CN110707158B - GaN microwave diode with floating anode edge and preparation method thereof - Google Patents
GaN microwave diode with floating anode edge and preparation method thereof Download PDFInfo
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- 239000002184 metal Substances 0.000 claims description 69
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- H—ELECTRICITY
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- 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
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/88—Tunnel-effect diodes
- H01L29/882—Resonant tunneling diodes, i.e. RTD, RTBD
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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
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
- H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
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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
- H01L29/66083—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
- H01L29/66196—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices with an active layer made of a group 13/15 material
- H01L29/66204—Diodes
- H01L29/66219—Diodes with a heterojunction, e.g. resonant tunneling diodes [RTD]
Abstract
The invention discloses a preparation method of a GaN microwave diode with an empty anode edge, which mainly solves the problems of large capacitance and slow frequency response of a GaN transverse microwave diode. The GaN-based floating anode structure comprises a substrate (1), a GaN buffer layer (2), a GaN channel layer (3) and an AlGaN barrier layer (4) from bottom to top, wherein circular grooves (5) are formed in the channel layer and the barrier layer, annular cathodes (6) are arranged on the peripheral barrier layer of each groove, anodes (7) are arranged above the bottom, the side wall and the edge barrier layer of each groove, and a gap of 80-300nm is formed between each anode above the edge barrier layer of each groove and the barrier layer below the corresponding groove to form a partial anode floating structure with the length of 0.3-2 mu m. The invention can greatly reduce the junction capacitance of the GaN microwave diode, obviously improve the frequency response of the device, and can be widely applied to microwave rectification and microwave amplitude limiting.
Description
Technical Field
The invention belongs to the technical field of microelectronics, and particularly relates to a GaN microwave diode with an anode with an edge floating, which can be used for microwave rectification or microwave amplitude limiting.
Technical Field
As a wide bandgap semiconductor material, a GaN material has great electrical performance advantages, an AlGaN/GaN heterojunction structure can induce high-concentration two-dimensional electron gas on one side of GaN near an interface due to strong spontaneous polarization and piezoelectric polarization effects, ionized impurity scattering and alloy disordered scattering are small due to the fact that electrons are contained in a potential well and impurity doping in the region is extremely small, and the two-dimensional electron gas has high mobility and electron saturation rate. And because of the inherent wide bandgap property of the material, the GaN has extremely high critical breakdown field intensity, and is suitable for manufacturing high-power high-frequency microwave devices. In order to further improve the frequency response of the GaN diode device, it is necessary to reduce the capacitance and resistance of the device.
One of the prior art is GaN lateral diode, which etches mesa isolation regions on AlGaN/GaN heterojunction and makes stripe-shaped ohmic contact and schottky contact on the mesa, respectively, as shown in fig. 1. In order to reduce the device capacitance, the size of the strip schottky contact metal must be continuously reduced, so a high-resolution stepper or an electron beam direct writing device is required, the two devices are expensive, the efficiency is low, the process yield is low, and the technology cannot avoid the overlapping of the schottky metal and the two-dimensional electron gas below, so the promotion level is limited.
The other prior art is a groove anode structure GaN lateral diode, which introduces an etching region below an anode based on the former technology, and since a heterojunction structure is damaged, the capacitance of the etching region is eliminated, and the capacitance of a device is reduced to a great extent, the structure of which is as shown in fig. 2. However, in order to ensure process feasibility, the anode edge needs to be lapped on the AlGaN barrier layer, and capacitance generated by overlapping of the schottky anode and the two-dimensional electron gas is still introduced to influence performance.
Disclosure of Invention
The invention aims to overcome the defects of a GaN microwave diode, provides the GaN microwave diode based on anode edge floating and a preparation method thereof, and aims to reduce junction capacitance, improve device performance and greatly improve device working frequency by combining a groove anode etching process.
In order to realize the aim, the GaN microwave diode with the floating anode edge comprises a substrate, a GaN buffer layer, a GaN channel layer and an AlGaN barrier layer from bottom to top, and is characterized in that circular grooves are arranged on the channel layer and the barrier layer, an annular cathode is arranged on the peripheral barrier layer of each groove, anodes are arranged at the bottom and the side wall of each groove and above the barrier layer at the edge of each groove, and a gap of 80-300nm is arranged between the anode above the barrier layer at the edge of each groove and the barrier layer below the barrier layer to form a partial anode floating structure with the length of 0.3-2 mu m.
Preferably, the depth of the recess is 5 to 25nm below the AlGaN barrier and the GaN surface.
Preferably, the substrate is a SiC substrate having a thickness of 400 μm to 600 μm, a sapphire substrate having a thickness of 400 μm to 600 μm, or a Si substrate having a thickness of 400 μm to 1000 μm.
Preferably, the epitaxial buffer layer is a GaN buffer layer having a thickness of 1 μm to 6 μm or an AlGaN graded buffer layer having a thickness of 1 μm to 6 μm.
Preferably, the GaN channel layer is formed of unintentionally doped GaN having a thickness of 100nm to 400 nm.
Preferably, the anode is a stack of Ni metal with a thickness of 30-200nm and Au metal with a thickness of 0-200 nm.
In order to achieve the purpose, the invention discloses a method for preparing a GaN microwave diode with an anode with a floating edge, which has the technical key points that: evaporating 80nm-300nm metal Ge on a device with cathode ohmic contact and mesa isolation by electron beam, etching the Ge metal in an anode region by adopting an RIE (reactive ion etching) dry etching process, etching a barrier layer and a channel layer to 5-25nm below an AlGaN/GaN heterojunction interface by adopting an ICP (inductively coupled plasma) etching process, manufacturing an anode with Ni/Au metal, and then passing through H2O2The floating structure is realized by selectively etching the characteristics of Ge metal, and the purpose of reducing junction capacitance of the device is achieved. The method comprises the following specific steps:
1) cleaning an epitaxial wafer:
soaking an epitaxial wafer with an AlGaN/GaN structure in an HF acid solution or an HCl acid solution for 30s, sequentially placing the epitaxial wafer in an acetone solution, an absolute ethyl alcohol solution and deionized water, ultrasonically cleaning for 5min respectively, and then drying by using nitrogen;
2) manufacturing a GaN microwave diode cathode:
2a) sequentially carrying out glue homogenizing, glue drying, device cathode region photoetching and developing on a clean epitaxial wafer, and depositing a Ti/Al/Ni/Au metal lamination on the epitaxial wafer by using electron beam evaporation equipment;
2b) soaking an epitaxial wafer deposited with the Ti/Al/Ni/Au metal lamination layer in an acetone solution to strip metal in a photoresist area, then sequentially putting the epitaxial wafer into acetone, absolute ethyl alcohol and a deionized water solution to perform ultrasonic cleaning for 5 minutes respectively, blow-drying by nitrogen, and then putting the epitaxial wafer into a rapid annealing furnace to perform annealing to form a device cathode;
3) manufacturing a table top for isolation:
3a) carrying out glue homogenizing, glue drying mesa isolation photoetching and developing on the epitaxial wafer subjected to cathode ohmic contact;
3b) etching the area outside the GaN mesa by using an ICP etching machine;
3c) sequentially putting the etched epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution for ultrasonic cleaning for 5 minutes respectively, and drying by using nitrogen to form device isolation;
4) depositing 80-300nm metal Ge on the epitaxial wafer with the mesa isolation by using electron beam evaporation equipment;
5) manufacturing an anode groove:
5a) sequentially carrying out glue homogenizing, glue drying, anode groove photoetching and developing on the epitaxial wafer deposited with the metal Ge;
5b) etching Ge metal in an anode open pore region of the epitaxial wafer to the surface of the barrier layer by using an RIE etching machine, etching the barrier layer and the channel layer to a position 5-25nm below an AlGaN/GaN interface by using an ICP etching machine, sequentially putting the barrier layer and the channel layer into solutions of acetone, absolute ethyl alcohol and deionized water, ultrasonically cleaning for 5 minutes respectively, drying by using nitrogen, and finishing the manufacture of an anode groove;
6) manufacturing an anode of the GaN microwave diode:
6a) sequentially carrying out glue homogenizing, glue drying, device anode area photoetching and developing on the epitaxial wafer etched with the anode groove, and depositing metal Ni with the thickness of 30-200nm and then depositing metal Au with the thickness of 0-200nm on the epitaxial wafer by using electron beam evaporation equipment;
6b) soaking the epitaxial wafer subjected to the operation of 6a) in an acetone solution to strip metal on a photoresist area, sequentially putting the epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution, ultrasonically cleaning for 5 minutes respectively, and drying by using nitrogen to finish the manufacture of the anode of the diode;
7) ge metal wet etching:
putting the epitaxial wafer with the anode into H with the temperature of 40-80 DEG C2O2Soaking the solution for 3-5 minutes, taking out, washing with deionized water, and blow-drying with nitrogen to complete the fabrication of the GaN microwave diode with the floating anode edge.
The invention has the following advantages:
1. the invention adopts a groove anode structure, so that the Schottky metal is directly contacted with the side wall of the two-dimensional electron gas area, and the two-dimensional electron gas in the etching area is removed, therefore, the anode metal and the lower capacitor do not exist in the area, the junction capacitance of the device is greatly reduced, the anode of the device is allowed to be made into a larger circle, the manufacturing cost is reduced, and the yield is improved.
2. The invention utilizes heated H2O2The method has the characteristics that the solution reacts with Ge metal but does not react with Ni/Au, the Ge metal deposited between the edge of the anode of the device and the barrier layer is removed, the anode structure with the floating edge of the anode is realized, the capacitance introduced by the part of the anode is further reduced, the frequency characteristic of the device is greatly improved, and the method is simple, effective and high in operability.
Drawings
FIG. 1 is a schematic cross-sectional view of a conventional GaN lateral diode;
FIG. 2 is a schematic view of a cross-sectional structure of a conventional trench anode GaN lateral diode;
FIG. 3 is a schematic cross-sectional view of a GaN microwave diode with an empty anode edge according to the present invention;
fig. 4 is a schematic flow chart of the present invention for manufacturing the diode of fig. 3.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
Referring to fig. 3, the device of the invention is carried out on an AlGaN/GaN epitaxial wafer, which comprises a substrate 1, an epitaxial buffer layer 2, a GaN channel layer 3 and an AlGaN barrier layer 4 from bottom to top, wherein the substrate 1 adopts a SiC substrate with a thickness of 400 μm-600 μm or a sapphire substrate with a thickness of 400 μm-600 μm or a Si substrate with a thickness of 400 μm-1000 μm, the epitaxial buffer layer 2 adopts a GaN buffer layer with a thickness of 1 μm-6 μm or an AlGaN graded buffer layer with a thickness of 1 μm-6 μm, the GaN channel layer 3 adopts unintentional doped GaN with a thickness of 100nm-400nm, and the AlGaN barrier layer 4 has a thickness of 20-30 nm. Circular grooves 5 are arranged on the channel layer 3 and the barrier layer 4, the depth of each groove is 5-25nm below the interface of the AlGaN barrier layer and the GaN channel layer, an annular cathode 6 is arranged on the barrier layer on the periphery of the groove 5, an anode 7 is arranged above the barrier layer on the bottom, the side wall and the edge of the groove 5, and the anode 7 is formed by laminating Ni metal with the thickness of 30-200nm and Au metal with the thickness of 0-200 nm. The length of the anode above the barrier layer at the edge of the groove is 0.3-2 μm, and a gap of 80-300nm is arranged between the anode and the barrier layer below the groove to form a floating structure of a part of the anode.
Referring to fig. 4, the method for preparing a microwave diode with floating GaN at the anode edge of the invention provides the following three examples:
in example 1, an anode edge floating GaN microwave diode was fabricated in which the anode recess was etched to 5nm below the AlGaN/GaN interface, the thickness of the anode Ni/Au metal was 30/200nm, and the gap between the anode above the recess edge barrier layer and the barrier layer below was 200 nm.
An epitaxial wafer of an AlGaN/GaN structure with a thickness of 400 mu m and a GaN buffer layer with a thickness of 1 mu m is firstly placed into an HF acid solution or an HCl acid solution to be soaked for 30s, then sequentially placed into an acetone solution, an absolute ethyl alcohol solution and deionized water to be ultrasonically cleaned for 5min respectively, and then dried by nitrogen.
And 2, manufacturing a GaN microwave diode cathode, as shown in a figure 4 (b).
2a) Sequentially carrying out glue homogenizing, glue drying, device cathode region photoetching and developing on a clean epitaxial wafer, and depositing a Ti/Al/Ni/Au metal lamination on the epitaxial wafer by using electron beam evaporation equipment, wherein the thicknesses of the Ti/Al/Ni/Au metal lamination are 22/140/55/45nm respectively;
2b) soaking the epitaxial wafer deposited with the Ti/Al/Ni/Au metal lamination layer in an acetone solution to strip the metal in the photoresist area, then putting the epitaxial wafer into acetone, absolute ethyl alcohol and deionized water solution in sequence to perform ultrasonic cleaning for 5 minutes respectively, blow-drying by nitrogen, and then putting the epitaxial wafer into a rapid annealing furnace to perform annealing to form the cathode of the device.
Step 3, fabricating mesa isolation as shown in fig. 4 (c).
3a) Sequentially carrying out glue homogenizing, glue drying, mesa isolation photoetching and developing on the epitaxial wafer subjected to cathode ohmic contact;
3b) and etching the mesa for isolation by using an ICP (inductively coupled plasma) etching machine, sequentially putting the etched epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution for ultrasonic cleaning for 5 minutes respectively, and drying by using nitrogen to form device isolation.
And 4, depositing 200nm of metal Ge on the epitaxial wafer subjected to mesa isolation by using an electron beam evaporation device, as shown in fig. 4 (d).
And 5, manufacturing an anode groove as shown in fig. 4 (e).
5a) The method comprises the following steps of sequentially carrying out glue homogenizing, glue drying, anode groove photoetching and developing on an epitaxial wafer deposited with metal Ge, and etching Ge metal in an anode opening area of the epitaxial wafer to the surface of a barrier layer by using an RIE etching machine, wherein the etching conditions are as follows:
CF4the gas flow is 6 sccm; CHF3The gas flow is 8 sccm; the flow rate of He gas is 120 sccm; the radio frequency power is 150W; the pressure of the reaction chamber is 1000 mTorr;
5b) etching the epitaxial wafer barrier layer and the channel layer to the position below the AlGaN/GaN interface by using an ICP etching machine under the etching conditions of: BCl3The gas flow rate is 20 sccm; the radio frequency power is 45W; the pressure of the reaction chamber is 15 mTorr;
5c) and sequentially putting the epitaxial wafer into acetone, absolute ethyl alcohol and deionized water solution, ultrasonically cleaning for 5 minutes respectively, and blow-drying by using nitrogen to finish the manufacture of the anode groove.
And 6, manufacturing an anode of the GaN microwave diode, as shown in the figure 4 (f).
6a) Sequentially carrying out glue homogenizing, glue drying, device anode area photoetching and developing on the epitaxial wafer etched with the anode groove, and depositing metal Ni with the thickness of 30nm and metal Au with the thickness of 200nm on the epitaxial wafer by using electron beam evaporation equipment;
6b) and soaking the epitaxial wafer evaporated with the metal Ni and the metal Au in an acetone solution to strip the metal on the photoresist area, then putting the epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution in sequence, ultrasonically cleaning for 5 minutes respectively, and drying by using nitrogen to finish the manufacture of the diode anode.
Step 7, Ge metal wet etching, as shown in fig. 4 (g).
Putting the epitaxial wafer with the anode into H with the temperature of 40-80 DEG C2O2Soaking the solution for 3-5 minutes, taking out, washing with deionized water, and blow-drying with nitrogen to complete the fabrication of the GaN microwave diode with the floating anode edge.
Example 2, an anode edge floating GaN microwave diode was fabricated with an anode recess etched 10nm below the AlGaN/GaN interface, an anode Ni/Au metal thickness of 45/150nm, and a gap of 300nm between the anode above the recess edge barrier layer and the underlying barrier layer.
Step one, the epitaxial wafer is cleaned, as shown in fig. 4 (a).
The epitaxial wafer of the AlGaN/GaN structure with the thickness of 800 mu m and the thickness of the GaN buffer layer of 6 mu m is firstly put into HF acid solution or HCl acid solution to be soaked for 30s, then sequentially put into acetone solution, absolute ethyl alcohol solution and deionized water to be ultrasonically cleaned for 5min respectively, and then is dried by nitrogen.
Step two, fabricating a GaN microwave diode cathode as shown in fig. 4 (b).
The specific implementation of this step is the same as step 2 of example 1.
Step three, fabricating mesa isolation, as shown in fig. 4 (c).
The specific implementation of this step is the same as step 3 of example 1.
And step four, depositing 300nm of metal Ge on the epitaxial wafer with the mesa isolation by using an electron beam evaporation device, as shown in fig. 4 (d).
And step five, manufacturing an anode groove as shown in fig. 4 (e).
5.1) sequentially carrying out spin coating, baking, anode groove photoetching and developing on the epitaxial wafer with the deposited Ge metal, and using an RIE etching machine to carry out CF etching on the epitaxial wafer4Gas flow rate of 8sccm, CHF3Etching Ge metal in an opening area of an anode of the epitaxial wafer to the surface of the barrier layer under the process conditions that the gas flow is 10sccm, the He gas flow is 150sccm, the radio frequency power is 250W and the pressure of the reaction chamber is 1500 mTorr;
5.2) reusing ICP etcher on BCl3Gas flow of 30sccm, RF power of 55W, and reaction chamberAnd etching the barrier layer and the channel layer of the epitaxial wafer to 10nm below the AlGaN/GaN interface under the pressure of 20mTorr, sequentially putting the epitaxial wafer into acetone, absolute ethyl alcohol and deionized water solution, ultrasonically cleaning for 5 minutes respectively, and blow-drying by using nitrogen to finish the manufacture of the anode groove.
And 6, manufacturing an anode of the GaN microwave diode, as shown in the figure 4 (f).
6.1) sequentially carrying out glue homogenizing, glue drying, device anode area photoetching and developing on the epitaxial wafer etched with the anode groove, and depositing 45 nm-thick metal Ni and 150 nm-thick metal Au on the epitaxial wafer by using electron beam evaporation equipment;
and 6.2) soaking the epitaxial wafer of the evaporated metal Ni and the metal Au in an acetone solution to strip the metal on the photoresist area, then putting the epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution in sequence, ultrasonically cleaning for 5 minutes respectively, and drying by using nitrogen to finish the manufacture of the diode anode.
Step 7, Ge metal wet etching, as shown in fig. 4 (g).
The specific implementation of this step is the same as step 7 of example 1.
Example 3, an anode edge floating GaN microwave diode was fabricated with anode grooves etched to 15nm below the AlGaN/GaN interface, an anode Ni/Au metal thickness of 60/100nm, and a gap of 100nm between the anode above the groove edge barrier layer and the underlying barrier layer.
Step A, cleaning the epitaxial wafer, as shown in FIG. 4 (a).
The epitaxial wafer of the AlGaN/GaN structure adopting the sapphire substrate with the thickness of 600 micrometers and the AlGaN gradual buffer layer with the thickness of 3 micrometers is firstly put into an HF acid solution or an HCl acid solution to be soaked for 30s, then sequentially put into an acetone solution, an absolute ethyl alcohol solution and deionized water to be ultrasonically cleaned for 5min respectively, and then is dried by nitrogen.
And step B, manufacturing a GaN microwave diode cathode, as shown in figure 4 (B).
The specific implementation of this step is the same as step 2 of example 1.
Step C, fabricating mesa isolation, as shown in fig. 4 (C).
The specific implementation of this step is the same as step 3 of example 1.
And D, depositing 150nm of metal Ge on the epitaxial wafer with the mesa isolation by using an electron beam evaporation device, as shown in a figure 4 (D).
And E, manufacturing an anode groove as shown in figure 4 (E).
E1) The method comprises the following steps of sequentially carrying out glue homogenizing, glue drying, anode groove photoetching and developing on an epitaxial wafer deposited with metal Ge, and etching the anode opening Ge metal of the epitaxial wafer to the surface of a barrier layer by using an RIE etching machine, wherein the etching conditions are as follows: CF (compact flash)4The gas flow is 10 sccm; CHF3The gas flow is 12 sccm; the flow rate of He gas is 180 sccm; the radio frequency power is 300W; the pressure of the reaction chamber is 2000 mTorr;
E2) etching the epitaxial wafer barrier layer and the channel layer to the position 15nm below the AlGaN/GaN interface by using an ICP etching machine, wherein the etching is as follows: BCl3The gas flow rate is 40 sccm; the radio frequency power is 65W; the pressure of the reaction chamber is 25 mTorr;
E3) and sequentially putting the etched epitaxial wafer into acetone, absolute ethyl alcohol and deionized water solution, ultrasonically cleaning for 5 minutes respectively, and blow-drying by using nitrogen to finish the manufacture of the anode groove.
And F, manufacturing an anode of the GaN microwave diode, as shown in figure 4 (F).
F1) Sequentially carrying out glue homogenizing, glue drying, device anode area photoetching and developing on the epitaxial wafer etched with the anode groove, and depositing metal Ni with the thickness of 60nm and metal Au with the thickness of 100nm on the epitaxial wafer by using electron beam evaporation equipment;
F2) and soaking the epitaxial wafer with evaporated metal Ni and metal Au in an acetone solution to strip the metal on the photoresist area, then putting the epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution in sequence, ultrasonically cleaning for 5 minutes respectively, and drying by using nitrogen to finish the manufacture of the diode anode.
Step G, Ge metal wet etch, FIG. 4 (G).
The specific implementation of this step is the same as step 7 of example 1.
The foregoing description is only three specific examples of the present invention and should not be construed as limiting the invention, it will be obvious to those skilled in the art that various changes and modifications in form and detail may be made therein without departing from the principle and structure of the invention after understanding the present disclosure, but such changes and modifications are to be considered within the scope of the appended claims.
Claims (3)
1. A preparation method of a GaN microwave diode with an empty anode edge comprises a substrate (1), a GaN buffer layer (2), a GaN channel layer (3) and an AlGaN barrier layer (4) from bottom to top, and is characterized in that circular grooves (5) are arranged on the channel layer (3) and the barrier layer (4), an annular cathode (6) is arranged on the peripheral barrier layer of each groove (5), anodes (7) are arranged at the bottoms and the side walls of the grooves (5) and above the groove edge barrier layer, and an 80-300nm gap is arranged between the anode above the groove edge barrier layer and the barrier layer below the groove edge barrier layer to form a partial anode empty structure with the length of 0.3-2 mu m; the method is characterized by comprising the following steps:
1) cleaning an epitaxial wafer:
soaking an epitaxial wafer with an AlGaN/GaN structure in an HF acid solution or an HCl acid solution for 30s, sequentially placing the epitaxial wafer in an acetone solution, an absolute ethyl alcohol solution and deionized water, ultrasonically cleaning for 5min respectively, and then drying by using nitrogen;
2) manufacturing a GaN microwave diode cathode:
2a) sequentially carrying out glue homogenizing, glue drying, device cathode region photoetching and developing on a clean epitaxial wafer, and depositing a Ti/Al/Ni/Au metal lamination on the epitaxial wafer by using electron beam evaporation equipment;
2b) soaking an epitaxial wafer deposited with the Ti/Al/Ni/Au metal lamination layer in an acetone solution to strip metal in a photoresist area, then sequentially putting the epitaxial wafer into acetone, absolute ethyl alcohol and a deionized water solution to perform ultrasonic cleaning for 5 minutes respectively, blow-drying by nitrogen, and then putting the epitaxial wafer into a rapid annealing furnace to perform annealing to form a device cathode;
3) manufacturing a table top for isolation:
3a) carrying out glue homogenizing, glue drying mesa isolation photoetching and developing on the epitaxial wafer subjected to cathode ohmic contact;
3b) etching the area outside the GaN mesa by using an ICP etching machine;
3c) sequentially putting the etched epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution for ultrasonic cleaning for 5 minutes respectively, and drying by using nitrogen to form device isolation;
4) depositing 80-300nm metal Ge on the epitaxial wafer with the mesa isolation by using electron beam evaporation equipment;
5) manufacturing an anode groove:
5a) sequentially carrying out glue homogenizing, glue drying, anode groove photoetching and developing on the epitaxial wafer deposited with the metal Ge;
5b) etching Ge metal in an anode open pore region of the epitaxial wafer to the surface of the barrier layer by using an RIE etching machine, etching the barrier layer and the channel layer to a position 5-25nm below an AlGaN/GaN interface by using an ICP etching machine, sequentially putting the barrier layer and the channel layer into solutions of acetone, absolute ethyl alcohol and deionized water, ultrasonically cleaning for 5 minutes respectively, drying by using nitrogen, and finishing the manufacture of an anode groove;
6) manufacturing an anode of the GaN microwave diode:
6a) sequentially carrying out glue homogenizing, glue drying, device anode area photoetching and developing on the epitaxial wafer etched with the anode groove, and depositing metal Ni with the thickness of 30-200nm and then depositing metal Au with the thickness of 0-200nm on the epitaxial wafer by using electron beam evaporation equipment;
6b) soaking the epitaxial wafer subjected to the operation of 6a) in an acetone solution to strip metal on a photoresist area, sequentially putting the epitaxial wafer into a clean acetone solution, an absolute ethyl alcohol solution and a deionized water solution, ultrasonically cleaning for 5 minutes respectively, and drying by using nitrogen to finish the manufacture of the anode of the diode;
7) ge metal wet etching:
putting the epitaxial wafer with the anode into H with the temperature of 40-80 DEG C2O2Soaking the solution for 3-5 minutes, taking out, washing with deionized water, and blow-drying with nitrogen to complete the manufacture of the GaN microwave diode with the floating anode edge.
2. The method of claim 1, wherein Ge metal is etched in 5b) under the following process conditions:
CF4gas flow rate: 6-10 sccm;
CHF3gas flow rate: 8-12 sccm;
flow rate of He gas: 120-;
radio frequency power: 150-300W;
reaction chamber pressure: 1000 and 2000 mTorr.
3. The method of claim 1, wherein the barrier layer and the channel layer are etched in 5b) under the following process conditions:
BCl3gas flow rate: 20-40 sccm;
radio frequency power: 45-65W;
reaction chamber pressure: 15-25 mTorr.
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| CN101027778A (en) * | 2004-09-24 | 2007-08-29 | 皇家飞利浦电子股份有限公司 | Field effect transistor |
| CN106158984A (en) * | 2015-04-24 | 2016-11-23 | 中央大学 | Diode element and manufacture method thereof |
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| CN101027778A (en) * | 2004-09-24 | 2007-08-29 | 皇家飞利浦电子股份有限公司 | Field effect transistor |
| CN106158984A (en) * | 2015-04-24 | 2016-11-23 | 中央大学 | Diode element and manufacture method thereof |
| CN107910371A (en) * | 2017-09-21 | 2018-04-13 | 中国电子科技集团公司第五十五研究所 | A kind of method of improvement GaN HEMT surface electronic beam direct write charge accumulateds |
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