A GaN-based HEMT device with a novel drain field plate and its preparation method

Abstract

The present invention discloses a GaN-based HEMT device with a novel drain field plate and a method for fabricating the same. The device comprises a substrate, an AlN nucleation layer, a GaN transition layer, and a barrier layer stacked sequentially from bottom to top. A source and a drain are disposed at opposite ends of the upper surface of the barrier layer, with a gate disposed between the source and drain. Mesas are formed on the outer sides of the source and drain, respectively, extending downward to the upper surface or interior of the AlN nucleation layer. The upper surface of the barrier layer is covered with a passivation layer. The upper surface of the passivation layer includes a curved drain field plate, one end of which extends above the source electrode and the other end above the drain electrode, and the drain field plate is electrically connected to the drain electrode. A protective layer is coated on the upper surface of the drain field plate and the remaining upper surface of the passivation layer. The present invention utilizes a curved drain field plate connected to the drain electrode to optimize the electric field distribution at a short drain-source spacing, effectively improving the long-term reliability and breakdown efficiency of the device.

Description

Technical Field

[0001] The present invention belongs to the technical field of third-generation semiconductor power devices, and in particular relates to a GaN-based HEMT device with a novel drain field plate and a preparation method thereof. Background Art

[0002] In recent years, research on traditional Si-based devices has gradually reached its physical limits. To further reduce chip area, increase breakdown voltage, and lower on-resistance, GaN materials have attracted considerable attention due to their wide bandgap, high breakdown electric field, radiation resistance, and high-temperature resistance. However, the withstand voltage and reliability of GaN-based HEMT devices are often limited by various factors. Researchers at home and abroad have found that the electric field intensity near the drain of GaN-based HEMT devices reaches a peak, causing device degradation or even outright breakdown under prolonged high-field stress.

[0003] To address this issue, many researchers have employed various field plate structures to homogenize the drain-source electric field, reduce the peak electric field, and thus increase the device's breakdown voltage. Existing field plate structures, such as those connecting a metal field plate to the drain terminal or placing the field plate above the passivation layer, have their own limitations. Especially for high-breakdown-field-strength materials like GaN, their effectiveness in homogenizing the surface electric field is limited. Consequently, the long-term reliability of GaN-based HEMT devices remains a pressing issue. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the present invention provides a novel drain field plate and its preparation method. A curved resistive field plate structure is used to connect the drain electrode of a GaN-based HEMT device. This optimizes the electric field distribution at a shorter drain-source distance, making the electric field distribution between the drain and source more uniform, thereby significantly improving the long-term reliability and breakdown efficiency of the device. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0005] One aspect of the present invention provides a GaN-based HEMT device with a novel drain field plate, comprising a substrate, an AlN nucleation layer, a GaN transition layer, and a barrier layer stacked sequentially from bottom to top, wherein:

[0006] A source electrode and a drain electrode are respectively provided at both ends of the upper surface of the barrier layer, a gate electrode is provided between the source electrode and the drain electrode, and a mesa is formed on the outer sides of the source electrode and the drain electrode, extending downward to the upper surface or the interior of the AlN nucleation layer;

[0007] The upper surfaces of the gate, the source, the drain and the upper surface of the remaining area of ​​the barrier layer are all covered with a passivation layer;

[0008] The upper surface of the passivation layer includes a bent drain field plate, the lower surface of the drain field plate extends into the interior of the passivation layer, and the upper surface is flush with the upper surface of the passivation layer; one end of the drain field plate extends above the source electrode and vertically covers at least a portion of the source electrode, and the other end extends above the drain electrode and vertically covers at least a portion of the drain electrode, and the drain field plate is electrically connected to the drain electrode;

[0009] The upper surface of the drain field plate and the upper surface of the remaining area of ​​the passivation layer are covered with a protective layer.

[0010] In one embodiment of the present invention, the drain field plate is in a bow-shaped structure or an S-shaped structure.

[0011] In one embodiment of the present invention, one end of the drain field plate extends to the edge of the passivation layer on the drain side, and the other end extends to the edge of the passivation layer on the source side.

[0012] In one embodiment of the present invention, the drain field plate is formed of oxygen-doped semi-insulating polysilicon material with an oxygen content of 0.3% to 20%.

[0013] In one embodiment of the present invention, the source electrode and the drain electrode are both made of Ti / Al / Ni / Au metal stacks, and the gate electrode is made of Ni / Au metal stacks.

[0014] In one embodiment of the present invention, the drain field plate has a depth of 0.14 μm and a total length of 10.4 μm.

[0015] In one embodiment of the present invention, the material of the barrier layer is Al 0.2 Ga 0.8 N.

[0016] Another aspect of the present invention provides a method for preparing a GaN-based HEMT device having a novel drain field plate, comprising:

[0017] AlN nucleation layer, GaN transition layer and AlN layer are grown on the substrate in sequence. 0.2 Ga 0.8 N barrier layer;

[0018] In the Al 0.2 Ga 0.8 Metal is deposited at both ends of the N barrier layer to form the source and drain respectively;

[0019] In the Al 0.2 Ga 0.8 Etching the left and right sides of the N barrier layer to form a mesa extending downward to the upper surface or interior of the AlN nucleation layer;

[0020] The Al between the source and the drain0.2 Ga 0.8 A metal is deposited on the upper surface of the N barrier layer to form a gate;

[0021] On the upper surfaces of the gate, the source, the drain and the Al 0.2 Ga 0.8 A passivation layer is formed on the upper surface of the remaining area of ​​the N barrier layer;

[0022] A meandering groove is formed on the passivation layer, wherein the depth of the groove is less than the thickness of the passivation layer, and one end of the groove extends to above the source electrode, and the other end extends to above the drain electrode;

[0023] Depositing a drain field plate in the groove, wherein the upper surface of the drain field plate is flush with the upper surface of the passivation layer, and the drain field plate is electrically connected to the drain;

[0024] A protective layer is deposited on the upper surface of the drain field plate and the upper surface of the remaining area of ​​the passivation layer.

[0025] In one embodiment of the present invention, an AlN nucleation layer, a transition layer and an AlN layer are sequentially grown on a substrate. 0.2 Ga 0.8 N barrier layer, including:

[0026] A silicon substrate or a sapphire substrate is selected as a substrate and cleaned, and a low-temperature AlN nucleation layer is formed on the surface of the substrate. The low-temperature AlN nucleation layer is grown at a temperature of about 700°C to 800°C, a pressure of 45 Torr, and an aluminum source flow rate of 5 μmol / min. A high-temperature AlN nucleation layer is then epitaxially grown on the low-temperature AlN nucleation layer. The high-temperature AlN nucleation layer is grown at a temperature of 900°C to 1100°C, a pressure of 45 Torr, and an aluminum source flow rate of 5 μmol / min.

[0027] Epitaxially growing GaN material on the AlN nucleation layer 2 to form a GaN transition layer with a thickness of 1 μm;

[0028] On the GaN transition layer 3, an undoped Al layer with a thickness of 10 nm is deposited. 0.2 Ga 0.8 N barrier layer.

[0029] In one embodiment of the present invention, depositing a drain field plate in the groove comprises:

[0030] The electron beam evaporation technology is used to deposit oxygen-doped semi-insulating polysilicon in the groove to form the drain field plate, and the oxygen content is between 0.3% and 20%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The GaN-based HEMT device of the present invention utilizes a bent drain field plate structure to connect the drain electrode of the device, optimizing the electric field distribution at a shorter drain-source distance, making the electric field distribution between the drain and source more uniform, thereby greatly improving the long-term reliability and breakdown efficiency of the device.

[0033] 2. The drain field plate of the present invention is made of semi-insulating polysilicon material, which can prevent contamination by harmful impurity ions from the outside and alleviate the influence of the ion-induced electric field on the electric field distribution of the device. The drain field plate adopts a bent distribution structure, fully utilizing the area of ​​the drift region, further optimizing the electric field distribution of the entire channel, making the distribution of the electric field more uniform, and greatly improving the breakdown efficiency of the lateral device. The density and dispersion of the curvature of the drain field plate can be modulated according to the actual channel electric field distribution, that is, the field plate bends densely at the peak of the electric field and sparsely at the flat electric field. This can maximize the effect of the field plate in uniformly distributing the channel electric field and improve the breakdown characteristics of the device.

[0034] 3. The GaN-based HEMT device of the present invention has the characteristics of uniform electric field distribution, high long-term reliability and high breakdown efficiency, and is of great significance to the industrialization of GaN-based HEMT.

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 1 is a schematic structural diagram of a GaN-based HEMT device with a novel drain field plate provided by an embodiment of the present invention;

[0037] Figure 2 1 is a schematic structural diagram of a drain field plate provided by an embodiment of the present invention;

[0038] Figure 3 1 is a schematic top view of a passivation layer capable of showing a groove (drain field plate) shape provided by an embodiment of the present invention;

[0039] Figure 4 1 is a schematic top view of another passivation layer capable of showing a groove (drain field plate) shape provided by an embodiment of the present invention;

[0040] Figure 5 This is a flow chart of a method for preparing a GaN-based HEMT device with a novel drain field plate provided by an embodiment of the present invention;

[0041] Figures 6a to 6j This is a schematic diagram of the preparation process of a GaN-based HEMT device with a novel drain field plate provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and advantages adopted by the present invention to achieve the predetermined object of the invention, a GaN-based HEMT device with a novel drain field plate and a preparation method thereof proposed in accordance with the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] The foregoing and other technical contents, features, and advantages of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and advantages adopted by the present invention to achieve the intended objectives can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.

[0044] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0045] Example 1

[0046] See Figure 1 and Figure 2 , Figure 1 1 is a schematic structural diagram of a GaN-based HEMT device with a novel drain field plate provided by an embodiment of the present invention; Figure 2 Schematic diagram of the structure of a drain field plate provided by an embodiment of the present invention. The GaN-based HEMT device of this embodiment includes a substrate 1, an AlN nucleation layer 2, a GaN transition layer 3, and a barrier layer 4 stacked in sequence from bottom to top, wherein a source 5 and a drain 6 are respectively provided on the upper surfaces of both ends of the barrier layer 4, a gate 8 is provided on the barrier layer 4 between the source 5 and the drain 6, and a mesa 7 is formed on the outer sides of the source 5 and the drain 6, extending downward to the upper surface or the interior of the AlN nucleation layer 2; on the upper surfaces of the gate 8, the source 5, the drain 6, and the remaining portion of the barrier layer 4 The upper surface of the region is covered with a passivation layer 9; a bent drain field plate 11 is provided on the upper surface of the passivation layer 9, the lower surface of the drain field plate 11 extends to the inside of the passivation layer 9, and the upper surface is flush with the upper surface of the passivation layer 9, one end of the drain field plate 11 extends to above the source 5 and vertically covers at least a portion of the source 5, and the other end extends to above the drain 6 and vertically covers at least a portion of the drain 6; a protective layer 12 is covered on the upper surface of the drain field plate 11 and the upper surface of the remaining area of ​​the passivation layer 9.

[0047] The AlN nucleation layer 2 of this embodiment includes a low-temperature AlN nucleation layer arranged on the surface of the substrate 1, and a high-temperature AlN nucleation layer arranged on the upper surface of the low-temperature AlN nucleation layer. Both the low-temperature AlN nucleation layer and the high-temperature AlN nucleation layer are prepared by MOCVD process, wherein the thickness of the low-temperature AlN nucleation layer is 30nm, the growth temperature is about 700℃~800℃, the pressure is 45Torr, and the aluminum source flow rate is 5μmol / min; the thickness of the high-temperature AlN nucleation layer 2 is 170nm, the growth temperature of the high-temperature AlN nucleation layer is 900℃~1100℃, the pressure is 45Torr, and the aluminum source flow rate is 5μmol / min. The thickness of the transition layer 3 is 1μm, and the material of the barrier layer 4 is undoped Al 0.2 Ga 0.8 N, with a thickness of 10nm. Both the source 5 and drain 6 utilize a Ti / Al / Ni / Au metal stack, with thicknesses of 0.018μm / 0.135μm / 0.046μm / 0.052μm, respectively. The gate 8 utilizes a Ni / Au metal stack, with a lower layer of 0.026μm Ni and an upper layer of 0.11μm Au. The passivation layer 9 is made of SiN and has a thickness of 2.0μm.

[0048] In this embodiment, the drain field plate 11 is formed of a plurality of rectangular parallelepiped structures connected vertically in sequence to form a bow-shaped structure. The rectangular parallelepiped structure at one end of the drain field plate 11 is located vertically above the source electrode 5 and is separated from the source electrode 5 by the passivation layer 9. The rectangular parallelepiped structure at the other end of the drain field plate 11 extends through the passivation layer 9 to vertically above the drain electrode 6 and is separated from the drain electrode 6 by the passivation layer 9. One end of the drain field plate 11 is electrically connected to the drain electrode 6.

[0049] Furthermore, if Figure 3 As shown, one end of the drain field plate 11 extends to the edge of the passivation layer on the drain 6 side, and the other end extends to the edge of the passivation layer on the source 5 side. Figure 4 As shown, both ends of the drain field plate 11 are spaced a certain distance from the edge of the passivation layer.

[0050] In other embodiments, the drain field plate 11 may also be a curved S-shaped structure. It should also be noted that the actual curved or bent shape of the drain field plate 11 may be appropriately adjusted based on the actual electric field distribution. The field plate may bend or have dense bends at the peak of the electric field, and may bend or have sparse bends at the flat electric field.

[0051] Furthermore, the drain field plate 11 is formed of oxygen-doped semi-insulating polysilicon material with an oxygen content of 0.3% to 20%. The drain field plate 11 has a depth of 0.14 μm, a total length of 10.4 μm, and a rectangular parallelepiped structure width of 0.47 μm.

[0052] The drain field plate of the embodiment of the present invention is made of semi-insulating polysilicon material, which can prevent contamination by harmful impurity ions from the outside and alleviate the influence of the ion-induced electric field on the electric field distribution of the device. The drain field plate adopts a bent distribution structure, fully utilizing the area of ​​the drift region, further optimizing the electric field distribution of the entire channel, making the distribution of the electric field more uniform, and greatly improving the breakdown efficiency of the lateral device. The density and dispersion of the curvature of the drain field plate can be modulated according to the actual channel electric field distribution, that is, the field plate bends densely at the peak of the electric field and sparsely at the flat electric field. This can maximize the effect of the field plate on uniform channel electric field distribution and improve the breakdown characteristics of the device. The GaN-based HEMT device of the embodiment of the present invention has the characteristics of uniform electric field distribution, high long-term reliability and high breakdown efficiency, which is of great significance to the industrialization of GaN-based HEMT.

[0053] Example 2

[0054] Based on the above embodiment, this embodiment provides a method for preparing a high-reliability GaN-based HEMT device. Figure 5 6 , the preparation method of this embodiment includes:

[0055] S1: AlN nucleation layer 2, transition layer 3 and AlN are grown on substrate 1 in sequence. 0.2 Ga 0.8 N barrier layer 4.

[0056] In this embodiment, step S1 includes:

[0057] S1.1: epitaxially grow AlN material on substrate 1 to form AlN nucleation layer 2, such as Figure 6a shown.

[0058] A silicon substrate or a sapphire substrate is selected as substrate 1 and cleaned. A low-temperature AlN nucleation layer with a thickness of 30 nm is formed on the surface of substrate 1 using an MOCVD process. The growth temperature of the low-temperature AlN nucleation layer is approximately 700°C to 800°C, the pressure is 45 Torr, and the aluminum source flow rate is 5 μmol / min. Then, a high-temperature AlN nucleation layer is epitaxially grown on the low-temperature AlN nucleation layer. The thickness of the high-temperature AlN nucleation layer 2 is 170 nm. The growth temperature of the high-temperature AlN nucleation layer is 900°C to 1100°C, the pressure is 45 Torr, and the aluminum source flow rate is 5 μmol / min.

[0059] S1.2: epitaxially grow GaN material on the AlN nucleation layer 2 to form a transition layer 3, such as Figure 6b shown.

[0060] Specifically, using the epitaxial lateral overgrowth technology (ELOG), a GaN transition layer 3 with a thickness of 1 μm is heteroepitaxially grown in a hydrogen (H2) environment at a temperature of 960°C and a pressure of 45 Torr. The GaN transition layer 3 covers the AlN nucleation layer 2. The advantage of this technology is that a GaN transition layer with a low defect density can be obtained.

[0061] S1.3: Al is deposited on the GaN transition layer 3 0.2 Ga 0.8 N barrier layer 4.

[0062] Metal organic chemical vapor deposition technology is used to deposit a 10 nm thick undoped Al layer on the GaN transition layer 3. 0.2 Ga 0.8 N barrier layer 4, such as Figure 6c The selected process conditions are: temperature of 980°C, pressure of 45 Torr, nitrogen source ammonia flow rate of 4800 sccm, aluminum source flow rate of 3 μmol / min, and gallium source flow rate of 8 μmol / min.

[0063] S2: In Al 0.2 Ga 0.8 Metal is deposited at both ends of the N barrier layer 4 to form a source 5 and a drain 6, respectively. Figure 6d shown.

[0064] Specifically, in Al 0.2 Ga 0.8 The first mask is made on the N barrier layer 4, and the Al 0.2 Ga 0.8 Metal is deposited at both ends of the N barrier layer 4, and then rapidly thermally annealed in N2 gas conditions to form the source 5 and drain 6. In this embodiment, the source 5 and drain 6 are made of the same metal, using a Ti / Al / Ni / Au metal stack from bottom to top, with thicknesses of 0.018μm, 0.135μm, 0.046μm, and 0.052μm, respectively.

[0065] S3: In Al 0.2 Ga 0.8 The left and right sides of the N barrier layer 4 are etched to form a mesa 7 extending downward to the upper surface or the interior of the AlN nucleation layer 2, as shown in FIG. Figure 6e shown.

[0066] In Al 0.2 Ga 0.8 A second mask is made on the N barrier layer 4, and reactive ion etching technology is used to etch the barrier layer 4 on the left side of the source 5 and the right side of the drain 6 to form a mesa 7 extending downward to the upper surface or inside of the AlN nucleation layer 2. The etching depth in this embodiment is 1.01 μm.

[0067] S4: In Al 0.2 Ga 0.8 A metal is deposited at the middle of the N barrier layer 4 to form a gate 8. Figure 6f shown.

[0068] Specifically, in Al 0.2 Ga 0.8 A third mask is made on the N barrier layer 4, and electron beam evaporation technology is used to deposit metal as the gate 8 in the middle position of the barrier layer 4 between the source 5 and the drain 6. The deposited metal material is Ni / Au stacked metal, wherein the lower layer is Ni metal with a thickness of 0.026μm and the upper layer is Au metal with a thickness of 0.11μm.

[0069] S5: On the upper surface of the gate 8, source 5, drain 6 and Al 0.2 Ga 0.8 A passivation layer 9 is formed on the upper surface of the remaining area of ​​the N barrier layer 4. Figure 6g shown.

[0070] Specifically, PECVD technology is used to deposit the gate 8, source 5, drain 6 and Al 0.2 Ga 0.8 A SiN passivation layer 9 with a thickness of 2.0 μm is deposited on the upper surface of the remaining area of ​​the N barrier layer 4 to alleviate the surface state caused by lattice defects on the heterojunction surface of the barrier layer. The surface passivation measure can effectively suppress the current collapse phenomenon.

[0071] S6: etching is performed in the passivation layer 9 above the gate 8 and the drain 6 to form a meandering groove 10, as shown in FIG6h.

[0072] Specifically, a fourth mask is made on the passivation layer 9, and the passivation layer 9 is etched using reactive ion etching technology to form a curved or bow-shaped groove 10. The depth of the groove 10 is less than the thickness of the passivation layer 9, and the length is equal to or slightly less than the length of the passivation layer 9. In this embodiment, the depth of the groove 10 is 0.14 μm, the width of the groove is 0.47 μm, and the length is 10.40 μm. The groove 10 bends and extends from above the drain 6 to above the source 5. In this embodiment, as shown in FIG. Figure 6h1 As shown, one end of the groove 10 extends to the edge of the passivation layer on the drain 6 side, and the other end extends to the edge of the passivation layer on the source 5 side. Figure 6h2 As shown, both ends of the groove 10 are spaced a certain distance from the edge of the passivation layer 9 .

[0073] Furthermore, in other embodiments, the groove 10 may be etched into a curved S-shaped structure.

[0074] S7: Depositing oxygen-doped semi-insulating polysilicon material in the groove 10 to form a drain field plate 11, and one end of the drain field plate 11 is electrically connected to the drain 6, as shown in FIG. Figure 6i shown.

[0075] Specifically, electron beam evaporation technology is used to deposit oxygen-doped semi-insulating polysilicon in the groove 10, with a thickness of 0.14μm, a width of 0.47μm, and a length of 10.40μm. It should be noted that the actual curvature or bending shape of the drain field plate 11 can be appropriately adjusted according to the actual electric field distribution. The field plate bends or bends densely at the peak of the electric field, and bends sparsely at the flat electric field. The deposited semi-insulating polysilicon should completely fill the groove 10, and one end of the drain field plate 11 should be electrically connected to the drain 6. In order to ensure that the drain field plate has a suitable resistance value, the oxygen doping amount of the semi-insulating polysilicon is determined by the actual length of the device. The oxygen content is generally between 0.3% and 20%. Preferably, the oxygen doping amount is 0.5%.

[0076] S8: Deposit a protective layer 12 on the upper surface of the drain field plate 11 and the upper surface of the remaining area of ​​the passivation layer 9, such as Figure 6j shown.

[0077] Specifically, a protective layer 12 of SiO2 is deposited using PECVD technology on the upper surface of the drain field plate 11 and the remaining upper surface of the passivation layer 9. The thickness of the protective layer 12 is selected to be 3.0 μm to reduce the impact of the ambient atmosphere on the electrical characteristics of the drain field plate. This completes the process flow for the high-reliability GaN-based HEMT device of this embodiment.

[0078] The GaN-based HEMT device prepared using the method of an embodiment of the present invention utilizes a folded drain field plate structure to connect the drain electrode of the device, optimizing the electric field distribution at a shorter drain-source distance, making the electric field distribution between the drain and source more uniform, thereby greatly improving the long-term reliability and breakdown efficiency of the device.

[0079] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A GaN-based HEMT device with a novel drain field plate, characterized in that: The invention comprises a substrate (1), an AlN nucleation layer (2), a GaN transition layer (3) and a barrier layer (4) stacked in sequence from bottom to top, wherein: A source electrode (5) and a drain electrode (6) are respectively provided at both ends of the upper surface of the barrier layer (4); a gate electrode (8) is provided between the source electrode (5) and the drain electrode (6); and a mesa (7) extending downward to the upper surface or the interior of the AlN nucleation layer (2) is respectively formed outside the source electrode (5) and the drain electrode (6); The upper surfaces of the gate electrode (8), the source electrode (5), the drain electrode (6), and the upper surface of the remaining area of ​​the barrier layer (4) are all covered with a passivation layer (9); The upper surface of the passivation layer (9) includes a bent drain field plate (11), the lower surface of the drain field plate (11) extends to the interior of the passivation layer (9), and the upper surface is flush with the upper surface of the passivation layer (9); along a direction perpendicular to the plane where the substrate (1) is located, the positive projection of the drain field plate (11) is a continuous bow-shaped structure or an S-shaped structure, one end of the drain field plate (11) extends above the source (5) and vertically covers at least a portion of the source (5), and the other end extends above the drain (6) and vertically covers at least a portion of the drain (6), and the drain field plate (11) is electrically connected to the drain (6); The upper surface of the drain field plate (11) and the upper surface of the remaining area of ​​the passivation layer (9) are covered with a protective layer (12).

2. The GaN-based HEMT device with a novel drain field plate according to claim 1, characterized in that: One end of the drain field plate (11) extends to the edge of the passivation layer on one side of the drain (6), and the other end extends to the edge of the passivation layer on one side of the source (5).

3. The GaN-based HEMT device with a novel drain field plate according to claim 1, wherein: The drain field plate (11) is formed of oxygen-doped semi-insulating polysilicon material, with an oxygen content of 0.3% to 20%.

4. The GaN-based HEMT device with a novel drain field plate according to claim 1, wherein: The source electrode (5) and the drain electrode (6) both adopt Ti / Al / Ni / Au metal stacking, and the gate electrode (8) adopts Ni / Au stacking metal.

5. The GaN-based HEMT device with a novel drain field plate according to claim 1, wherein: The drain field plate (11) has a depth of 0.14 μm and a total length of 10.4 μm.

6. The GaN-based HEMT device with a novel drain field plate according to any one of claims 1 to 5, characterized in that: The material of the barrier layer (4) is Al 0.2 Ga 0.8 N.

7. A method for preparing a GaN-based HEMT device with a novel drain field plate, characterized in that: include: AlN nucleation layer, GaN transition layer and AlN layer are grown on the substrate in sequence. 0.2 Ga 0.8 N barrier layer; In the Al 0.2 Ga 0.8 Metal is deposited at both ends of the N barrier layer to form the source and drain respectively; In the Al 0.2 Ga 0.8 Etching the left and right sides of the N barrier layer to form a mesa extending downward to the upper surface or interior of the AlN nucleation layer; The Al between the source and the drain 0.2 Ga 0.8 A metal is deposited on the upper surface of the N barrier layer to form a gate; On the upper surfaces of the gate, the source, the drain and the Al 0.2 Ga 0.8 A passivation layer is formed on the upper surface of the remaining area of ​​the N barrier layer; A meandering groove is formed on the passivation layer, wherein the depth of the groove is less than the thickness of the passivation layer, and one end of the groove extends to above the source electrode, and the other end extends to above the drain electrode; A drain field plate is deposited in the groove, wherein the upper surface of the drain field plate is flush with the upper surface of the passivation layer, the drain field plate is electrically connected to the drain, and the orthographic projection of the drain field plate along the direction perpendicular to the plane of the substrate is a continuous bow-shaped structure or an S-shaped structure; A protective layer is deposited on the upper surface of the drain field plate and the upper surface of the remaining area of ​​the passivation layer.

8. The method for preparing a GaN-based HEMT device with a novel drain field plate according to claim 7, wherein: AlN nucleation layer, transition layer and AlN layer are grown on the substrate in sequence. 0.2 Ga 0.8 N barrier layer, including: A silicon substrate or a sapphire substrate is selected as a substrate and cleaned, and a low-temperature AlN nucleation layer is formed on the surface of the substrate. The low-temperature AlN nucleation layer is grown at a temperature of 700°C to 800°C, a pressure of 45 Torr, and an aluminum source flow rate of 5 µmol / min. A high-temperature AlN nucleation layer is then epitaxially grown on the low-temperature AlN nucleation layer. The high-temperature AlN nucleation layer is grown at a temperature of 900°C to 1100°C, a pressure of 45 Torr, and an aluminum source flow rate of 5 µmol / min. Epitaxially growing GaN material on the AlN nucleation layer to form a GaN transition layer with a thickness of 1 μm; An undoped Al layer with a thickness of 10 nm is deposited on the GaN transition layer. 0.2 Ga 0.8 N barrier layer.

9. The method for preparing a GaN-based HEMT device with a novel drain field plate according to claim 8, wherein: Depositing a drain field plate in the groove includes: Oxygen-doped semi-insulating polysilicon is deposited in the groove using electron beam evaporation technology to form the drain field plate, with the oxygen content being between 0.3% and 20%.

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