CN107104046B - Preparation method of gallium nitride Schottky diode - Google Patents
Preparation method of gallium nitride Schottky diode Download PDFInfo
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- CN107104046B CN107104046B CN201610099349.4A CN201610099349A CN107104046B CN 107104046 B CN107104046 B CN 107104046B CN 201610099349 A CN201610099349 A CN 201610099349A CN 107104046 B CN107104046 B CN 107104046B
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- 229910002601 GaN Inorganic materials 0.000 title claims abstract description 60
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 title claims abstract description 58
- 238000002360 preparation method Methods 0.000 title claims abstract description 25
- 229910052751 metal Inorganic materials 0.000 claims abstract description 145
- 239000002184 metal Substances 0.000 claims abstract description 145
- 238000002161 passivation Methods 0.000 claims abstract description 65
- 238000000151 deposition Methods 0.000 claims abstract description 41
- 238000000137 annealing Methods 0.000 claims abstract description 29
- 238000005530 etching Methods 0.000 claims abstract description 21
- 238000001259 photo etching Methods 0.000 claims abstract description 18
- 238000001312 dry etching Methods 0.000 claims abstract description 15
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 13
- 239000010936 titanium Substances 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims description 35
- 238000004519 manufacturing process Methods 0.000 claims description 18
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 14
- 230000004888 barrier function Effects 0.000 claims description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 239000010949 copper Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 238000005566 electron beam evaporation Methods 0.000 claims description 6
- 239000000758 substrate Substances 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 238000004518 low pressure chemical vapour deposition Methods 0.000 claims description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 description 9
- 238000000206 photolithography Methods 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 229910052733 gallium Inorganic materials 0.000 description 2
- -1 gallium nitride compound Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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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
- H01L29/6609—Diodes
- H01L29/66143—Schottky diodes
-
- 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
- H01L29/86—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
- H01L29/872—Schottky diodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2229/00—Indexing scheme for semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, for details of semiconductor bodies or of electrodes thereof, or for multistep manufacturing processes therefor
Abstract
The invention provides a preparation method of a gallium nitride Schottky diode, which comprises the steps of depositing a passivation layer on the surface of a gallium nitride epitaxial wafer; preparing a cathode of the gallium nitride Schottky diode; performing dry etching on the center of the passivation layer to form a Schottky contact hole; depositing metal titanium in the Schottky contact hole, the surface of the passivation layer and the surface of the cathode to form an ohmic metal layer; photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid structure; preparing an anode of the gallium nitride Schottky diode; wherein, the ohmic metal structure is in a grid structure and is wrapped by the anode. Therefore, the Schottky junction area is reduced under the condition that the output performance of the gallium nitride Schottky diode is not influenced, the Schottky contact resistance is reduced, and the device performance and the service life of the gallium nitride Schottky diode are improved.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a preparation method of a gallium nitride Schottky diode.
Background
A schottky diode is a semiconductor device made using a metal to contact a semiconductor layer. Compared with the traditional semiconductor diode, the Schottky diode has the characteristic of extremely short reverse recovery time, so that the Schottky diode is widely applied to circuits such as a switching power supply, a frequency converter, a driver and the like. The gallium nitride material is a third generation wide bandgap semiconductor material, and has the characteristics of large bandgap width, high electronic saturation rate, high breakdown electric field, high thermal conductivity, corrosion resistance, radiation resistance and the like, so that the gallium nitride material becomes an optimal material for preparing short-wave photoelectronic devices and high-voltage high-frequency high-power devices. In conclusion, the Schottky diode prepared by using the gallium nitride material combines the advantages of the special effect diode and the gallium nitride material, has the characteristics of high frequency and low loss, and has good application prospect in a switching power system.
In the fabrication of conventional gan schottky diodes, the anode metal is in contact with the gan material to form a schottky contact, and the cathode metal is in contact with the gan material to form an ohmic contact. However, due to the difference between the metal materials of the anode metal and the cathode metal for preparation and the preparation process, the schottky contact resistance is much larger than the ohmic contact resistance, which results in that when the gan schottky diode is used, large energy consumption is generated due to the large schottky contact resistance, and further, a large amount of heat is generated, and the service life of the diode is reduced.
Disclosure of Invention
The invention provides a preparation method of a gallium nitride Schottky diode, which is used for solving the problem that the Schottky contact resistance generated in the preparation process of the existing gallium nitride Schottky diode is far larger than the ohmic contact resistance, and has the beneficial effects of reducing the Schottky contact resistance and prolonging the service life of the gallium nitride Schottky diode.
The invention provides a preparation method of a gallium nitride Schottky diode, which comprises the following steps:
depositing a passivation layer on the surface of the gallium nitride epitaxial wafer;
preparing a cathode of the gallium nitride Schottky diode;
performing dry etching on the center of the passivation layer to form a Schottky contact hole;
depositing metal titanium in the Schottky contact hole, the surface of the passivation layer and the surface of the cathode to form an ohmic metal layer; photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid-shaped structure;
preparing an anode of the gallium nitride Schottky diode;
wherein, the ohmic metal structure is in a grid structure and is wrapped by the anode.
Further, in the above manufacturing method, the manufacturing a cathode of the gan schottky diode includes:
performing dry etching on the passivation layer to form two ohmic contact holes;
depositing a first metal in the two ohmic contact holes and on the surface of the passivation layer to form a first metal layer;
and photoetching, etching and annealing the first metal layer to form the cathode.
Further, in the above manufacturing method, depositing a first metal in the two ohmic contact holes and on the surface of the passivation layer to form a first metal layer includes:
and sequentially depositing metal titanium, metal aluminum, metal nickel and metal copper in the two ohmic contact holes and on the surface of the passivation layer by adopting an electron beam evaporation process to form the first metal layer.
Further, in the above manufacturing method, the manufacturing an anode of the gan schottky diode includes:
depositing a second metal on the surface of the passivation layer, the surface of the cathode and the surface of the ohmic metal structure in the Schottky contact hole to form a second metal layer;
and photoetching and etching the second metal layer to form the anode.
Further, in the above manufacturing method, depositing a second metal on the surface of the passivation layer, the surface of the cathode, and the surface of the ohmic metal structure in the schottky contact hole to form a second metal layer includes:
and depositing metal nickel and metal copper in the Schottky contact hole, the surface of the passivation layer, the surface of the cathode and the surface of the ohmic metal structure in sequence by adopting an electron beam evaporation process to form the second metal layer.
Further, in the above preparation method, the annealing treatment is an annealing process performed at an annealing temperature of 840 ℃ for 30s under a nitrogen atmosphere.
Further, in the above preparation method, the depositing a passivation layer on the surface of the gallium nitride epitaxial wafer includes:
and depositing silicon nitride on the surface of the gallium nitride epitaxial wafer by adopting a low-pressure chemical vapor deposition method to form the passivation layer.
Further, in the above manufacturing method, the number of the grid bars of the ohmic metal structure includes 3.
Further, in the above manufacturing method, the thickness of the ohmic metal structure is 30 nm.
Further, in the above preparation method, before depositing a passivation layer on the surface of the gallium nitride epitaxial wafer, the method further includes:
and sequentially preparing the substrate, the buffer layer and the barrier layer of the gallium nitride epitaxial wafer.
The invention provides a preparation method of a gallium nitride Schottky diode, which comprises the steps of depositing a passivation layer on the surface of a gallium nitride epitaxial wafer; preparing a cathode of the gallium nitride Schottky diode; performing dry etching on the center of the passivation layer to form a Schottky contact hole; depositing metal titanium in the Schottky contact hole, the surface of the passivation layer and the surface of the cathode to form an ohmic metal layer; photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid structure; preparing an anode of the gallium nitride Schottky diode; wherein, the ohmic metal structure is in a grid structure and is wrapped by the anode. According to the preparation method provided by the invention, before the anode is prepared, the ohmic metal structure in the grid-shaped structure is prepared in the Schottky contact hole and is wrapped by the anode, so that the Schottky junction area is reduced under the condition of not influencing the output performance of the gallium nitride Schottky diode, the Schottky contact resistance is reduced, and the device performance and the service life of the gallium nitride Schottky diode are improved.
Drawings
Fig. 1 is a schematic flow chart illustrating a method for manufacturing a gan schottky diode according to an embodiment of the present invention;
fig. 2 is a schematic flow chart illustrating a method for manufacturing a nitrided schottky diode according to a second embodiment of the present invention;
fig. 3 is a schematic cross-sectional view of the gan schottky diode after performing step 200 according to the second embodiment;
fig. 4 is a schematic cross-sectional view of the gan schottky diode after performing step 201 according to the second embodiment;
fig. 5 is a schematic cross-sectional view of the gan schottky diode after performing step 202 according to the second embodiment;
fig. 6 is a schematic cross-sectional view of the gan schottky diode after performing step 203 according to the second embodiment;
fig. 7 is a schematic cross-sectional view of the gan schottky diode after performing step 204 according to the second embodiment;
fig. 8 is a schematic cross-sectional view of the gan schottky diode after performing step 205 according to the second embodiment;
fig. 9 is a schematic cross-sectional view of the gan schottky diode after performing step 206 according to the second embodiment;
fig. 10 is a schematic cross-sectional view of the gan schottky diode after performing step 207 of the second embodiment;
fig. 11 is a schematic cross-sectional view of the gan schottky diode after step 208 of the second embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic flow chart of a method for manufacturing a gan schottky diode according to an embodiment of the present invention, where the method shown in fig. 1 includes the following steps:
and 101, depositing a passivation layer on the surface of the gallium nitride epitaxial wafer.
And 102, preparing a cathode of the gallium nitride Schottky diode.
Specifically, a passivation layer is deposited on the surface of the gan epitaxial wafer, for example, a low pressure chemical vapor deposition method may be used to deposit silicon nitride on the surface of the gan epitaxial wafer, so as to form the passivation layer; wherein, the thickness of the passivation layer may be 30 nanometers. The preparation process of the cathode of the gan schottky diode can adopt the current mature preparation process, and the skilled person can select the cathode according to the actual situation, which is not limited by the invention.
And 103, performing dry etching on the center of the passivation layer to form a Schottky contact hole.
104, depositing metal titanium on the surface of the passivation layer and the surface of the cathode in the Schottky contact hole to form an ohmic metal layer; and photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid structure.
Specifically, after the preparation of the cathode is completed, the passivation layer is subjected to dry etching at the center of the passivation layer, and a schottky contact hole reaching as deep as the surface of the gallium nitride epitaxial wafer is formed. Depositing metal titanium on the surface of the passivation layer and the surface of the cathode in the Schottky contact hole so as to form an ohmic metal layer; and photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid structure. The annealing treatment may be specifically an annealing process performed at an annealing temperature of 840 ℃ for 30s under the condition of nitrogen. The number of the grid bars of the ohmic metal structure comprises 3, and the thickness of the ohmic metal structure is 30 nanometers.
And 105, preparing an anode of the gallium nitride Schottky diode, and enabling the ohmic metal structure to be wrapped by the anode.
And preparing an anode of the gallium nitride Schottky diode along the surface of the ohmic metal structure in the Schottky contact hole, so that the ohmic metal structure is wrapped by the anode. The anode of the gan schottky diode may be prepared by a conventional mature process, which may be selected by a person skilled in the art according to practical situations, but the invention is not limited thereto.
The embodiment of the invention provides a preparation method of a gallium nitride Schottky diode, which comprises the steps of depositing a passivation layer on the surface of a gallium nitride epitaxial wafer; preparing a cathode of the gallium nitride Schottky diode; performing dry etching on the center of the passivation layer to form a Schottky contact hole; depositing metal titanium in the Schottky contact hole, the surface of the passivation layer and the surface of the cathode to form an ohmic metal layer; photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid structure; preparing an anode of the gallium nitride Schottky diode; wherein, the ohmic metal structure is in a grid structure and is wrapped by the anode. According to the preparation method provided by the invention, before the anode is prepared, the ohmic metal structure in the grid-shaped structure is prepared in the Schottky contact hole and is wrapped by the anode, so that the Schottky junction area is reduced under the condition of not influencing the output performance of the gallium nitride Schottky diode, the Schottky contact resistance is reduced, and the device performance and the service life of the gallium nitride Schottky diode are improved.
To further explain the method for manufacturing the gan schottky diode provided by the present invention, on the basis of the manufacturing method shown in fig. 1, fig. 2 is a schematic flow chart of a method for manufacturing the gan schottky diode provided by the second embodiment of the present invention, and the embodiment shown in fig. 2 describes the method for manufacturing the gan schottky diode in detail.
And 200, sequentially preparing a substrate, a buffer layer and a barrier layer of the gallium nitride epitaxial wafer.
Step 200 may also be included prior to step 101 in the method of fig. 1. Specifically, fig. 3 is a schematic cross-sectional structure diagram of a gan schottky diode after performing step 200 of the second embodiment, and as shown in fig. 3, a substrate 11, a buffer layer 12 and a barrier layer 13 in a gan epitaxial wafer are sequentially prepared by using a deposition process, wherein the substrate 11 is made of silicon and has a thickness of 625 μm; the buffer layer 12 is made of gallium nitride compound, and the thickness of the buffer layer can be 3 microns; the material of the barrier layer 13 is made of gallium aluminum nitride compound, and the thickness thereof can be 25 μm. Through the step 200, the gallium nitride epitaxial wafer is prepared, and a foundation is laid for the preparation of other parts of subsequent devices.
Specifically, fig. 4 is a schematic cross-sectional structure diagram of the gan schottky diode after step 201 of the second embodiment, and as shown in fig. 4, a passivation layer 14 is deposited on the surface of the barrier layer 13 in the gan epitaxial wafer. The execution method of step 201 is the same as step 101 in fig. 1, and is not described herein again.
And 204, carrying out photoetching, etching and annealing treatment on the first metal layer to form a cathode.
The step 102 of the method shown in FIG. 1 may specifically include the steps 202 and 204. Specifically, fig. 5 is a schematic cross-sectional structure diagram of the gan schottky diode after step 202 of the second embodiment is performed, and as shown in fig. 5, the passivation layer 14 is etched and two centrosymmetric ohmic contact holes 15 are formed at the edge of the passivation layer 14 of the gan schottky diode by using a dry etching process, and the diameter of each ohmic contact hole 15 may be 5 micrometers.
Fig. 6 is a schematic cross-sectional view of the gan schottky diode after step 203 of the second embodiment, and as shown in fig. 6, a first metal layer 16 is formed by first depositing a first metal in the two ohmic contact holes 15 and on the surface of the passivation layer 14. Further, titanium metal, aluminum metal, nickel metal and copper metal may be sequentially deposited in the two ohmic contact holes 15 and on the surface of the passivation layer 14 using an electron beam evaporation process to form the first metal layer 16, and the thickness of the first metal layer 16 may be 300 nm.
Fig. 7 is a schematic cross-sectional view of the gan schottky diode after step 204 of the second embodiment, and as shown in fig. 7, after the first metal layer 16 is formed, the cathode 17 is formed on the first metal layer 16 by photolithography, etching and annealing. Specifically, the first metal layer 16 is subjected to photolithography and etching, so that only the first metal layer 16 in the ohmic contact hole 15 and at the edge portion thereof is retained, and then, annealing treatment is performed, so that an alloy of titanium, aluminum, nickel and copper is formed, and the first metal layer 16 can also be alloyed on the contact surface thereof after reacting with gallium aluminum nitride in the barrier layer 13, thereby obtaining the cathode 17 having a low ohmic contact resistance. The photoetching process comprises gluing, exposing and developing, and the annealing treatment can be specifically an annealing process which is carried out for 30s at an annealing temperature of 840 ℃ under the condition of nitrogen.
And 205, performing dry etching on the center of the passivation layer to form a Schottky contact hole.
Fig. 8 is a schematic cross-sectional view of the gan schottky diode after performing step 205 of the second embodiment, and fig. 9 is a schematic cross-sectional view of the gan schottky diode after performing step 206 of the second embodiment. As shown in fig. 8, dry etching is performed in the center of the passivation layer 14 to form a schottky contact hole 18; depositing metal titanium on the surface of the passivation layer 14 and the surface of the cathode 17 in the Schottky contact hole 18 to form an ohmic metal layer; as shown in fig. 9, the ohmic metal layer is subjected to photolithography, etching and annealing to form an ohmic metal structure 19 in a gate structure. The number of the grid bars in the ohmic metal structure 19 includes 3, and the thickness of the ohmic metal structure 19 may be 30 nanometers. The execution methods of step 205 and step 206 are the same as step 103 and step 104 in fig. 1, respectively, and are not described herein again.
And step 207, depositing a second metal on the surface of the passivation layer, the surface of the cathode and the surface of the ohmic metal structure in the Schottky contact hole to form a second metal layer.
And 208, photoetching and etching the second metal layer to form an anode.
Step 105 of the method shown in fig. 1 may specifically include step 207 and step 208. Fig. 10 is a schematic cross-sectional view of the gan schottky diode after step 207 of the second embodiment, as shown in fig. 10, after the ohmic metal structure 19 is prepared, a second metal is deposited in the schottky contact hole 18, on the surface of the passivation layer 14, on the surface of the cathode 17, and on the surface of the ohmic metal structure 19 to form a second metal layer 20. Specifically, an electron beam evaporation process may be used to sequentially deposit metal nickel and metal copper in the schottky contact hole 18, the surface of the passivation layer 14, the surface of the cathode 17 and the surface of the ohmic metal structure 19 to form the second metal layer 20, wherein the thickness of the second metal layer 20 may be 300 nm.
Fig. 11 is a schematic cross-sectional view of the gan schottky diode after step 208 of the second embodiment, as shown in fig. 11, after forming the second metal layer 20, a photolithography and etching process is performed on the second metal layer 20, only the second metal layer 20 at the schottky contact hole 18 and at the edge thereof is remained, and the anode 21 is formed, wherein the photolithography process includes a photoresist coating, an exposure and a development, and the thickness of the anode 21 can be 300 nm. It should be noted that the formed anode 21 contacts the barrier layer 13 in the gan epitaxial wafer to form a schottky contact, and at the same time, completely covers the ohmic metal structure 19, so that the ohmic metal structure 19 is isolated from air, thereby reducing the schottky contact resistance and improving the device performance and lifetime of the gan schottky diode.
The second embodiment of the invention provides a preparation method of a gallium nitride Schottky diode, which comprises the steps of sequentially preparing a substrate, a buffer layer and a barrier layer of a gallium nitride epitaxial wafer; depositing a passivation layer on the surface of the gallium nitride epitaxial wafer; performing dry etching on the passivation layer to form two ohmic contact holes; depositing a first metal in the two ohmic contact holes and on the surface of the passivation layer to form a first metal layer; carrying out photoetching, etching and annealing treatment on the first metal layer to form a cathode; performing dry etching on the center of the passivation layer to form a Schottky contact hole; depositing metal titanium on the surface of the passivation layer and the surface of the cathode in the Schottky contact hole to form an ohmic metal layer; photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid-shaped structure; depositing a second metal on the surface of the passivation layer, the surface of the cathode and the surface of the ohmic metal structure in the Schottky contact hole to form a second metal layer; and photoetching and etching the second metal layer to form an anode, so that the ohmic metal structure is wrapped by the anode, thereby realizing that the Schottky junction area is reduced under the condition of not influencing the output performance of the gallium nitride Schottky diode, reducing the Schottky contact resistance, and improving the device performance and service life of the gallium nitride Schottky diode.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. A method for preparing a GaN Schottky diode is characterized by comprising the following steps:
depositing a passivation layer on the surface of the gallium nitride epitaxial wafer;
preparing a cathode of the gallium nitride Schottky diode;
performing dry etching on the center of the passivation layer to form a Schottky contact hole;
depositing metal titanium in the Schottky contact hole, the surface of the passivation layer and the surface of the cathode to form an ohmic metal layer; photoetching, etching and annealing the ohmic metal layer to form an ohmic metal structure in a grid-shaped structure;
preparing an anode of the gallium nitride Schottky diode;
the ohmic metal structure is of a grid-shaped structure and is wrapped by the anode;
the preparation of the cathode of the gallium nitride Schottky diode comprises the following steps:
performing dry etching on the passivation layer to form two ohmic contact holes; depositing a first metal in the two ohmic contact holes and on the surface of the passivation layer to form a first metal layer; carrying out photoetching, etching and annealing treatment on the first metal layer to form the cathode;
the preparation of the anode of the gallium nitride Schottky diode comprises the following steps:
depositing a second metal on the surface of the passivation layer, the surface of the cathode and the surface of the ohmic metal structure in the Schottky contact hole to form a second metal layer; and photoetching and etching the second metal layer to form the anode.
2. The method according to claim 1, wherein depositing a first metal in the two ohmic contact holes and on the surface of the passivation layer to form a first metal layer comprises:
and sequentially depositing metal titanium, metal aluminum, metal nickel and metal copper in the two ohmic contact holes and on the surface of the passivation layer by adopting an electron beam evaporation process to form the first metal layer.
3. The method of claim 2, wherein depositing a second metal in the schottky contact hole, on the surface of the passivation layer, the surface of the cathode, and the surface of the ohmic metal structure to form a second metal layer comprises:
and depositing metal nickel and metal copper in the Schottky contact hole, the surface of the passivation layer, the surface of the cathode and the surface of the ohmic metal structure in sequence by adopting an electron beam evaporation process to form the second metal layer.
4. The production method according to any one of claims 1 to 3, wherein the annealing treatment is an annealing process performed at an annealing temperature of 840 ℃ for an annealing time of 30s under a nitrogen atmosphere.
5. The preparation method according to any one of claims 1 to 3, wherein the depositing of the passivation layer on the surface of the gallium nitride epitaxial wafer comprises:
and depositing silicon nitride on the surface of the gallium nitride epitaxial wafer by adopting a low-pressure chemical vapor deposition method to form the passivation layer.
6. The method according to any one of claims 1 to 3, wherein the number of the bars of the ohmic metal structure comprises 3.
7. A method of manufacturing as claimed in any one of claims 1 to 3, wherein the ohmic metallic structure has a thickness of 30 nm.
8. The preparation method according to any one of claims 1 to 3, characterized by further comprising, before depositing a passivation layer on the surface of the gallium nitride epitaxial wafer:
and sequentially preparing the substrate, the buffer layer and the barrier layer of the gallium nitride epitaxial wafer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610099349.4A CN107104046B (en) | 2016-02-23 | 2016-02-23 | Preparation method of gallium nitride Schottky diode |
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