Lateral AlN epitaxial Schottky diode and its fabrication process

Abstract

The present invention discloses a Schottky diode with a lateral AlN epitaxial structure and a manufacturing process. The diode comprises: a substrate layer having a first surface and a second surface arranged opposite each other; a back electrode disposed on the first surface of the substrate layer; an AlN buffer layer, a UID-AlN layer, and a N-AlN layer stacked in sequence on the second surface of the substrate layer; a GaN protective layer grown on the surface of the N-AlN layer; an isolation ring disposed at the edges of the UID-AlN layer, the N-AlN layer, and the GaN protective layer; an ohmic contact metal layer deposited on the GaN protective layer; a Schottky contact metal layer deposited on the GaN protective layer; and a SiO2 passivation layer deposited on the ohmic contact metal layer, the Schottky contact metal layer, the isolation ring, and the GaN protective layer. The present invention aims to achieve a Schottky diode that meets the requirements of higher breakdown voltage, lower on-state voltage drop, and high frequency and low switching loss.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a Schottky diode with a lateral AlN epitaxial structure and a manufacturing process thereof. Background Art

[0002] Power diodes are widely used in high-frequency inverters, digital products, generators, televisions and other electronic products. Power diodes usually include ordinary rectifier diodes, Schottky diodes, and PIN diodes. Among them, Schottky diodes have the characteristics of low on-state voltage drop, large leakage current, and almost zero reverse recovery time. Existing Schottky diodes usually use semiconductor materials such as Si, SiC or GaN for Schottky contacts, which are gradually unable to meet the requirements of higher breakdown voltage, lower on-state voltage drop, and high frequency and low switching loss. Summary of the Invention

[0003] The main purpose of the present invention is to propose a lateral structure AlN epitaxial Schottky diode and its manufacturing process, aiming to enable the Schottky diode to meet the requirements of higher breakdown voltage, lower conduction voltage drop and high frequency and low switching loss.

[0004] To achieve the above object, the present invention provides a lateral structure AlN epitaxial Schottky diode and a manufacturing process thereof, comprising: a substrate layer having a first surface and a second surface disposed opposite to each other;

[0005] a back electrode, disposed on the first surface of the substrate layer;

[0006] An AlN buffer layer, a UID-AlN layer, and an N-AlN layer are sequentially stacked on the second surface of the substrate layer;

[0007] A GaN protective layer grown on a surface of the N-AlN layer;

[0008] An isolation ring is provided at the edges of the UID-AlN layer, the N-AlN layer and the GaN protective layer;

[0009] an ohmic contact metal layer, the ohmic contact metal layer being deposited on the GaN protective layer and disposed close to the isolation ring;

[0010] a Schottky contact metal layer, wherein the Schottky contact metal layer is deposited on the GaN protective layer and is located at the center of the Schottky diode;

[0011] A SiO2 passivation layer is deposited on the ohmic contact metal layer, the Schottky contact metal layer, the isolation ring and the GaN protection layer.

[0012] Optionally, the thickness of the UID-AlN layer is 100 nm to 300 nm, and the thickness of the N-AlN layer is 1 μm to 3 μm.

[0013] Optionally, the isolation ring is formed by implanting He and / or Ar and / or In particles.

[0014] Optionally, the ohmic contact metal layer is composed of one or more of Ti, Al, Ni or Au.

[0015] Optionally, the ohmic contact metal layer includes a first Ti metal layer, an Al metal layer, a second Ti metal layer and an Au metal layer formed sequentially on the surface of the N-AlN layer; wherein the thickness of the first Ti metal layer is 10nm to 30nm, the thickness of the Al metal layer is 50nm to 150nm, the thickness of the Ti metal layer is 3nm to 10nm and the thickness of the Au metal layer is 20nm to 80nm.

[0016] Optionally, the Schottky metal layer includes a Pt metal layer and an Au metal layer sequentially formed on the surface of the N-AlN layer; wherein the thickness of the Pt metal layer is 10nm to 50nm, and the thickness of the Au metal layer is 50nm to 300nm.

[0017] Optionally, the distance between the ohmic contact metal layer and the Schottky contact metal layer is 15 μm to 20 μm.

[0018] Optionally, the substrate is a high-resistance sapphire substrate with a bevel cut of 0.1 to 0.5 degrees.

[0019] Optionally, the back electrode includes an Ag metal layer, a Ni metal layer and a third Ti metal layer sequentially formed on the first surface of the substrate layer.

[0020] The present invention provides a process for manufacturing a Schottky diode, comprising the following steps:

[0021] preparing the substrate;

[0022] coating an AlN material on the substrate to form an AlN buffer layer;

[0023] epitaxially growing on the AlN buffer layer to form an n-type AlN epitaxial barrier layer;

[0024] doping Si into the n-type AlN epitaxial barrier layer to divide the n-type AlN epitaxial barrier layer into a UID-AlN layer and an N-AlN layer;

[0025] Epitaxially growing GaN material on the n-type AlN epitaxial barrier layer to form a GaN protective layer;

[0026] Implanting He and / or Ar and / or In particles at the edges of the UID-AlN layer, the N-AlN layer and the GaN protective layer by ion implantation to form an isolation ring;

[0027] forming an ohmic contact and a Schottky contact on the GaN protective layer by physical vapor deposition;

[0028] Depositing a SiO2 passivation layer on the ohmic contact metal layer, the Schottky contact metal layer, the isolation ring and the GaN protective layer;

[0029] The substrate was thinned to 150 μm and Ti / Ni / Ag ions were evaporated to form the back electrode.

[0030] The present invention provides a Schottky diode with a lateral AlN epitaxial structure, which includes a substrate layer having a first surface and a second surface arranged opposite to each other; a back electrode arranged on the first surface of the substrate layer; an AlN buffer layer, a UID-AlN layer and an N-AlN layer stacked in sequence on the second surface of the substrate layer; a GaN protective layer, the GaN protective layer grown on the surface of the N-AlN layer; an isolation ring, the isolation ring being arranged at the edges of the UID-AlN layer, the N-AlN layer and the GaN protective layer; an ohmic contact metal layer, the ohmic contact metal layer being deposited on the GaN protective layer and being arranged close to the isolation ring; a Schottky contact metal layer, the Schottky contact metal layer being deposited on the GaN protective layer and being located at the center of the Schottky diode; and a SiO2 passivation layer, the SiO2 passivation layer being deposited on the ohmic contact metal layer, the Schottky contact metal layer, the isolation ring and the GaN protective layer. A barrier layer is formed during epitaxial growth on the substrate. The AlN material has a higher bandgap width than the materials used for epitaxial growth in the prior art. The barrier layer of the same width has a higher breakdown voltage, which can reduce device current leakage. At the same time, because the Schottky contact only conducts electrons and has no charge storage effect, it can be used in high-frequency and low-switching-loss conditions, meeting the requirements of high breakdown voltage, high frequency, and low-switching-loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0033] Figure 1 This is a front cross-sectional structural diagram of an embodiment of a Schottky diode with a lateral AlN epitaxial structure according to the present invention;

[0034] Figure 2 A top-down cross-sectional structural diagram of an embodiment of a Schottky diode with a lateral AlN epitaxial structure according to the present invention;

[0035] Figure 3 FIG1 is a process flow chart of an embodiment of a process for manufacturing a Schottky diode according to the present invention;

[0036] Figures 4 to 9 This is a cross-sectional structural diagram of a device during the manufacturing process of a vertical Schottky diode provided by a specific embodiment of the present invention.

[0037] Description of Figure Numbers:

[0038] Label name Label name 10 substrate layer 20 AlN buffer layer 21 UID-AlN layer 22 N-AlN layer 30 GaN protective layer 40 Isolation ring 50 Ohmic contact metal layer 51 Schottky contact metal layer 60 SiO2 passivation layer 70 Barrier region

[0039] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0041] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] A lateral AlN epitaxial Schottky diode and its fabrication process are proposed, aiming to achieve the Schottky diode meeting the requirements of higher breakdown voltage, lower on-state voltage drop, and high frequency and low switching loss.

[0043] Reference Figure 1 and Figure 2 In one embodiment of the present invention, the lateral AlN epitaxial Schottky diode comprises:

[0044] A substrate layer 10, wherein the substrate layer 10 has a first surface and a second surface opposite to each other;

[0045] a back electrode, disposed on the first surface of the substrate layer 10;

[0046] An AlN buffer layer 20, a UID-AlN layer 21 and an N-AlN layer 22 are sequentially stacked on the second surface of the substrate layer 10;

[0047] A GaN protective layer 30 grown on the surface of the N-AlN layer 22;

[0048] an isolation ring 40 , the isolation ring 40 being disposed around the edges of the UID-AlN layer 21 , the N-AlN layer 22 , and the GaN protective layer 30 ;

[0049] an ohmic contact metal layer 50 , wherein the ohmic contact metal layer 50 is deposited on the GaN protective layer 30 and is disposed close to the isolation ring 40 ;

[0050] a Schottky contact metal layer 51 , wherein the Schottky contact metal layer 51 is deposited on the GaN protective layer 30 and is located at the center of the Schottky diode;

[0051] A SiO 2 passivation layer 60 is deposited on the ohmic contact metal layer 50 , the Schottky contact metal layer 51 , the isolation ring 40 and the GaN protection layer 30 .

[0052] Existing Schottky diodes often use Si, SiC, and GaN as epitaxial materials. This embodiment uses AlN epitaxy to produce Schottky diodes. AlN material has a wider bandgap than Si, SiC, and GaN materials. The barrier layer of the same width has a higher breakdown voltage. When forward conducting, the Schottky contact provides a lower conduction voltage drop. At the same time, because the Schottky contact only conducts electrons and has no charge storage effect, it can be used in high-frequency and low-switching loss conditions.

[0053] In this embodiment, an N-AlN layer 22 (n-type AlN epitaxial barrier layer) is grown on the substrate layer 10. The AlN epitaxial barrier layer is a high-resistivity epitaxial layer, which ensures that the Schottky diode has a high breakdown voltage, reduces device current leakage, and prevents performance deterioration caused by increased device operating temperature. In other words, it has good thermal conductivity, optimizes switching characteristics, ensures the growth quality of other epitaxial layers thereon, and improves performance.

[0054] The UID-AlN layer 21 (unintentionally doped AlN layer) has high resistivity and is typically micron-thick. It is used to form a two-dimensional electron gas (2DEG) structure and reduce background carrier concentration, thereby minimizing drain current collapse caused by the buffer layer trap effect. The epitaxy of the AlN layer requires a buffer layer, which effectively alleviates the lattice and thermal mismatch between the III-nitride epilayer and the substrate, reducing stress-induced strain in the III-nitride epilayer and minimizing the occurrence of dislocations and defects. Furthermore, the seed layer between the substrate and the buffer layer effectively prevents silicon from diffusing from the substrate into the III-nitride epilayer.

[0055] The AlN buffer layer 20 can effectively alleviate the lattice mismatch and thermal mismatch between the N-AlN layer 22 and the substrate layer 10 , reduce the strain of the N-AlN layer 22 caused by stress, and reduce the occurrence of dislocations and defects.

[0056] The GaN protection layer 30 is mainly responsible for preventing the AlN material from being oxidized, so as to prevent the device performance from being affected.

[0057] The isolation ring 40 is formed by implanting inert ions to destroy the AlN material lattice to obtain a high resistance region.

[0058] The Schottky contact forms a Schottky barrier to increase resistance, and the ohmic contact is formed to reduce resistance. In this embodiment, the metal materials used for the Schottky contact and the ohmic contact are not limited.

[0059] The SiO2 passivation layer 60 is deposited on the front side of the Schottky diode to provide anti-oxidation and insulation.

[0060] The Schottky diode in this embodiment uses AlN material, and a barrier layer is formed by epitaxial growth of the substrate layer 10. The AlN material has a higher band gap width than the materials used for epitaxial growth in the prior art. The barrier layer of the same width has a higher breakdown voltage, which can reduce device current leakage and prevent performance deterioration caused by increased device operating temperature. That is, it has good thermal conductivity and optimizes switching characteristics. When forward conducting, the Schottky contact provides a lower conduction voltage drop. At the same time, because the Schottky contact only conducts electrons and has no charge storage effect, it can be used in high-frequency and low-switching loss conditions, and can meet the use requirements of high breakdown voltage, high frequency, and low switching loss.

[0061] The present invention provides a Schottky diode with a lateral AlN epitaxial structure, including a substrate layer 10, wherein the substrate layer 10 has a first surface and a second surface arranged opposite to each other; a back electrode, which is arranged on the first surface of the substrate layer 10; an AlN buffer layer 20, a UID-AlN layer 21 and an N-AlN layer 22, which are sequentially stacked and arranged on the second surface of the substrate layer 10; a GaN protective layer 30, which is grown on the surface of the N-AlN layer 22; an isolation ring 40, which is arranged around the UID-AlN layer 21, The edges of the N-AlN layer 22 and the GaN protective layer 30; the ohmic contact metal layer 50, which is deposited on the GaN protective layer 30 and positioned near the isolation ring 40; the Schottky contact metal layer 51, which is deposited on the GaN protective layer 30 and located at the center of the Schottky diode; and the SiO2 passivation layer 60, which is deposited on the ohmic contact metal layer 50, the Schottky contact metal layer 51, the isolation ring 40, and the GaN protective layer 30. The epitaxial growth of the substrate layer 10 forms a barrier layer. The AlN material has a higher bandgap than the materials used for epitaxial growth in the prior art. A barrier layer of the same width has a higher breakdown voltage, which can reduce device current leakage. Furthermore, because the Schottky contact only conducts electrons and has no charge storage effect, it can be used in high-frequency and low-switching-loss conditions, meeting the requirements of high breakdown voltage, high frequency, and low switching loss.

[0062] Reference Figure 2 , SiO2 passivation layer 60, the SiO2 passivation layer 60 is deposited on the ohmic contact metal layer 50, the Schottky contact metal layer 51, the isolation ring 40 and the GaN protective layer 30, and the SiO2 passivation layer 60 is arranged on the front side of the Schottky diode to protect the entire Schottky diode and play an anti-oxidation and insulation role.

[0063] The barrier region 70 is composed of the AlN buffer layer 20 , the UID-AlN layer 21 , and the N—AlN and GaN protection layers 30 .

[0064] The Schottky contact forms a Schottky barrier to increase resistance, while the ohmic contact forms a barrier to reduce resistance. In this embodiment, the metal materials used for the Schottky and ohmic contacts are not limited. The Schottky contact is formed in the middle of the barrier region 70, and the ohmic contact is formed at the edge of the barrier region 70.

[0065] In one embodiment, the thickness of the UID-AlN layer 21 is 100 nm to 300 nm, and the thickness of the N-AlN layer 22 is 1 μm to 3 μm.

[0066] In one embodiment, the isolation ring 40 is formed by implanting He and / or Ar and / or In particles.

[0067] In this embodiment, the edge protection of the barrier region 70 may be achieved by implanting He and / or Ar and / or In particles to destroy the material lattice and obtain a high resistance region.

[0068] In one embodiment, the ohmic contact metal layer 50 is composed of one or more of Ti, Al, Ni, or Au.

[0069] In one embodiment, the ohmic contact metal layer 50 includes a first Ti metal layer, an Al metal layer, a second Ti metal layer and an Au metal layer sequentially formed on the surface of the N-AlN layer 22; wherein the thickness of the first Ti metal layer is 10nm to 30nm, the thickness of the Al metal layer is 50nm to 150nm, the thickness of the Ti metal layer is 3nm to 10nm, and the thickness of the Au metal layer is 20nm to 80nm.

[0070] In one embodiment, the Schottky metal layer includes a Pt metal layer and an Au metal layer sequentially formed on the surface of the N-AlN layer 22 ; wherein the thickness of the Pt metal layer is 10 nm to 50 nm, and the thickness of the Au metal layer is 50 nm to 300 nm.

[0071] The GaN protective layer is used to protect the metal materials involved in the Schottky and ohmic contact reactions. Since Schottky and ohmic contacts require relatively high temperatures, and both are interface contacts, the GaN protective layer acts as an anti-oxidation layer, protecting the metal materials involved in the reaction.

[0072] In one embodiment, the distance between the ohmic contact metal layer 50 and the Schottky contact metal layer 51 is 15 μm to 20 μm.

[0073] In one embodiment, the substrate layer 10 is a high-resistance sapphire substrate layer 10 with a bevel cut of 0.1 to 0.5 degrees.

[0074] In this embodiment, sapphire is an excellent insulating material with a large bandgap (10 eV at room temperature) and low leakage current and parasitic capacitance. The AlN buffer layer 20 formed on the high-resistance sapphire substrate has high resistance and good insulation.

[0075] The high-resistance sapphire substrate layer 10 used in this embodiment is lattice-matched with AlN, which is conducive to good bonding between the chip and the substrate.

[0076] In one embodiment, the back electrode includes an Ag metal layer, a Ni metal layer, and a third Ti metal layer sequentially formed on the first surface of the substrate layer 10 .

[0077] The present invention provides a manufacturing process for a Schottky diode.

[0078] Reference Figure 3 , the production process includes the following steps:

[0079] Step S10: preparing a substrate layer 10, and coating an AlN material on the substrate layer 10 to form an AlN buffer layer 20;

[0080] Step S20, epitaxially growing on the AlN buffer layer 20 to form an n-type AlN epitaxial barrier layer;

[0081] Step S30 , doping Si into the n-type AlN epitaxial barrier layer to divide the n-type AlN epitaxial barrier layer into a UID-AlN layer 21 and an N-AlN layer 22 ;

[0082] Step S40, epitaxially growing a GaN protective layer 30 on the n-type AlN epitaxial barrier layer;

[0083] Step S50, implanting He and / or Ar and / or In particles at the edges of the UID-AlN layer 21, the N-AlN layer 22 and the GaN protective layer 30 by ion implantation to form an isolation ring 40;

[0084] Step S60, forming an ohmic contact and a Schottky contact on the GaN protective layer 30 by physical vapor deposition;

[0085] Step S70 , depositing a SiO 2 passivation layer 60 on the ohmic contact metal layer 50 , the Schottky contact metal layer 51 , the isolation ring 40 and the GaN protection layer 30 ;

[0086] Step S80 , thinning the substrate layer 10 to 150 μm and evaporating Ti / Ni / Ag ions to form a back electrode.

[0087] In one embodiment of step S10, an n-type AlN epitaxial barrier layer, a 1μm to 3um UID-AlN21 layer (unintentionally doped AlN layer), a 100nm to 300nm silicon-doped N-AlN layer 22, and a 1nm to 3nm GaN protective layer 30 are grown on a 0.1 to 0.5 degree bevel-cut sapphire substrate by MOCVD (metal organic chemical vapor deposition). The sapphire substrate is a high-resistance substrate that matches the aluminum nitride lattice and is conducive to good bonding with the substrate. The high-resistivity epitaxial layer ensures that the tube has a high breakdown voltage, reduces device current leakage, and prevents performance deterioration caused by increased device operating temperature. That is, it has good thermal conductivity, optimizes switching characteristics, ensures the growth quality of other epitaxial layers thereon, and improves performance.

[0088] In steps S20 to S40, the UID-AlN layer 21 (unintentionally doped AlN layer) has high resistivity and is typically micron-thick. It is used to form a two-dimensional electron gas (2DEG) structure and reduce background carrier concentration to mitigate drain current collapse caused by the buffer layer trap effect. The epitaxial growth of the AlN layer requires a buffer layer, which effectively alleviates the lattice and thermal mismatch between the III-nitride epitaxial layer and the substrate, reducing stress-induced strain in the III-nitride epitaxial layer and minimizing the occurrence of dislocations and defects. Furthermore, the seed layer between the substrate and the buffer layer effectively prevents silicon from diffusing from the substrate into the III-nitride epitaxial layer.

[0089] In one embodiment of step S50 , the edge protection may be performed by implanting He and / or Ar and / or In particles to destroy the material lattice to obtain a high resistance region, thereby forming a cutoff ring.

[0090] In an embodiment of step S60 , the key to Schottky contact is interface contact, and the GaN protection layer 30 can prevent oxidation damage.

[0091] In one embodiment of step S70, a SiO2 passivation layer covers the front surface of the Schottky diode to provide anti-oxidation and insulation.

[0092] Reference Figure 4 After executing steps S10 to S40, AlN material is deposited on the high-resistance sapphire substrate layer 10 to form an AlN buffer layer 20, and an epitaxial barrier layer is epitaxially grown. An N-AlN layer 22 and a UID-AlN layer 21 are formed on the epitaxial barrier layer by doping Si, wherein the Si-doped area is the N-AlN layer 22, and the remaining area is the UID-AlN. A GaN protective layer 30 is epitaxially grown on the N-AlN layer 22.

[0093] Reference Figure 5 After step S50 is executed, the implanted particles form an isolation ring 40 at the edge of the Schottky diode.

[0094] Reference Figure 6 and Figure 7 After executing step S60, ohmic contacts and Schottky contacts are formed by physical vapor deposition technology and then high temperature annealing.

[0095] Reference Figure 8 After executing step S70 , a passivation layer is formed on the ohmic contact metal layer 50 , the Schottky contact metal layer 51 , the isolation ring 40 and the GaN protection layer 30 , covering the front side of the Schottky diode.

[0096] Reference Figure 9 After step S80, a back electrode of three metal layers of Ti, Ni, and Ag is formed on the substrate layer 10. The back substrate is thinned to 150 μm, and Ti / Ni / Ag is evaporated to serve as the back electrode (grounded).

[0097] The present invention proposes a Schottky diode fabrication process for fabricating the aforementioned lateral AlN epitaxial Schottky diode. Because the present invention utilizes all of the technical solutions of all of the aforementioned embodiments, it possesses at least all of the beneficial effects of the technical solutions of the aforementioned embodiments, and therefore will not be further detailed here.

[0098] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention's description and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A lateral AlN epitaxial Schottky diode, comprising: a substrate layer having a first surface and a second surface opposite to each other; a back electrode, disposed on the first surface of the substrate layer; An AlN buffer layer is formed, and an n-type AlN epitaxial barrier layer is formed by epitaxial growth on the AlN buffer layer, wherein the n-type AlN epitaxial barrier layer is a high-resistivity epitaxial layer, wherein the n-type AlN epitaxial barrier layer is divided into a UID-AlN layer and an N-AlN layer, wherein the AlN buffer layer, the UID-AlN layer, and the N-AlN layer are sequentially stacked on the second surface of the substrate layer; the substrate layer is lattice-matched to the AlN; A GaN protective layer grown on the surface of the N-AlN layer; An isolation ring is provided at the edges of the UID-AlN layer, the N-AlN layer and the GaN protective layer; an ohmic contact metal layer, the ohmic contact metal layer being deposited on the GaN protective layer and disposed close to the isolation ring; a Schottky contact metal layer, wherein the Schottky contact metal layer is deposited on the GaN protective layer and is located at the center of the Schottky diode; A SiO2 passivation layer is deposited on the ohmic contact metal layer, the Schottky contact metal layer, the isolation ring and the GaN protection layer.

2. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The thickness of the UID-AlN layer is 100 nm to 300 nm, and the thickness of the N-AlN layer is 1 μm to 3 μm.

3. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The isolation ring is formed by implanting He and / or Ar and / or In particles.

4. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The ohmic contact metal layer is composed of one or more of Ti, Al, Ni or Au.

5. The lateral AlN epitaxial Schottky diode according to claim 4, characterized in that: The ohmic contact metal layer includes a first Ti metal layer, an Al metal layer, a second Ti metal layer and an Au metal layer formed sequentially on the surface of the N-AlN layer; wherein the thickness of the first Ti metal layer is 10nm~30nm, the thickness of the Al metal layer is 50nm~150nm, the thickness of the Ti metal layer is 3nm~10nm and the thickness of the Au metal layer is 20nm~80nm.

6. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The Schottky contact metal layer includes a Pt metal layer and an Au metal layer sequentially formed on the surface of the N-AlN layer; wherein the thickness of the Pt metal layer is 10nm~50nm, and the thickness of the Au metal layer is 50nm~300nm.

7. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The distance between the ohmic contact metal layer and the Schottky contact metal layer is 15 μm to 20 μm.

8. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The substrate is a high-resistance sapphire substrate with a bevel cut of 0.1 to 0.5 degrees.

9. The lateral AlN epitaxial Schottky diode according to claim 1, wherein: The back electrode includes an Ag metal layer, a Ni metal layer and a third Ti metal layer sequentially formed on the first surface of the substrate layer.

10. A process for manufacturing a Schottky diode, characterized in that: The following steps are involved: preparing the substrate; coating an AlN material on the substrate to form an AlN buffer layer; epitaxially growing on the AlN buffer layer to form an n-type AlN epitaxial barrier layer; doping Si into the n-type AlN epitaxial barrier layer to divide the n-type AlN epitaxial barrier layer into a UID-AlN layer and an N-AlN layer; Epitaxially growing GaN material on the n-type AlN epitaxial barrier layer to form a GaN protective layer; Implanting He and / or Ar and / or In particles at the edges of the UID-AlN layer, the N-AlN layer and the GaN protective layer by ion implantation to form an isolation ring; forming an ohmic contact metal layer and a Schottky contact metal layer on the GaN protective layer by physical vapor deposition; Depositing a SiO2 passivation layer on the ohmic contact metal layer, the Schottky contact metal layer, the isolation ring and the GaN protective layer; The substrate was thinned to 150 μm and Ti / Ni / Ag ions were evaporated to form the back electrode.

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