CN109950323B - Polarized superjunction III-nitride diode device and method of making the same - Google Patents

Abstract

The invention discloses a polarized super junction III-family nitride diode device and a manufacturing method thereof. The device comprises: a first heterojunction including first and second semiconductors, the first heterostructure having a two-dimensional electron gas formed therein; a second heterojunction including the second semiconductor and a third semiconductor, the second heterojunction having a two-dimensional hole gas formed therein; a fourth semiconductor formed on the second semiconductor, the fourth semiconductor being closely connected to the third semiconductor in a horizontal direction; the fourth semiconductor is doped in a p type mode, and two-dimensional electron gas in the first heterojunction can be exhausted; and the anode and the cathode are electrically connected with the two-dimensional electron gas in the first heterojunction, and the anode is simultaneously electrically connected with the fourth semiconductor.

Description

Group III nitride diode device with polarized superjunction and method of making the same

technical field

The invention relates to a diode device, in particular to a polarized superjunction III-nitride diode device and a manufacturing method thereof, belonging to the technical field of power semiconductors.

Background technique

Group III nitrides (such as GaN) have the advantages of large band gap, high electron mobility, high breakdown field strength, etc., which can meet the requirements of next-generation power electronic systems for power devices with higher power, higher frequency, smaller size and more space. Due to the requirements of high temperature operation, diode devices made of group III nitrides have become a hot spot in the research of new generation power devices. Conventional III-nitride diodes using Schottky metal contacts also face many problems, such as large turn-on voltage, low breakdown voltage and large reverse leakage.

The AlGaN/GaN diode device prepared by Jae-Gil Lee et al by etching the AlGaN barrier layer has a turn-on voltage of 0.37V, which is much lower than the turn-on voltage of a diode with a conventional Schottky structure, but the reverse leakage current is relatively large (IEEE Electron Device Letters , vol.34, no.2, Feb2013).

The Schottky diode device prepared by Silvia Lenci et al. using junction termination technology has effectively reduced the reverse current, but the forward current density is still very low (IEEE ElectronDevice Letters, vol.34, no.8, Aug2013).

Zhou Qi et al. proposed a method using ohmic contact as anode and cathode, using two-dimensional electron gas of AlGaN/GaN heterojunction as conductive channel, and etching the AlGaN barrier layer near the anode to a certain depth to prepare a metal-insulating layer- The semiconductor contacts, the metal is connected to the anode, thereby realizing the forward voltage turn-on and reverse voltage turn-off functions (CN103872145A). The device can achieve lower threshold voltage and on-current density. However, due to the technical difficulty of etching the AlGaN barrier layer and the high etching damage, the preparation of the device has certain difficulties.

In a word, the existing III-nitride diodes still have many defects, such as large turn-on voltage, low breakdown voltage and low saturation current, etc., which are also difficult problems that the art has been eager to solve.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a polarized superjunction III-nitride diode device and a fabrication method to overcome the deficiencies of the prior art.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

An embodiment of the present invention provides a polarized superjunction III-nitride diode device, which includes:

A first heterojunction includes a first semiconductor and a second semiconductor formed on the first semiconductor, the second semiconductor has a wider band gap than the first semiconductor, and two semiconductors are formed in the first heterostructure. dimensional electronic gas;

A second heterojunction including the second semiconductor and a third semiconductor formed on the second semiconductor, the third semiconductor having a narrower band gap than the second semiconductor, the second heterojunction A two-dimensional hole gas is formed in the junction;

a fourth semiconductor formed on the second semiconductor and in close connection with the third semiconductor and capable of depleting the two-dimensional electron gas in the first heterojunction;

an anode and a cathode, wherein the anode includes a first anode and a second anode electrically connected to each other, the first anode and cathode being electrically connected to two-dimensional electrons in the first heterojunction, the second anode is electrically connected to the fourth semiconductor.

Preferably, the fourth semiconductor and the third semiconductor are closely combined in a direction perpendicular to the axis of the group III nitride diode device.

Further, the fourth semiconductor is a p-type semiconductor.

Preferably, an ohmic contact or a Schottky contact is formed between the second anode and the fourth semiconductor.

Preferably, the first anode and the cathode form ohmic contact with the second semiconductor.

Further, for the group III nitride diode device of the present invention, when the voltage applied on the second anode is greater than a turn-on voltage, the diode device is in an on state, and the turn-on voltage is at least sufficient to make the second anode A two-dimensional electron gas is formed in the local area of the first heterojunction directly below the contact with the fourth semiconductor and the first anode and the cathode are electrically connected; and when the voltage applied on the second anode is less than the turn-on voltage , the diode device is turned off.

Preferably, the cathode is grounded.

An embodiment of the present invention also provides a method for fabricating the group III nitride diode device of the polarized superjunction, which includes: sequentially disposing a first semiconductor, a second semiconductor and a fourth semiconductor on a substrate,

An anode and a cathode are fabricated, the anode includes a first anode and a second anode electrically connected to each other, the first anode and the cathode are electrically connected to the two-dimensional electrons in the first heterojunction, and the second anode is electrically connected forming an ohmic or Schottky contact with the fourth semiconductor; and

A third semiconductor is formed by doping the fourth semiconductor distributed between the anode and the cathode.

In the aforementioned fabrication method, the fourth semiconductor can be doped by at least any one of ion implantation, high temperature diffusion and plasma treatment, thereby forming the third semiconductor.

Preferably, the doping element used therein includes F, N, Ar or H, but is not limited thereto.

An embodiment of the present invention also provides a method for manufacturing the group III nitride diode device of the polarized superjunction, which includes: sequentially arranging a first semiconductor, a second semiconductor, and a third semiconductor on a substrate;

fabricating a first anode and a cathode, and electrically connecting the first anode and the cathode with the two-dimensional electrons in the first heterojunction;

Doping the third semiconductor on the side close to the first anode to form a fourth semiconductor; and

A second anode is fabricated, and the second anode is made to form an ohmic contact or a Schottky contact with the fourth semiconductor.

In the aforementioned fabrication method, at least the third semiconductor can be doped by ion implantation and high temperature annealing activation mode or low energy electron radiation activation mode to form the fourth semiconductor.

Preferably, the doping element used therein includes magnesium or zinc, but is not limited thereto.

In the aforementioned manufacturing method of the present invention, the first semiconductor, the second semiconductor and the The third semiconductor or the fourth semiconductor.

Preferably, the substrate includes a gallium nitride, silicon carbide, silicon or sapphire substrate, but is not limited thereto.

Compared with the prior art, the polarized superjunction III-nitride diode device provided by the present invention has a simple structure, has a p-type depletion region and a high-resistance cap at the same time, can more conveniently adjust the turn-on voltage of the device, and improve the device resistance. voltage and frequency characteristics; at the same time, the third and fourth semiconductors can realize the mutual conversion of p-type and high resistance through the process, the process is simple, can avoid excessive etching damage, the process window is large, the damage to the device is small, and the process High reproducibility, low cost, and easy mass production.

Description of drawings

1 is a schematic diagram of a partial structure of a group III nitride diode with a polarized superjunction in a typical embodiment of the present invention;

FIG. 2 is a flow chart of a manufacturing process of a polarized superjunction III-nitride diode according to a specific embodiment of the present invention;

3 is a process flow diagram of another polarized superjunction III-nitride diode according to an embodiment of the present invention;

DESCRIPTION OF REFERENCE NUMERALS: substrate 1, first semiconductor 2, second semiconductor 3, fourth semiconductor 4, first anode 5, cathode 6, second anode 7, two-dimensional electron gas 8, third semiconductor 9, two-dimensional Hole gas 10 , source 11 , drain 12 , and gate 13 .

Detailed ways

In view of the deficiencies in the prior art, the inventor of the present application was able to propose the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

The technical solutions of the present invention will be explained in more detail below. However, it should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (eg, the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, it is not repeated here.

An aspect of a polarized superjunction III-nitride diode device provided in an embodiment of the present invention includes:

A first heterojunction includes a first semiconductor and a second semiconductor formed on the first semiconductor, the second semiconductor has a wider band gap than the first semiconductor, and two semiconductors are formed in the first heterostructure. dimensional electronic gas;

A second heterojunction comprising the second semiconductor and a third semiconductor formed on the second semiconductor, the third semiconductor having a narrower bandgap than the second semiconductor, the second heterojunction A two-dimensional hole gas is formed in the junction;

a fourth semiconductor formed on the second semiconductor and in close connection with the third semiconductor and capable of depleting the two-dimensional electron gas in the first heterojunction;

an anode and a cathode, wherein the anode includes a first anode and a second anode electrically connected to each other, the first anode and cathode being electrically connected to two-dimensional electrons in the first heterojunction, the second anode is electrically connected to the fourth semiconductor.

Further, the third semiconductor and the fourth semiconductor may be of an integral structure. Wherein the third semiconductor may be formed by the transformation of a local area in the fourth semiconductor, or the fourth semiconductor may be formed by the transformation of a local area in the third semiconductor.

For example, a local area of the fourth semiconductor can be transformed into a high-resistance third semiconductor through a certain process.

Further, the materials of the first semiconductor, the second semiconductor and the third semiconductor may be selected from group III nitrides.

Preferably, the material of the first semiconductor includes GaN, but is not limited thereto.

Preferably, the material of the second semiconductor includes _{AlxGa (1-x) N} , AlInGaN or InxAl _(1-x) N, 0<x≤1, but not limited thereto.

Preferably, the material of the third semiconductor includes high-resistance or intrinsic GaN, high-resistance or intrinsic InGaN, high-resistance or intrinsic InN, or GaO, and more preferably includes high-resistance GaN, high-resistance InGaN or high-resistance InN For example, the material of the third semiconductor includes C-doped or Fe-doped high-resistance GaN, InGaN or InN, but not limited thereto.

Further, an insertion layer may be distributed between the first semiconductor and the second semiconductor.

Preferably, the material of the insertion layer includes AlN, but is not limited thereto.

Further, the fourth semiconductor is a p-type semiconductor.

Preferably, the material of the fourth semiconductor includes a p-type wide bandgap semiconductor.

More preferably, the p-type wide bandgap semiconductor includes p-type group III nitrides, such as p-GaN or p-InGaN, but not limited thereto.

More preferably, the wide bandgap semiconductor includes p-NiO, but is not limited thereto.

Further, the p-type doping concentration and thickness of the fourth semiconductor are sufficient to deplete the two-dimensional electron gas in the first heterojunction. In some embodiments, the third semiconductor may be formed from the fourth semiconductor by any one of ion implantation, high temperature diffusion, and plasma treatment. Preferably, the elements for ion implantation, diffusion or plasma treatment include hydrogen, fluorine, etc., but are not limited thereto.

In some embodiments, the fourth semiconductor may be formed from the third semiconductor by ion implantation and high temperature annealing activation or low energy electron radiation activation. Preferably, the implanted element may be magnesium, zinc, etc., but is not limited thereto.

Preferably, the third semiconductor between the anode and the cathode is formed by at least any one of ion implantation, plasma treatment and thermal diffusion process.

In some embodiments, the first anode is integral with the second anode.

In some embodiments, the fourth semiconductor is masked by the second anode.

Furthermore, the fourth semiconductor can deplete the two-dimensional electron gas in the region below the fourth semiconductor in the first heterojunction, so that the two-dimensional electron gas in the first heterojunction can conduct conduction channels. The channel is disconnected and no current path can be formed.

In some embodiments, an Ohmic or Schottky contact is formed between the second anode and the fourth semiconductor.

In some embodiments, the first anode and cathode form ohmic contact with the second semiconductor.

Further, for the polarized superjunction III-nitride diode device of the present invention, when the voltage applied to the second anode is greater than a turn-on voltage, the diode device is in an on state, and the turn-on voltage is at least sufficient A two-dimensional electron gas is formed in the local area of the first heterojunction directly below the contact between the second anode and the fourth semiconductor and the first anode and the cathode are electrically connected; and when the voltage applied on the second anode When less than the turn-on voltage, the diode device is in an off state. Preferably, the cathode is grounded.

Preferably, the turn-on voltage is a positive voltage.

In some more specific embodiments, the diode device is in an off state when no voltage is applied on the anode or the applied voltage is below zero voltage, and when the applied voltage on the anode is greater than zero voltage and Above the turn-on voltage, the diode device is turned on.

In some more specific embodiments, when zero bias voltage or no bias voltage is applied on the anode, there is no accumulation of two-dimensional electron gas in the local area of the first heterojunction directly below the anode, And when the voltage applied on the anode is greater than the turn-on voltage, a two-dimensional electron gas can be formed in the local area of the first heterojunction directly under the anode.

In some specific embodiments, when the diode device is turned on, the two-dimensional electron gas and the two-dimensional hole gas simultaneously exist in the first heterojunction and the second heterojunction; when the diode device is turned on In the off state, the two-dimensional electron gas leaks to the cathode and leaves a positive charge at the interface within the first heterojunction, and the two-dimensional hole gas leaks to the anode through the fourth semiconductor and leaves a positive charge at the interface within the first heterojunction. Negative charges are left at the interface within the second heterojunction, and the positive and negative charges create a uniform electric field distribution in the diode between the anode and the cathode.

The polarized superjunction III-nitride diode device provided by the present invention is simple in structure, has a p-type depletion region and a high resistance cap, the turn-on voltage of the device can be adjusted more conveniently, and the withstand voltage and frequency characteristics of the device can be adjusted more conveniently. also significantly improved.

Another aspect of the embodiments of the present invention provides a method for fabricating the polarized superjunction group III nitride diode device, comprising:

A first semiconductor, a second semiconductor and a fourth semiconductor are sequentially arranged on the substrate,

An anode and a cathode are fabricated, the anode includes a first anode and a second anode electrically connected to each other, the first anode and the cathode are electrically connected to the two-dimensional electrons in the first heterojunction, and the second anode is electrically connected forming an ohmic or Schottky contact with the fourth semiconductor; and

Doping treatment is performed on the fourth semiconductor distributed between the anode and the cathode, thereby forming the third semiconductor.

In the aforementioned fabrication method, a local area of the fourth semiconductor may be doped by at least any one of ion implantation, high temperature diffusion and plasma treatment, thereby forming the third semiconductor.

Preferably, the doping element used therein includes F, N, Ar or H, but is not limited thereto.

Alternatively, in the aforementioned fabrication method, the fourth semiconductor may also be oxidized by high-temperature thermal oxidation, thereby forming the third semiconductor (eg, GaO, etc.).

For example, in some specific embodiments, the p-type fourth semiconductor located between the anode and the cathode can be transformed into a high-resistance third semiconductor through processes such as ion implantation, plasma bombardment, and thermal diffusion. The doping elements used therein may include F, N, Ar, H, and the like.

Another aspect of the embodiments of the present invention provides a method for fabricating the polarized superjunction group III nitride diode device, comprising:

Disposing a first semiconductor, a second semiconductor, and a third semiconductor in sequence on the substrate;

fabricating a first anode and a cathode, and electrically connecting the first anode and the cathode with the two-dimensional electrons in the first heterojunction;

Doping the third semiconductor on the side close to the first anode to form a fourth semiconductor;

A second anode is fabricated, and the second anode is made to form an ohmic contact or a Schottky contact with the fourth semiconductor.

In the aforementioned fabrication method, at least the third semiconductor can be doped by ion implantation and high temperature annealing activation mode or low energy electron radiation activation mode to form the fourth semiconductor.

Preferably, the doping element used therein includes magnesium or zinc, but is not limited thereto.

For example, in some specific embodiments, the high-resistance third semiconductor near the anode portion can be subjected to low-energy electron radiation activation and high-temperature annealing to activate Mg doping, so that the third semiconductor can be converted into a p-type semiconductor. , namely the fourth semiconductor.

In the aforementioned manufacturing method of the present invention, the first semiconductor, the second semiconductor and the The third semiconductor or the fourth semiconductor.

Preferably, the substrate includes a gallium nitride, silicon carbide, silicon or sapphire substrate, but is not limited thereto.

In the aforementioned fabrication method of the present invention, the anode (first anode) region and the cathode region of the third semiconductor or the fourth semiconductor may be removed by dry etching or wet etching.

In some more specific embodiments, the fabrication method of the polarized superjunction III-nitride diode device may include:

(1) Material growth: grow the structure of HR GaN/AlGaN/GaN/substrate, in which two-dimensional electron gas (2DEG) and two-dimensional hole gas (2DHG) exist at the interface of two heterojunctions at the same time; High-resistance (HR) GaN is obtained mainly by doping acceptor impurities Mg, Zn, etc. when growing GaN (here, GaN doped with acceptor impurities is unactivated GaN).

(2) Anode and cathode preparation: first pattern, then use etching equipment (ICP, RIE, ECR, etc.) to etch away HR GaN in anode and cathode regions, and then use coating equipment (such as e-book evaporation, magnetron sputtering, etc.) ohmic metal was deposited on AlGaN, and finally alloyed by rapid annealing (RTA) to realize the preparation of ohmic contact electrodes.

(3) Local activation: prepare a mask (the mask material can be photoresist, SiO ₂ , silicon nitride, etc.), and pattern the anode region (the photoresist is developed, and other masks are wet or dry) Corrosion), and then locally activate HRGaN in the windowed area (also understood as an area without mask protection) by low-energy electron beam radiation (LEEBI), so that HR GaN is transformed into p-GaN, a device for low-energy electron beam radiation. Including SEM (scanning electron microscope), electron beam lithography machine and other equipment that can form low-energy electron beams.

(4) Anode preparation: first pattern, use coating equipment to deposit a layer of metal (Ni/Au, Pd/Pt/Au, etc.) that can form ohmic contact with p-GaN, and then obtain ohmic contact through peeling, annealing and other processes. Or use coating equipment to deposit a layer of metal (Ti/Au, TiN, etc.) that can form Schottky contact with p-GaN, and then obtain Schottky contact through processes such as lift-off and annealing.

In some more specific embodiments, the fabrication method of the polarized superjunction III-nitride diode device may also include:

(1) Material growth: grow the structure of p-GaN/AlGaN/GaN/substrate, in this structure, when the hole concentration in p-GaN is too high, neither 2DEG nor 2DHG exists in the two heterojunctions at the interface. The main method of obtaining p-GaN is by doping acceptor impurities such as Mg and Zn during the growth of GaN, and then by annealing and activation in the growth equipment (such as MOCVD, MBE, PLD, etc.).

(2) Preparation of anode and cathode: patterning is performed first, and then etching equipment (ICP inductively coupled plasma, RIE reactive ion etching, ECR electron cyclotron resonance, etc.) is used to etch away the HR GaN in the anode and cathode regions, and then pass through Coating equipment (such as e-book evaporation, magnetron sputtering, thermal evaporation, etc.) deposits ohmic metal on AlGaN, and finally performs alloying by rapid annealing (RTA) to realize the preparation of ohmic electrodes.

(3) Anode preparation: first pattern, use coating equipment to deposit a layer of metal (such as Ni/Au, Pd/Pt/Au, etc.) that can form ohmic contact with p-GaN, and then obtain ohmic contact through peeling, annealing and other processes . Or use coating equipment to deposit a layer of metal (Ti/Au, TiN, etc.) that can form Schottky contact with p-GaN, and then obtain Schottky contact through processes such as lift-off and annealing.

(4) Local passivation: Using electrodes or other insulating layers as masks, the p-GaN in the non-electrode area is processed to convert it into high-resistance GaN; the processing methods include ion implantation, plasma surface passivation or high temperature Passivation, etc.; wherein the ion implanted elements include F, N, Ar, H, etc., preferably, the plasma surface passivation can be carried out in an atmosphere of H ₂ or NH ₃ or high temperature passivation can be carried out at 300-800 °C.

The material of the foregoing substrate may be any one or a combination of silicon, sapphire, silicon carbide, and gallium nitride, but is not limited thereto. The polarization superjunction group III nitride diode device provided by the invention has a simple preparation process, can avoid excessive etching damage, has a large process window, small damage to the device, high repeatability, low cost, and is easy to carry out large-scale production. .

The technical solutions of the present invention will be further explained below with reference to the accompanying drawings and embodiments.

Please refer to FIG. 1 , which is a schematic structural diagram of a polarized superjunction enhancement diode device realized by a high-resistance cap layer and p-type gate technology in a typical embodiment of the present invention (taking an AlGaN/GaN device as an example). This device can be achieved by growing a p-GaN layer as the fourth semiconductor layer 4 on an AlGaN/GaN heterojunction (including a GaN layer as the first semiconductor 2 and an AlGaN layer as the second semiconductor 3), and then passivation The p-GaN layer 4 other than the anode region is changed to high resistance GaN as the third semiconductor layer 9 by chemical or ion implantation, and the fourth semiconductor and the third semiconductor are closely connected in the horizontal direction. Therefore, the high-resistance GaN layer 9 between the anode 7 and the cathode 6 will have a negative polarization with the underlying AlGaN layer 3, and a high concentration of two-dimensional hole gas will be formed at the heterojunction interface. When the device is in the off state, the electric field between the anode 7 and the cathode 6 will be uniformly distributed, and the area below the anode 7 is still the p-GaN layer 4. The use of p-type materials can effectively increase the energy band below the anode 7, so that the entire device achieves enhanced performance.

Similarly, for material epitaxy, a layer of Mg-doped high-resistance GaN layer 9 can also be epitaxially formed on the AlGaN/GaN heterojunction, and then the region below the anode 7 can be locally activated by low-energy electron beam radiation to obtain p-GaN Layer 4. In this device structure, the enhancement-type p-type gate structure and the polarized superjunction structure are integrated, and the enhancement-type can be realized through the p-GaN layer 4, and the p-GaN layer 4 can also be used in the off-state. The dimensional hole gas is discharged to obtain a uniform electric field distribution. At the same time, the process of this device avoids a complicated and difficult-to-control etching process, which greatly reduces the difficulty of the process.

It should be noted that HR GaN and p-GaN do not necessarily have to be formed by the above-mentioned mutual conversion, but can also be grown by secondary epitaxy of p-GaN, or growth of other p-type materials, such as ALD (atomic layer deposition) growth The p-NiO can also replace p-GaN, in this case, the thickness of HR GaN and p-GaN can also be different.

Referring to FIG. 1 and FIG. 2 , a method for fabricating a polarized superjunction III-nitride diode realized by a high-resistance cap layer and a p-type gate technology in a typical implementation involved in this embodiment may include the following steps:

(1) Epitaxial growth of AlGaN/GaN epitaxial layer and p-GaN on the substrate, wherein the thickness of GaN is 1 μm-8 μm, the thickness of AlGaN is 14 nm-30 nm, and the molar content of Al element is 15%-30%, p -The thickness of GaN is 50-110nm, and the Mg doping concentration is in the order of 10 ¹⁹ ;

(2) Using photoresist or dielectric film as a mask to isolate the mesa, ion implantation or plasma etching can be used;

(3) Using photoresist as a mask, the anode and cathode regions are etched, the p-type doping layer is etched away, and then placed in an electron beam deposition platform to deposit ohmic contact metal Ti/Al/Ni/Au (20nm/130 /nm/50nm/150nm) and stripping and cleaning, and then annealing the samples at 890°C for 30s to form ohmic contacts, which are anode and cathode respectively;

(4) Using photoresist as a mask, also using electron beam deposition Ni/Au (50/150nm) for stripping, annealing at 400°C for 10min under nitrogen atmosphere to form ohmic contact or Schottky contact with the p-type fourth semiconductor, Finish the production of the anode.

(5) Use the anode and the cathode as masks for ion implantation, and use an ion implanter to perform ion implantation (preferably, the implanted elements can be F, H, N, etc., and the ion implantation energy should be low, so as not to enter the two Dimensional electron gas channel region is suitable), so that the ion implantation area becomes a high resistance area. After the ion implantation is completed, annealing at 400° C. for 10 minutes is performed to repair the damage, and the fabrication of the device is completed.

Referring again to FIG. 1 and FIG. 3 , another method for fabricating a group III nitride diode with a polarized superjunction realized by a high-resistance cap layer and a p-type gate technology in a typical implementation involved in this embodiment may include the following: step:

(1) Epitaxial growth of AlGaN/GaN epitaxial layer and Mg-doped inactivated high-resistance GaN on the substrate, wherein the thickness of GaN is 1 μm-8 μm, the thickness of AlGaN is 14 nm-30 nm, and the molar content of Al element is 15 %-30%, the thickness of high-resistance GaN is 50-110nm, and the Mg doping concentration is in the order of 10 ¹⁹ ;

(2) Using photoresist or dielectric film as a mask to isolate the mesa, ion implantation or plasma etching can be used;

(3) Using photoresist as a mask, the anode and cathode regions are etched, the p-type doping layer is etched away, and then placed in an electron beam deposition platform to deposit ohmic contact metal Ti/Al/Ni/Au (20nm/130 /nm/50nm/150nm) and stripping and cleaning, and then annealing the samples at 890°C for 30s to form ohmic contacts, which are anode and cathode respectively;

(4) The anode region 7 is formed by photolithography, and the high-resistance GaN in the anode region is locally activated by means of low-energy electron beam radiation, so that the high-resistance GaN in the anode region becomes p-GaN, and then Ni/Au is deposited by electron beam. (50/150nm) for peeling off, and annealing at 400°C for 10min under nitrogen atmosphere to form ohmic contact or Schottky contact with p-GaN to complete the fabrication of the device.

The working principle of the aforementioned polarized superjunction diode is as follows: the turn-on voltage Vth is a positive value, and when the anode voltage Va<Vth, the two-dimensional electron gas under the anode and p-GaN is depleted, so the device is turned off. At the same time, the two-dimensional electron gas and two-dimensional hole gas at the interface of the double heterojunction are discharged to the cathode 6 and the anode 7 respectively under the action of the reverse bias voltage, and the positive and negative charges left at the interface of the two heterojunctions make the cathode 6 and the anode 7 respectively. The electric field of the anode 7 is uniformly distributed. When the bias voltage of anode 7 reaches Vg>Vth, the two-dimensional electron gas under the anode and p-GaN is induced, and the two-dimensional electron gas and two-dimensional hole gas at the double heterojunction interface reappear, making the anode 5 and the p-GaN interface reappear. The cathode 6 is turned on, and the device is in an on state.

Due to the existence of the high-resistance GaN capping layer and 2DHG, the trapping effect of surface states on 2DEG during high-frequency switching can be effectively shielded, the current collapse can be reduced, and the dynamic characteristics of the device can be improved.

The diode device of the invention has a simple structure, and the p-GaN anode can be used to improve the current density and reduce the on-resistance through the conductance modulation effect. The mutual conversion between p-type and high resistance is realized, the process is simple, excessive etching damage can be avoided, the cost is low, and mass production is easy. It should be noted that the "anode region and cathode region" mentioned in the present invention refers to the region directly under the anode and the cathode; the "non-electrode region" refers to the "region other than the anode and the cathode".

It should be understood that the above-mentioned embodiments are only intended to illustrate the technical concept and characteristics of the present invention, and the purpose thereof is to enable those who are familiar with the art to understand the content of the present invention and implement it accordingly, and cannot limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included within the protection scope of the present invention.

Claims (15)

1. A polarized superjunction iii-nitride diode device, comprising:

a first heterojunction including a first semiconductor and a second semiconductor formed on the first semiconductor, the second semiconductor having a wider band gap than the first semiconductor, and a two-dimensional electron gas formed in the first heterostructure;

a second heterojunction including the second semiconductor and a third semiconductor formed on the second semiconductor, the third semiconductor having a band gap narrower than the second semiconductor, the second heterojunction having a two-dimensional hole gas formed therein;

a fourth semiconductor formed on the second semiconductor for depleting the two-dimensional electron gas in the first heterojunction below the fourth semiconductor, and the fourth semiconductor and the third semiconductor are closely bonded in a direction perpendicular to the axis of the group iii nitride diode device;

an anode and a cathode, wherein the anode comprises a first anode and a second anode electrically connected to each other, the first anode and the cathode being electrically connected to the two-dimensional electron gas in the first heterojunction, the second anode being electrically connected to a fourth semiconductor;

the first semiconductor is made of GaN;

the material of the second semiconductor is selected from Al_xGa_(1-x)N, AlInGaN or In_xAl_(1-x)N，0＜x≤1；

The third semiconductor is made of high-resistance or intrinsic GaN, high-resistance or intrinsic InGaN, high-resistance or intrinsic InN or GaO;

the fourth semiconductor is made of p-type GaN, p-type InGaN, p-type InN, p-NiO or p-GaO.

2. The polarized superjunction group iii nitride diode device of claim 1, wherein: the first anode and the second anode are integrally arranged.

3. The polarized superjunction group iii nitride diode device of claim 1 or 2, wherein: the fourth semiconductor is masked by a second anode.

4. The polarized superjunction group iii nitride diode device of claim 1, wherein: and an ohmic contact or a Schottky contact is formed between the second anode and the fourth semiconductor.

5. The polarized superjunction group iii nitride diode device of claim 1, wherein: the first anode and the cathode both form ohmic contact with the second semiconductor.

6. The polarized superjunction group iii nitride diode device of claim 1, wherein: the diode device is in an on state when a voltage applied across the second anode is greater than an on voltage at least sufficient to form a two-dimensional electron gas in a localized area of the first heterojunction directly beneath the contact of the second anode with the fourth semiconductor and electrically connect the first anode with the cathode; and when the voltage applied across the second anode is less than the turn-on voltage, the diode device is in an off state.

7. The polarized superjunction group iii nitride diode device of claim 6, wherein: the cathode is grounded.

8. The method of fabricating a polarized superjunction group iii nitride diode device of any of claims 1-7, comprising:

a first semiconductor, a second semiconductor and a fourth semiconductor are sequentially provided on a substrate,

manufacturing an anode and a cathode, wherein the anode comprises a first anode and a second anode which are electrically connected with each other, the first anode and the cathode are electrically connected with the two-dimensional electron gas in the first heterojunction, and the second anode and the fourth semiconductor form ohmic contact or Schottky contact; and

and carrying out doping treatment on the fourth semiconductor distributed between the anode and the cathode to form a third semiconductor.

9. The method of manufacturing according to claim 8, comprising: the first semiconductor, the second semiconductor and the fourth semiconductor are grown in any one of metal organic chemical vapor deposition, molecular beam epitaxy, atomic layer deposition, physical vapor deposition and magnetron sputtering.

10. The method of manufacturing according to claim 9, comprising: the substrate is selected from a gallium nitride, silicon carbide, silicon or sapphire substrate.

11. The method of manufacturing according to claim 8, comprising: performing doping treatment on the fourth semiconductor by any one of ion implantation, high-temperature diffusion and plasma treatment to form a third semiconductor, wherein the adopted doping element is selected from F, N, Ar or H; alternatively, the fourth semiconductor is subjected to oxidation treatment by high-temperature thermal oxidation, thereby forming a third semiconductor.

12. The method of fabricating a polarized superjunction group iii nitride diode device of any of claims 1-7, comprising:

sequentially arranging a first semiconductor, a second semiconductor and a third semiconductor on a substrate;

manufacturing a first anode and a cathode, and electrically connecting the first anode and the cathode with the two-dimensional electrons in the first heterojunction in a gas-electric mode;

doping the third semiconductor close to one side of the first anode to form a fourth semiconductor; and

and manufacturing a second anode, and enabling the second anode to form ohmic contact or Schottky contact with the fourth semiconductor.

13. The method of manufacturing according to claim 12, comprising: and growing and forming the first semiconductor, the second semiconductor and the third semiconductor in any one mode of metal organic chemical vapor deposition, molecular beam epitaxy, atomic layer deposition, physical vapor deposition and magnetron sputtering.

14. The method of manufacturing according to claim 13, comprising: the substrate is selected from a gallium nitride, silicon carbide, silicon or sapphire substrate.

15. The method of manufacturing according to claim 12, comprising: and doping the third semiconductor by ion implantation and high-temperature annealing activation or low-energy electron radiation activation to form a fourth semiconductor, wherein the adopted doping elements comprise Mg or Zn.

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