Fin-type enhancement-mode high-al-component gallium nitride power device with p-gan gate-source bridge and preparation method thereof

Abstract

This invention discloses a fin-enhanced high-Al-content gallium nitride power device with a P-GaN gate-source bridge, mainly addressing the problems of low threshold voltage, low breakdown voltage, and poor gate control capability in existing similar devices. From bottom to top, it includes: a substrate (1), a nucleation layer (2), a buffer layer (3), a high-Al-content AlGaN channel layer (4), a barrier layer (5), a P-GaN cap layer (6), a gate-source bridge (7), and a gate electrode (8), with source and drain electrodes (9, 10) distributed at both ends of the barrier layer. The channel layer and the barrier layer together form a fin-type nanochannel; the nucleation layer added between the substrate layer and the buffer layer reduces lattice mismatch and interlayer stress; the P-GaN cap layer covers both sides and the top of the fin-type nanochannel, with fin-type gate electrodes (8) distributed outside it. This invention features a high threshold voltage, high breakdown voltage, and strong gate control capability, significantly improving performance and making it applicable to high-power, high-speed switching devices.

Description

Technical Field

[0001] This invention belongs to the field of microelectronic device technology, and specifically relates to a gallium nitride power device that can be used for high-speed, high-power switching. Background Technology

[0002] Compared to first-generation semiconductor material Si and second-generation semiconductor material GaAs, gallium nitride (GaN), as a representative of third-generation wide-bandgap semiconductor materials, has become a research hotspot due to its wide bandgap, high electron saturation rate, high temperature resistance, and radiation resistance, especially showing great application prospects in high-temperature, high-power, and microwave fields. Meanwhile, GaN semiconductor devices are highly compatible with the relatively mature Si semiconductor processes, can be integrated with other semiconductor devices, and possess good thermal stability, high-voltage stability, and corrosion resistance. GaN power devices fabricated from GaN can meet the application requirements of future power electronics.

[0003] The AlGaN / GaN heterojunction interface exhibits strong spontaneous and piezoelectric polarization, forming a two-dimensional electron gas that makes gallium nitride (GaN) devices naturally depletion-type devices. Simultaneously, the two-dimensional electron gas possesses high mobility and a large saturation electron velocity, resulting in excellent performance for GaN devices. Currently, GaN power devices primarily utilize planar gate structures, leading to relatively poor gate control capabilities. Therefore, developing fin-gate power devices with stronger gate control capabilities is a viable strategy.

[0004] Patent document CN111863948A discloses a GaN-based P-GaN enhancement-mode HEMT device with a gate-source bridge and its fabrication method, with the structure as follows: Figure 1 As shown, it includes: a substrate, source and drain electrodes, a gate electrode, a GaN cap layer, a passivation dielectric layer, a gate-source bridge, and a P-GaN cap layer. The source and drain electrodes are disposed on the barrier layer, the gate electrode is disposed on the P-GaN cap layer, and the gate-source bridge is disposed between the passivation dielectric layer and the GaN cap layer, with one end connected to the P-GaN cap layer and the other end connected to the source electrode. Due to the use of a GaN channel layer and an AlGaN / InGaN layer with a low Al / In composition, this device has a low threshold voltage and breakdown voltage, failing to achieve a high Barley factor and thus not meeting the application requirements of high-voltage, high-power scenarios. Furthermore, the planar gate structure results in poor gate control capability, failing to fully utilize the excellent performance of gallium nitride material and thus not meeting the application requirements of high-speed switching and power electronic systems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by proposing a fin-type enhancement-mode high-Al-content gallium nitride power device with a P-GaN gate-source bridge, which enhances the device's gate control capability, increases the device's threshold voltage and breakdown voltage, and meets the application requirements in high-voltage, high-speed, and high-power scenarios.

[0006] To achieve the above objectives, the technical solution of the present invention includes the following:

[0007] 1. A fin-type enhancement-mode high-Al-content gallium nitride power device with a P-GaN gate-source bridge, comprising: a substrate, a buffer layer, a channel layer, a barrier layer, a P-GaN cap layer, a gate-source bridge, and a gate electrode, wherein source and drain electrodes are distributed at both ends of the barrier layer, characterized in that:

[0008] A nucleation layer is provided between the substrate and the buffer layer;

[0009] The channel layer is made of high-Al content AlGaN material, with an Al molar fraction of 60% to 75% and a thickness of 100 nm to 300 nm.

[0010] The barrier layer is located above the channel layer, and the two are combined to form a fin-type nanochannel.

[0011] The P-GaN cap layer is located outside the fin nanochannel, covering the two sides and the top of the fin nanochannel;

[0012] The gate electrode adopts a fin gate structure and is distributed on the outside of the P-GaN cap layer, covering the two sides and the top of the P-GaN cap layer.

[0013] Furthermore, the nucleation layer is made of AlN or AlGaN material and has a thickness of 20nm to 50nm.

[0014] Furthermore, the substrate is made of Si, sapphire, or SiC material.

[0015] Furthermore, the barrier layer is made of AlGaN or InGaN material, with a thickness of 10nm to 30nm, and the molar fraction of Al or In is 75% to 80%.

[0016] Furthermore, both the gate-source bridge and the P-GaN cap layer are made of Mg-doped P-type GaN material, with a Mg doping concentration of 1×10⁻⁶. 19 cm -3 ~1×10 20 cm -3 The thickness is 80nm to 100nm, and the two are closely attached to each other and located on the barrier layer.

[0017] 2. A method for fabricating a fin-enhanced high-Al-content gallium nitride power device with a P-GaN gate-source bridge, characterized by comprising the following steps:

[0018] S1: Select the substrate layer;

[0019] S2: A nucleation layer, a buffer layer, a high-Al content AlGaN channel layer, and a barrier layer are sequentially grown on a substrate using a chemical vapor deposition method. The nucleation layer has a thickness of 20 nm to 50 nm; the buffer layer has a thickness of 500 nm to 800 nm; the high-Al content AlGaN channel layer has a thickness of 100 nm to 300 nm and an Al molar fraction of 60% to 75%; and the barrier layer has a thickness of 10 nm to 30 nm and an Al molar fraction of 75% to 80%.

[0020] S3: Deposit metal Ti / Al / Ni / Au at both ends of the barrier layer to form the source electrode and the drain electrode, and etch the barrier layer and the high Al composition AlGaN channel layer between the source and drain electrodes to form several nanochannels.

[0021] S4: Mg doping concentration of 1×10⁻⁶ is grown on both sides and top of the plurality of nanochannels. 19 cm -3 ~1×10 20 cm -3 Several P-GaN layers with a thickness of 80nm to 100nm;

[0022] S5: Etch several P-GaN layers to form several P-GaN cap layers covering the nanochannels and several gate-source bridges in close contact with the P-GaN cap layers;

[0023] S6: Deposit Ni / Au metal on both sides and top of each P-GaN cap layer to form several fin gates covering the three sides of each P-GaN cap layer, thus completing the device fabrication.

[0024] Further, in step S3, etching the barrier layer between the source and drain and the high-Al composition AlGaN channel layer is achieved as follows:

[0025] S31: Electron beam lithography is used to create photolithographic masks for the source and drain regions, exposing the pattern of the etchable areas of the device.

[0026] S32: An inductively coupled plasma etching machine is used to etch the photolithographic pattern in a Cl2 plasma gas with a width of 100-300 nm to form several fin-type nanochannels.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] First, the present invention adds a nucleation layer between the substrate and the buffer layer, which helps to reduce the lattice mismatch between the substrate and the buffer layer, thereby reducing interlayer stress and avoiding the adverse effects of interlayer stress on the device's conduction current and breakdown voltage.

[0029] First, the present invention improves the depletion effect of the two-dimensional electron gas at the heterojunction interface by using a P-GaN cap layer to cover the three sides of the fin-type nanochannel, which is beneficial to reduce subthreshold leakage current and increase the threshold voltage of the device.

[0030] Second, the present invention uses a high-Al content AlGaN channel layer to replace the existing GaN channel layer, which is beneficial to reduce the degradation of two-dimensional electron gas mobility, increase carrier concentration and improve breakdown voltage characteristics, thereby improving the device breakdown voltage.

[0031] Third, because the present invention adopts a fin gate structure that covers the outside of the nanochannel, it greatly enhances the control capability of the channel, improves the gate control capability of the device, increases the switching response speed of the device, and reduces the power consumption of the device in the off state, making the device more suitable for high-speed, high-voltage, and high-power switching applications. Attached Figure Description

[0032] Figure 1 This is a 3D structural diagram of an existing GaN-based P-GaN enhancement-mode HEMT device with a gate-source bridge;

[0033] Figure 2 This is a three-dimensional structural diagram of the fin-type enhancement-mode high-Al-content gallium nitride power device with a P-GaN gate-source bridge according to the present invention.

[0034] Figure 3 This invention is prepared Figure 2 A schematic diagram of the device's flow chart. Detailed Implementation

[0035] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of the device and its preparation method based on the present invention is provided in conjunction with the accompanying drawings and specific embodiments.

[0036] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0037] Reference Figure 2This example of a fin-type enhancement-mode high-Al-content gallium nitride power device with a P-GaN gate-source bridge includes: a substrate 1, a nucleation layer 2, a buffer layer 3, a channel layer 4, a barrier layer 5, a P-GaN cap layer 6, a gate-source bridge 7, a gate 8, a source electrode 9, and a drain electrode 10. Wherein:

[0038] The substrate 1 is made of Si, sapphire, or SiC material;

[0039] The nucleation layer 2 is located on the substrate 1 and is made of AlN or AlGaN material with a thickness of 20nm to 50nm.

[0040] The channel layer 4 is located above the buffer layer 3 and has a thickness of 100nm to 300nm. It is made of high Al content AlGaN material and the molar fraction of Al is 60% to 75%.

[0041] The barrier layer 5 is located above the channel layer 4 and has a thickness of 10nm to 30nm. It is made of AlGaN or InGaN material and the molar fraction of Al or In is 75% to 80%. The barrier layer 5 and the channel layer 4 together form a fin nanochannel.

[0042] Both the gate-source bridge 7 and the P-GaN cap layer 6 are made of Mg-doped P-type GaN material, with a Mg doping concentration of 1×10⁻⁶. 19 cm -3 ~1×10 20 cm -3 The thickness is 80nm to 100nm, and the two are closely attached and located on top of the barrier layer 5;

[0043] The gate 8 adopts a fin gate structure and covers the two sides and top of the P-GaN cap layer 6.

[0044] Reference Figure 3 The present invention provides the following three embodiments for fabricating the above-mentioned fin-type enhancement-mode high-Al-content gallium nitride power device with a P-GaN gate-source bridge:

[0045] Example 1: Fabrication of a fin-enhanced high-Al-content gallium nitride power device with a P-GaN gate-source bridge, wherein the substrate is Si, the nucleation layer is AlN, the high-Al-content AlGaN channel layer has an Al content of 60%, and the barrier layer is AlGaN.

[0046] Step 1: Select a Si substrate and clean it.

[0047] Select sapphire substrate material 1, ultrasonically clean it with acetone and isopropanol solutions for 5 minutes each, and then dry it with a nitrogen gun. Figure 3 As shown in (a).

[0048] Step 2: Using chemical vapor deposition, a core layer, a buffer layer, a high-Al composition AlGaN channel layer, and an AlGaN barrier layer are sequentially grown on the cleaned Si substrate 1, as follows: Figure 3 As shown in (b).

[0049] 2.1) Set the process conditions as follows: growth temperature 700℃, hydrogen flow rate 2500 sccm, nitrogen flow rate 3000 sccm, aluminum source flow rate 20 sccm, ammonia flow rate 3000 sccm, and pressure 40 Torr to grow an AlN nucleation layer 2 with a thickness of 20 nm on Si substrate 1.

[0050] 2.2) Set the process conditions as follows: growth temperature 1000℃, ammonia flow rate 4000sccm, hydrogen flow rate 2000sccm, gallium source flow rate 200sccm, aluminum source flow rate 500sccm, and pressure 50Torr to grow a GaN buffer layer 3 with a thickness of 500nm on nucleation layer 2.

[0051] 2.3) Set the growth temperature to 700℃, the pressure to 40 Torr, the ammonia flow rate to 3000 sccm, the hydrogen flow rate to 2500 sccm, the aluminum source flow rate to 120 sccm, the gallium source flow rate to 60 sccm, and control the aluminum flow rate ratio to 60% and the gallium flow rate ratio to 40% to grow a high-Al composition AlGaN channel layer 4 with a thickness of 100 nm and an Al fraction of 60% on the buffer layer 3.

[0052] 2.4) Set the growth temperature to 800℃, the pressure to 40 Torr, the ammonia flow rate to 3000 sccm, the hydrogen flow rate to 2500 sccm, the aluminum source flow rate to 200 sccm, the gallium source flow rate to 60 sccm, and control the aluminum flow rate ratio to 75% and the gallium flow rate ratio to 25% to grow an AlGaN barrier layer with a thickness of 10 nm and an Al molar fraction of 80%.

[0053] Step 3: Fabricate source and drain electrodes and etch nanochannels, such as... Figure 3 As shown in (c).

[0054] 3.1) A homogenizer was used to homogenize the barrier layer 5 on the substrate, and an electron beam lithography machine was used to expose it to form source and drain mask patterns.

[0055] 3.2) Using an electron beam evaporation stage, metal Ti / Al / Ni / Au with a thickness of 20 / 120 / 45 / 55 nm was deposited in the source and drain mask pattern regions at an evaporation rate of 0.1 nm / s. After the source and drain ohmic metals were evaporated, metal stripping was performed.

[0056] 3.3) Rapid thermal annealing was performed at 870℃ in a N2 atmosphere for 30s to complete the preparation of the source electrode 9 and the drain electrode 10;

[0057] 3.4) A spin coater was used for spin coating. After spin coating, an electron beam lithography machine was used to expose the area between the source electrode 9 and the drain electrode 10. An inductively coupled plasma etching machine filled with Cl2 plasma atmosphere was used to etch the high Al composition AlGaN channel layer 4 and barrier layer 5 in the area with a spacing of 100 nm. Each channel has a depth of 110 nm and a width of 100 nm, resulting in several nanochannels.

[0058] Step 4: Fabricate the P-GaN cap layer and gate-source bridge, such as... Figure 3 As shown in (d).

[0059] 4.1) Mg doping concentration of 1×10⁻⁶ is deposited on both sides and top of the plurality of nanochannels. 19 cm -3 Several P-GaN layers with a thickness of 80nm;

[0060] 4.2) The P-GaN layer was thermally annealed for 20 min in a N2 atmosphere at 900℃ to activate the doped Mg, resulting in several P-GaN layers located on the outside of several nanochannels.

[0061] 4.3) A spin coater is used to spin coat the surface of several nanochannels. After spin coating, a SUSS MA6 lithography machine is used to expose the connection area between the source electrode and the P-GaN cap layer above the nanochannels of the substrate. Then, the exposed substrate is placed in an inductively coupled plasma etching machine and SF6 and BCl3 plasmas are introduced to etch the P-GaN material above the nanochannels to form several P-GaN gate-source bridges 7, each with a width of 50 nm.

[0062] Step 5: Fabricate the gate electrode, such as Figure 3 As shown in (e).

[0063] Using an electron beam evaporation stage at an evaporation rate of 0.1 nm / s, metallic Ni / Au with a thickness of 20 / 200 nm was deposited on both sides and top of each P-GaN cap layer to obtain several fin gates 8 covering the three sides of the P-GaN cap layer, thus completing the device fabrication.

[0064] Example 2: Fabrication of a fin-enhanced high-Al-content gallium nitride power device with a P-GaN gate-source bridge, wherein the substrate is sapphire, the nucleation layer is AlGaN, the high-Al-content AlGaN channel layer has an Al content of 70%, and the barrier layer is InGaN.

[0065] Step 1: Select a sapphire substrate and clean it.

[0066] The specific implementation of this step is the same as step 1 in Example 1.

[0067] Step 2: Using chemical vapor deposition, a core layer, a buffer layer, a high-Al content AlGaN channel layer, and an InGaN barrier layer are sequentially grown on the cleaned sapphire substrate 1.

[0068] 2a) An AlGaN nucleation layer 2 with a thickness of 35 nm was grown on a sapphire substrate 1 by chemical vapor deposition under the following process conditions: growth temperature of 850 °C, hydrogen flow rate of 3000 sccm, nitrogen flow rate of 3500 sccm, aluminum source flow rate of 30 sccm, ammonia flow rate of 3500 sccm, and pressure of 150 Torr.

[0069] 2b) A GaN buffer layer 3 with a thickness of 650 nm was grown on the nucleation layer 2 by chemical vapor deposition under the following process conditions: growth temperature of 1100℃, aluminum source flow rate of 650 sccm, hydrogen flow rate of 2500 sccm, gallium source flow rate of 350 sccm, and pressure of 70 Torr.

[0070] 2c) Using chemical vapor deposition at a growth temperature of 950℃, a pressure of 120 Torr, an ammonia flow rate of 4000 sccm, a hydrogen flow rate of 3500 sccm, an aluminum source flow rate of 200 sccm, a gallium source flow rate of 120 sccm, and controlling the aluminum flow rate ratio to be 70% and the gallium flow rate ratio to be 30%, a high Al composition AlGaN channel layer 4 with a thickness of 200 nm and an Al molar fraction of 70% is grown on the buffer layer 3.

[0071] 2d) An InGaN barrier layer with a thickness of 20 nm and an In molar fraction of 78% was grown by chemical vapor deposition under the following process conditions: growth temperature of 1000℃, pressure of 120 Torr, ammonia flow rate of 4000 sccm, hydrogen flow rate of 3500 sccm, gallium source flow rate of 120 sccm, indium source flow rate of 300 sccm, and control of indium flow rate ratio of 78% and gallium flow rate ratio of 22%.

[0072] Step 3: Fabricate source and drain electrodes and etch nanochannels.

[0073] 3a) A homogenizer is used to homogenize the substrate barrier layer 5, and an electron beam lithography machine is used to expose it to form source and drain mask patterns.

[0074] 3b) Using an electron beam evaporation stage at an evaporation rate of 0.1 nm / s, metal Ti / Al / Ni / Au with a thickness of 20 / 120 / 45 / 55 nm was deposited in the source and drain mask pattern regions. After the metal evaporated at the source and drain ohmic contact, the metal was stripped off.

[0075] 3c) Rapid thermal annealing was performed at 870℃ in a N2 atmosphere for 30s to complete the preparation of source electrode 9 and drain electrode 10;

[0076] 3d) A spin coater was used for spin coating. After spin coating, an electron beam lithography machine was used to expose the area between the source electrode 9 and the drain electrode 10. An inductively coupled plasma etching machine filled with Cl2 plasma atmosphere was used to etch the high Al composition AlGaN channel layer 4 and barrier layer 5 in the area with a spacing of 200 nm. Each channel has a depth of 220 nm and a width of 200 nm, resulting in several nanochannels.

[0077] Step 4: Fabricate the P-GaN cap layer and gate-source bridge.

[0078] 4a) Mg doping concentration of 5 × 10⁻⁶ is deposited on both sides and top of the plurality of nanochannels. 19 cm -3 Several P-GaN layers with a thickness of 90nm;

[0079] 4b) The P-GaN layer was thermally annealed for 20 min in a N2 atmosphere at 900 °C to activate the doped Mg, resulting in several P-GaN layers located on the outside of several nanochannels.

[0080] 4c) A spin coater is used to spin coat the surface of several nanochannels. After spin coating, a SUSS MA6 lithography machine is used to expose the connection area between the source electrode and the P-GaN cap layer above the nanochannels of the substrate. Then, the exposed substrate is placed in an inductively coupled plasma etching machine and SF6 and BCl3 plasmas are introduced to etch the P-GaN material above the nanochannels to form several P-GaN gate-source bridges 7. The width of each P-GaN gate-source bridge is 150nm.

[0081] Step 5: Fabricate the gate electrode to complete device fabrication.

[0082] The specific implementation of this step is the same as step 5 in Example 1.

[0083] Example 3: Fabrication of a fin-enhanced high-Al-content gallium nitride power device with a P-GaN gate-source bridge, wherein the substrate is SiC, the nucleation layer is AlN, the high-Al-content AlGaN channel layer has an Al content of 75%, and the barrier layer is AlGaN.

[0084] Step A: Select a SiC substrate and clean it.

[0085] The specific implementation of this step is the same as step 1 in Example 1.

[0086] Step B: Using chemical vapor deposition, a core layer, a buffer layer, a high-Al content AlGaN channel layer, and a barrier layer are sequentially grown on the cleaned SiC substrate 1.

[0087] B1) An AlN nucleation layer 2 with a thickness of 50 nm is grown on SiC substrate 1, and the process conditions are as follows:

[0088] The growth temperature was 1100℃, the hydrogen flow rate was 4000 sccm, and the aluminum source flow rate was 40 sccm.

[0089] Ammonia flow rate is 4000 sccm, pressure is 200 Torr;

[0090] B2) A GaN buffer layer 3 with a thickness of 800 nm is grown on the nucleation layer 2, and the process conditions are as follows:

[0091] The growth temperature was 1200℃, the aluminum source flow rate was 800 sccm, and the gallium source flow rate was 500 sccm.

[0092] The hydrogen flow rate is 3000 sccm, the ammonia flow rate is 5000 sccm, and the pressure is 100 Torr.

[0093] B3) A high-Al composition AlGaN channel 4 with a thickness of 300 nm and an Al molar fraction of 75% is grown on the buffer layer 3.

[0094] The process conditions are as follows:

[0095] The growth temperature was 1200℃, the pressure was 200 Torr, the ammonia flow rate was 4500 sccm, and the hydrogen flow rate was 4000 sccm.

[0096] The aluminum source flow rate is 300 sccm, the gallium source flow rate is 200 sccm, the aluminum flow rate accounts for 75%, and the gallium flow rate accounts for 25%.

[0097] B4) An AlGaN barrier layer 5 with a thickness of 30 nm and an Al molar fraction of 80% is grown on the channel layer 4, and the process conditions are as follows:

[0098] The growth temperature was 1200℃, the pressure was 200 Torr, the ammonia flow rate was 4500 sccm, and the hydrogen flow rate was 4000 sccm.

[0099] The aluminum source flow rate is 600 sccm, the gallium source flow rate is 200 sccm, the aluminum flow rate accounts for 80%, and the gallium flow rate accounts for 20%.

[0100] Step C: Fabricate source and drain electrodes and etch nanochannels.

[0101] C1) A homogenizer is used to homogenize the barrier layer 5 of the substrate, and an electron beam lithography machine is used to expose it to form source and drain mask patterns.

[0102] C2) Using an electron beam evaporation stage at an evaporation rate of 0.1 nm / s, metal Ti / Al / Ni / Au with a thickness of 20 / 120 / 45 / 55 nm is deposited in the source and drain mask pattern regions. After the metal evaporates at the source and drain ohmic contact, the metal is stripped off.

[0103] C3) The source electrode 9 and the drain electrode 10 were prepared by rapid thermal annealing in a N2 atmosphere at 870℃ for 30s.

[0104] C4) A spin coater was used for spin coating. After spin coating, an electron beam lithography machine was used to expose the area between the source electrode 9 and the drain electrode 10. An inductively coupled plasma etching machine filled with Cl2 plasma atmosphere was used to etch the high Al composition AlGaN channel layer 4 and barrier layer 5 in the area at intervals of 300 nm. Each channel has a depth of 330 nm and a width of 300 nm, resulting in several nanochannels.

[0105] Step D: Prepare the P-GaN cap layer and gate-source bridge.

[0106] D1) Mg doping concentration of 1×10⁻⁶ is deposited on both sides and top of the plurality of nanochannels. 20 cm -3 Several P-GaN layers with a thickness of 100nm;

[0107] D2) The P-GaN layer was thermally annealed for 20 min in a N2 atmosphere at 900℃ to activate the doped Mg, resulting in several P-GaN layers located on the outside of several nanochannels.

[0108] D3) A spin coater is used to spin coat the surface of several nanochannels. After spin coating, a SUSS MA6 lithography machine is used to expose the connection area between the source electrode and the P-GaN cap layer above the nanochannels of the substrate. Then, the exposed substrate is placed in an inductively coupled plasma etching machine and SF6 and BCl3 plasma is introduced to etch away the P-GaN material above the nanochannels, forming several P-GaN gate-source bridges with a width of 200nm 7.

[0109] Step E: Fabricate the gate electrode to complete device fabrication.

[0110] The specific implementation of this step is the same as step 5 in Example 1.

[0111] The above descriptions are merely three specific examples of the present invention and do not constitute any limitation on the present invention. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention. For example, a termination structure can be added to this device; in addition to Ti / Al / Ni / Au used in the examples, Ti / Al / Mo / Au, Ti / Al / Ti / Au, or Ti / Al can also be used for the source and drain metals; in addition to Ni / Au used in the examples, Mo / Au, W / Au, Pt / Au, Pd / Au, or Ni / Au / Ni can also be used for the gate metal. These simple modifications all fall within the protection scope of the present invention.

Claims

1. Fin-type enhancement-mode high-Al-content gallium nitride power devices with P-GaN gate-source bridges, including: The substrate (1), buffer layer (3), channel layer (4), barrier layer (5), P-GaN cap layer (6), gate-source bridge (7) and gate electrode (8), with source and drain electrodes (9, 10) distributed at both ends of the barrier layer (5), characterized in that: A nucleation layer (2) is provided between the substrate (1) and the buffer layer (3); The channel layer (4) is made of high Al content AlGaN material, with an Al molar fraction of 60% to 75% and a thickness of 100 nm to 300 nm; The barrier layer (5) is located above the channel layer (4), and the two are combined to form a fin-type nanochannel; The P-GaN cap layer (6) is located on the outside of the fin nanochannel and covers the two sides and the top of the fin nanochannel; The gate electrode (8) adopts a fin gate structure and is distributed on the outside of the P-GaN cap layer (6), covering the two sides and the top of the P-GaN cap layer (6).

2. The device according to claim 1, characterized in that: The nucleation layer (2) is made of AlN or AlGaN material and has a thickness of 20nm to 50nm.

3. The device according to claim 1, characterized in that: The substrate (1) is made of Si, sapphire, or SiC material; The barrier layer (5) is made of AlGaN or InGaN material with a thickness of 10nm to 30nm and a molar fraction of Al or In of 75% to 80%.

4. The device according to claim 1, characterized in that: Both the gate-source bridge (7) and the P-GaN cap layer (6) are made of Mg-doped P-type GaN material with a Mg doping concentration of 1×10⁻⁶. 19 cm -3 ~1×10 20 cm -3 The thickness is 80nm to 100nm, and the two are closely attached to each other and located on the barrier layer (5).

5. A method for fabricating a fin-type enhancement-mode high-Al-content gallium nitride power device with a P-GaN gate-source bridge, characterized in that: Includes the following steps: S1: Select substrate layer (1); S2: A nucleation layer (2), a buffer layer (3), a high-Al content AlGaN channel layer (4), and a barrier layer (5) are sequentially grown on a substrate layer (1) using a chemical vapor deposition method. The nucleation layer (2) has a thickness of 20 nm to 50 nm; the buffer layer (3) has a thickness of 500 nm to 800 nm; the high-Al content AlGaN channel layer (4) has a thickness of 100 nm to 300 nm and an Al molar fraction of 60% to 75%; and the barrier layer (5) has a thickness of 10 nm to 30 nm and an Al molar fraction of 75% to 80%. S3: Deposit metal Ti / Al / Ni / Au at both ends of the barrier layer (5) to form source electrode (9) and drain electrode (10), and etch the barrier layer (5) and high Al composition AlGaN channel layer (4) between the source and drain electrodes to form several nanochannels. S4: Mg doping concentration of 1×10⁻⁶ is grown on both sides and top of the plurality of nanochannels. 19 cm -3 ~1×10 20 cm -3 Several P-GaN layers with a thickness of 80nm to 100nm; S5: Etch several P-GaN layers to form several P-GaN cap layers (6) covering the nanochannel and several gate-source bridges (7) closely attached to the P-GaN cap layers; S6: Deposit metal Ni / Au on both sides and top of each P-GaN cap layer (6) to form several fin gates (8) covering the three sides of each P-GaN cap layer, thus completing the device fabrication.

6. The method according to claim 5, characterized in that, In step S3, etching the barrier layer between the source and drain and the high-Al composition AlGaN channel layer is achieved through the following steps: S31: Electron beam lithography is used to perform photolithographic masking on the source and drain regions to expose the pattern of the etchable areas of the device. S32: An inductively coupled plasma etching machine is used to etch the photolithographic pattern in a Cl2 plasma gas with a width of 100nm to 300nm to form several nanochannels.

7. The method according to claim 5, characterized in that, In step S2, a nucleation layer is grown on the substrate using chemical vapor deposition, and the process conditions are as follows: The growth temperature is 700℃~1100℃; Hydrogen flow rate is 2500 sccm to 4000 sccm; The nitrogen flow rate is 3000 sccm to 4000 sccm; The aluminum source flow rate is 20 sccm to 40 sccm; The ammonia flow rate is 3000 sccm to 4000 sccm; The pressure is 40 Torr to 200 Torr.

8. The method according to claim 5, characterized in that, In step S2, a buffer layer is grown on the nucleation layer using chemical vapor deposition, and the process conditions are as follows: The growth temperature is 1000℃~1200℃; The aluminum source flow rate is 500 sccm to 800 sccm; The hydrogen flow rate is 2000 sccm to 3000 sccm; Gallium source flux is 200 sccm to 500 sccm The ammonia flow rate is 4000 sccm to 5000 sccm; The pressure is 50 Torr to 100 Torr.

9. The method according to claim 5, characterized in that, In step S2, a high-Al content AlGaN channel layer is grown on the buffer layer using chemical vapor deposition, and the process conditions are as follows: The growth temperature is 700℃~1200℃; The pressure is 40 Torr to 200 Torr; Ammonia flow rate is 3000 sccm~4500 ccm; Hydrogen flow rate is 2500 sccm to 4000 sccm; The aluminum source flow rate is 120 sccm to 300 sccm; Gallium source flow rate is 60 sccm to 200 sccm; The aluminum flow rate is controlled to account for 60%–75%, and the gallium flow rate is controlled to account for 25%–40%.

10. The method according to claim 5, characterized in that, In step S2, a barrier layer is grown on the channel layer using chemical vapor deposition, and the process conditions are as follows: The growth temperature is 800℃~1200℃; The pressure is 40 Torr to 200 Torr; Ammonia flow rate is 3000 sccm~4500 ccm; Hydrogen flow rate is 2500 sccm to 4000 sccm; The aluminum source flow rate is 200 sccm to 600 sccm; Gallium source flow rate is 60 sccm to 200 sccm; The indium source flow rate is 150 sccm to 400 sccm; The aluminum flow rate is controlled to account for 75%–80%, and the gallium flow rate is controlled to account for 20%–25%.

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