AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation and preparation method thereof

Abstract

The invention discloses an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation and a preparation method thereof. The AlN-based radio frequency power transistor comprises a substrate layer, an AlN nucleating layer, a GaN channel layer and an AlN barrier layer which are sequentially stacked from bottom to top, the source electrode and the drain electrode are located at the two ends of the upper surface of the AlN barrier layer; the first passivation layer is positioned on the upper surface of the AlN barrier layer between the source electrode and the drain electrode; the second passivation layer is located on the upper surface of the first passivation layer; wherein the second passivation layer is made of a high-thermal-conductivity material BeO; and the T-shaped grid electrode penetrates through the second passivation layer to the upper surface of the first passivation layer, is in lap joint with part of the upper surface of the second passivation layer and is close to the source electrode. The method has the remarkable advantages in the aspects of improving the heat conductivity, improving the withstand voltage and the power density of the device, reducing the current collapse, reducing the working temperature of the device and enhancing the working stability of the device, and indicates that the method has a wide application prospect in the high-frequency and high-power field.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation and a preparation method thereof. Background Art

[0002] RF power transistors are widely used in wireless communications, radar systems, and various high-frequency electronic devices. With the vigorous development of new energy vehicles, 5G communications, aerospace, and other fields, people have put forward a series of requirements for electronic equipment, such as integration, miniaturization, high voltage, high power, and low loss. The performance requirements for RF power devices are getting higher and higher, especially in terms of power handling capacity and operating frequency. In high-voltage and high-power scenarios, a large amount of heat will be generated inside the RF power transistor. If the heat cannot be effectively dissipated, the device temperature will rise, thereby affecting its performance and shortening its life.

[0003] The third-generation semiconductor material GaN has excellent material properties such as wide bandgap, high electron drift rate, and high breakdown field strength. GaN-based RF power devices prepared with GaN material as the substrate are widely used in modern communications and radar systems due to their superior electrical and thermal properties. However, RF power devices are mostly used in high-power, high-frequency, high-efficiency and high-temperature resistant application scenarios, and have very high requirements for the device's heat dissipation, high-temperature resistance, and breakdown voltage. Currently, GaN-based RF power transistors have the following problems:

[0004] (1) Existing research results show that in most cases, the breakdown of GaN-based RF power transistors under high voltage conditions is caused by the punch-through effect caused by a large number of electrons below the gate depletion region crossing the barrier layer. For existing GaN-based RF power transistors, electrons are well confined by the barrier height between the AlGaN barrier layer above the GaN channel layer and the channel. However, the barrier height generated by the AlGaN barrier layer depends greatly on the content of the Al component. If the Al component of the barrier layer is low, the low barrier will cause weaker carrier confinement, and the device may also be broken down at a lower voltage.

[0005] (2) Although the current GaN-based RF power transistors use SiC substrates with good thermal conductivity for heat dissipation, the thermal conductivity of the single-layer SiN passivation layer is too low, which makes the thermal conductivity of the base RF power transistor insufficient when working at high power. This will cause the GaN-based RF power transistor to have heat accumulation problems under normal working conditions. Poor heat dissipation leads to limited power density of the device, which in turn affects the overall efficiency and performance of the transistor, making the GaN-based RF power transistor unsuitable for applications in high-frequency, high-voltage, and high-power scenarios.

[0006] (3) Currently, GaN-based RF power transistors are surface devices, and their conductive channels are only tens of nanometers away from the device surface. Channel carriers are easily affected by surface states, resulting in current collapse, causing device reliability problems and affecting the overall efficiency and performance of the device.

[0007] Therefore, designing RF power transistors with high voltage resistance, high power, high heat dissipation and high reliability has become a key research direction. Summary of the invention

[0008] In order to solve the above problems existing in the prior art, the present invention provides an AlN-based RF power transistor based on high thermal conductivity BeO passivation and a preparation method. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0009] In a first aspect, an embodiment of the present invention provides an AlN-based RF power transistor based on high thermal conductivity BeO passivation, wherein the AlN-based RF power transistor comprises:

[0010] The substrate layer, AlN nucleation layer, GaN channel layer, and AlN barrier layer are stacked in sequence from bottom to top;

[0011] A source electrode and a drain electrode, located at two ends of the upper surface of the AlN barrier layer;

[0012] A first passivation layer is located on an upper surface of the AlN barrier layer between the source electrode and the drain electrode;

[0013] A second passivation layer is located on the upper surface of the first passivation layer; wherein the second passivation layer is made of BeO, a high thermal conductivity material;

[0014] The T-shaped gate penetrates the second passivation layer to the upper surface of the first passivation layer, overlaps a portion of the upper surface of the second passivation layer, and is close to the source.

[0015] In one embodiment of the present invention, the AlN-based RF power transistor further includes an AlGaN buffer layer or a GaN buffer layer; the AlGaN buffer layer or the GaN buffer layer is located between the GaN channel layer and the AlN barrier layer.

[0016] In one embodiment of the present invention, the substrate layer is one of a SiC substrate, a diamond substrate, and a sapphire substrate.

[0017] In one embodiment of the present invention, the material of the first passivation layer is one of SiN, Al2O3, and SiO2.

[0018] In one embodiment of the present invention, the thickness of the first passivation layer is 25 nm to 35 nm.

[0019] In one embodiment of the present invention, the thickness of the second passivation layer is 20 nm to 50 nm.

[0020] In a second aspect, an embodiment of the present invention provides a method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation, the preparation method comprising:

[0021] Acquiring a substrate layer, and cleaning the substrate layer;

[0022] growing an AlN nucleation layer on the substrate layer;

[0023] growing a GaN channel layer on the AlN nucleation layer;

[0024] growing an AlN barrier layer on the GaN channel layer;

[0025] growing a first passivation layer on the AlN barrier layer;

[0026] Growing a second passivation layer on the first passivation layer; wherein the second passivation layer is BeO, a material with high thermal conductivity;

[0027] Etching the second passivation layer at both ends of the device until the upper surface of the AlN barrier layer, so as to deposit an ohmic metal on the AlN barrier layer at one end of the device to form a source electrode, and deposit an ohmic metal on the AlN barrier layer at the other end of the device to form a drain electrode;

[0028] The second passivation layer close to the source is etched until the upper surface of the first passivation layer forms a gate groove, and a gate metal is deposited in the gate groove and on a portion of the upper surface of the second passivation layer to form a T-shaped gate.

[0029] In one embodiment of the present invention, growing a first passivation layer on the AlN barrier layer comprises:

[0030] A first passivation layer with a thickness of 25 nm to 35 nm is grown on the AlN barrier layer by using a PECVD process.

[0031] In one embodiment of the present invention, growing a second passivation layer on the first passivation layer comprises:

[0032] A second passivation layer with a thickness of 20 nm to 50 nm is grown on the first passivation layer by using an ALD process.

[0033] In one embodiment of the present invention, before growing the AlN barrier layer on the GaN channel layer, the method further comprises:

[0034] An AlGaN buffer layer or a GaN buffer layer is grown on the GaN channel layer, and an AlN barrier layer is grown on the AlGaN buffer layer or the GaN buffer layer.

[0035] Beneficial effects of the present invention:

[0036] The AlN-based RF power transistor based on high thermal conductivity BeO passivation proposed in the present invention has significant advantages in improving thermal conductivity, improving device withstand voltage and power density, reducing current collapse, lowering device operating temperature and enhancing device operating stability, indicating broad application prospects in high frequency and high power fields. Different from the structure of traditional GaN-based RF power transistors, the AlN-based RF power transistor proposed in the present invention changes the AlGaN barrier layer in the traditional GaN-based RF power transistor into an AlN barrier layer, and adopts a double-layer passivation layer combining a first passivation layer and a second passivation layer, thereby avoiding the problem that the traditional GaN-based RF power transistor only includes a single-layer SiN passivation, resulting in insufficient thermal conductivity and unable to meet high-power and high-frequency requirements. Since the high thermal conductivity material BeO is grown on the basis of the first passivation layer as the second passivation layer, the heat of the power transistor in the working state can be effectively dissipated to prevent heat accumulation, and at the same time, the problem of lattice mismatch caused by directly growing BeO on the AlN barrier layer is avoided. The combination of the first passivation layer and the second passivation layer is adopted to achieve good heat dissipation of the AlN-based RF power transistor, thereby improving the performance in high-power and high-frequency scenarios. In general, the present invention innovatively introduces high thermal conductivity material BeO into AlN-based RF power transistors. Combining the superior properties of BeO with AlN-based RF power transistors, it can achieve higher power and higher frequency processing capabilities while solving the shortcomings of current technology in heat dissipation performance. This research direction not only has important theoretical significance, but also has a far-reaching impact on promoting the advancement and application of RF device technology.

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic structural diagram of an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation provided by an embodiment of the present invention;

[0039] Figure 2 It is a schematic structural diagram of another AlN-based RF power transistor based on high thermal conductivity BeO passivation provided by an embodiment of the present invention;

[0040] Figure 3 It is a schematic flow chart of a method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation provided by an embodiment of the present invention;

[0041] Figure 4a to Figure 4h It is a schematic diagram of the corresponding structure during the preparation process of the AlN-based RF power transistor based on high thermal conductivity BeO passivation provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0043] The inventors have discovered that AlN material, as an AlGaN material with an Al component of 100%, not only has an ultra-wide direct band gap (6.2eV), high thermal conductivity, high resistivity, high breakdown field strength, excellent piezoelectric properties, good optical properties and high temperature resistance, but also has a high lattice constant match, thermal match and compatibility with GaN. Therefore, RF power transistors using AlN as a barrier layer can greatly improve the device's voltage resistance and high-frequency performance, and can be better used in high-power, high-frequency RF devices. However, RF power transistors that directly use AlN barrier layers to replace AlGaN barrier layers still cannot meet application requirements under high power and high frequency conditions. This is because: in high power and high frequency scenarios, if a single-layer SiN dielectric layer or other ceramic materials are continued to be used as a solution for passivation layer heat dissipation, the heat dissipation performance of the device will be improved to a certain extent. However, the current passivation layer technology is mostly silicon-based passivation or silicon nitride passivation. These materials perform well in electrical insulation, but their thermal conductivity is still not high enough, which will lead to heat accumulation, resulting in excessively high temperatures and unstable operation of the device during operation. The device itself will be damaged or even cause the entire module circuit to fail, thereby limiting the heat dissipation effect and working stability in high power applications. Therefore, finding effective passivation and heat dissipation materials to optimize device heat dissipation has become a key research direction.

[0044] In response to this problem, the inventors further studied and found that the high thermal conductivity material BeO (beryllium oxide) can be used as an ideal passivation layer material due to its excellent thermal conductivity and electrical insulation. The thermal conductivity of BeO can reach several hundred watts per meter per Kelvin (W / m·K), which is much higher than traditional materials. This enables BeO to effectively transfer the heat generated by the device to the substrate or external heat dissipation system, thereby reducing the operating temperature of the device. In addition, BeO also has good dielectric properties, which can effectively isolate the current, prevent breakdown, and improve the long-term stability and stability of the device. However, the inventors found that if BeO is directly grown on the AlGaN barrier layer in the GaN-based RF power device, the lattice mismatch between AlGaN and BeO is small, which can play a passivation effect and achieve good heat dissipation. If BeO is directly grown on the AlN barrier layer in the Al-based RF power device, due to the large lattice mismatch between the nitride and the oxide, lattice distortion will occur, affecting the interface quality and passivation effect. In order to solve this problem, the inventors added a layer of material such as SiN between the AlN barrier layer and BeO as the first passivation layer, which not only avoided the lattice mismatch problem caused by direct contact between BeO and the AlN barrier layer, but also dealt with the surface charge of the device and reduced current collapse. On this basis, BeO was used as the second passivation layer, which not only played the role of passivation, but also played a role in heat dissipation with high thermal conductivity, thus making the design of AlN-based RF power transistors for high-power and high-frequency scenarios possible.

[0045] Based on the above research, an embodiment of the present invention proposes an AlN-based RF power transistor based on high thermal conductivity BeO passivation and a preparation method thereof.

[0046] First, see Figure 1 The embodiment of the present invention provides an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation, and the AlN-based radio frequency power transistor includes:

[0047] The substrate layer, AlN nucleation layer, GaN channel layer, and AlN barrier layer are stacked in sequence from bottom to top;

[0048] A source electrode and a drain electrode are located at two ends of the upper surface of the AlN barrier layer;

[0049] A first passivation layer is located on the upper surface of the AlN barrier layer between the source and the drain;

[0050] A second passivation layer is located on the upper surface of the first passivation layer; wherein the second passivation layer is made of BeO, a material with high thermal conductivity;

[0051] The T-shaped gate penetrates the second passivation layer to the upper surface of the first passivation layer, overlaps a portion of the upper surface of the second passivation layer, and is close to the source electrode.

[0052] The substrate layer in the embodiment of the present invention may be one of a SiC substrate, a diamond substrate and a sapphire substrate.

[0053] The thickness of the AlN nucleation layer in the embodiment of the present invention is 45nm to 55nm, and more preferably the thickness is 50nm; the thickness of the GaN channel layer is 90nm to 110nm, and more preferably the thickness is 100nm; the thickness of the AlN barrier layer is 15nm to 25nm, and more preferably the thickness is 20nm. The embodiment of the present invention uses an AlN barrier layer, which increases the barrier height between the channel layer and the barrier layer of the device, increases the barrier height when the device is working when electrons penetrate, and increases the confinement of the carriers of the device, thereby improving the high-voltage resistance of the device. By increasing the barrier height between the barrier layer and the GaN channel layer, the concentration of 2DEG generated by spontaneous polarization and piezoelectric polarization is increased, thereby increasing the current density of the device, and then increasing the power density of the device, and finally preparing an AlN-based RF power transistor that can be applied to high power and high frequency.

[0054] The material of the first passivation layer of the embodiment of the present invention is one of SiN, Al2O3, and SiO2; the thickness of the first passivation layer is 25nm to 35nm. The material of the second passivation layer of the embodiment of the present invention is BeO, a material with high thermal conductivity; the thickness of the second passivation layer is 20nm to 50nm. The embodiment of the present invention adopts a double-layer passivation structure of a first passivation layer and a second passivation layer. The first passivation layer reduces the lattice mismatch between the second passivation layer and the AlN barrier layer. At the same time, the double-layer passivation greatly improves the heat dissipation performance, reduces the impact of current collapse on the device, and improves the working reliability of the device.

[0055] In the embodiment of the present invention, the material of the gate electrode may be Ni / Au (45nm / 200nm); the material of the source electrode and the drain electrode may be Ti / Al / Ni / Au (20nm / 120nm / 45nm / 55nm). Figure 1 In the figure, S indicates the source, D indicates the drain, and G indicates the gate.

[0056] See also Figure 2 In the embodiment of the present invention, the AlN-based RF power transistor further includes an AlGaN buffer layer or a GaN buffer layer; the AlGaN buffer layer or the GaN buffer layer is located between the GaN channel layer and the AlN barrier layer; the thickness of the AlGaN buffer layer or the GaN buffer layer is 100nm to 200nm, and more preferably the thickness of the AlGaN buffer layer or the GaN buffer layer is 180nm. Adding a buffer layer between the substrate layer and the GaN channel layer can reduce the lattice mismatch and stress mismatch caused by the difference between GaN and the substrate material, and effectively reduce the dislocation density. When the device is working, the buffer layer will prevent the current from leaking from the substrate.

[0057] The embodiment of the present invention is based on the combination of AlN-based RF power transistors and BeO materials as top-layer passivation, and has broad application prospects: First, in 5G and future 6G communication technologies, the demand for high-frequency, high-power RF devices continues to increase. The structure proposed in the present invention can effectively improve the power handling capability and thermal management performance of the device, thereby meeting the strict requirements for RF components in high-speed communications. Secondly, with the rapid development of emerging applications such as the Internet of Things, smart homes, and autonomous driving, the integration and reliability of RF power devices are particularly important. The structure proposed in the present invention can achieve more reliable signal transmission and reduce system failure rates in these fields by optimizing thermal management, reducing device current collapse, and improving device stability; finally, high-end application scenarios such as aerospace, automotive electronics, and radar systems have extremely high performance requirements for RF devices. The structure proposed in the present invention can still maintain excellent performance under high voltage, high frequency, and high power, which is helpful for application in actual scenarios.

[0058] In summary, the AlN-based RF power transistor based on high thermal conductivity BeO passivation proposed in the embodiment of the present invention has significant advantages in improving thermal conductivity, improving device withstand voltage and power density, reducing current collapse, lowering device operating temperature and enhancing device operating stability, indicating broad application prospects in high frequency and high power fields. Different from the structure of traditional GaN-based RF power transistors, the AlN-based RF power transistor proposed in the embodiment of the present invention changes the AlGaN barrier layer in the traditional GaN-based RF power transistor into an AlN barrier layer, and adopts a double-layer passivation layer combining a first passivation layer and a second passivation layer, thereby avoiding the problem that the traditional GaN-based RF power transistor only includes a single-layer SiN passivation, resulting in insufficient thermal conductivity and unable to meet high-power and high-frequency requirements. Since the high thermal conductivity material BeO is grown on the basis of the first passivation layer as the second passivation layer, the heat of the power transistor in the working state can be effectively dissipated to prevent heat accumulation. At the same time, the problem of lattice mismatch caused by directly growing BeO on the AlN barrier layer is avoided. The combination of the first passivation layer and the second passivation layer is adopted to achieve good heat dissipation of the AlN-based RF power transistor, thereby improving the performance in high-power and high-frequency scenarios. In general, the embodiments of the present invention innovatively introduce the high thermal conductivity material BeO into the AlN-based RF power transistor. Combining the superior properties of BeO with the AlN-based RF power transistor, it can achieve higher power and higher frequency processing capabilities while solving the shortcomings of the current technology in heat dissipation performance. This research direction not only has important theoretical significance, but also has a far-reaching impact on promoting the advancement and application of RF device technology.

[0059] Second, see Figure 3 The embodiment of the present invention provides a method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation, the preparation method comprising:

[0060] S10, obtaining a substrate layer, and cleaning the substrate layer.

[0061] The embodiment of the present invention first obtains a substrate layer, which may be a SiC substrate, a diamond substrate, or a sapphire substrate, and then cleans the obtained substrate layer. Specifically, the substrate layer is sequentially placed in acetone, ethanol, and deionized water for ultrasonic cleaning for 10 minutes, and then blown dry with a nitrogen gun.

[0062] S20, growing an AlN nucleation layer on the substrate layer.

[0063] In the embodiment of the present invention, the cleaned substrate layer is immersed in a HF (hydrofluoric acid) solution for 30 seconds, and after being cleaned and blown dry with an organic solvent, the substrate layer is placed in a MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber, and an AlN nucleation layer with a thickness of 45nm to 55nm is epitaxially grown on the substrate layer by a MOCVD process, and more preferably an AlN nucleation layer with a thickness of 50nm is epitaxially grown, such as Figure 4a shown.

[0064] S30, growing a GaN channel layer on the AlN nucleation layer.

[0065] In the embodiment of the present invention, a flow rate of Ga source, hydrogen and ammonia is simultaneously introduced into the MOCVD reaction chamber to grow a GaN channel layer with a thickness of 90nm to 110nm on the AlN nucleation layer, and more preferably a GaN channel layer with a thickness of 100nm is grown. Figure 4b shown.

[0066] S40 , growing an AlN barrier layer on the GaN channel layer.

[0067] In the embodiment of the present invention, Al source, hydrogen and ammonia are introduced into the MOCVD reaction chamber at the same time, and an AlN barrier layer with a thickness of 15nm to 25nm is grown on the GaN channel layer, and more preferably an AlN barrier layer with a thickness of 20nm is grown. Figure 4c As shown, it is removed after growth is completed.

[0068] It should be noted that before growing the AlN barrier layer on the GaN channel layer, the process may further include: growing an AlGaN buffer layer or a GaN buffer layer with a thickness of 100nm to 200nm on the GaN channel layer, more preferably growing an AlGaN buffer layer or a GaN buffer layer with a thickness of 180nm, so as to grow an AlN barrier layer on the AlGaN buffer layer or the GaN buffer layer. Taking the GaN buffer layer as an example: simultaneously introducing a flow rate of Ga source, hydrogen and ammonia into the MOCVD reaction chamber, growing a GaN buffer layer with a thickness of 100nm to 200nm on the GaN channel layer, more preferably growing a GaN buffer layer with a thickness of 180nm, such as Figure 4d shown.

[0069] S50 , growing a first passivation layer on the AlN barrier layer.

[0070] In the embodiment of the present invention, the device structure obtained in S40 is placed in a PECVD (Plasma Enhanced Chemical Vapor Deposition) reaction chamber, and a first passivation layer with a thickness of 25 nm to 35 nm is deposited at a high temperature of 400° C., more preferably, a first passivation layer with a thickness of 30 nm is deposited. Figure 4e The material of the first passivation layer can be SiN, Al2O3 and SiO2, and it is taken out after the growth is completed.

[0071] S60, growing a second passivation layer on the first passivation layer; wherein the second passivation layer is BeO, a material with high thermal conductivity.

[0072] In the embodiment of the present invention, the device structure obtained in S50 is placed in an ALD (Atomic Layer Deposition) reaction chamber, and the high thermal conductivity material BeO is deposited with a thickness of 20nm to 50nm at a temperature of 300°C to form a second passivation layer, and more preferably, the high thermal conductivity material BeO is deposited with a thickness of 45nm to form a second passivation layer, such as Figure 4f As shown. The thickness and quality of the grown high thermal conductivity material BeO can be precisely controlled through the ALD process.

[0073] S70, etching the second passivation layer at both ends of the device until the upper surface of the AlN barrier layer, so as to deposit an ohmic metal on the AlN barrier layer at one end of the device to form a source electrode, and deposit an ohmic metal on the AlN barrier layer at the other end of the device to form a drain electrode.

[0074] In the embodiment of the present invention, a mask is made on the second passivation layer, and the second passivation layer at both ends of the device obtained by etching S60 is obtained by using the mask until the upper surface of the AlN barrier layer, and Ti / Al / Ni / Au (20nm / 120nm / 45nm / 55nm) is deposited on the AlN barrier layer by using an electron beam evaporation device, so as to deposit an ohmic metal on the AlN barrier layer at one end of the device to form a source electrode, and deposit an ohmic metal on the AlN barrier layer at the other end to form a drain electrode, such as Figure 4g At this time, the mesa isolation is achieved by etching simultaneously.

[0075] S80, etching the second passivation layer close to the source until the upper surface of the first passivation layer forms a gate groove, and depositing a gate metal in the gate groove and on a portion of the upper surface of the second passivation layer to form a T-shaped gate.

[0076] In the embodiment of the present invention, a mask is made on the second passivation layer near the source electrode, and the second passivation layer is etched by using the mask until a gate groove is formed on the upper surface of the first passivation layer, and a gate metal such as Ni / Au (45nm / 200nm) is deposited on a portion of the second passivation layer in the gate groove and on both sides of the gate groove by using an electron beam evaporation device to form a T-shaped gate. Figure 4h shown.

[0077] The embodiment of the present invention provides a preparation method based on the structure proposed in the first aspect, which has a simple manufacturing process, good economy, and is suitable for large-scale commercial production and application.

[0078] As for the preparation method embodiment of the second aspect, since it is basically similar to the structural embodiment of the first aspect, the description is relatively simple, and the relevant parts may refer to the partial description of the structural embodiment of the first aspect.

[0079] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0080] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the specification and its drawings. In the specification, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude multiple situations. Certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0081] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. An AlN-based RF power transistor based on high thermal conductivity BeO passivation, characterized in that: The AlN-based radio frequency power transistor comprises: The substrate layer, AlN nucleation layer, GaN channel layer, and AlN barrier layer are stacked in sequence from bottom to top; A source electrode and a drain electrode, located at two ends of the upper surface of the AlN barrier layer; A first passivation layer is located on an upper surface of the AlN barrier layer between the source electrode and the drain electrode; A second passivation layer is located on the upper surface of the first passivation layer; wherein the second passivation layer is made of BeO, a high thermal conductivity material; The T-shaped gate penetrates the second passivation layer to the upper surface of the first passivation layer, overlaps a portion of the upper surface of the second passivation layer, and is close to the source.

2. The AlN-based RF power transistor based on high thermal conductivity BeO passivation according to claim 1, characterized in that: The AlN-based radio frequency power transistor further includes an AlGaN buffer layer or a GaN buffer layer; the AlGaN buffer layer or the GaN buffer layer is located between the GaN channel layer and the AlN barrier layer.

3. The AlN-based RF power transistor based on high thermal conductivity BeO passivation according to claim 1, characterized in that: The substrate layer is one of a SiC substrate, a diamond substrate and a sapphire substrate.

4. The AlN-based RF power transistor based on high thermal conductivity BeO passivation according to claim 1, characterized in that: The material of the first passivation layer is one of SiN, Al2O3 and SiO2.

5. The AlN-based RF power transistor based on high thermal conductivity BeO passivation according to claim 1, characterized in that: The thickness of the first passivation layer is 25 nm to 35 nm.

6. The AlN-based RF power transistor based on high thermal conductivity BeO passivation according to claim 1, characterized in that: The thickness of the second passivation layer is 20 nm to 50 nm.

7. A method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation, characterized in that: The preparation method comprises: Acquiring a substrate layer, and cleaning the substrate layer; growing an AlN nucleation layer on the substrate layer; growing a GaN channel layer on the AlN nucleation layer; growing an AlN barrier layer on the GaN channel layer; growing a first passivation layer on the AlN barrier layer; Growing a second passivation layer on the first passivation layer; wherein the second passivation layer is BeO, a material with high thermal conductivity; Etching the second passivation layer at both ends of the device until the upper surface of the AlN barrier layer, so as to deposit an ohmic metal on the AlN barrier layer at one end of the device to form a source electrode, and deposit an ohmic metal on the AlN barrier layer at the other end of the device to form a drain electrode; The second passivation layer close to the source is etched until the upper surface of the first passivation layer forms a gate groove, and a gate metal is deposited in the gate groove and on a portion of the upper surface of the second passivation layer to form a T-shaped gate.

8. The method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation according to claim 7, characterized in that: Growing a first passivation layer on the AlN barrier layer, comprising: A first passivation layer with a thickness of 25 nm to 35 nm is grown on the AlN barrier layer by using a PECVD process.

9. The method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation according to claim 7, characterized in that: Growing a second passivation layer on the first passivation layer, comprising: A second passivation layer with a thickness of 20 nm to 50 nm is grown on the first passivation layer by using an ALD process.

10. The method for preparing an AlN-based radio frequency power transistor based on high thermal conductivity BeO passivation according to claim 7, characterized in that: Before growing the AlN barrier layer on the GaN channel layer, the method further comprises: An AlGaN buffer layer or a GaN buffer layer is grown on the GaN channel layer, and an AlN barrier layer is grown on the AlGaN buffer layer or the GaN buffer layer.

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