CN113113478B - GaN-based radio frequency power device based on ohmic regrowth and preparation method thereof - Google Patents

Abstract

The invention relates to a GaN-based radio frequency power device based on ohmic regrowth and a preparation method thereof, wherein the method comprises the following steps: s1: growing a GaN-based heterojunction on a substrate; s2: etching the ohmic region of the GaN-based heterojunction by adopting a dry etching process to form an ohmic regrowth region for ohmic regrowth; s3: epitaxially growing n on the surface of the device ⁺ A GaN layer; s4: using dry etching process to n ⁺ The GaN layer is self-terminated etched to remove n between ohmic regrowth regions ⁺ A GaN layer; s5: forming isolation regions on both sides of the device by using ion implantation equipment; s6: at n ⁺ Depositing metal on the GaN layer to form a source electrode and a drain electrode; s7: forming a passivation layer on the surface of the device; s8: and etching the passivation layer of the gate region by adopting a dry etching process to form a gate groove, and depositing metal in the gate groove to form a gate. The preparation method simplifies the preparation process of ohmic regrowth, and simultaneously continues the advantages of the conventional ohmic regrowth technology.

Description

GaN-based radio frequency power device based on ohmic regrowth and preparation method thereof

technical field

The invention belongs to the technical field of semiconductor devices, and in particular relates to a GaN-based radio frequency power device based on ohmic regrowth and a preparation method thereof.

Background technique

Group III nitride semiconductor heterojunction, with its large forbidden band width, high two-dimensional electron gas density and electron saturation drift velocity, and large critical breakdown electric field, make it a high-temperature, radiation-resistant, high-frequency The material of choice for the preparation of high-power electronic devices, the types of electronic devices mainly include high electron mobility transistors (HEMTs) and Schottky barrier diodes (SBDs), which are used in RF power amplifiers and power switch modules, respectively. Among them, GaN-based high-frequency (microwave, millimeter-wave) high-power HEMT devices are usually used in key fields such as satellites, radars and base stations.

With the improvement of nitride material growth technology and device process level, the RF power characteristics of GaN-based HEMT devices have been continuously improved, which are embodied in higher cut-off frequency and operating frequency, higher output power, and higher power added efficiency. . With the advent of the 5G era and the proposal of 6G, the operating frequency of GaN RF power devices is required to be further improved, and the output power and efficiency at high operating frequencies need to be improved at the same time. Reducing the parasitic resistance of the device is one of the most fundamental solutions. . Specific methods include reducing device contact resistance, heterojunction sheet resistance and device size. For the preparation of GaN-based HEMT devices, the methods for reducing contact resistance include: optimizing the conventional rapid thermal annealing process; upgrading the ohmic stacked metal; depositing Ge/Si dopant before ohmic metal evaporation, and forming an ohmic region n-type dopant after annealing Impurity; n-type heavy doping in the ohmic region, realized by ion implantation technology or ohmic regrowth technology. Among the above methods, the ohmic regrowth technology can achieve the lowest ohmic contact resistance, and at the same time, without annealing or low-temperature annealing, it can ensure a good ohmic morphology, which is helpful to further reduce the source-drain spacing of the device.

However, the conventional ohmic regrowth technique relies on _SiO2 mask, and its "thin film deposition", "thin film patterning" and "wet etching" make the device fabrication process more complicated. In addition, "wet etching" has higher requirements on the concentration of BOE etching solution, etching temperature and etching time, which directly leads to the difficulty of conventional ohmic regrowth technology.

SUMMARY OF THE INVENTION

In order to solve the above problems existing in the prior art, the present invention provides a GaN-based radio frequency power device based on ohmic regrowth and a preparation method thereof. The technical problem to be solved by the present invention is realized by the following technical solutions:

The invention provides a preparation method of a GaN-based radio frequency power device based on ohmic regrowth, comprising:

S1: growing a GaN-based heterojunction on a substrate;

S2: use a dry etching process to etch the ohmic region of the GaN-based heterojunction to at least 20 nm below the interface of the GaN-based heterojunction to form an ohmic regrowth region for ohmic regrowth ;

S3: epitaxial growth of n ⁺ GaN layer on the surface of the device;

S4: use a dry etching process to perform self-termination etching on the n ⁺ GaN layer, and remove the n ⁺ GaN layer between the ohmic regrowth regions;

S5: use ion implantation equipment to form isolation regions on both sides of the device;

S6: depositing metal on the n ⁺ GaN layer to form a source electrode and a drain electrode;

S7: forming a passivation layer on the surface of the device;

S8: The passivation layer in the gate region is etched by a dry etching process to form a gate groove, and metal is deposited in the gate groove to form a gate.

In an embodiment of the present invention, the S1 includes: using MOCVD equipment to sequentially stack and grow a GaN buffer layer and a barrier layer on the substrate from bottom to top, wherein,

The GaN buffer layer includes an Fe or C doped GaN layer and an unintentionally doped GaN layer stacked sequentially from bottom to top;

The barrier layer is one of AlN, ScAlN, InAlN or AlGaN, and the Al composition of AlGaN is greater than 50%.

In an embodiment of the present invention, the S2 includes:

S21: coating photoresist on the barrier layer, and exposing and developing on both sides of the top surface of the device to form an etching area;

S22: Using ICP etching equipment, the etching region is etched by a dry etching process, and is etched to at least 20 nm below the interface between the GaN buffer layer and the barrier layer to form an ohmic regrowth region In order to perform ohmic regrowth, the etching gas is a mixed gas of BCl ₃ and Cl ₂ .

In an embodiment of the present invention, in the S3, the doping concentration of the n ⁺ GaN layer is 5×10 ¹⁹ cm ⁻³ to 5×10 ²⁰ cm ⁻³ .

In an embodiment of the present invention, the S4 includes:

S41: coating photoresist on the n ⁺ GaN layer, and exposing and developing between the ohmic regrowth regions to form a self-terminating etching region;

S42: Using ICP etching equipment, a dry etching process is used to perform self-termination etching on the n ⁺ GaN layer in the self-terminated etching region, and the n ⁺ GaN layer between the ohmic regrowth regions is removed.

In one embodiment of the present invention, the self-terminating etching gas is a mixed gas of SF ₆ and BCl ₃ , wherein the gas flow ratio of SF ₆ and BCl ₃ is 1:3, and the gas flow rate of SF ₆ is 5-15sccm, BCl ₃ flow is 15-45sccm;

The etching process parameters are: the power of the upper electrode of the ICP is 160-240W, the power of the lower electrode of the ICP is 24-36W, and the pressure is 2-8mTorr.

In an embodiment of the present invention, the S6 includes: depositing Ti/Al/Ni/Au ohmic stacked metal on the n ⁺ GaN layer by using electron beam evaporation equipment to form a source electrode and a drain electrode.

The present invention provides a GaN-based radio frequency power device based on ohmic regrowth, which is prepared by using the preparation method described in any of the above embodiments, and the GaN-based radio frequency power device includes:

The substrate layer, the buffer layer and the barrier layer are sequentially stacked from bottom to top;

n ⁺ GaN ohmic regions, disposed inside the buffer layer and the barrier layer, and located on both sides of the device;

a source electrode and a drain electrode, respectively arranged on the n ⁺ GaN ohmic region;

a gate, disposed on the barrier layer and located between the source and the drain;

A passivation layer is provided on the surface of the device between the source electrode and the gate electrode and between the drain electrode and the gate electrode.

In an embodiment of the present invention, the buffer layer includes an Fe or C doped GaN layer and an unintentionally doped GaN layer that are sequentially stacked from bottom to top;

The barrier layer is one of AlN, ScAlN, InAlN or AlGaN, and the Al composition of AlGaN is greater than 50%.

In an embodiment of the present invention, the doping concentration of the n ⁺ GaN ohmic region is 5×10 ¹⁹ cm ⁻³ to 5×10 ²⁰ cm ⁻³ .

Compared with the prior art, the beneficial effects of the present invention are:

1. The preparation method of the GaN-based radio frequency power device based on ohmic regrowth of the present invention, based on the self-terminating etching technology, can be processed to obtain the same device structure as the conventional ohmic regrowth technology. Compared with the conventional ohmic regrowth technology, Not relying on SiO ₂ mask simplifies the fabrication process, while continuing the advantages of conventional ohmic regrowth technology.

2. The GaN-based radio frequency power device based on ohmic regrowth of the present invention has low ohmic contact resistance and good ohmic topography. The good ohmic topography can further reduce the source and drain dimensions of the device and help to achieve ultra-low parasitic resistance , to improve the RF power characteristics of the device.

The above description is only an overview of the technical solutions of the present invention, in order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand , the following specific preferred embodiments, and in conjunction with the accompanying drawings, are described in detail as follows.

Description of drawings

1 is a flowchart of a method for preparing a GaN-based radio frequency power device based on ohmic regrowth provided by an embodiment of the present invention;

2a-2j are schematic diagrams of a preparation process of a GaN-based radio frequency power device based on ohmic regrowth provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a GaN-based radio frequency power device based on ohmic regrowth provided by an embodiment of the present invention.

Detailed ways

In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a GaN-based radio frequency power device based on ohmic regrowth and a preparation method thereof proposed in accordance with the present invention are described below with reference to the accompanying drawings and specific embodiments. Detailed description.

The foregoing and other technical contents, features and effects of the present invention can be clearly presented in the following detailed description of the specific implementation with the accompanying drawings. Through the description of the specific embodiments, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the accompanying drawings are only for reference and description, not for the technical analysis of the present invention. program is restricted.

Example 1

Please refer to FIG. 1. FIG. 1 is a flowchart of a method for manufacturing a GaN-based radio frequency power device based on ohmic regrowth provided by an embodiment of the present invention. As shown in the figure, the preparation method of a GaN-based radio frequency power device based on ohmic regrowth in this embodiment includes:

S1: growing a GaN-based heterojunction on a substrate;

Specifically, including:

A GaN buffer layer and a barrier layer are grown sequentially from bottom to top on the substrate by using MOCVD equipment. in,

Optionally, the substrate is a SiC or Si substrate material.

Optionally, the GaN buffer layer includes an Fe or C doped GaN layer and an unintentionally doped GaN layer stacked sequentially from bottom to top.

Optionally, the barrier layer is one of AlN, ScAlN, InAlN or AlGaN, and the Al composition of AlGaN is greater than 50%.

In this embodiment, the barrier layer is a high polarization barrier layer, and the GaN buffer layer and the barrier layer constitute a low square resistance heterojunction material.

Regarding the barrier layer, the higher the Al composition, the higher the polarization strength. For example, the Al composition of AlN is 100%, the Al composition of lattice-matched ScAlN is 82%, and the Al composition of lattice-matched InAlN is 82%. 83%. The Al composition of conventional AlGaN is 20-30%. In this embodiment, if the barrier layer is AlGaN, it is necessary to select AlGaN with a high Al composition, that is, AlGaN with an Al composition greater than 50%.

Furthermore, it should be noted that these high polarization barriers typically have typical layer thickness values, such as: 2-6nm for AlN, 2-15nm for lattice-matched ScAlN, 3-15nm for lattice-matched InAlN, high Al The composition AlGaN is 7-25 nm.

S2: use a dry etching process to etch the ohmic region of the GaN-based heterojunction, and etch to at least 20 nm below the interface of the GaN-based heterojunction to form an ohmic regrowth region for ohmic regrowth;

Specifically, including:

S21: Coat photoresist on the barrier layer, and expose and develop on both sides of the top surface of the device to form an etched area;

S22: Using ICP etching equipment, dry etching process is used to etch the etched region to at least 20 nm below the interface between the GaN buffer layer and the barrier layer to form an ohmic regrowth region for ohmic regrowth, Since the GaN HEMT device relies on the 2DEG channel for conduction, and the distribution range of the 2DEG is generally considered to be in the range from the heterojunction interface to the lower 10nm, in order to make the n ⁺ GaN in the ohmic regrowth region form an effective contact with the 2DEG, it is ensured that the etching It is etched to at least 20 nm below the interface of the GaN buffer layer and the barrier layer. The etching gas is a mixed gas of BCl ₃ and Cl ₂ .

In this embodiment, the flow rates of the mixed gas of BCl ₃ and Cl ₂ are respectively 20/8sccm, and the etching process parameters are: the power of the upper electrode of the ICP is 51W, the power of the lower electrode of the ICP is 14W, and the pressure is 5mTorr.

S3: epitaxial growth of n ⁺ GaN layer on the surface of the device;

Specifically, the low-temperature epitaxy of the n ⁺ GaN layer is performed on the surface of the device by using MBE equipment, and the low-temperature epitaxy process is used to avoid the degradation of the barrier quality caused by the high-temperature epitaxy.

In this embodiment, the regrown GaN is heavily doped by in-situ Si doping, and the doping concentration of the n ⁺ GaN layer is 5×10 ¹⁹ cm ^-3 -5×10 ²⁰ cm ^-3 . The doping concentration in this range is selected because lower doping concentration is not easy to achieve low n ⁺ GaN square resistance, although higher doping concentration is easy to achieve low n ⁺ GaN square resistance, but the quality of n ⁺ GaN crystal will be worse. Therefore, the doping concentration range is taken as 5×10 ¹⁹ cm ^-3 -5×10 ²⁰ cm ^-3 .

It should be noted that the thickness of the n ⁺ GaN layer is usually twice the etch depth of the ohmic region nitride.

S4: use a dry etching process to perform self-termination etching on the n ⁺ GaN layer to remove the n ⁺ GaN layer between the ohmic regrowth regions;

Specifically, including:

S41: Coating photoresist on the n ⁺ GaN layer, exposing and developing between the ohmic regrowth regions to form a self-terminating etching region;

S42 : using ICP etching equipment, a dry etching process is used to perform self-termination etching on the n ⁺ GaN layer in the self-terminated etching region, and the n ⁺ GaN layer between the ohmic regrowth regions is removed.

In this embodiment, the self-terminating etching gas is a mixed gas of SF ₆ and BCl ₃ , wherein the gas flow ratio of SF ₆ and BCl ₃ is 1:3, the gas flow rate of SF ₆ is 5-15sccm, and the flow rate of BCl ₃ 15-45sccm.

Further, the etching process parameters are: the power of the electrode on the ICP is 160-240W, in order to ensure that the etching gas forms a plasma state, the power of the electrode under the ICP is 24-36W, giving the plasma a certain bombardment and etching ability, and the pressure is 2. -8mTorr.

In this embodiment, the mixed gas of SF ₆ and BCl ₃ is used to etch the n ⁺ GaN layer. After the etching of the n ⁺ GaN layer is completed, when SF ₆ contacts with the barrier layer containing Al to form AlF ₃ , it can be The etching of the barrier layer by the mixed gas of SF ₆ and BCl ₃ is blocked, that is, self-terminating etching is realized.

S5: use ion implantation equipment to form isolation regions on both sides of the device;

Specifically, using ion implantation equipment, B or Ar is implanted on both sides of the device to form an isolation region to realize device isolation.

S6: depositing metal on the n ⁺ GaN layer to form source and drain electrodes;

Specifically, the Ti/Al/Ni/Au ohmic stack metal is deposited on the n ⁺ GaN layer by using electron beam evaporation equipment to form the source electrode and the drain electrode.

S7: forming a passivation layer on the surface of the device;

Specifically, first, a SiN passivation layer is deposited on the surface of the device by using PECVD equipment, and then the SiN passivation layer on the source electrode and the drain electrode is removed by a dry etching process using an ICP etching device, wherein the etching gas is _The mixed gas of CF4 and _O2 , the gas flow rate is 25/5sccm, the chamber pressure is 5mTorr, the ICP upper electrode power is 80W, and the lower electrode power is 10W.

S8: The passivation layer in the gate region is etched by a dry etching process to form a gate groove, and metal is deposited in the gate groove to form a gate.

In this embodiment, first, the SiN passivation layer in the gate region is etched by dry etching process using ICP etching equipment to form gate grooves, wherein the etching gas is _CF4 and _O2 Mixed gas, the gas flow was 25/5sccm, the chamber pressure was 5mTorr, the ICP upper electrode power was 80W, and the lower electrode power was 10W; then, Ni/Au stacked metal was deposited in the gate groove by electron beam evaporation equipment to form a gate pole.

The preparation method of the GaN-based radio frequency power device based on ohmic regrowth in this embodiment, based on the self-terminating etching technology, can be processed to obtain a device structure that is essentially the same as that of the conventional ohmic regrowth technology. Compared with the conventional ohmic regrowth technology, it is not Relying on the _SiO2 mask simplifies the fabrication process while continuing the advantages of conventional ohmic regrowth techniques.

Embodiment 2

Taking the InAlN/GaN heterojunction as an example, the preparation method of the GaN-based radio frequency power device based on ohmic regrowth in this embodiment will be specifically described. Please refer to FIGS. 2a to 2j in combination. FIGS. 2a to 2j are schematic diagrams of a fabrication process of a GaN-based radio frequency power device based on ohmic regrowth provided by an embodiment of the present invention.

The specific preparation steps include:

Step 1: Use MOCVD equipment to grow the GaN layer 202 and the InAlN layer 203 in sequence on the SiC substrate 201, wherein the GaN layer 202 is composed of bottom-up Fe- or C-doped high-resistance GaN and UID-GaN (non- intentionally doped-GaN) composition, as shown in Fig. 2a.

Step 2: Coating photoresist PR on the InAlN layer 203, and exposing and developing on both sides of the top surface of the device to form an etched region 204, as shown in FIG. 2b;

Step 3: Using ICP etching equipment, dry etching process is used to etch the etched region 204 to at least 20 nm below the interface between the GaN layer 202 and the InAlN layer 203 to form an ohmic regrowth region for ohmic regeneration. growth, as shown in Fig. 2c.

The etching gas was a mixed gas of BCl ₃ and Cl ₂ , the gas flow was 20/8 sccm, the chamber pressure was 5 mTorr, the ICP upper electrode power was 51 W, and the lower electrode power was 14 W.

Step 4: Low temperature epitaxy of the n ⁺ GaN layer 205 on the surface of the device using MBE equipment, as shown in FIG. 2d .

Step 5: Coat the photoresist PR on the n ⁺ GaN layer 205, and expose and develop between the ohmic regrowth regions to form a self-terminated etching region 206, as shown in FIG. 2e.

Step 6: Using ICP etching equipment, a dry etching process is used to perform self-termination etching on the n ⁺ GaN layer 205 in the self-terminated etching region 206 to remove the n ⁺ GaN layer 205 between the ohmic regrowth regions, as shown in the figure 2f is shown.

In this embodiment, the self-terminating etching gas is a mixed gas of SF ₆ and BCl ₃ , wherein the gas flow rate of SF ₆ is 10 sccm, and the flow rate of BCl ₃ is 30 sccm. The etching process parameters are: the power of the upper electrode of the ICP is 200W, the power of the lower electrode of the ICP is 30W, and the pressure is 5mTorr.

Step 7: Using ion implantation equipment, implant B or Ar on both sides of the device to form an isolation region to achieve device isolation, as shown in Figure 2g.

Step 8: Using electron beam evaporation equipment to deposit Ti/Al/Ni/Au ohmic stack metal on the n ⁺ GaN layer 205 to form a source electrode 207 and a drain electrode 208, as shown in FIG. 2h.

Step 9: Use PECVD equipment to deposit SiN passivation layer 209 on the surface of the device, and then use ICP etching equipment to remove the SiN passivation layer 209 on the source electrode 207 and drain electrode 208 by dry etching process, as shown in FIG. 2i Show.

Among them, the etching gas was a mixture of CF4 and _O2 , the gas flow was 25/5 _sccm , the chamber pressure was 5 mTorr, the ICP upper electrode power was 80W, and the lower electrode power was 10W.

Step 10: Use ICP etching equipment to etch the SiN passivation layer 209 in the gate area with a dry etching process to form a gate groove, and then use electron beam evaporation equipment to deposit Ni/ Au stacks metal to form a gate 210, as shown in FIG. 2j, in this embodiment, the gate 210 is a T-type gate.

Among them, the etching gas was a mixture of CF4 and _O2 , the gas flow was 25/5 _sccm , the chamber pressure was 5 mTorr, the ICP upper electrode power was 80W, and the lower electrode power was 10W.

Embodiment 3

This embodiment provides a GaN-based radio frequency power device based on ohmic regrowth, which is prepared by using the preparation method described in any of the above embodiments. Please refer to FIG. 3 , which is a schematic structural diagram of a GaN-based radio frequency power device based on ohmic regrowth provided by an embodiment of the present invention. As shown in the figure, the GaN-based radio frequency power device of this embodiment includes: a substrate layer 301, a buffer layer 302, a barrier layer 303, an n ⁺ GaN ohmic region 304, a source electrode 305, a drain electrode 306, a gate electrode 307 and passivation Layer 308. The substrate layer 301 , the buffer layer 302 and the barrier layer 303 are sequentially stacked from bottom to top. The n ⁺ GaN ohmic regions 304 are disposed inside the buffer layer 302 and the barrier layer 303 and on both sides of the device. The source electrode 305 and the drain electrode 306 are respectively disposed on the n ⁺ GaN ohmic region 304 . The gate electrode 307 is disposed on the barrier layer 303 and located between the source electrode 305 and the drain electrode 306 . A passivation layer 308 is provided on the surface of the device between the source electrode 305 and the gate electrode 307 and between the drain electrode 306 and the gate electrode 307 .

Optionally, the buffer layer 302 includes an Fe or C doped GaN layer and an unintentionally doped GaN layer stacked sequentially from bottom to top; the barrier layer 303 is one of AlN, ScAlN, InAlN or AlGaN, and the AlGaN Al composition is greater than 50%.

In this embodiment, the barrier layer 303 is a high polarization barrier layer, and the buffer layer 302 and the barrier layer 303 form a low square resistance heterojunction material.

In this embodiment, the doping concentration of the n ⁺ GaN ohmic region 304 is 5×10 ¹⁹ cm ⁻³ to 5×10 ²⁰ cm ⁻³ .

The GaN-based RF power device based on ohmic regrowth in this embodiment has low ohmic contact resistance and good ohmic topography. Improve device RF power characteristics.

It should be noted that, herein, the terms "comprising", "comprising" or any other variation are intended to encompass a non-exclusive inclusion such that an article or device comprising a list of elements includes not only those elements, but also includes not explicitly other elements listed. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the article or device that includes the element. Words like "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The orientation or positional relationship indicated by "up", "bottom", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying The device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (8)

1. A preparation method of a GaN-based radio frequency power device based on ohmic regrowth is characterized by comprising the following steps:

s1: growing a GaN-based heterojunction on a substrate, comprising: sequentially stacking and growing a GaN buffer layer and a barrier layer on the substrate from bottom to top by using MOCVD equipment;

s2: etching the ohmic region of the GaN-based heterojunction by adopting a dry etching process until the position of at least 20nm below the interface of the GaN-based heterojunction is etched to form an ohmic regrowth region for ohmic regrowth; the method comprises the following steps:

s21: coating photoresist on the barrier layer, and exposing and developing the two sides of the top surface of the device to form an etching area;

s22: etching the etching region by using an ICP (inductively coupled plasma) etching device by adopting a dry etching process until the etching region is at least 20nm below the interface of the GaN buffer layer and the barrier layer to form an ohmic regrowth region for ohmic regrowth, wherein the etching gas is BCl ₃ And Cl ₂ Mixing the gas;

s3: epitaxially growing n on the surface of the device ⁺ A GaN layer;

s4: applying dry etching process to n ⁺ The GaN layer is self-terminated etched to remove n between the ohmic regrowth regions ⁺ A GaN layer; the method comprises the following steps:

s41: at the n ⁺ Coating photoresist on the GaN layer, and exposing and developing between the ohm regrowth areas to form a self-termination etching area;

s42: utilizing ICP etching equipment and adopting dry etching process to etch n of the self-termination etching area ⁺ The GaN layer is self-terminated etched to remove n between the ohmic regrowth regions ⁺ GaN layer of n between ohmic regrowth regions ⁺ The middle part of the GaN layer is removed, and n at the two end parts ⁺ The GaN layer is remained on the barrier layer;

s5: forming isolation regions on both sides of the device by using ion implantation equipment;

s6: n in the ohmic regrowth region ⁺ Depositing metal on the GaN layer to form a source electrode and a drain electrode;

s7: forming a passivation layer on the surface of the device;

s8: and etching the passivation layer of the grid region by adopting a dry etching process to form a grid groove, and depositing metal in the grid groove to form a grid.

2. The method of claim 1, wherein the GaN buffer layer comprises an Fe-or C-doped GaN layer and an unintentionally doped GaN layer stacked in sequence from bottom to top;

the barrier layer is one of AlN, scAlN, inAlN or AlGaN, and the Al component of the AlGaN is more than 50%.

3. The method of claim 1, wherein in S3, n is ⁺ The doping concentration of the GaN layer is 5 × 10 ¹⁹ cm ^-3 -5×10 ²⁰ cm ^-3 。

4. The method of claim 1, wherein the self-terminating etch gas is SF ₆ And BCl ₃ Wherein, SF ₆ And BCl ₃ The gas flow ratio of (1) ₆ The gas flow rate of (B) is 5-15sccm ₃ The flow rate is 15-45sccm;

the parameters of the etching process are as follows: the power of an electrode on the ICP is 160-240W, the power of an electrode under the ICP is 24-36W, and the pressure is 2-8mTorr.

5. The method of claim 1, wherein the S6 comprises: n in the ohmic regrowth region using electron beam evaporation equipment ⁺ And depositing Ti/Al/Ni/Au ohmic laminated metal on the GaN layer to form a source electrode and a drain electrode.

6. A GaN-based rf power device based on ohmic regrowth, characterized by being prepared by the preparation method of any one of claims 1-5, comprising:

the substrate layer, the buffer layer and the barrier layer are sequentially stacked from bottom to top;

n ⁺ the GaN ohmic region is arranged in the buffer layer and the barrier layer and positioned on two sides of the device; n is ⁺ N is provided on both ends of the barrier layer between the GaN ohmic regions ⁺ A GaN layer of which n ⁺ GaN layer and corresponding n ⁺ GaN ohmic region contact;

a source and a drain respectively disposed at the n ⁺ A GaN ohmic region;

the grid electrode is arranged on the barrier layer and is positioned between the source electrode and the drain electrode;

and the passivation layer is arranged on the surface of the device between the source electrode and the grid electrode and between the drain electrode and the grid electrode.

7. The ohmic-regrowth-based GaN-based radio frequency power device of claim 6, wherein the buffer layer comprises an Fe-or C-doped GaN layer and an unintentionally doped GaN layer stacked in this order from bottom to top;

the barrier layer is one of AlN, scAlN, inAlN or AlGaN, and the Al component of the AlGaN is more than 50%.

8. The ohmic-regrowth-based GaN-based radio frequency power device of claim 6, wherein the n ⁺ The doping concentration of GaN ohmic region is 5 × 10 ¹⁹ cm ^-3 -5×10 ²⁰ cm ^-3 。

Images