealing temperature was 800 ℃, the holding time was 40s, and the temperature rise rate was 15 ℃/s, the results are shown in fig. 8;
step 8, performing photoetching, evaporation plating of Ni/Au metal material and stripping on amorphous SiO2The gate metal electrode is formed on the upper surface of the monocrystalline AlN layer above the layer, completing the device fabrication, the result of which is shown in fig. 9.
The transfer characteristic curve and the output characteristic curve of the device measured by the enhanced AlN/AlGaN/GaN HEMT device prepared in this embodiment are respectively shown in fig. 10 and fig. 11, the threshold voltage of the obtained device is 1V, and when the gate voltage is 4V, the output saturation current density is 700mA/mm, and the device realizes enhancement while maintaining a high output saturation current density.
Example 2
The structure diagram of the enhanced AlN/AlGaN/GaN HEMT device of this embodiment is shown in fig. 1, and includes: substrate 1, GaN channel layer 2, AlGaN ultrathin barrier layer 3, amorphous SiO2 layer 4, single crystal AlN layer 5, drain metal electrode 6, source metal electrode 7 and gate metal electrode 8, wherein:
the substrate 1, the GaN channel layer 2 and the AlGaN ultrathin barrier layer 3 are sequentially laminated from bottom to top;
the amorphous SiO2The layer 4 covers partial area of the upper surface of the AlGaN ultrathin barrier layer 3;
the drain metal electrode 6 and the source metal electrode 7 are respectively positioned on the upper surface of the AlGaN ultrathin barrier layer 3 and are not coated with amorphous SiO2Ohmic contact is formed between the drain metal electrode 6, the source metal electrode 7 and the AlGaN ultrathin barrier layer 3 in the areas at two sides covered by the layer 4;
the monocrystalline AlN layer 5 covers the area which is not covered by the source drain metal electrode on the upper surface of the AlGaN ultrathin barrier layer 3 and covers the amorphous SiO2A layer 4;
the gate metal electrode 8 is positioned on the amorphous SiO2Layer 4On the upper surface of the upper single crystal AlN layer 5, Schottky contact is formed between the gate metal electrode 8 and the AlGaN ultrathin barrier layer 3.
The enhanced AlN/AlGaN/GaN HEMT device of the embodiment is prepared by the following method:
step 1, extending a GaN channel layer with the thickness of 5 microns and an AlGaN ultrathin barrier layer with the thickness of 5nm on a silicon substrate by utilizing a Metal Organic Chemical Vapor Deposition (MOCVD) process, wherein the molar content of Al element is 25%, the growth temperature is 900 ℃, and the result is shown in figure 2;
step 2, growing amorphous SiO with the thickness of 10nm on the AlGaN ultrathin barrier layer by utilizing a plasma enhanced chemical vapor deposition process2Layer, growth temperature 300 ℃, results are shown in fig. 3;
step 3, in the amorphous SiO2Coating positive photoresist on the layer, hardening, exposing, developing, exposing the region except the gate metal electrode, soaking in a buffer oxide etchant with HF (HF: HN 4F) at a mass ratio of 1:7 for 15s, and removing SiO in the region outside the gate2Layer, retention of SiO under gate2Layer, results are shown in fig. 4;
step 4, depositing a single crystal AlN layer with the thickness of 20nm on the surface of the substrate obtained in the step 3 by using a pulse laser deposition technology, wherein the growth temperature is 850 ℃, and the result is shown in figure 5;
step 5, performing photolithography and Inductively Coupled Plasma (ICP) etching on the single crystal AlN layer to form mesa isolation, the result is shown in FIG. 6, wherein the etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 6mTorr, the upper radio frequency power is 250W, the lower radio frequency power is 70W, and the etching time is 120 s;
step 6, photoetching is carried out on the single crystal AlN layer again to expose the source and drain metal electrode area, and the single crystal AlN layer under the source and drain metal electrode area is removed through ICP etching, wherein etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 6mTorr, the upper radio frequency power is 250W, the lower radio frequency power is 70W, the etching time is 30s, and the result is shown in FIG. 7;
7, forming the metal leakage electrode by evaporating Ti/Al/Ni/Au metal materials, stripping and rapid thermal annealingAnd a source metal electrode, wherein the annealing atmosphere is N2The annealing temperature was 850 ℃, the holding time was 30s, and the temperature rise rate was 15 ℃/s, the results are shown in fig. 8;
step 8, performing photoetching, evaporation plating of Ni/Au metal material and stripping on amorphous SiO2The gate metal electrode is formed on the upper surface of the monocrystalline AlN layer above the layer, completing the device fabrication, the result of which is shown in fig. 9.
The results of the device transfer characteristic curve and the output characteristic curve measured by the enhanced AlN/AlGaN/GaN HEMT device prepared in this example are similar to those of example 1, which proves that the device prepared according to this example has stable performance.
Example 3
The structure diagram of the enhanced AlN/AlGaN/GaN HEMT device of this embodiment is shown in fig. 1, and includes: substrate 1, GaN channel layer 2, AlGaN ultrathin barrier layer 3, amorphous SiO2 layer 4, single crystal AlN layer 5, drain metal electrode 6, source metal electrode 7 and gate metal electrode 8, wherein:
the substrate 1, the GaN channel layer 2 and the AlGaN ultrathin barrier layer 3 are sequentially laminated from bottom to top;
the amorphous SiO2 layer 4 covers the partial area of the upper surface of the AlGaN ultrathin barrier layer 3;
the drain metal electrode 6 and the source metal electrode 7 are respectively positioned in the two side areas of the upper surface of the AlGaN ultrathin barrier layer 3 which are not covered by the amorphous SiO2 layer 4, and ohmic contact is formed between the drain metal electrode 6 and the source metal electrode 7 and the AlGaN ultrathin barrier layer 3;
the monocrystalline AlN layer 5 covers the area which is not covered by the source drain metal electrode on the upper surface of the AlGaN ultrathin barrier layer 3 and covers the amorphous SiO2A layer 4;
the gate metal electrode 8 is positioned on the amorphous SiO2On the upper surface of the monocrystalline AlN layer 5 above the layer 4, Schottky contact is formed between the gate metal electrode 8 and the AlGaN ultrathin barrier layer 3.
The enhanced AlN/AlGaN/GaN HEMT device of the embodiment is prepared by the following method:
step 1, extending a GaN channel layer with the thickness of 5 microns and an AlGaN ultrathin barrier layer with the thickness of 7nm on a silicon substrate by utilizing a Metal Organic Chemical Vapor Deposition (MOCVD) process, wherein the molar content of Al element is 30%, the growth temperature is 950 ℃, and the result is shown in figure 2;
step 2, growing amorphous SiO with the thickness of 15nm on the AlGaN ultrathin barrier layer by utilizing a plasma enhanced chemical vapor deposition process2Layer, growth temperature 320 ℃, results are shown in fig. 3;
step 3, coating positive photoresist, hardening film, exposing and developing on the amorphous SiO2 layer, placing the amorphous SiO2 layer into a buffer oxide etching agent with the mass fraction ratio of HF to HN4F to 1 to 5 to soak for 20s after the region except the gate metal electrode is exposed, and removing SiO of the region outside the gate2Layer, retention of SiO under gate2Layer, results are shown in fig. 4;
step 4, depositing a 25 nm-thick monocrystalline AlN layer on the surface of the substrate obtained in the step 3 by using a pulsed laser deposition technology, wherein the growth temperature is 900 ℃, and the result is shown in FIG. 5;
step 5, performing photolithography and Inductively Coupled Plasma (ICP) etching on the single crystal AlN layer to form mesa isolation, the result is shown in FIG. 6, wherein the etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 7mTorr, the upper radio frequency power is 300W, the lower radio frequency power is 100W, and the etching time is 100 s;
step 6, photoetching is carried out on the single crystal AlN layer again to expose the source and drain metal electrode area, and the single crystal AlN layer under the source and drain metal electrode area is removed through ICP etching, wherein etching reaction gas is Cl2And BCl3The pressure of the mixed gas is 7mTorr, the upper radio frequency power is 300W, the lower radio frequency power is 100W, the etching time is 20s, and the result is shown in FIG. 7;
7, forming the drain metal electrode and the source metal electrode by evaporating a Ti/Al/Ni/Au metal material, stripping and rapid thermal annealing, wherein the annealing atmosphere is N2The annealing temperature was 900 ℃, the holding time was 20s, and the temperature rise rate was 20 ℃/s, the results are shown in fig. 8;
step 8, performing photoetching, evaporation plating of Ni/Au metal material and stripping on amorphous SiO2The gate metal electrode is formed on the upper surface of the monocrystalline AlN layer above the layer, completing the device fabrication, the result of which is shown in fig. 9.
The results of the device transfer characteristic curve and the output characteristic curve measured by the enhanced AlN/AlGaN/GaN HEMT device prepared in this example are similar to those of example 1, which proves that the device prepared according to this example has stable performance.
The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be equivalent replacement modes, and all are included in the scope of the present invention.

Claims (6)

1. An enhancement mode AlN/AlGaN/GaN HEMT device is characterized in that: the device comprises: substrate, GaN channel layer, AlGaN ultrathin barrier layer and amorphous SiO2Layer, monocrystalline AlN layer, leak metal electrode, source metal electrode and gate metal electrode, wherein:
the substrate, the GaN channel layer and the AlGaN ultrathin barrier layer are sequentially laminated from bottom to top;
the amorphous SiO2The layer covers a partial area of the upper surface of the AlGaN ultrathin barrier layer;
the drain metal electrode and the source metal electrode are respectively positioned on the upper surface of the AlGaN ultrathin barrier layer and are not coated with amorphous SiO2Ohmic contact is formed between the drain metal electrode, the source metal electrode and the AlGaN ultrathin barrier layer in the areas on the two sides covered by the layer;
the monocrystalline AlN layer covers the area of the upper surface of the AlGaN ultrathin barrier layer which is not covered by the source drain metal electrode and covers the amorphous SiO2A layer;
the gate metal electrode is positioned on the amorphous SiO2And Schottky contact is formed between the gate metal electrode and the AlGaN ultrathin barrier layer on the upper surface of the monocrystal AlN layer above the layer.
2. An enhanced AlN/AlGaN/GaN HEMT device according to claim 1, wherein: the substrate is a silicon substrate.
3. According toAn enhanced AlN/AlGaN/GaN HEMT device according to claim 1, wherein: the thickness of the GaN channel layer is 1-5 mu m; the amorphous SiO2The thickness of the layer is 5-15 nm; the thickness of the single crystal AlN layer is 15-25 nm.
4. An enhanced AlN/AlGaN/GaN HEMT device according to claim 1, wherein: the thickness of the AlGaN ultrathin barrier layer is 5-7 nm, and the molar content of Al element is 25% -30%.
5. An enhanced AlN/AlGaN/GaN HEMT device according to claim 1, wherein: the drain metal electrode and the source metal electrode are made of four layers of metals including Ti, Al, Ni and Au; the material of the gate metal electrode consists of two layers of Ni and Au.
6. An enhanced AlN/AlGaN/GaN HEMT device according to claim 1, wherein: the gate metal electrode is positioned on one side close to the source metal electrode.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110459595A (en) * 2019-08-29 2019-11-15 华南理工大学 A kind of enhanced AlN/AlGaN/GaN HEMT device and preparation method thereof
CN113053742A (en) * 2021-03-12 2021-06-29 浙江集迈科微电子有限公司 GaN device and preparation method
CN113823675A (en) * 2021-08-23 2021-12-21 华南理工大学 HEMT device with novel source-drain field plate structure and preparation method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110459595A (en) * 2019-08-29 2019-11-15 华南理工大学 A kind of enhanced AlN/AlGaN/GaN HEMT device and preparation method thereof
CN113053742A (en) * 2021-03-12 2021-06-29 浙江集迈科微电子有限公司 GaN device and preparation method
CN113823675A (en) * 2021-08-23 2021-12-21 华南理工大学 HEMT device with novel source-drain field plate structure and preparation method
CN113823675B (en) * 2021-08-23 2023-09-29 华南理工大学 HEMT device with novel source drain field plate structure and preparation method

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