High-heat-dissipation GaN nanowire radio frequency device and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductor devices, and particularly relates to a high-heat-dissipation GaN nanowire radio frequency device and a preparation method thereof.The radio frequency device comprises a heterogeneous bonding substrate, a bonding middle layer, an AlGaN / GaN nanowire (a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer and a GaN cap layer), a passivation layer and an electrode layer, and the electrode layer comprises a source electrode, a gate electrode and a drain electrode; the passivation layer covers the gaps between the nanowires through front deposition, so that the preparation of the high-heat-dissipation nanowire transistor is realized, and the problem that the linearity of the device is reduced due to a self-heating effect is solved; holes are formed in the grid electrode, the thickness of the passivation layer on each nanowire is controlled, equal difference distribution is achieved, the linearity of the device is improved through the transconductance compensation effect, the grid voltage swing of the radio frequency device can be effectively improved, and therefore the available range of the device is greatly widened.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, and particularly relates to a high heat dissipation GaN nanowire radio frequency device and its fabrication method. Background Technology

[0002] GaN materials are chosen as radio frequency (RF) materials due to their inherent high-frequency characteristics. HEMT devices, composed of AlGaN / GaN heterostructures, are particularly outstanding because they can achieve high carrier concentration and high mobility without doping. However, parasitic capacitance, nonlinear transconductance, and trap defects often hinder GaN devices from fully realizing their material advantages in the RF field. The nonlinearity of transconductance is a major factor affecting device nonlinearity. During fast switching, GaN devices are affected by polar optical phonon scattering and interface roughness scattering, which limits carrier mobility. At the same time, self-heating during fast switching increases channel resistance and reduces transconductance. Combined with surface defect states, these factors collectively limit the RF performance of HEMT devices. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a high-heat-dissipation GaN nanowire radio frequency device and its fabrication method. This method utilizes dry etching, laser lift-off, and heterogeneous bonding to achieve nanowire epitaxy fabrication. Nanowire transistors are then fabricated using photolithography. The nanowires further reduce carrier scattering, overcoming the limitation on carrier mobility in current HEMT devices caused by scattering. Simultaneously, a boron nitride (BN) passivation layer with excellent heat dissipation properties is deposited between the nanowires for sidewall protection and heat dissipation filling. The high heat dissipation coefficient further resolves the channel self-heating effect, preventing heat generation from increasing resistance and limiting the device's radio frequency performance. Furthermore, this invention provides a transconductance compensation method to increase the linear amplification region. By controlling the passivation layer thickness above each nanochannel, a gradual passivation thickness gradient effectively alters the threshold voltage of each nanowire device, achieving transconductance compensation and improving the overall device gate voltage swing. This ensures the transconductance remains constant over a large gate voltage range, effectively increasing the device's linearity.

[0004] To achieve the above objectives, the present invention provides a high-heat-dissipation GaN nanowire radio frequency device, which includes a heterostructure substrate and a SiO2 bonding layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, a GaN cap layer, a first passivation layer, an electrode layer, and a second passivation layer arranged sequentially. The electrode layer is configured as a source electrode, a gate electrode, and a drain electrode at intervals. The GaN channel layer, AlN insertion layer, AlGaN barrier layer, and GaN cap layer constitute a nanowire array, which is fabricated by etching.

[0005] Furthermore, the nanowire array is in groups of 8-15, and a GaN buffer layer is etched within a certain range around the nanowire array to form a mesa isolation; a first passivation layer with a high heat dissipation coefficient and low dielectric constant is deposited, and the passivation layer completely covers the upper surface and sides of the nanowires.

[0006] Furthermore, the source electrode and drain electrode are deposited on the AlGaN barrier layer through the first passivation layer and GaN cap layer respectively by a passivation aperture method, and the bottom of the gate electrode is connected to the upper surface of the first passivation layer; the source electrode is close to the gate electrode, and the drain electrode is far away from the gate electrode.

[0007] Furthermore, the second passivation layer is connected to the first passivation layer, thus completing the openings for the source electrode PAD, the gate electrode PAD, and the drain electrode PAD.

[0008] Furthermore, the heterogeneous substrate includes any one of diamond, aluminum nitride, or sapphire, and the first passivation layer and the second passivation layer are materials with high heat dissipation coefficient and low dielectric constant.

[0009] This invention also provides a method for fabricating a high-heat-dissipation GaN nanowire radio frequency device, the method comprising the following steps:

[0010] (1) An AlN nucleation layer, a GaN high-resistivity buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer and a GaN cap layer are sequentially grown on a heterogeneous substrate.

[0011] (2) Nanowire array patterning is achieved based on photolithography, and nanowire array is prepared by inductively coupled plasma etching to expose GaN high-resistivity buffer layer.

[0012] (3) Temporary bonding of the nanowire array epitaxial wafer to the Si temporary substrate was completed by using temporary bonding adhesive, and the sapphire substrate was polished.

[0013] (4) Laser lift-off is used to lift the sapphire substrate, and hydrochloric acid immersion is used to remove the bottom Ga atoms;

[0014] (5) Chemical mechanical polishing was used to polish the surface of the nanowire array wafer with a temporary support substrate, and atomic layer deposition equipment was used to deposit SiO2 on the surface and the heterogeneous substrate.

[0015] (6) The nanowire array wafer and the heterostructure are activated and bonded by plasma surface activation bonding. The temporary bonding substrate is removed by laser debonding. The bonding adhesive is removed by soaking in debonding solution to obtain the heterostructure nanowire array wafer.

[0016] (7) Deposit the first passivation layer BN film on the top and sides of the nanowire, make source and drain holes by photolithography, etch to expose the AlGaN barrier layer, deposit source and drain electrodes by electron beam evaporation, and achieve ohmic contact by high temperature annealing.

[0017] In this step, BN has excellent electrical insulation properties and a relatively low dielectric constant (3-4), making it suitable for use in high-frequency applications. It will not generate excessive parasitic capacitance, and its heat dissipation coefficient is relatively high at 60W / m·K, which is beneficial for heat dissipation.

[0018] Meanwhile, by dividing the conventional AlGaN / GaN channel into multiple nanowire channels and using high thermal conductivity BN as a passivation layer, the heat source concentration in the HEMT channel is effectively alleviated, especially the heat source concentration on the side of the gate near the drain. Continuous heat sources are etched into separated channels, and BN is deposited between the heat sources to effectively dissipate heat. At the same time, shortening the distance between the channel and the substrate and using diamond (or AlN) with the highest thermal conductivity greatly alleviates the channel self-heating effect, reduces the transconductance change caused by the increase in channel resistance under high-frequency switching, and improves linearity.

[0019] (8) Gate windowing, electron beam evaporation deposition of gate electrode above first passivation layer; deposition of second passivation layer to protect electrode;

[0020] This step uses ALD to deposit a dense, high-heat-dissipation passivation layer (such as AlN) to cover the first passivation layer and the upper surface of the electrode, which can be used to protect the electrode area and further improve the heat dissipation capability of the device.

[0021] (9) The source, drain, and gate electrodes PAD are opened and etched to expose the metal surface of PAD, thus obtaining the high heat dissipation GaN nanowire RF device.

[0022] Furthermore, after step (4), the method further includes a step of exposing the GaN channel layer by inductively coupled plasma etching to further reduce the thickness of the buffer layer.

[0023] This step can reduce the distance of the device channel for heat dissipation and improve heat dissipation capacity.

[0024] The present invention also provides a method for transconductance-compensated GaN nanowire radio frequency devices, the method comprising the following steps:

[0025] (1) After the high heat dissipation GaN nanowire radio frequency device is fabricated to step (7) by the above method, photoresist is patterned in the gate region of each nanowire using photolithography, and inductively coupled plasma etching is used to obtain GaN nanowire arrays with different passivation layer thicknesses.

[0026] (2) The wafer with the first passivation layer is photolithographically etched again to deposit a gate electrode, which is deposited on an opening region with different thicknesses of the first passivation layer.

[0027] (3) Deposit a second passivation layer, open the source drain gate PAD, and etch to expose the PAD metal surface, so as to realize the transconductance compensation of the GaN nanowire radio frequency device.

[0028] The present invention also provides a high linearity GaN nanowire RF device fabricated using the above-described transconductance-compensated GaN nanowire RF device method. The high linearity GaN nanowire RF device increases the line size of the GaN nanowire RF device by controlling the passivation layer thickness above each nanochannel, with a gradual change in the passivation thickness gradient.

[0029] The above methods can improve the linearity of GaN RF devices. By bonding to heterogeneous substrates and depositing high thermal conductivity passivation before the nanowires, the problem of heat accumulation in the GaN channel region is largely solved. Transconductance compensation is achieved by controlling the thickness of the passivation layer under the gate, which effectively increases the power amplification capability of GaN RF devices. This avoids the complexity and integration difficulties caused by setting external feedback circuits in conventional GaN devices, and also avoids the short-channel effect caused by shortening the channel.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] This invention fabricates nanowire transistors using photolithography. The nanowires further reduce carrier scattering, overcoming the limitation on carrier mobility in current HEMT devices caused by scattering. Simultaneously, a boron nitride (BN) passivation layer with excellent heat dissipation properties is deposited between the nanowires for sidewall protection and heat dissipation filling. The high heat dissipation coefficient further solves the channel self-heating effect, preventing heat generation from increasing resistance and limiting the device's RF performance. Furthermore, this invention provides a transconductance compensation method to increase the linear amplification region. By controlling the passivation layer thickness above each nanochannel, the passivation thickness gradient effectively changes the threshold voltage of each nanowire device, achieving transconductance compensation and improving the gate voltage swing of the entire device. This keeps the transconductance constant over a large gate voltage range, effectively increasing the device's linearity. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the overall structure of the heterogeneous substrate GaN nanowire radio frequency device in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of the GaN radio frequency epitaxial wafer on a sapphire substrate in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the fabrication of nanochannels in an embodiment of the present invention, wherein the left figure is the front view and the right figure is the top view;

[0036] Figure 4 This is a schematic diagram of temporary bonding in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the laser ablation method in an embodiment of the present invention;

[0038] Figure 6 This is a structural diagram of the sapphire substrate removed in an embodiment of the present invention;

[0039] Figure 7 This is a schematic diagram of removing the GaN high-resistivity buffer layer in an embodiment of the present invention;

[0040] Figure 8 This is a schematic diagram of SiO2 deposition on a heterogeneous substrate and nanowire wafer in an embodiment of the present invention;

[0041] Figure 9 This is a schematic diagram of heterogeneous bonding in an embodiment of the present invention;

[0042] Figure 10 This is a schematic diagram of the temporary substrate after heterobonding in an embodiment of the present invention;

[0043] Figure 11 This is a schematic diagram of the deposition of the first passivation layer on a heterogeneous bonded GaN nano-RF wafer in an embodiment of the present invention;

[0044] Figure 12 This is a schematic diagram of the open-source drain gate window deposition electrode in an embodiment of the present invention;

[0045] Figure 13 This is a schematic diagram of the structure for fabricating a high linearity device in an embodiment of the present invention;

[0046] Figure 14 This is a schematic diagram of the structure of the transconductance-compensated high linearity device in an embodiment of the present invention. Detailed Implementation

[0047] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0048] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0049] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0050] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0051] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0052] The high-heat-dissipation GaN nanowire radio frequency device prepared in this invention includes a diamond heterostructure substrate and, in sequence, a SiO2 bonding layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, a GaN cap layer, a passivation layer, an electrode layer, and a second passivation layer. The electrode layer is sequentially arranged as a source electrode, a gate electrode, and a drain electrode. The GaN channel layer, AlN insertion layer, AlGaN barrier layer, and GaN cap layer are fabricated as a nanowire array by etching. The first passivation layer is located above the nanowires and between the nanowires. The passivation layer is typically made of a material with low dielectric constant and excellent heat dissipation performance.

[0053] Specifically, the nanowire array mentioned above is usually a group of 8-15 nanowires. A certain range around the nanowire array is etched to the GaN buffer layer to form a mesa isolation. A first passivation layer with a high heat dissipation coefficient and low dielectric constant is deposited. The first passivation layer completely covers the upper surface and sides of the nanowires.

[0054] The aforementioned source electrode and drain electrode are deposited on the AlGaN barrier layer by passing through the first passivation layer and the GaN cap layer through passivation openings, respectively. The bottom of the gate electrode is connected to the upper surface of the first passivation layer. The source electrode is close to the gate electrode, and the drain electrode is far from the gate electrode.

[0055] The second passivation layer is connected to the first passivation layer, thus completing the opening of the source electrode PAD, the gate electrode PAD, and the drain electrode PAD.

[0056] Specifically, the aforementioned nanowire array GaN RF device also includes the etching of the GaN high-resistivity buffer layer and the deposition of an ALD SiO2 bonding layer, with the heterostructure substrate located below the SiO2 bonding layer.

[0057] A schematic diagram of the overall structure of the high heat dissipation GaN nanowire radio frequency device prepared in this invention is shown below. Figure 1 In the aforementioned nanowire array GaN RF device, the nanowires are arranged in an array according to actual needs. Plasma-activated bonding is used to enhance the activation characteristics of the SiO2 surface, and a heterogeneous bonding channel is completed with a high-heat-dissipating heterogeneous substrate (such as diamond or aluminum nitride) to form the overall device. The nanochannel and the nanowires are composed of a passivation layer with a high heat dissipation coefficient and low dielectric constant (such as boron nitride). While separating the dense heat source, the passivation layer effectively improves heat dissipation. In addition, the passivation layer itself has a low dielectric constant and low parasitic capacitance under high-speed switching, which is very suitable for use in RF devices. The source and drain electrodes are deposited on the exposed AlGaN through windows opened by the first passivation layer, and ohmic contact electrodes are prepared by high-temperature annealing in a nitrogen atmosphere. The gate electrode is deposited on the first passivation layer to form a MIS structure, which further reduces gate leakage and improves device performance. A second passivation layer is covered on the first passivation layer and the electrodes. The second passivation layer is etched to expose the electrode PAD surface.

[0058] The present invention will be described in further detail below with reference to specific embodiments and accompanying drawings, but this does not limit the implementation of the present invention.

[0059] Example 1

[0060] Embodiment 1 of the present invention provides a method for fabricating a GaN nanowire radio frequency device with high heat dissipation, comprising the following steps:

[0061] (1) An epitaxial wafer is obtained by sequentially growing a 40-50 nm AlN nucleation layer, a 1-3 μm GaN high-resistivity buffer layer, a 100-200 nm GaN channel layer, a 1-3 nm AlN insertion layer, a 15-40 nm AlxGa1-xN barrier layer (x = 0.2-0.4), and a 1-3 nm GaN layer on a sapphire substrate;

[0062] (2) Based on photolithography, the patterning of the nanowire array was realized. The HEMT nanowire array was prepared by inductively coupled plasma (ICP) dry etching equipment. The specific parameters are as follows: for the wafer after photolithography, Cl2 / BCl3 (60 / 10 sccm) was used to etch to the GaN high-resistivity buffer layer in an atmosphere with a power of 200W and a pressure of 8Pa. The etching depth was (117nm~246nm).

[0063] (3) Use a spin coater to spin coat temporary bonding adhesive (laser debonding adhesive). The spin coating process is 500 rpm for 5 seconds and then 2000 rpm for 30 seconds. The thickness of the spin coat is 0.9 to 1.1 μm. The adhesive is cured by heating on a hot table at 250 to 300 degrees Celsius for 5 to 10 minutes. Select a Si wafer or sapphire substrate as a temporary substrate and bond it to the spin-coated bonding substrate using a bonding device. The bonding parameters are 200°C and 500 to 1000 N. Place the bonded substrate in a polishing machine to polish the sapphire substrate.

[0064] (4) The polished epitaxial wafer is placed in a laser lift-off device. The laser wavelength is a 248nm KrF excimer laser with photon energy in the range of 3.50-5.00eV, which is lower than the bandgap energy of sapphire (9.9eV) but higher than that of GaN (3.44eV). This ensures that the laser energy is absorbed by the GaN layer, thus achieving the lift-off of the sapphire substrate. After lift-off, the epitaxial wafer with the temporary substrate is placed in a solution of HCl:H2O (1:1) for 5-10 minutes to further remove the Ga elements remaining on the back side due to the high-energy laser. Then, it is washed with deionized water, dried, and finally dried using inductively coupled plasma (ICP). The etching equipment is used to etch and prepare the GaN buffer layer, further reducing the thickness, easing the distance for heat dissipation in the device channel, and improving heat dissipation capacity. The specific parameters are as follows: for the photolithographic wafer, Cl2 / BCl3 (60 / 10 sccm) is used in an atmosphere with a power of 200W and a pressure of 8Pa to etch to the GaN high-resistivity buffer layer, with an etching depth of (1μm~3μm), to obtain a nanowire array of temporary substrate, bonding adhesive and GaN cap layer, AlGaN barrier layer, AlN insertion layer, and GaN channel layer;

[0065] (5) The surface of the process wafer, i.e. the GaN channel layer surface, is chemically polished using CMP equipment to achieve global planarization and achieve a surface roughness of <0.5nm. SiO2 is deposited on the CMP-treated process wafer and the heterogeneous bonding substrate (diamond, AlN) using atomic layer deposition equipment (ALD) with a deposition thickness of 30-50nm.

[0066] (6) Plasma surface activation bonding was used to activate and bond the nanowire array wafer to the heterogeneous substrate, achieving wafer bonding. Specific parameters are as follows: oxygen plasma was introduced into a vacuum environment of 0.1-0.5 Pa to bombard the SiO2 surface with a power of 60-150 W. After surface activation, a robotic arm was controlled to perform alignment bonding. Heterogeneous substrate bonding was achieved at a pressure of 2000-3500 N and a temperature of 200-300 degrees Celsius, resulting in a substrate with a diamond substrate (or AlN) and SiO2. The process involves fabricating a wafer with a bonding layer, GaN channel layer, AlN insertion layer, AlGaN barrier layer, GaN cap layer, bonding adhesive, and temporary substrate. A laser debonding process is then used to remove the temporary substrate, resulting in a nanowire wafer with a heterogeneous substrate. Specifically, a laser irradiation process with a wavelength less than 355 nm and an instantaneous power density of 180-300 mJ / cm² is performed to remove the bonding adhesive after removing the temporary substrate. This yields a complete nanowire array wafer with a heterogeneous substrate.

[0067] (7) Using an atomic layer deposition equipment, boron trifluoride (BF3) and ammonia (NH3) are introduced to deposit the first passivation layer BN film on the nanowire and the side at 200-300℃ and 10-100Pa, with a deposition thickness of 200-300nm. Then, photolithography and ICP dry etching are used to passivate the source and drain electrodes and open them. Then, Ti / Al / Ni / Au (20 / 120 / 30 / 60nm) is deposited by electron beam evaporation (EBL). The electrode is placed in a high-temperature rapid annealing furnace, and a nitrogen atmosphere of 5-10slm is introduced. The temperature is rapidly increased to 850℃ and annealed for 30-60s to achieve a contact resistance of less than 0.5Ω*mm. The first passivation layer in the gate region is thinned to (10-20nm) by photolithography and dry etching. Ni / Au (30nm / 100nm) is deposited by electron beam evaporation to prepare the gate electrode of the MIS structure.

[0068] (8) A dense, high-heat-dissipation passivation layer (such as AlN) is deposited using ALD to cover the first passivation layer and the upper surface of the electrode. Second passivation layer openings are made for the gate PAD, source PAD, and drain PAD to expose the electrode PAD, thus completing the fabrication of the final device.

[0069] The detailed flowchart of the high-heat-dissipation GaN nanowire RF device in this invention is shown below. Figures 2-12The presence of nanowires in the product prepared in this invention transforms the planar two-dimensional electron gas channel into an array of one-dimensional nanowire channels, resulting in less Coulomb scattering, improved transconductance, and increased linearity. Simultaneously, a passivation layer with a high heat dissipation coefficient is dispersed between the nanochannels, effectively alleviating the problem of heat source concentration in the planar two-dimensional electron gas channel, greatly mitigating self-heating effects, and improving linearity. Furthermore, this invention further reduces the transmission distance between the carrier channel and the high-heat-dissipation substrate, shortening the heat transfer path and improving heat dissipation, thereby effectively enhancing the device's RF amplification capability under high-speed switching.

[0070] Example 2

[0071] Embodiment 2 of the present invention provides a method for fabricating a transconductance-compensated GaN nanowire radio frequency device. The initial steps of this fabrication method are the same as those before step (8) in Embodiment 1. The subsequent fabrication steps are as follows:

[0072] During gate electrode fabrication, photolithography and ICP dry etching are used to achieve equal thicknesses of the passivation layer under the gate. For a group of nanowire devices, the passivation layers under the gate have sequentially equal thicknesses (e.g., 4 / 6 / 8 / 10 / 12 / 14 / 16 / 18 nm). The threshold voltage of the device exhibits different gate control capabilities due to the different thicknesses of the passivation layer. Therefore, the threshold voltage of each nanochannel also exhibits different turn-on voltages due to the different thicknesses of the dielectric layer under the gate, resulting in nanowires with different transfer characteristic curves. Furthermore, by achieving common source and common drain in a single deposition of the nanowire array, overall transconductance compensation is achieved, resulting in a larger gate voltage swing and stable transconductance, improving the linearity of the GaN RF device. This leads to a transconductance-compensated GaN nanowire RF device. A schematic diagram of the transconductance-compensated high linearity device fabricated in this embodiment is shown below. Figure 13-14 .

[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high heat dissipation GaN nanowire radio frequency device, characterized in that: include: A heterogeneous substrate and a SiO2 bonding layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, a GaN cap layer, a first passivation layer, an electrode layer and a second passivation layer sequentially arranged on the heterogeneous substrate, wherein the electrode layer sequentially arranges a source electrode, a gate electrode and a drain electrode at intervals, and the GaN channel layer, the AlN insertion layer, the AlGaN barrier layer and the GaN cap layer constitute a nanowire array, which is prepared by an etching method.

2. The high heat dissipation GaN nanowire RF device according to claim 1, characterized in that: The nanowire array is a group of 8 to 15 nanowires, and etching is performed to the GaN buffer layer within a certain range outside the nanowire array to form a mesa isolation; A first passivation layer with a high heat dissipation coefficient and a low dielectric constant is deposited, wherein the first passivation layer completely covers the upper surface and the side of the nanowire.

3. The high heat dissipation GaN nanowire RF device according to claim 1, characterized in that: The source electrode and the drain electrode are respectively deposited on the AlGaN barrier layer through the first passivation layer and the GaN cap layer by a passivation opening method, and the bottom of the gate electrode is connected to the upper surface of the first passivation layer; The source electrode is close to the gate electrode, and the drain electrode is far away from the gate electrode.

4. The high heat dissipation GaN nanowire RF device according to claim 1, characterized in that: The second passivation layer is connected to the first passivation layer to complete the opening of the source electrode PAD, the gate electrode PAD and the drain electrode PAD.

5. The high heat dissipation GaN nanowire RF device according to claim 1, characterized in that: The foreign substrate includes any one of diamond, aluminum nitride or sapphire, and the first passivation layer and the second passivation layer are materials with high heat dissipation coefficient and low dielectric constant.

6. A method for preparing a high heat dissipation GaN nanowire radio frequency device according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) An AlN nucleation layer, a GaN high-resistance buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer and a GaN cap layer are sequentially grown on a foreign substrate; (2) Patterning of the nanowire array is achieved based on mask lithography, and the nanowire array is prepared by inductively coupled plasma etching to expose the GaN high-resistance buffer layer; (3) Using temporary bonding glue and Si temporary substrate to complete temporary bonding of the nanowire array epitaxial wafer, and polishing the sapphire substrate; (4) Laser stripping is used to strip the sapphire substrate, and immersion in hydrochloric acid is used to remove the Ga atoms at the bottom; (5) Chemical mechanical polishing is used to polish the surface of the nanowire array wafer with a temporary support substrate, and an atomic layer deposition device is used to deposit SiO2 on the surface and the foreign substrate; (6) using plasma surface activation bonding to complete the activation and bonding of the nanowire array wafer and the heterogeneous substrate, using a laser debonding method to remove the temporary bonding substrate, and soaking in a debonding solution to remove the bonding glue to obtain a heterogeneous substrate nanowire array wafer; (7) depositing the first passivation layer BN thin film on the top and side of the nanowire, photolithography holes for source and drain, etching to expose the AlGaN barrier layer, electron beam evaporation to deposit source and drain electrodes, and high temperature annealing to achieve ohmic contact; (8) Opening a gate window, depositing a gate electrode on the first passivation layer by electron beam evaporation; depositing a second passivation layer to protect the electrode; (9) Opening holes in the source, drain, gate electrode PAD and etching to expose the PAD metal surface, thereby obtaining the high heat dissipation GaN nanowire RF device.

7. The method for preparing a high heat dissipation GaN nanowire radio frequency device according to claim 6, characterized in that: After step (4), the method further includes exposing the GaN channel layer by inductively coupled plasma etching to further reduce the thickness of the buffer layer.

8. A method for transconductance compensation of GaN nanowire radio frequency devices, characterized in that: The method comprises the following steps: (1) After the preparation method of claim 6 reaches step (7), photolithography is used to pattern photoresist in the gate region of each nanowire, and inductively coupled plasma etching is used to obtain GaN nanowire arrays with different passivation layer thicknesses; (2) performing photolithography again on the wafer with the first passivation layer to deposit a gate electrode, wherein the gate electrode is deposited on an opening area with a different first passivation layer thickness; (3) Depositing a second passivation layer, opening source, drain, gate and PAD holes, and etching to expose the PAD metal surface, thereby achieving transconductance compensation of the GaN nanowire RF device.

9. A high linearity GaN nanowire radio frequency device manufactured by the method of claim 8, characterized in that: The high linearity GaN nanowire RF device changes the threshold voltage of each nanowire device by controlling the thickness of the passivation layer above each nanochannel, thereby increasing the wire grain size of the GaN nanowire RF device.

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