CN114373805A - Schottky barrier diode structure with polarized p-type doped [0001] crystal orientation aluminum gallium nitrogen field ring terminal - Google Patents
Schottky barrier diode structure with polarized p-type doped [0001] crystal orientation aluminum gallium nitrogen field ring terminal Download PDFInfo
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- 230000004888 barrier function Effects 0.000 title claims abstract description 32
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims description 37
- 239000013078 crystal Substances 0.000 title claims description 34
- 229910052757 nitrogen Inorganic materials 0.000 title claims description 18
- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical compound [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 title claims description 17
- 239000000758 substrate Substances 0.000 claims abstract description 20
- 229910002704 AlGaN Inorganic materials 0.000 claims abstract description 15
- 230000010287 polarization Effects 0.000 claims abstract description 14
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- QZQVBEXLDFYHSR-UHFFFAOYSA-N gallium(III) oxide Inorganic materials O=[Ga]O[Ga]=O QZQVBEXLDFYHSR-UHFFFAOYSA-N 0.000 claims description 8
- 230000003247 decreasing effect Effects 0.000 claims description 6
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- 229910002601 GaN Inorganic materials 0.000 description 14
- 230000005684 electric field Effects 0.000 description 14
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- 230000002441 reversible effect Effects 0.000 description 12
- 239000004065 semiconductor Substances 0.000 description 10
- 239000002019 doping agent Substances 0.000 description 7
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- 238000005530 etching Methods 0.000 description 5
- 229910010271 silicon carbide Inorganic materials 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
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- 238000005468 ion implantation Methods 0.000 description 3
- 238000001259 photo etching Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
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- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 2
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
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- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 1
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- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 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 specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
- H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
- H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
- H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
- H01L29/0619—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
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Abstract
The invention relates to a p-type doped [0001] with polarization]A Schottky barrier diode structure at the end of the crystal-oriented AlGaN field ring. The device structure sequentially comprises along the epitaxial growth direction: ohmic contact electrode, N+Substrate, N‑A drift layer; n is a radical of‑2-10 concentric Al with different radiuses are distributed on the drift layerx→0Ga1‑x→1An N field ring; outermost Alx→0Ga1‑x→1Inner edge and inner side Al of N field ringx→0Ga1‑x→1The N field ring is covered with an ohmic contact electrode, the ohmic contact electrode and Alx→0Ga1‑x→1Schottky electrodes are arranged in the grooves between the N field rings. The invention can effectively improve the breakdown voltage of the device and can not cause the forward characteristic degradation of the deviceThe preparation method has strong operability, low cost and simple and reliable process, and is suitable for industrial popularization and application.
Description
Technical Field
The invention relates to power electronicsThe field of devices, in particular to a [0001] doped device with polarized p-type]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) field ring terminal Schottky barrier diode structure and method of manufacture.
Background
At the present stage, the power electronic device technology is a key core device for developing national core capital construction engineering, and mainly relates to a plurality of social reputation key industries such as communication, electric power, traffic, numbers and the like; the method is a fundamental driving force for realizing 5G base stations, ultra-high voltage transmission, high-speed inter-city rail transit and high-efficiency new energy automobiles and realizing the targets of carbon peak reaching and carbon neutralization. In recent years, wide bandgap semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), and even gallium oxide (Ga)2O3) These materials have received much attention from many researchers, and are gradually replacing silicon (Si) -based power devices. Among them, a GaN-based Schottky Barrier Diode (SBD) has a low turn-on voltage (V)on) And high operating frequencies are rapidly gaining the interest of researchers. However, at high reverse bias, local electric field crowding occurs at the metal-to-semiconductor contact interface and contact edge, which can cause premature breakdown of the device. Therefore, in order to reduce the strong electric field at the edge of the metal-semiconductor contact, and achieve low leakage current and high breakdown voltage, many effective edge termination techniques have been proposed, such as field ring structure (field ring), field plate structure (field plate), ion implantation termination (ion implantation termination), etc. Among these, the field ring structure is one of the most commonly used edge termination techniques in Si-based, and even SiC-based, power devices. However, for the wide bandgap semiconductor GaN, and Ga2O3In other words, the further development of the P-type wide bandgap semiconductor field ring termination structure is limited by the problems of lack of effective P-type dopant ions, low activation rate of P-type impurities, high activation annealing temperature, etc. Accordingly, more researchers have begun investigating other field ring techniques, such as fluoride ion (F)-) Injection field rings, junction edge high resistance field rings, and junction edge isolation field rings, etc. However, these field ring techniques may reduce the reliability of the device to some extent, and even increase the forward on-resistance of the device, resulting in a decrease in the device reliabilityDegradation of the forward characteristics of the device. Therefore, it is a focus of researchers at this stage and even in the future to find a junction fringing field ring termination that can effectively increase the breakdown voltage of a device without degrading the forward characteristics of the device.
Disclosure of Invention
The invention aims to provide a [0001] doped Schottky barrier diode with polarized p-type for overcoming the defects in the conventional Schottky Barrier Diode (SBD) structure and technology]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) field ring termination. The device structure is formed by adding N-A layer of [0001] with gradually reduced aluminum (Al) component is grown on the drift layer]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) layer, and then forming a plurality of Al layers by etchingx→0Ga1-x→1An N-field ring structure. Al with gradually decreasing aluminum compositionx→0Ga1-x→1The N layer can realize the p-type AlGaN layer without any p-type doping due to the polarizer charges with negative charge characteristics formed by polarization effect. The method has strong operability, low cost and simple and reliable process, and is suitable for industrial popularization and application.
The technical scheme adopted by the invention for solving the technical problem is as follows:
polarized p-type doped [0001]A Schottky barrier diode structure at the end of the crystal-oriented AlGaN field ring; the device structure sequentially comprises along the epitaxial growth direction: ohmic contact electrodes 101, N+Substrate 102, N- A drift layer 103; n is a radical of-2-10 concentric Al with different radiuses are distributed on the drift layer 103x→0Ga1-x→1An N-field ring 105; outermost Alx→0Ga1-x→1Inner edge and inner Al of N-field ring 105x→0Ga1-x→1The N-field ring 105 is covered with an ohmic contact electrode 106, an ohmic contact electrode 106 and Alx→0Ga1-x→1A Schottky electrode 104 is arranged in a groove between the N field rings 105;
wherein, the convex Alx→0Ga1-x→1The projected area of the N field rings 105 occupies the whole N-55% -90% of the area of the drift layer 103; outermost Alx→0Ga1-x→1The ohmic contact electrode 106 on the N field ring 105 only partially covers the inner edge, and the coverage area of the Al occupying the outermost sidex→0Ga1-x→150% -80% of the upper surface of the N field ring 105;
outermost Alx→0Ga1-x→1The width (i.e., the difference between the inner and outer diameters) of the N-field ring 105 is Al of the inner portionx→0Ga1-x→1110% -195% of the width of the N field ring 105;
the substrate 102 is made of Si, SiC, GaN or Ga2O3Doping concentration of 1.0X 1018cm-3～5.0×1019cm-3；
Said N-The drift layer 103 is made of Si, SiC, GaN or Ga2O3The thickness of the material is 1.0-15 μm, and the doping concentration of Si is 1.0 × 1015cm-3～8.0×1016cm-3；
The Al isx→0Ga1-x→1The thickness of the material of the N layer 105 is 0.05-2 μm; al with gradually decreasing aluminum compositionx→ 0Ga1-x→1The N layer 105 has a polarizer charge with a negative charge characteristic due to polarization effect, and the density of the polarizer charge is 1.0 × 1017cm-3～1.0×1019cm-3；
The ohmic contact metal 101 is Ti/Au, Ti/Al/Ti/Au or Ti/Al/Ni/Au;
said N-The Schottky contact metal 104 on the drift layer 103 is Ni/Au;
the Al isx→0Ga1-x→1The ohmic contact electrode 106 on the N layer 105 is Ni/Au;
the Al isx→0Ga1-x→1In the N layer, Al is [0001] in composition]The grain direction is continuously and gradually reduced, and the value of the Al component x ranges from: al (Al)x→yGa1-x→1-yN,0<x≤1，0≤y<x；
The above novel p-type doped [ 0001%]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) Schottky barrier diode with field ring terminal, the raw materials involved can all pass through oneThe preparation method has the operation processes in the preparation method which are possessed by the technical personnel in the technical field.
The invention has the substantive characteristics that:
the invention creatively provides Alx→0Ga1-x→1N/N--GaN heterojunction and metal/N--a hybrid power diode structure consisting of GaN schottky junctions.
The invention is in N-Forming a plurality of Al with gradually reduced Al components on the upper surface of the GaN drift region through MOCVD epitaxial growth and ICP etching processx→0Ga1-x→1And an N field ring structure is adopted, so that the power diode structure with both a PN junction and a Schottky junction is integrally formed. Wherein, Alx→0Ga1-x→1N layer is along [0001]The crystal orientation epitaxial growth is performed, the crystal orientation epitaxial process is mature, the dislocation density is small, and the most important is that the crystal orientation epitaxial growth is performed only along [0001]]The AlGaN material grown by epitaxial growth in the crystal direction can generate a polarizer charge with negative electricity characteristic only after Al component is gradually reduced (reduced to a certain value or zero) so as to form a p-type AlGaN layer.
The invention has the beneficial effects that:
1) the invention adopts [0001] with gradually reduced Al component]Al of crystal orientationx→0Ga1-x→1An N-field ring structure substantially characterized by Alx→0Ga1-x→1N layer is along [0001]The crystal orientation epitaxial growth is performed, the crystal orientation epitaxial process is mature, the dislocation density is small, and the most important is along [0001]]The AlGaN material with epitaxial growth in crystal orientation can generate a polarizer charge with negative electricity characteristic after the Al composition is gradually reduced (reduced to a certain value or to zero), so the material can also form p-type Al without any p-type dopingx→0Ga1-x→1N layer, so that p-type wide bandgap semiconductor material can be well replaced. Therefore, the problems of high acquisition difficulty and high work efficiency of the wide bandgap semiconductor material P-type layer can be effectively solvedImmature technology and the like;
2) the invention designs a p-type doped [0001] with polarization]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) Schottky barrier diode structure with field ring termination, Al when reverse bias is appliedx→0Ga1-x→1The N/N-GaN is in a reverse bias state, so that the boundary of a depletion region can be effectively expanded, and the electric field crowding effect is weakened. For example, when the reverse bias is 500V, the electric field of the gold-half contact interface is effectively reduced from 3MV/cm to 2.6MV/cm, so that the strong electric field of the gold-half contact interface and the edge is reduced, and the breakdown voltage of the device is further improved. Therefore, compared with the traditional plane SBD, the breakdown voltage of the structure is improved from 200V to 850V, and is improved by nearly 3.25 times;
3) the method has strong operability, low cost and simple and reliable process, and is suitable for industrial popularization and application.
Drawings
The invention will be further described with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a standard planar sbd (planar sbd) device in the prior art.
FIG. 2 shows a p-type dopant [0001] with polarization in example 1]Aluminum gallium nitrogen (Al) of crystal orientationx→ 0Ga1-x→1N) Schottky barrier diode structure schematic diagram of field ring terminal.
FIG. 3 shows a p-type dopant of [0001] with polarization in example 1]Aluminum gallium nitrogen (Al) of crystal orientationx→ 0Ga1-x→1N) a transverse electric field distribution pattern near the bottom of the gold half-contact of the Schottky barrier diode structure at the field ring termination.
FIG. 4 shows a p-type dopant of [0001] with polarization in example 1]Aluminum gallium nitrogen (Al) of crystal orientationx→ 0Ga1-x→1N) reverse I-V characteristic curve map of Schottky barrier diode structure at field ring termination.
FIG. 5 shows N in example 1- Drift layer 103 and Alx→0Ga1-x→1Top view of the distribution of N field rings 105.
101-bottom ohmic contact electrode; 102-N+A substrate; 103-N-A drift layer; 104-schottky contact electrode; 105-Alx→0Ga1-x→1N layers; 106-Alx→0Ga1-x→1And an ohmic contact electrode on the N layer.
Detailed Description
The present invention will be further described with reference to the following examples and drawings, which should be construed as limiting the scope of the claims.
A schematic diagram of a standard planar SBD device in the prior art is shown in fig. 1. The device specific structure sequentially comprises along the epitaxial growth direction: bottom ohmic contact electrodes 101, N+Substrate 102, N- A drift layer 103 and a schottky contact electrode 104. The device utilizes metal and N-And a Schottky barrier mechanism is formed on the surface of the GaN drift layer to realize forward bias and reverse bias of the device. However, the planar structure is prone to generate an electric field concentration phenomenon at the schottky contact interface and the edge, especially at the contact edge, so the above-mentioned strong electric field is prone to cause the device to generate a large leakage current, and even to generate premature breakdown, which makes it difficult to adapt to the operating environment of medium and high voltage.
[0001] with polarized p-type doping of the invention]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) the Schottky barrier diode structure at the terminal of the field ring is shown in figure 2, and the Schottky barrier diode structure is cylindrical and is centrosymmetric; the device structure sequentially comprises along the epitaxial growth direction: ohmic contact electrodes 101, N+Substrate 102, N- A drift layer 103; n is a radical of-2-10 concentric Al with different radiuses are distributed on the drift layer 103x→0Ga1-x→1An N-field ring 105; outermost layer of Alx→0Ga1-x→1Inner edge of N field ring 105 and inner layer Alx→0Ga1-x→1The N-field ring 105 is covered with an ohmic contact electrode 106, an ohmic contact electrode 106 and Alx→0Ga1-x→1A Schottky electrode 104 is arranged in a groove between the N field rings 105;
wherein, the convex Alx→0Ga1-x→1The projected area of the N field rings 105 occupies the whole N-55% ~ of drift layer 103 area90 percent; outermost Alx→0Ga1-x→1The ohmic contact electrode 106 on the N field ring 105 only partially covers the inner edge, and the coverage area of the Al occupying the outermost sidex→0Ga1-x→150% -80% of the upper surface of the N field ring 105; outermost Al of devicex→0Ga1-x→1The width (i.e., the difference between the inner and outer diameters) of the N-field ring 105 is Al of the inner portionx→0Ga1-x→1110% -195% of the width of the N field ring 105;
the epitaxial direction of the device preparation is the [0001] crystal direction;
the substrate 102 is made of Si, SiC, GaN or Ga2O3Doping concentration of 1.0X 1018cm-3～5.0×1019cm-3；
Said N-The drift layer 103 is made of Si, SiC, GaN or Ga2O3The thickness of the material is 1.0-15 μm, and the doping concentration of Si is 1.0 × 1015cm-3～8.0×1016cm-3；
The Al isx→0Ga1-x→1The thickness of the material of the N layer 105 is 0.05-2 μm; al with gradually decreasing aluminum compositionx→ 0Ga1-x→1The N layer 105 has a polarizer charge with a negative charge characteristic due to polarization effect, and the density of the polarizer charge is 1.0 × 1017cm-3～1.0×1019cm-3；
The ohmic contact metal 101 at the bottom of the substrate 102 is Ti/Au, Ti/Al/Ti/Au or Ti/Al/Ni/Au;
said N-The Schottky contact metal 104 on the drift layer 103 is Ni/Au;
the Al isx→0Ga1-x→1The ohmic contact electrode 106 on the N layer 105 is Ni/Au.
The [0001] crystal orientation is one of the epitaxial growth directions of the AlGaN material, because the epitaxial process of the crystal orientation is more mature, the dislocation density is smaller, and most importantly, the AlGaN material epitaxially grown along the [0001] crystal orientation can generate the polarized body charge with negative electricity characteristic only after the Al component of the AlGaN material is gradually reduced (reduced to a certain value or zero), so that a p-type AlGaN layer is formed.
Example 1
This example employs a [0001] dopant with polarized p-type doping]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) field ring terminal Schottky barrier diode structure is shown in figure 2, the structure is cylindrical and centrosymmetric, and the specific diameter of the device is 32 μm. The structure sequentially comprises the following components along the epitaxial direction of the device: ohmic contact electrodes 101, N+Substrate 102, N-Drift layer 103, N-3 concentric Al with different radiuses are distributed on the drift layer 103x→0Ga1-x→1An N-field ring 105; the spacing between the field rings 105 was 2 μm, and the outermost layer Alx→0Ga1-x→1The width of the N field rings 105 is 5 μm, and the width of the inner field rings is the same and is 3 μm;
outermost layer of Al as described abovex→0Ga1-x→1Inner edge of N field ring 105 and inner layer Alx→0Ga1-x→1The N-field ring 105 is covered with an ohmic contact electrode 106, an ohmic contact electrode 106 and Alx→0Ga1-x→1 A Schottky electrode 104 is arranged in a groove between the N field rings 105; wherein the convex Alx→0Ga1-x→1The N field ring is formed by ICP etching and is raised Alx→0Ga1-x→1The projected area of the N field rings 105 occupies the whole N-76.17% of the area of the drift layer 103; wherein the ohmic contact electrode 106 only partially covers the outermost Alx→0Ga1-x→1The upper surface of the N field ring 105, the coverage area of which is the outermost Alx→0Ga1-x→155.56% of the upper surface of the N field ring 105;
the substrate 102 is made of GaN, the thickness of the material is 100 μm, and the doping concentration is 5.0 × 1018cm-3；
N is as defined above-The drift layer 103 was made of GaN, had a thickness of 13 μm and a doping concentration of 2.0X 1016cm-3；
[0001] above]Al of crystal orientationx→0Ga1-x→1The material thickness of the N layer 105 is 0.2 μm; al with gradually decreasing aluminum compositionx→0Ga1-x→1 The N layer 105 has a negative charge characteristic due to polarization effectHas a polarizer charge density of 5.0X 1017cm-3；
Al mentioned abovex→0Ga1-x→1The Al composition x of the N layer 105 was gradually decreased from 0.3 to 0;
the ohmic contact metal 101 at the bottom of the substrate 102 is Ti/Al/Ti/Au, and the thickness is respectively 10nm/30nm/60nm/100 nm;
n is as defined above-The Schottky contact metal 104 on the drift layer 103 is Ni/Au with a thickness of 360nm (i.e. the Ni/Au thicknesses are 30nm/330nm, respectively);
[0001] above]Al of crystal orientationx→0Ga1-x→1The ohmic contact electrode 106 on the N layer 105 is Ni/Au, and the thickness thereof is 30nm/100 nm;
the above-mentioned one with polarized p-type doping [0001]]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) Schottky barrier diode structure of field ring terminal, its concrete preparation method is as follows:
a first step of performing a high temperature 960 c heat treatment on the substrate 102 in a Metal Organic Chemical Vapor Deposition (MOCVD) reactor to remove impurities attached to the surface of the substrate 102;
second, N is epitaxially grown on the surface of the substrate 102 processed in the first step in an MOCVD reactor-The drift layer 103, the temperature is 1060 ℃, and the air pressure is 125 mbar;
thirdly, epitaxially growing N-Cleaning the substrate 102 of the drift layer 103 with an organic solvent and alcohol respectively, washing with high-purity deionized water, and drying with nitrogen;
fourthly, putting the cleaned sample into an MOCVD furnace, and performing reaction in N-Epitaxial growth of [0001] on the surface of drift layer 103]Al of crystal orientationx→0Ga1-x→1 An N layer 105; among them, trimethyl gallium (TMGa), trimethyl aluminum (TMAl) and ammonia (NH)3) Hydrogen (H) as a source of gallium, aluminum and nitrogen2) As a carrier gas, Al with the Al component gradually reduced from 0.3 (namely x is 0.3) to 0 is grown under the conditions of 1080 ℃ and 10kPa pressure by setting relevant parameters of an MOCVD furnace and controlling the dosages of a gallium source and an aluminum source in real timex→ 0Ga1-x→1N layers;
the fifth step, will [0001]]Al of crystal orientationx→0Ga1-x→1Coating photoresist on the surface of the N layer 105, forming a pattern after photoetching steps such as exposure, development and the like, then taking the photoresist as a mask layer, and finally forming a plurality of raised field ring structures by ICP etching, wherein the vertical height from the upper surface of the non-raised part to the upper surface of the middle raised part, namely the etching depth is 0.2 mu m; al on the outermost layer sidex→0Ga1-x→1The N field ring is 2 μm wider than the inner one;
sixthly, putting the cleaned sample into an electron beam evaporation chamber, and sequentially evaporating and depositing Ti/Al/Ti/Au metal with the thickness of 10nm/30nm/60nm/100nm on the back surface of the substrate 102; then in N2Performing rapid thermal annealing treatment at 500 deg.C for 60s in N+An ohmic contact electrode 101, such as Ti/Al/Ti/Au, is formed at the bottom of the substrate 102;
seventhly, the etched sample is added with Alx→0Ga1-x→1After the N layer is subjected to a photoetching process, evaporating and plating an ohmic contact electrode Ni/Au on the surface, wherein the thickness is 30nm/100 nm;
eighthly, photoetching the sample evaporated with the ohmic contact metal again, and then evaporating metal Ni/Au with the thickness of 30nm/330nm on the surface, wherein the metal and the N are-The surface of the drift layer 103 forms a schottky contact electrode 104 such as Ni/Au.
Thus obtaining the p-type doped [0001] with polarization]Aluminum gallium nitrogen (Al) of crystal orientationx→0Ga1-x→1N) field ring termination.
FIG. 3 shows a p-type dopant of [0001] with polarization in example 1]Aluminum gallium nitrogen (Al) of crystal orientationx→ 0Ga1-x→1N) field ring termination the electric field profile spectrum across the schottky barrier diode device near the bottom of the gold half contact, taken from a reverse bias voltage of-500V. The grey lines are the cross-sectional electric field profile of the device of the invention, from which it can be seen that the structure of the invention has a much smaller electric field distribution at the same reverse bias voltage, i.e. the electric field at the gold half-contact interface is effectively reduced from 3MV/cm to 2.6 MV/cm.
FIG. 4 shows a p-type dopant of [0001] with polarization in example 1]Aluminum gallium nitrogen (Al) of crystal orientationx→ 0Ga1-x→1N) reverse I-V characteristic map of Schottky barrier diode device at field ring terminal, wherein I-V curve obviously shows that the structure of the invention has larger breakdown voltage, for example, 1mA/cm in reverse leakage current2In the invention, the breakdown voltage value is 850V, and the breakdown voltage values of the traditional plane SBD are respectively about 200V under the condition of the same leakage current magnitude.
Example 2
The other steps are the same as those of embodiment 1 except that the material of the substrate 102 is replaced by Ga2O3；
The performance of the resulting device was close to that of example 1.
Example 3
The other steps are the same as example 1 except that N is-5 concentric Al with different radiuses are distributed on the drift layer 103x→ 0Ga1-x→1An N-field ring 105; the spacing between the field rings 105 was 1 μm, and the outermost layer Alx→0Ga1-x→1The width of the N field ring 105 is 3.5 μm, and the width of the inner field ring is the same and is 2 μm;
the performance of the resulting device was close to that of example 1.
Example 4
The other steps are the same as example 1, except that Alx→0Ga1-x→1The Al composition x of the N-field ring 105 is gradually reduced from 0.6 to 0;
the performance of the resulting device was close to that of example 1.
Example 5
The other steps are the same as example 1, except that Alx→0Ga1-x→1The Al composition x of the N field ring 105 is gradually reduced from 0.7 to 0.3;
the performance of the resulting device was close to that of example 1.
It can be seen from the above embodiments that the present invention performs a structural innovation on the basis of the conventional planar schottky barrier diode, i.e., N-Growing Al component on the drift layer with gradually reduced value0001]Al of crystal orientationx→0Ga1-x→1N layer, not requiring doping for polarization reasons, Alx→0Ga1-x→1The N can generate the polarizer charges with negative charge characteristics, so that a so-called p-type field ring terminal structure can be well formed instead of a p-type wide bandgap semiconductor material. This has Alx→0Ga1-x→1The Schottky barrier diode at the N field ring terminal can effectively reduce the problem of a strong electric field at a gold-semiconductor contact interface and the edge, thereby preventing the device from being broken down prematurely and reducing leakage current.
Wherein there are a plurality of Al whose Al composition is gradually reducedx→0Ga1-x→1The N field ring terminal structure is an important characteristic of the device.
The invention can well solve the problem that the wide bandgap semiconductor material is immature in the epitaxial growth process and the ion implantation process of the P-type layer at the present stage; in addition, Al is present when the device is reverse biasedx→0Ga1-x→1The N/GaN is in a reverse bias state, so that the structure can effectively reduce the electric field crowding problem of a gold-half contact interface and the edge, thereby relieving the Schottky barrier lowering effect caused by the image force to a greater extent and further improving the breakdown voltage of the device.
The invention is not the best known technology.
Claims (6)
1. Polarized p-type doped [0001]The Schottky barrier diode structure of the aluminum gallium nitrogen field ring terminal of the crystal orientation is characterized in that the device structure sequentially comprises the following components along the epitaxial growth direction: ohmic contact electrode, N+Substrate, N-A drift layer; n is a radical of-2-10 concentric Al with different radiuses are distributed on the drift layerx→0Ga1-x→1An N field ring; outermost Alx→0Ga1-x→1Inner edge and inner side Al of N field ringx→0Ga1-x→1The N field ring is covered with an ohmic contact electrode, the ohmic contact electrode and Alx→0Ga1-x→1Schottky electrodes are arranged in the grooves between the N field rings.
2. The tool of claim 1With polarised p-type doping [0001]The Schottky barrier diode structure of the crystal-oriented AlGaN field ring terminal is characterized in that the Schottky barrier diode structure is formed by Alx→0Ga1-x→1The N field ring projection area accounts for all N-55% -90% of the area of the drift layer; outermost Alx→0Ga1-x→1The ohmic contact electrode on the N field ring only partially covers the inner edge, and the coverage area of the Al occupying the outermost sidex→0Ga1-x→150% -80% of the upper surface of the N field ring.
3. [0001] with polarized p-type doping according to claim 1]The Schottky barrier diode structure with crystal-oriented AlGaN field ring terminal is characterized in that the outermost Alx→0Ga1-x→1Al with N field ring width insidex→0Ga1-x→1The width of the N field ring is 110-195%.
4. [0001] with polarized p-type doping according to claim 1]The Schottky barrier diode structure with crystal-oriented AlGaN field ring terminal is characterized in that the substrate material is Si, SiC, GaN or Ga2O3Doping concentration of 1.0X 1018cm-3～5.0×1019cm-3；
Said N-The drift layer is made of Si, SiC, GaN or Ga2O3The thickness of the material is 1.0-15 μm, and the doping concentration of Si is 1.0 × 1015cm-3～8.0×1016cm-3；
The ohmic contact metal is Ti/Au, Ti/Al/Ti/Au or Ti/Al/Ni/Au;
said N-The Schottky contact metal 104 on the drift layer is Ni/Au;
the Al isx→0Ga1-x→1The ohmic contact electrode on the N layer is Ni/Au.
5. [0001] with polarized p-type doping according to claim 1]The Schottky barrier diode structure of the crystal-oriented AlGaN field ring terminal is characterized in that the Schottky barrier diode structure is formed by Alx→0Ga1-x→1N layerWherein the Al component is [0001]]The grain direction is continuously and gradually reduced, and the value of the Al component x ranges from: al (Al)x→yGa1-x→1-yN,0<x≤1，0≤y<x。
6. [0001] with polarized p-type doping according to claim 1]The Schottky barrier diode structure of the crystal-oriented AlGaN field ring terminal is characterized in that the Schottky barrier diode structure is formed by Alx→0Ga1-x→1The thickness of the N layer is 0.05-2 μm; al with gradually decreasing aluminum compositionx→0Ga1-x→1The N layer has negative polar charge due to polarization effect, and the polar charge density is 1.0 × 1017cm-3～1.0×1019cm-3。
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