Gallium nitride power device and method of manufacturing the same

Abstract

The application belongs to the technical field of power devices, and provides a gallium nitride power device and a preparation method thereof. The gallium nitride power device comprises a gallium nitride layer, a gallium nitride cap layer, a silicon nitride layer, a source region, a drain region, a first gate layer, a second gate layer, a pre-embedded field plate layer and an air-bridge field plate layer. The first gate layer with an area smaller than that of the second gate layer is arranged between the second gate layer and the gallium nitride cap layer, the pre-embedded field plate layer is arranged at positions not in contact with the second gate layer, and the air-bridge field plate layer is connected to the source region and the pre-embedded field plate layer. Therefore, the electric field between the drain end and the gate end can be adjusted by designing a process flow at the cost of only one photo mask, and the reliability and performance of the power device are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power devices, and particularly relates to a gallium nitride power device and a preparation method thereof. BACKGROUND

[0002] The reverse breakdown voltage (BV) of a gallium nitride (GaN) standard device is usually determined by the distance between the drain end and the gate end. At present, there are many methods to increase the reverse breakdown voltage of the device, for example, by designing an air bridge field plate (AFP) layer, that is, using a bridge-shaped metal to cross the gate to change the electric field distribution between the drain end and the gate end, or by using a gate top end deformation design, also known as a slant field plate (SFP), to change the electric field distribution between the drain end and the gate end.

[0003] However, in the current preparation process, the air bridge field plate layer cannot form a large-area contact with silicon nitride, and is prone to falling off to cause an open circuit problem, which greatly affects the reliability and performance of the device. SUMMARY

[0004] The purpose of the application is to provide a gallium nitride power device and a preparation method thereof, aiming to provide a device structure and a preparation process, to design a process flow and at the same time complete the electric field adjustment between the drain end and the gate end at the cost of only one additional mask, and to improve the reliability and performance of the power device.

[0005] The first aspect of the embodiment of the application provides a gallium nitride power device, which comprises:

[0006] A gallium nitride layer, a gallium nitride cap layer and a silicon nitride layer are sequentially stacked from bottom to top;

[0007] A source region and a drain region are arranged on both sides of the silicon nitride layer, wherein the source region and the drain region penetrate into the gallium nitride layer;

[0008] A first gate layer and a second gate layer are arranged in the silicon nitride layer, and the first gate layer is arranged between the second gate layer and the gallium nitride cap layer, wherein the area of the first gate layer is smaller than the area of the second gate layer;

[0009] A pre-embedded field plate layer is arranged in the silicon nitride layer and does not contact the second gate layer and the gallium nitride cap layer;

[0010] An air bridge field plate layer is connected between the source region and the pre-embedded field plate layer.

[0011] In one embodiment, the second gate layer has an area at least twice as large as that of the first gate layer.

[0012] In one embodiment, the thickness of the pre-embedded field plate layer is less than that of the silicon nitride layer.

[0013] In one embodiment, the distance between the gallium nitride cap layer and the pre-embedded field plate layer is greater than 20% of the thickness of the silicon nitride layer.

[0014] In one embodiment, the distance between the pre-embedded field plate layer and the second gate layer is greater than 20% of the length of the air-bridge field plate layer.

[0015] In one embodiment, the air-bridge field plate layer is in the shape of a concave.

[0016] In one embodiment, the width of the pre-embedded field plate layer is greater than the contact area between the air-bridge field plate layer and the pre-embedded field plate layer.

[0017] In one embodiment, the gallium nitride cap layer is AlGaN.

[0018] The second aspect of the embodiments of the present application further provides a preparation method of a gallium nitride power device, the preparation method comprising:

[0019] sequentially preparing a gallium nitride layer, a gallium nitride cap layer and a silicon nitride layer from bottom to top, and forming a source region and a drain region on both sides of the silicon nitride layer, wherein the source region and the drain region extend into the gallium nitride layer;

[0020] forming a first trench on the silicon nitride layer;

[0021] etching the first trench to form a second trench, and forming a third trench on the silicon nitride layer; wherein the second trench and the third trench do not contact each other, and the second trench is in the shape of a convex and contacts the gallium nitride cap layer;

[0022] filling a metal material in the first trench to form a gate layer, and filling the metal material in the third trench to form a pre-embedded field plate layer; wherein the gate layer comprises a first gate layer and a second gate layer, and the area of the first gate layer is less than that of the second gate layer;

[0023] preparing an air-bridge field plate layer between the source region and the pre-embedded field plate layer.

[0024] In one embodiment, the step of filling a metal material in the first trench to form a gate layer, and filling the metal material in the third trench to form a pre-embedded field plate layer comprises:

[0025] adopting a damascene process to form a gate layer in the first trench, and to form a pre-embedded field plate layer in the third trench.

[0026] The application provides a gallium nitride power device and a preparation method thereof. The gallium nitride power device comprises a gallium nitride layer, a gallium nitride cap layer, a silicon nitride layer, a source region, a drain region, a first gate layer, a second gate layer, a pre-embedded field plate layer and an air-bridge field plate layer. The first gate layer with an area smaller than that of the second gate layer is arranged between the second gate layer and the gallium nitride cap layer, the pre-embedded field plate layer is arranged at a position not in contact with the second gate layer, and the air-bridge field plate layer is connected to the source region and the pre-embedded field plate layer. Therefore, the electrical field adjustment between the drain terminal and the gate terminal can be completed by a set of process flow only by increasing one mask, and the reliability and performance of the power device are improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is an example of a gallium nitride power device provided by an embodiment of the application Figure 1 ;

[0028] Figure 2 FIG. 2 is an example of a gallium nitride power device provided by an embodiment of the application Figure 2 ;

[0029] Figure 3 FIG. 3 is a flowchart of a preparation method of a gallium nitride power device provided by an embodiment of the application

[0030] Figure 4 FIG. 4 is an example diagram of forming a gallium nitride layer 100, a gallium nitride cap layer 200 and a silicon nitride layer 300 provided by an embodiment of the application

[0031] Figure 5 FIG. 5 is an example diagram of forming a first trench provided by an embodiment of the application

[0032] Figure 6 FIG. 6 is an example diagram of forming a second trench and a third trench provided by an embodiment of the application

[0033] Figure 7 FIG. 7 is an example diagram of forming a gate layer and a pre-embedded field plate layer 600 provided by an embodiment of the application

[0034] Figure 8 FIG. 8 is an example diagram of forming an air-bridge field plate layer 700 provided by an embodiment of the application. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and should not be used to limit the application.

[0036] It should be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or indirectly connected to the other element.

[0037] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate directions or positions based on the directions or positions shown in the drawings, and are used only for the purpose of facilitating this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0038] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0039] The embodiment of the application provides a gallium nitride power device, referring to Figure 1 As shown in the figure, the gallium nitride power device comprises a gallium nitride layer 100, a gallium nitride cap layer 200, a silicon nitride layer 300, a source region 410, a drain region 420, a first gate layer 510, a second gate layer 520, a pre-embedded field plate layer 600 and a gas bridge field plate layer 700.

[0040] Specifically, the gallium nitride layer 100, the gallium nitride cap layer 200 and the silicon nitride layer 300 are sequentially stacked from bottom to top, the source region 410 and the drain region 420 are arranged on both sides of the silicon nitride layer 300, and the source region 410 and the drain region 420 penetrate into the gallium nitride layer 100; the first gate layer 510 and the second gate layer 520 are arranged in the silicon nitride layer 300, and the first gate layer 510 is arranged between the second gate layer 520 and the gallium nitride cap layer 200, the area of the first gate layer 510 is smaller than the area of the second gate layer 520; the pre-embedded field plate layer 600 is arranged in the silicon nitride layer 300 and does not contact the second gate layer 520 and the gallium nitride cap layer 200; the gas bridge field plate layer 700 is connected between the source region 410 and the pre-embedded field plate layer 600.

[0041] In the embodiment, the first trench for forming the first gate layer 510 is prepared by adding a layer of mask, and then on the basis of the first trench, the third trench for forming the pre-embedded field plate layer 600 and the second trench for forming the second gate layer 520 are simultaneously prepared on the silicon nitride layer 300 by one etching process, and the source region and the pre-embedded field plate layer 600 are connected by the air-bridge field plate, the air-bridge field plate layer 700 and the pre-embedded field plate layer 600 are both metal and have good contact, thus avoiding the problem of poor contact between the air-bridge field plate layer 700 and the silicon nitride layer 300, and the electric field distribution between the drain terminal and the gate terminal is adjusted by adjusting the area of the pre-embedded field plate layer 600, so that the reverse withstand voltage is increased without affecting the reliability and performance of the device.

[0042] In a specific application embodiment, the first gate layer 510, the second gate layer 520 and the pre-embedded field plate layer 600 can adopt a damascene process, so that the gate field plate and the pre-embedded field plate layer 600 of the gate region are formed in the same process step, and the effect and reliability of the gate field plate and the pre-embedded field plate layer 600 are improved.

[0043] In an embodiment, the first gate layer 510, the second gate layer 520 and the pre-embedded field plate layer 600 can adopt a damascene process in an advanced copper process, so that a copper layer is simultaneously formed in the second trench and the third trench, so that the gate field plate and the pre-embedded field plate layer 600 of the gate region are formed in the same process step, and the effect and reliability of the gate field plate and the pre-embedded field plate layer 600 are improved.

[0044] In an embodiment, referring to FIG. 2, Figure 1 As shown in FIG. 2, the area of the second gate layer 520 is at least twice the area of the first gate layer 510.

[0045] In the embodiment, the area of the second gate layer 520 can be adjusted by adjusting the shape of the mask for etching the second trench, and by adjusting the area of the second gate layer 520, for example, referring to FIG. 3, Figure 2 As shown in FIG. 3, the sum of the thickness of the first gate layer 510 and the thickness of the second gate layer 520 is equal to the thickness of the silicon nitride layer 300, the first gate layer 510 is in direct contact with the gallium nitride cap layer 200, and at this time, the part of the second gate layer 520 that is not in contact with the first gate layer 510 produces a parasitic capacitance C1 between the second gate layer 520 and the gallium nitride cap layer 200, which can be used to improve the reverse withstand voltage of the device, so that the reverse withstand voltage of the device can be adjusted by adjusting the area of the second gate layer 520.

[0046] In some embodiments, the length or width of the second gate layer 520 can be adjusted to obtain a larger capacitance to improve the reverse withstand voltage.

[0047] Furthermore, the parasitic capacitance between the second gate layer 520 and the gallium nitride cap layer 200 can be increased by reducing the thickness of the first gate layer 510.

[0048] In one embodiment, see Figure 2 As shown, the thickness of the embedded field plate layer 600 is less than the thickness of the silicon nitride layer 300.

[0049] In this embodiment, since the thickness of the embedded field plate 600 is less than the thickness of the silicon nitride layer 300, a parasitic capacitance C2 is formed between the embedded field plate 600 and the gallium nitride cap layer 200. The size of the parasitic capacitance C2 can be adjusted by adjusting the area of ​​the embedded field plate 600, thereby adjusting the reverse withstand voltage of the device. At the same time, it also overcomes the problem in the traditional process that the air bridge field plate 700 and the silicon nitride layer 300 are in direct contact, which makes it impossible to form a large-area contact.

[0050] In some embodiments, the length or width of the embedded field plate 600 can be adjusted to obtain a larger parasitic capacitance, thereby improving the reverse withstand voltage.

[0051] In one embodiment, the distance between the gallium nitride cap layer 200 and the embedded field plate layer 600 is greater than 20% of the thickness of the silicon nitride layer 300.

[0052] In this embodiment, since the embedded field plate 600 is disposed in the silicon nitride layer 300, and the silicon nitride layer 300 is made of insulating material, the parasitic capacitance between the gallium nitride cap layer 200 and the embedded field plate 600 is determined by the area of ​​the embedded field plate 600 and the distance between the gallium nitride cap layer 200 and the embedded field plate 600. By setting the distance between the gallium nitride cap layer 200 and the embedded field plate 600 to be greater than 20% of the thickness of the silicon nitride layer 300, leakage problems caused by the distance between the gallium nitride cap layer 200 and the embedded field plate 600 being too close during the actual fabrication process can be avoided.

[0053] In one embodiment, see Figure 1 As shown, the distance between the embedded field plate layer 600 and the second gate layer 520 is greater than 20% of the length of the air bridge field plate layer 700.

[0054] In this embodiment, both the embedded field plate 600 and the second gate layer 520 are made of metal materials, and the silicon nitride layer 300 is an insulating medium. Therefore, parasitic capacitance will also be formed between the embedded field plate 600 and the second gate layer 520. By setting the distance between the embedded field plate 600 and the second gate layer 520 to be greater than 20% of the length of the air bridge field plate 700, the parasitic capacitance between the two can be avoided from affecting the device performance.

[0055] In one embodiment, referring to Figure 1 As shown, the air-bridge field plate layer 700 is in a concave shape.

[0056] In this embodiment, the air-bridge field plate layer 700 is in a concave shape, one end of which is connected to the source electrode, and the other end is connected to the pre-embedded field plate layer 600, and the air-bridge field plate layer 700 has a gap between the second gate layer 520, which is located in the groove of the concave structure.

[0057] In specific applications, the gap between the air-bridge field plate layer 700 and the second gate layer 520 can be set to be greater than the thickness of the second gate layer 520, and the thickness can be set according to the device parameters.

[0058] In one embodiment, the area of the pre-embedded field plate layer 600 is greater than the contact area of the air-bridge field plate layer 700 and the pre-embedded field plate layer 600.

[0059] In this embodiment, the pre-embedded field plate layer 600 and the air-bridge field plate layer 700 are both metal materials, and in specific applications, the air-bridge field plate layer 700 is in an air-bridge structure, which can be welded to the designated contact area in the pre-embedded field plate layer 600 through the second gate layer 520, and the contact area between the two is less than the contact area of the pre-embedded field plate layer 600.

[0060] Specifically, the width of the designated contact area in the pre-embedded field plate layer 600 is also less than the width of the pre-embedded field plate layer 600, and the width of the pre-embedded field plate layer 600 can be adjusted by adjusting the size of the mask, so as to adjust the parasitic capacitance between the pre-embedded field plate layer 600 and the gallium nitride cap layer 200, so as to obtain greater parasitic capacitance to improve the reverse withstand voltage of the device. Further, the problem that the traditional air-bridge field plate layer 700 and the silicon nitride layer 300 cannot be well contacted to cause the contact area to be unable to increase can be avoided.

[0061] In one embodiment, the gallium nitride cap layer 200 is AlGaN.

[0062] The embodiments of the present application also provide a preparation method of a gallium nitride power device, referring to Figure 3 As shown, the preparation method comprises steps S100 to S500.

[0063] In step S100, the gallium nitride layer 100, the gallium nitride cap layer 200, and the silicon nitride layer 300 are sequentially prepared from bottom to top, and the source electrode area 410 and the drain electrode area 420 are formed on both sides of the silicon nitride layer 300.

[0064] In this embodiment, referring to Figure 4As shown, the gallium nitride layer 100, the gallium nitride cap layer 200 and the silicon nitride layer 300 are sequentially stacked from bottom to top, the source region 410 and the drain region 420 are arranged on both sides of the silicon nitride layer 300, and the source region 410 and the drain region 420 penetrate into the gallium nitride layer 100.

[0065] In step S200, a first trench 511 is formed on the silicon nitride layer 300.

[0066] In this embodiment, referring to Figure 5 As shown, the area of the first trench 511 is determined by the first mask 301, and the position of the first trench 511 is used to form the first gate layer 510. Since the second trench 521 also needs to be formed by etching subsequently, in order to avoid the subsequent etching process from continuing to etch the first trench 511, resulting in the trench depth exceeding the silicon nitride layer 300, the depth of the first trench 511 is set to be less than the silicon nitride layer 300.

[0067] In step S300, the first trench 511 is etched to form a second trench 521, and a third trench 611 is formed on the silicon nitride layer 300.

[0068] In this embodiment, referring to Figure 6 As shown, the positions of the second trench 521 and the third trench 611 are defined under the coverage of the second mask 302, wherein the second trench 521 and the third trench 611 do not contact each other. At this time, the area of the second trench 521 covers the area of the first trench 511. In the second etching process, on the basis of the first trench 511, the third trench 611 for forming the pre-embedded field plate layer 600 and the second trench for forming the second gate layer 520 are simultaneously prepared on the silicon nitride layer 300 by one etching process. In this etching process, the first trench 511 will be etched again until it contacts the gallium nitride cap layer 200. By etching on the basis of the first trench 511, the second trench 521 formed is in a convex shape and contacts the gallium nitride cap layer 200.

[0069] In step S400, a gate layer is formed by filling a metal material in the first trench, and a pre-embedded field plate layer 600 is formed in the third trench.

[0070] In this embodiment, referring to Figure 7 As shown, the gate layer includes the first gate layer 510 and the second gate layer 520, and the area of the first gate layer 510 is less than the area of the second gate layer 520. At this time, the gate layer is in a convex structure.

[0071] In a specific application embodiment, the area of the second gate layer 520 can be adjusted by adjusting the shape of the second mask used to etch the second trench 521. By adjusting the area of the second gate layer 520, for example, referring toFigure 7 As shown, the sum of the thickness of the first gate layer 510 and the thickness of the second gate layer 520 is equal to the thickness of the silicon nitride layer 300, the first gate layer 510 is in direct contact with the gallium nitride cap layer 200, at this time, the part of the second gate layer 520 which is not in contact with the first gate layer 510 and the gallium nitride cap layer 200 generates a parasitic capacitance, which can be used to improve the reverse withstand voltage of the device, therefore, by adjusting the area of the second gate layer 520, the reverse withstand voltage of the device can be adjusted.

[0072] In some embodiments, by adjusting the length or width of the second gate layer 520, a larger capacitance can be obtained to improve the reverse withstand voltage.

[0073] Further, by reducing the thickness of the first gate layer 510, the parasitic capacitance between the second gate layer 520 and the gallium nitride cap layer 200 can be improved.

[0074] In a specific application embodiment, the thickness of the pre-embedded field plate layer 600 is less than the thickness of the silicon nitride layer 300, at this time, the pre-embedded field plate layer 600 and the gallium nitride form a parasitic capacitance, by adjusting the area of the pre-embedded field plate layer 600, the size of the parasitic capacitance can be adjusted, thereby adjusting the reverse withstand voltage of the device, and at the same time, the problem that in the traditional process, the air-bridge field plate layer 700 and the silicon nitride layer 300 are in direct contact, which results in that a large-area contact cannot be formed, is overcome.

[0075] In some embodiments, by adjusting the length or width of the pre-embedded field plate layer 600, a larger parasitic capacitance can be obtained to improve the reverse withstand voltage.

[0076] In an embodiment, the distance between the gallium nitride cap layer 200 and the pre-embedded field plate layer 600 is greater than 20% of the thickness of the silicon nitride layer 300.

[0077] In the present embodiment, since the pre-embedded field plate layer 600 is arranged in the silicon nitride layer 300, the silicon nitride layer 300 is prepared from an insulating material, at this time, the parasitic capacitance between the gallium nitride cap layer 200 and the pre-embedded field plate layer 600 is determined by the area of the pre-embedded field plate layer 600 and the distance between the gallium nitride cap layer 200 and the pre-embedded field plate layer 600, by setting the distance between the gallium nitride cap layer 200 and the pre-embedded field plate layer 600 to be greater than 20% of the thickness of the silicon nitride layer 300, the problem of electric leakage due to the distance between the gallium nitride cap layer 200 and the pre-embedded field plate layer 600 being too close in the actual preparation process can be avoided.

[0078] In step S500, an air-bridge field plate layer 700 is prepared between the source region 410 and the pre-embedded field plate layer 600.

[0079] In the embodiment, referring to Figure 8 The source region and the pre-embedded field plate layer 600 are connected by the air-bridge field plate, the air-bridge field plate layer 700 and the pre-embedded field plate layer 600 are both metal, which has the advantage of good contact, and the problem of poor contact between the air-bridge field plate layer 700 and the silicon nitride layer 300 is avoided. The area of the pre-embedded field plate layer 600 is adjusted to adjust the electric field distribution between the drain end and the gate end, so that the reverse withstand voltage is increased without affecting the reliability and performance of the device.

[0080] In one embodiment, referring to Figure 8 The air-bridge field plate layer 700 is in the shape of a concave character.

[0081] In the embodiment, one end of the air-bridge field plate in the shape of a concave character is connected to the source, the other end is connected to the pre-embedded field plate layer 600, and there is a gap between the air-bridge field plate layer 700 and the second gate layer 520, which is located in the groove of the concave character structure.

[0082] In specific applications, the gap width between the air-bridge field plate layer 700 and the second gate layer 520 can be set to be greater than the thickness of the second gate layer 520, and the thickness can be set according to the device parameters.

[0083] In one embodiment, the area of the pre-embedded field plate layer 600 is greater than the contact area of the air-bridge field plate layer 700 and the pre-embedded field plate layer 600.

[0084] In the embodiment, the pre-embedded field plate layer 600 and the air-bridge field plate layer 700 are both metal materials. In specific applications, the air-bridge field plate layer 700 is in the air-bridge structure, and the second gate layer 520 can be welded to the designated contact area in the pre-embedded field plate layer 600 by wire bonding, and the contact area between the two is less than the contact area of the pre-embedded field plate layer 600.

[0085] Specifically, the width of the designated contact area in the pre-embedded field plate layer 600 is also less than the width of the pre-embedded field plate layer 600, and the width of the pre-embedded field plate layer 600 can be adjusted by adjusting the size of the mask, so as to adjust the parasitic capacitance between the pre-embedded field plate layer 600 and the gallium nitride cap layer 200, so as to obtain greater parasitic capacitance to improve the reverse withstand voltage of the device. Further, the problem that the air-bridge field plate layer 700 and the silicon nitride layer 300 cannot be well contacted to increase the contact area can be avoided.

[0086] In one embodiment, the step of filling the metal material in the first trench to form a gate layer and in the third trench to form a pre-embedded field plate layer 600 includes: using a damascene process to form a gate layer in the first trench and a pre-embedded field plate layer 600 in the third trench.

[0087] In the embodiment, the first gate layer 510, the second gate layer 520 and the pre-embedded field plate layer 600 can adopt a damascene process, so that the gate field plate of the gate region and the pre-embedded field plate layer 600 are formed in the same process step, and the effect and reliability of the gate field plate and the pre-embedded field plate layer 600 are improved.

[0088] In one embodiment, the first gate layer 510, the second gate layer 520 and the pre-embedded field plate layer 600 can adopt a damascene process in an advanced copper process, so that a copper layer is simultaneously formed in the second trench and the third trench, so that the gate field plate of the gate region and the pre-embedded field plate layer 600 are formed in the same process step, and the effect and reliability of the gate field plate and the pre-embedded field plate layer 600 are improved.

[0089] The gallium nitride power device and the preparation method thereof provided in the application, the gallium nitride power device comprises a gallium nitride layer, a gallium nitride cap layer, a silicon nitride layer, a source region, a drain region, a first gate layer, a second gate layer, a pre-embedded field plate layer and an air bridge field plate layer, the first gate layer with an area smaller than that of the second gate layer is arranged between the second gate layer and the gallium nitride cap layer, the pre-embedded field plate layer is arranged at a position not in contact with the second gate layer, and the air bridge field plate layer is connected to the source region and the pre-embedded field plate layer, so that the process flow is designed to complete the electric field adjustment between the drain terminal and the gate terminal at the cost of only one additional mask, and the reliability and performance of the power device are improved.

[0090] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned doping regions is exemplified, and in actual application, the above-mentioned functional regions can be allocated by different doping regions, that is, the internal structure of the device is divided into different doping regions to complete all or part of the functions described above.

[0091] The doping regions in the embodiments can be integrated in one functional region, or each doping region can exist physically alone, or two or more doping regions can be integrated in one functional region, and the integrated functional region can be realized by the same doping ion or by multiple doping ions. In addition, the specific names of the doping regions are only for mutual differentiation, and do not limit the protection scope of the application. The specific working process of the doping region in the preparation method of the device can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0092] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method of fabricating a gallium nitride power device, comprising: The preparation method comprises: ​ sequentially preparing a gallium nitride layer, a gallium nitride cap layer and a silicon nitride layer from bottom to top, and forming a source region and a drain region on both sides of the silicon nitride layer; wherein the source region and the drain region extend to the gallium nitride layer; forming a first trench on the silicon nitride layer; etching the first trench to form a second trench, and forming a third trench on the silicon nitride layer; wherein the second trench and the third trench are not in contact with each other, the second trench is in the shape of a convex letter, and the second trench is in contact with the gallium nitride cap layer; filling a metal material in the second trench to form a gate layer, and filling a metal material in the third trench to form a pre-embedded field plate layer; wherein the gate layer comprises a first gate layer and a second gate layer, the area of the first gate layer is smaller than the area of the second gate layer; the first gate layer, the second gate layer and the pre-embedded field plate layer are simultaneously formed in the second trench and the third trench by damascene process, respectively; preparing an air-bridge field plate layer between the source region and the pre-embedded field plate layer; the sum of the thickness of the first gate layer and the thickness of the second gate layer is equal to the thickness of the silicon nitride layer; a parasitic capacitor is formed between the pre-embedded field plate layer and the gallium nitride cap layer, the thickness of the pre-embedded field plate layer is smaller than the thickness of the silicon nitride layer; the distance between the gallium nitride cap layer and the pre-embedded field plate layer is greater than 20% of the thickness of the silicon nitride layer.

2. The production method according to claim 1, wherein The area of the second gate layer is at least twice the area of the first gate layer.

3. The production method according to claim 1, wherein The distance between the pre-embedded field plate layer and the second gate layer is greater than 20% of the length of the air-bridge field plate layer.

4. The production method according to claim 1, wherein The air-bridge field plate layer is in the shape of a concave letter.

5. The production method according to claim 1, wherein The width of the pre-embedded field plate layer is greater than the contact area of the air-bridge field plate layer and the pre-embedded field plate layer.

6. The production method according to any one of claims 1 to 5, wherein The gallium nitride cap layer is AlGaN.

7. A gallium nitride power device, characterized by, The gallium nitride power device is prepared by the preparation method of any one of claims 1-6.

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