阅读说明：本技术 基于P+型保护环结构的AlGaN/GaN肖特基势垒二极管及制作方法 (AlGaN/GaN Schottky barrier diode based on P + type guard ring structure and manufacturing method ) 是由 赵胜雷 宋秀峰 张进成 朱丹 陈大正 张春福 张金风 毛维 郝跃 于 2019-11-12 设计创作，主要内容包括：本发明公开了一种基于P+型保护环结构的AlGaN/GaN肖特基势垒二极管器件及制作方法,主要解决现有技术击穿电压较低,可靠性较差的问题。其自下而上包括衬底(1)、成核层(2)、缓冲层(3)、插入层(4)、势垒层(5),势垒层(5)上方设有阳极(7)和阴极(8),势垒层(5)中的阳极下方1～3μm长度内注有Mg离子,形成P+型保护环(6),该阳极与阴极之间为钝化层(9)。本发明由于在势垒层中设有P+型保护环,降低了阳极下方边缘电场峰值,提高了击穿电压,且工艺简单、成品率高和可靠性好,可作为大功率系统以及开关应用的基本器件。(The invention discloses an AlGaN/GaN Schottky barrier diode device based on a P + type guard ring structure and a manufacturing method thereof, and mainly solves the problems of low breakdown voltage and poor reliability in the prior art. The protective layer comprises a substrate (1), a nucleating layer (2), a buffer layer (3), an insertion layer (4) and a barrier layer (5) from bottom to top, wherein an anode (7) and a cathode (8) are arranged above the barrier layer (5), Mg ions are injected into the barrier layer (5) within the length of 1-3 mu m below the anode to form a P + type protective ring (6), and a passivation layer (9) is arranged between the anode and the cathode. The invention reduces the peak value of the edge electric field below the anode and improves the breakdown voltage because the P + type protection ring is arranged in the barrier layer, has simple process, high yield and good reliability, and can be used as a basic device for a high-power system and a switch.)

1. The utility model provides a AlGaN/GaN schottky barrier diode based on P + type guard ring structure, includes substrate (1), nucleation layer (2), buffer layer (3), insertion layer (4) and barrier layer (5) from bottom to top, and the top of barrier layer (5) is equipped with positive pole (7) and negative pole (8), is passivation layer (9) between this positive pole (7) and negative pole (8), characterized in that, annotate Mg ion in the positive pole below 1 ~ 3 mu m length in barrier layer (5), forms P + type guard ring (6) for reduce positive pole below fringe electric field peak value, improve breakdown voltage.

2. Diode according to claim 1, characterized in that the substrate (1) is of sapphire or Si or SiC or GaN bulk material.

3. The diode of claim 1, wherein:

the nucleating layer (2) is made of AlN and has the thickness of 30-90 nm.

The buffer layer (3) is made of GaN and has a thickness of 0.5-5 μm.

4. The diode of claim 1, wherein:

the insertion layer (4) is made of AlN and has the thickness of 0.5-2 nm;

the barrier layer (5) is made of AlGaN and has a thickness of 15-30 nm.

5. The diode of claim 1, wherein: the passivation layer (9) adopts SiN or SiO₂Or Al₂O₃Or HfO₂A medium.

6. A manufacturing method of an AlGaN/GaN Schottky barrier diode based on a P + type guard ring structure is characterized by comprising the following steps:

1) pretreating the surface of the substrate for eliminating dangling bonds, and placing the pretreated substrate in H₂Carrying out heat treatment in the reaction chamber at 950 ℃ and carrying out epitaxial growth of an AlN nucleating layer with the thickness of 30-90 nm on the substrate by adopting an MOCVD (metal organic chemical vapor deposition) process;

2) depositing an intrinsic GaN buffer layer with the thickness of 0.5-5 mu m on the AlN nucleating layer by adopting an MOCVD (metal organic chemical vapor deposition) process;

3) depositing an AlN insert layer with the thickness of 0.5-2 nm on the GaN buffer layer by adopting an MOCVD process;

4) depositing an AlGaN barrier layer with the thickness of 15-30 nm on the AlN insert layer by adopting an MOCVD (metal organic chemical vapor deposition) process;

5) making mask on AlGaN barrier layer and ion implantationThe implantation process comprises implanting energy of 30-50 keV and dose of 5 × 10 in the barrier layer¹³～5×10¹⁴cm^-2Forming a P + type guard ring with the length of 1-3 mu m by the Mg ions;

6) manufacturing a mask on the AlGaN barrier layer, depositing cathode metal above the barrier layer by adopting a magnetron sputtering process, annealing at the high temperature of 830 ℃, and depositing anode metal on the other side above the barrier layer by adopting the magnetron sputtering process, wherein the cathode metal adopts Ti/Al or Ti/Al/Ni/Au or Ti/Al/Mo/Au, and the anode metal adopts Ni/Au/Ni or Ni/Au or W/Au or Mo/Au;

7) placing the epitaxial wafer subjected to the steps into a Plasma Enhanced Chemical Vapor Deposition (PECVD) reaction chamber for carrying out passivation layer deposition;

8) and photoetching and etching the passivation layers on the anode and the cathode to form an anode contact hole and a cathode contact hole, thereby finishing the manufacture of the whole device.

7. The method of claim 6, wherein: the MOCVD process parameters of the step 1) and the step 3) are as follows: the pressure in the reaction chamber is 10-100 Torr, the flow rate of Al source is 40-100 μmol/min, the flow rate of ammonia gas is 3000-6000sccm, and the flow rate of hydrogen gas is 1000-2000 sccm.

8. The method of claim 6, wherein: the MOCVD process parameters of the step 2) are as follows: the pressure in the reaction chamber is 10-100 Torr, the flow rate of Ga source is 40-100 μmol/min, the flow rate of ammonia gas is 3000-6000sccm, and the flow rate of hydrogen gas is 1000-2000 sccm.

9. The method of claim 6, wherein: the MOCVD process parameters in the step 4) are as follows: the pressure in the reaction chamber is 10-100 Torr, the flow rate of Al source is 40-100 μmol/min, the flow rate of Ga source is 40-100 μmol/min, the flow rate of ammonia gas is 3000-6000sccm, and the flow rate of hydrogen gas is 1000-2000 sccm.

10. The method according to claim 6, characterized in that in step 6) the magnetron sputtering process is carried out with the conditions: all adopt purity99.999% of aluminum, titanium, nickel, mold, tungsten, lead and gold as target materials, and the pressure in the reaction chamber is kept between 8.8 and 9.2 multiplied by 10^{- 2}Pa。

Technical Field

The invention belongs to the technical field of semiconductor devices, and particularly relates to an AlGaN/GaN Schottky barrier diode which can be used as a basic device for a high-power system and a switch.

Background

The power semiconductor device is a core element of power electronic technology, and with the increasingly prominent energy and environmental problems, the development of a novel high-performance and low-loss power device becomes one of effective ways for improving the utilization rate of electric energy, saving energy and relieving the energy crisis. In the research of power devices, a severe restriction relationship exists between high speed, high voltage and low on-resistance, and the key for improving the overall performance of the device is to reasonably and effectively improve the restriction relationship. With the development of microelectronic technology, the performance of the traditional first-generation Si semiconductor and second-generation GaAs semiconductor power devices is close to the theoretical limit determined by the materials. In order to further reduce the chip area, improve the working frequency, improve the working temperature, reduce the on-resistance, improve the breakdown voltage, reduce the volume of the whole machine and improve the efficiency of the whole machine, the wide-bandgap semiconductor material represented by GaN is distinguished in the aspect of preparing a high-performance power device by virtue of the larger bandgap, the higher critical breakdown electric field and the higher electronic saturation drift speed, and the excellent physical and chemical properties such as stable chemical performance, high temperature resistance, radiation resistance and the like, and has great application potential. Among them, the GaN-based schottky barrier diode is an important GaN-based device, which is a majority carrier semiconductor device, and the minority carrier charge storage effect is weak. GaN can be used not only for making GaN schottky barrier diode by using bulk material, but also for making high performance device, i.e. heterojunction AlGaN/GaN schottky barrier diode, by using its heterostructure, as shown in fig. 1, it includes a substrate, a nucleation layer, a buffer layer, an insertion layer, a barrier layer from bottom to top, an anode and a cathode are arranged above the barrier layer, and a passivation layer is arranged between the anode and the cathode. The AlGaN/GaN transverse heterojunction Schottky barrier diode has the excellent characteristics of high breakdown voltage, low on-resistance, short reverse recovery time and the like, is easy to realize large current density and power density, and can greatly improve the electric energy conversion efficiency of a system and reduce the preparation cost when being applied to power conversion. However, when the heterojunction AlGaN/GaN schottky diode is reversely biased, the electric field below the anode is not uniformly distributed in the horizontal direction, that is, the closer to the edge of the electrode, the denser the electric field lines are distributed, so that the maximum value of the electric field appears at the edge below the anode, which easily causes avalanche breakdown at the edge, causes the actual breakdown voltage and output power of the AlGaN/GaN schottky diode to be reduced, increases the reverse leakage current, and reduces the reliability of the device.

Disclosure of Invention

The present invention aims to overcome the defects of the prior art, and provides an AlGaN/GaN schottky barrier diode based on a P + type guard ring structure and a manufacturing method thereof, so as to reduce the peak value of the fringe electric field below an anode and the reverse leakage current under a high field, improve the breakdown characteristics and reliability of the device, and realize high output power.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

1. an AlGaN/GaN Schottky barrier diode based on a P + type guard ring structure comprises a substrate, a nucleating layer, a buffer layer, an insertion layer and a barrier layer from bottom to top, wherein an anode and a cathode are arranged above the barrier layer, and a passivation layer is arranged between the anode and the cathode.

Further, the substrate is made of sapphire, Si, SiC or GaN bulk material.

Further, the nucleation layer is made of AlN and has the thickness of 30-90 nm; the buffer layer adopts GaN, and thickness is 0.5 ~ 5 um.

Further, the inserting layer is made of AlN and has the thickness of 0.5-2 nm; the barrier layer is made of AlGaN and has the thickness of 15-30 nm; the passivation layer is made of SiN or SiO₂Or Al₂O₃Or HfO₂And the like.

2. A manufacturing method of an AlGaN/GaN Schottky barrier diode based on a P + type guard ring structure is characterized by comprising the following steps:

1) pretreating the surface of the substrate for eliminating dangling bonds, and placing the pretreated substrate in H₂Carrying out heat treatment in the reaction chamber at 950 ℃ and carrying out epitaxial growth of an AlN nucleating layer with the thickness of 30-90 nm on the substrate by adopting an MOCVD (metal organic chemical vapor deposition) process;

2) depositing an intrinsic GaN buffer layer with the thickness of 0.5-5 mu m on the AlN nucleating layer by adopting an MOCVD (metal organic chemical vapor deposition) process;

3) depositing an AlN insert layer with the thickness of 0.5-2 nm on the GaN buffer layer by adopting an MOCVD process;

4) depositing an AlGaN barrier layer with the thickness of 15-30 nm on the AlN insert layer by adopting an MOCVD (metal organic chemical vapor deposition) process;

5) manufacturing a mask on the AlGaN barrier layer, and implanting the barrier layer with an ion implantation process at an energy of 30-50 keV and a dose of 5 × 10¹³～5×10¹⁴cm^-2Forming a P + type guard ring with the length of 1-3 mu m by the Mg ions;

6) manufacturing a mask on the AlGaN barrier layer, depositing cathode metal above the barrier layer by adopting a magnetron sputtering process, annealing at the high temperature of 830 ℃, and depositing anode metal on the other side above the barrier layer by adopting the magnetron sputtering process, wherein the cathode metal adopts Ti/Al or Ti/Al/Ni/Au or Ti/Al/Mo/Au, and the anode metal adopts Ni/Au/Ni or Ni/Au or W/Au or Mo/Au;

7) placing the epitaxial wafer subjected to the steps into a Plasma Enhanced Chemical Vapor Deposition (PECVD) reaction chamber for carrying out passivation layer deposition;

8) and photoetching and etching the passivation layers on the anode and the cathode to form an anode contact hole and a cathode contact hole, thereby finishing the manufacture of the whole device.

The device of the invention has the following advantages compared with the prior art because the P + type guard ring is arranged below the anode in the barrier layer:

1. the peak value of the fringe electric field below the anode is reduced, the breakdown voltage is increased, and high output power is realized;

2. reverse electric leakage under a high field is reduced, and reliability is improved;

3. the process is simple and the finished product rate is high.

Drawings

Fig. 1 is a structural view of a conventional AlGaN/GaN schottky barrier diode.

Fig. 2 is a structural view of an AlGaN/GaN schottky barrier diode based on a P + -type guard ring structure according to the present invention.

Fig. 3 is a flow chart illustrating the fabrication of the device of fig. 2 according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and examples.

Referring to fig. 2, the AlGaN/GaN schottky barrier diode device having a P + -type guard ring according to the present invention sequentially includes, from bottom to top: the structure comprises a substrate 1, a nucleating layer 2, a buffer layer 3, an insertion layer 4 and a barrier layer 5, wherein F ions are injected into the barrier layer 5 within the length of 1-3 mu m below an anode to form a P + type guard ring 6, so that the edge electric field peak value below the anode is reduced, the breakdown voltage is improved, the anode 7 and the cathode 8 are arranged on two sides above the barrier layer 5, and a passivation layer 9 is arranged between the anode 7 and the cathode 8. Wherein:

the substrate 1 is made of sapphire, Si, SiC or GaN bulk material; the nucleation layer 2 adopts AlN with the thickness of 30-90 nm; the buffer layer 3 is made of GaN with the thickness of 0.5-5 mu m; the insertion layer 4 adopts AlN with the thickness of 0.5-2 nm; the barrier layer 5 adopts AlGaN with the thickness of 15-30 nm, and the P + type guard ring 6 adopts P + type AlGaN with the length of 1-3 mu m; the passivation layer 9 is made of SiN or SiO₂Or Al₂O₃Or HfO₂A medium; the cathode metal adopts the metal layer combination of Ti/Al or Ti/Al/Ni/Au or Ti/Al/Mo/Au; the anode metal adopts Ni/Au/Ni or Ni/Au or W/Au or MoMetal layer combination of/Au.

Referring to fig. 3, the present invention manufactures an AlGaN/GaN schottky barrier diode based on a P + type guard ring structure, and three examples are given as follows: