Gallium nitride schottky diode and method of making the same

Abstract

The application relates to a gallium nitride Schottky diode and a preparation method thereof. The gallium nitride Schottky diode comprises a semiconductor substrate, a channel layer, an ohmic metal cathode, a barrier layer, an ohmic metal anode, a Schottky metal anode, an insulation layer and a cathode metal layer. The channel layer comprises a first channel step layer and a second channel step layer which are in contact with each other, and the first channel step layer and the second channel step layer are arranged on the front surface of the semiconductor substrate; the ohmic metal cathode is in contact with the first channel step layer; the barrier layer is arranged on the front surface of the second channel step layer; the ohmic metal anode is arranged on the front surface of the barrier layer; the Schottky metal anode is embedded on the front surface of the barrier layer and located between the ohmic metal cathode and the ohmic metal anode and in contact with the ohmic metal anode. When a large voltage forward bias is applied to the gallium nitride Schottky diode, the current can be directly transmitted through the Schottky metal anode, the conduction current is significantly increased, and the high-voltage resistance performance is improved.

Description

Technical Field

[0001] This application belongs to the field of semiconductor technology, and in particular relates to a gallium nitride Schottky diode and its fabrication method. Background Technology

[0002] Currently, as the demand for Schottky diodes increases, the requirements for their performance are also becoming more stringent. The performance of traditional silicon-based Schottky diodes is approaching its theoretical limits. Gallium nitride (GaN), as a third-generation semiconductor material, possesses characteristics such as a large breakdown electric field and high electron drift velocity. Schottky diodes made from GaN exhibit excellent properties such as high temperature resistance, high voltage resistance, and low on-resistance, making them an ideal material for fabricating next-generation Schottky diodes. However, existing GaN Schottky diodes with silicon carbide substrates still fall far short of ideal values ​​in terms of high voltage resistance and on-resistance, making them susceptible to breakdown by high voltage and unable to operate at higher power levels. Summary of the Invention

[0003] The purpose of this application is to provide a gallium nitride Schottky diode and its fabrication method, which aims to solve the problem that traditional Schottky diodes are easily broken down by high voltage.

[0004] A first aspect of this application provides a gallium nitride Schottky diode, comprising: a semiconductor substrate; a channel layer including a first channel step layer and a second channel step layer in contact with each other, both the first and second channel step layers being disposed on the front side of the semiconductor substrate, the thickness of the first channel step layer being less than the thickness of the second channel step layer; an ohmic metal cathode in contact with the first channel step layer; a barrier layer disposed on the front side of the second channel step layer; and an insulating layer having an L-shaped structure, the vertical portion of which is disposed on... Between the ohmic metal cathode and the second channel stepped layer, the horizontal portion of the insulating layer is disposed on the barrier layer; the Schottky metal anode has a convex structure, the convex portion of the Schottky metal anode is embedded in the barrier layer, and the horizontal portion of the Schottky metal anode is disposed on the horizontal portion of the insulating layer; the ohmic metal anode is disposed on the front side of the barrier layer and is in contact with the Schottky metal anode; wherein, the convex portion of the Schottky metal anode is disposed between the ohmic metal anode and the horizontal portion of the insulating layer; a cathode metal layer is disposed on the ohmic metal cathode.

[0005] In one embodiment, the cathode metal layer has an L-shaped structure, with the vertical portion of the cathode metal layer disposed on the ohmic metal cathode and in contact with the insulating layer; the horizontal portion of the cathode metal layer is disposed above the insulating layer.

[0006] In one embodiment, the cathode metal layer is made of Schottky metal.

[0007] In one embodiment, the protrusion of the Schottky metal anode extends into the barrier layer to a depth less than half the thickness of the barrier layer.

[0008] In one embodiment, the ohmic metal cathode is disposed on the front side of the first channel stepped layer.

[0009] In one embodiment, the ohmic metal cathode is disposed on the front side of the semiconductor substrate and contacts the side of the first channel step layer.

[0010] In one embodiment, the semiconductor substrate is made of silicon carbide, the channel layer is made of N-type gallium nitride, the barrier layer is made of aluminum gallium nitride, and the insulating layer is made of a high-dielectric material.

[0011] In one embodiment, the dielectric constant of the horizontal portion of the insulating layer is greater than the dielectric constant of the vertical portion of the insulating layer.

[0012] A second aspect of this application provides a method for fabricating a gallium nitride Schottky diode, comprising: sequentially forming a channel layer and a barrier layer on a semiconductor substrate; etching the edges of the barrier layer and the channel layer on a first side to divide the channel layer into a first channel step layer and a second channel step layer; wherein the thickness of the first channel step layer is less than the thickness of the second channel step layer; depositing an insulating material on the barrier layer and the channel layer to form an insulating layer; wherein the insulating layer has an L-shaped structure; etching the edges of the first side of the insulating layer until the channel layer is exposed to form a cathode-filled trench; etching the edges of the second side of the insulating layer until the barrier layer is exposed to form an anode-filled trench; the first side and the second side of the insulating layer are further etched to form an anode-filled trench. The second side is opposite; an ohmic metal material is deposited at the bottom of the cathode filling trench to form an ohmic metal cathode, and an ohmic metal material is deposited in the anode filling trench to form an ohmic metal anode; the edge of the second side of the insulating layer is etched until a portion of the barrier layer is etched to form a Schottky filling trench; the Schottky filling trench is located between the insulating layer and the ohmic metal anode; a Schottky metal material is deposited in the Schottky filling trench to form a Schottky metal anode; wherein the Schottky metal anode has a convex structure, the convex portion of the Schottky metal anode is located in the Schottky filling trench, and the horizontal portion of the Schottky metal anode is disposed on the horizontal portion of the insulating layer; a cathode metal layer is formed on the ohmic metal cathode.

[0013] In one embodiment, the barrier layer is etched to a depth less than half the thickness of the barrier layer.

[0014] The beneficial effects of this application embodiment compared with the prior art are as follows: When the barrier layer and the channel layer are in contact, a two-dimensional electron gas (2DEG) is formed between the barrier layer and the channel layer. Electrons can move through the two-dimensional electron gas to realize current transmission. When a large forward bias voltage is applied to the Schottky metal anode and the ohmic metal cathode, the high voltage can open the Schottky contact formed between the Schottky metal anode and the barrier layer. Current can be transmitted simultaneously through the Schottky metal anode and the ohmic metal anode to the two-dimensional electron gas, and finally to the ohmic metal cathode, thereby significantly increasing the conduction current and improving the high voltage withstand performance of the gallium nitride Schottky diode of this application. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a gallium nitride Schottky diode provided in the first embodiment of this application;

[0016] Figure 2 This is a schematic diagram of the structure of a gallium nitride Schottky diode provided in another embodiment of this application;

[0017] Figure 3 A flowchart illustrating the fabrication method of a gallium nitride Schottky diode provided in the second embodiment of this application;

[0018] Figure 4 A schematic diagram of the gallium nitride Schottky diode after performing step S100;

[0019] Figure 5 A schematic diagram of the gallium nitride Schottky diode after step S200 is performed;

[0020] Figure 6 A schematic diagram of the gallium nitride Schottky diode after step S300 is performed;

[0021] Figure 7 A schematic diagram of the gallium nitride Schottky diode after step S400 is executed;

[0022] Figure 8 A schematic diagram of the gallium nitride Schottky diode after step S500 is executed;

[0023] Figure 9 A schematic diagram of the gallium nitride Schottky diode after step S600 is performed;

[0024] Figure 10 This is a schematic diagram of the structure of a gallium nitride Schottky diode after step S700 is executed.

[0025] The above figures illustrate the following: 100, semiconductor substrate; 200, channel layer; 210, first channel step layer; 220, second channel step layer; 300, ohmic metal cathode; 400, barrier layer; 500, ohmic metal anode; 600, Schottky metal anode; 700, insulating layer; 800, cathode metal layer; 910, cathode-filled trench; 920, anode-filled trench; 930, Schottky-filled trench. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0027] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0028] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] Figure 1 A schematic diagram of the structure of a gallium nitride Schottky diode according to the first embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0031] A gallium nitride Schottky diode includes: a semiconductor substrate 100, a channel layer 200, an ohmic metal cathode 300, a barrier layer 400, an ohmic metal anode 500, a Schottky metal anode 600, an insulating layer 700, and a cathode metal layer 800.

[0032] The channel layer 200 is stepped, comprising a first channel step layer 210 and a second channel step layer 220 in contact with each other. Both the first and second channel step layers 210 and 220 are disposed on the front side of the semiconductor substrate 100. The thickness of the first channel step layer 210 is less than the thickness of the second channel step layer 220. The ohmic metal cathode 300 is in contact with the first channel step layer 210; specifically, the ohmic metal cathode 300 and the first channel step layer 210 are in ohmic contact. The front side of the semiconductor substrate 100 is also its top surface.

[0033] The barrier layer 400 is disposed on the front side of the second channel step layer 220. The ohmic metal anode 500 is disposed on the front side of the barrier layer 400 and is in ohmic contact with the barrier layer 400.

[0034] The insulating layer 700 has an L-shaped structure. The vertical part of the insulating layer 700 is located between the ohmic metal cathode 300 and the second channel step layer 220, and the horizontal part of the insulating layer 700 is located on the barrier layer 400.

[0035] The Schottky metal anode 600 is embedded on the front side of the barrier layer 400. Specifically, the Schottky metal anode 600 and the barrier layer 400 form a Schottky contact, and the Schottky metal anode 600 has a convex structure. More specifically, the Schottky metal anode 600 can have a T-shaped structure, with the convex portion located below the horizontal portion of the Schottky metal anode 600. The convex portion of the Schottky metal anode 600 is embedded in the barrier layer 400, and the horizontal portion of the Schottky metal anode 600 is located on the horizontal portion of the insulating layer 700.

[0036] An ohmic metal anode 500 is disposed on the front side of the barrier layer 400 and is in contact with a Schottky metal anode 600. The protrusion of the Schottky metal anode 600 is located between the ohmic metal anode 500 and the horizontal portion of the insulating layer 700.

[0037] The cathode metal layer 800 is disposed on the ohmic metal cathode 300.

[0038] It should be noted that when the barrier layer 400 and the channel layer 200 are in contact, a two-dimensional electron gas is formed between them. Electrons can move within this two-dimensional electron gas, thus enabling energy transfer. When the Schottky metal anode 600 is embedded in the barrier layer 400, it forms a Schottky contact with the barrier layer 400, and the ohmic metal anode 500 forms an ohmic contact with the barrier layer 400. When a reverse bias or zero bias is applied to the Schottky metal anode 600 and the cathode metal layer 800, the two-dimensional electron gas beneath the Schottky metal anode 600 is depleted. Electrons cannot move through this two-dimensional electron gas to the Schottky metal anode 600 and the ohmic metal anode 500, and energy cannot be transferred between the anode and cathode of the diode. When a forward bias is applied to the Schottky metal anode 600 and the cathode metal layer 800, the two-dimensional electron gas beneath the Schottky metal anode 600 resumes conduction. Electrons can travel from the ohmic metal cathode 300 through the two-dimensional electron gas to the ohmic metal anode 500, thus enabling current conduction. At this time, both the on-state voltage and on-state resistance are relatively low. However, when a large forward bias is applied to the Schottky metal anode 600 and the ohmic metal cathode 300, the high voltage can open the Schottky contact formed between the Schottky metal anode 600 and the barrier layer 400. Therefore, current can simultaneously travel through both the Schottky metal anode 600 and the ohmic metal anode 500 to the two-dimensional electron gas, significantly increasing the on-state current and improving high-voltage withstand performance.

[0039] In one embodiment, the barrier layer 400 has a concave structure. In this case, the protrusion of the Schottky metal anode 600 extends into the groove of the barrier layer 400. Specifically, the width of the protrusion of the Schottky metal anode 600 is equal to the width of the groove of the barrier layer 400, and the protrusion of the Schottky metal anode 600 contacts the bottom surface of the groove of the barrier layer 400.

[0040] In one embodiment, the horizontal portion on the left side of the Schottky metal anode 600 is disposed on the insulating layer 700, and the horizontal portion on the right side of the Schottky metal anode 600 is disposed on the ohmic metal anode 500.

[0041] In one embodiment, the width of the horizontal portion on the right side of the Schottky metal anode 600 is not less than the width of the ohmic metal anode 500. Specifically, the right end of the horizontal portion of the Schottky metal anode 600 may be aligned with the right end of the ohmic metal anode 500.

[0042] In one embodiment, the protrusion of the Schottky metal anode 600 extends into the barrier layer 400 to a depth less than half the thickness of the barrier layer 400, i.e., the depth of the groove in the barrier layer 400 is less than half the thickness of the barrier layer 400. In one example, the depth of the groove in the barrier layer 400 is equal to half the thickness of the barrier layer 400.

[0043] In one embodiment, the depth to which the protrusion of the Schottky metal anode 600 penetrates into the barrier layer 400 is less than one-third of the height of the protrusion of the Schottky metal anode 600. In one example, the depth to which the protrusion of the Schottky metal anode 600 penetrates into the barrier layer 400 is equal to one-third of the height of the protrusion of the Schottky metal anode 600.

[0044] In one embodiment, the semiconductor substrate 100 may be made of silicon carbide (SiC).

[0045] In one embodiment, the material of the channel layer 200 may be N-type gallium nitride (N-type GaN).

[0046] In one embodiment, the material of the barrier layer 400 may be aluminum gallium nitride (AlGaN).

[0047] In one embodiment, the insulating layer 700 covers the surfaces of the channel layer 200 and the barrier layer 400. The insulating layer 700 has an L-shaped structure, such as... Figure 2 As shown, the horizontal portion of the insulating layer 700 is located above the vertical portion of the insulating layer 700. Specifically, the vertical portion of the insulating layer 700 is disposed on the front side of the first channel step layer 210 and contacts the side surfaces of the second channel step layer 220 and the barrier layer 400. The horizontal portion of the insulating layer 700 is disposed on the front side of the vertical portion of the insulating layer 700 and the front side of the barrier layer 400. The sum of the thicknesses of the vertical portion of the insulating layer 700 and the first channel step layer 210 is equal to the sum of the thicknesses of the second channel step layer 220 and the barrier layer 400; the thickness of the horizontal portion of the insulating layer 700 is equal to the thickness of the ohmic metal anode 500. The insulating layer 700 can be made of a high-dielectric material. High-dielectric materials include silicon nitride (Si3N4), silicon oxynitride (SiON), and other similar materials.

[0048] The insulating layer 700 can cover the exposed surfaces of the channel layer 200 and the barrier layer 400 to protect the channel layer 200 and the barrier layer 400. At the same time, the insulating layer 700 covering the side of the channel layer 200 can also reduce leakage current caused by lattice damage of the channel layer 200.

[0049] In another embodiment, the dielectric constant of the horizontal portion of the insulating layer 700 is greater than that of the vertical portion; that is, the material of the vertical portion of the insulating layer 700 is a low-dielectric material, and the material of the horizontal portion is a high-dielectric material. By employing a hybrid dielectric, the insulating layer 700 can reduce edge electric field spikes. The low-dielectric material includes fluorine-doped silicon dioxide (SiOF).

[0050] In one embodiment, the cathode metal layer 800 has an L-shaped structure, with its horizontal portion located above its vertical portion. Specifically, the vertical portion of the cathode metal layer 800 is disposed on the front side of the ohmic metal cathode 300 and contacts the insulating layer 700. The horizontal portion of the cathode metal layer 800 is disposed on the front side of both the vertical portion of the cathode metal layer 800 and the horizontal portion of the insulating layer 700. Figure 2 As shown, in one example, the horizontal portion of the Schottky metal anode 600 and the horizontal portion of the cathode metal layer 800 are the same size and do not contact each other. The horizontal portions of the Schottky metal anode 600 and the cathode metal layer 800 can be connected to an external circuit to receive voltage. Furthermore, since the horizontal portions of the Schottky metal anode 600 and the cathode metal layer 800 are located on the same horizontal plane, they can be fabricated using the same mask, simplifying the manufacturing process.

[0051] The horizontal portion of the Schottky metal anode 600 and the horizontal portion of the cathode metal layer 800 can achieve the effect of a uniform electric field, thereby increasing the breakdown voltage.

[0052] In one embodiment, the distance between the horizontal portion of the Schottky metal anode 600 and the horizontal portion of the cathode metal layer 800 is greater than the width of the protrusion of the Schottky metal anode 600.

[0053] In one embodiment, the ohmic metal cathode 300 is disposed on the front side of the first channel step layer 210. When a forward bias is applied to the gallium nitride Schottky diode, electrons can be transported to the ohmic metal cathode 300 through the two-dimensional electron gas and the first channel step layer 210. Figure 1 As shown, in one example, the first channel step layer 210 is disposed to the left of the second channel step layer 220, the ohmic metal cathode 300 is disposed on the front of the first channel step layer 210, and the vertical portion of the insulating layer 700 is disposed between the ohmic metal cathode 300 and the second channel step layer 220.

[0054] In another embodiment, the ohmic metal cathode 300 is disposed on the front side of the semiconductor substrate 100 and contacts the side surface of the first channel step layer 210. For example... Figure 2 As shown, in one example, the ohmic metal cathode 300 is disposed on the front side of the semiconductor substrate 100 and contacts the left side of the first channel step layer 210. Compared with the above embodiment, by extending the ohmic metal cathode 300 downward to the surface of the semiconductor substrate 100, so that the ohmic metal cathode 300 contacts the side of the first channel step layer 210, the on-resistance can be reduced and the on-current can be increased.

[0055] In one embodiment, the ohmic metal cathode 300, ohmic metal anode 500, Schottky metal anode 600, and cathode metal layer 800 can all employ a multilayer metal structure. In one example, both the ohmic metal cathode 300 and the ohmic metal anode 500 include titanium (Ti), aluminum (Al), and gold (Au) layers stacked sequentially from bottom to top. The protrusions of the Schottky metal anode 600 and the vertical portions of the cathode metal layer 800 are made of any one of nickel nitride (N2Ni3), aluminum (Al), and platinum (Pt) to form a Schottky contact with the barrier layer 400. The horizontal portions of the Schottky metal anode 600 and the horizontal portions of the cathode metal layer 800 are made of gold (Au) to improve conductivity.

[0056] Figure 3 A flowchart illustrating the fabrication method of the gallium nitride Schottky diode according to the second embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are detailed below:

[0057] A method for fabricating a gallium nitride Schottky diode, which can be used to fabricate the gallium nitride Schottky diode of any of the above embodiments. The method for fabricating a gallium nitride Schottky diode includes steps S100 to S700:

[0058] In step S100, a channel layer 200 and a barrier layer 400 are sequentially formed on the semiconductor substrate 100. For example... Figure 4 As shown, in one example, after step S100 is performed, the channel layer 200 is disposed on the front side of the semiconductor substrate 100, and the semiconductor substrate 100, the channel layer 200 and the barrier layer 400 are stacked in sequence.

[0059] In step S200, the edges of the barrier layer 400 and the first side of the channel layer 200 are etched to divide the channel layer 200 into a first channel step layer 210 and a second channel step layer 220. The thickness of the first channel step layer 210 is less than the thickness of the second channel step layer 220. Figure 5 As shown, in one example, the first side corresponds to the left side. After step S200 is executed, the left side of the barrier layer 400 is etched away from the edge, and the channel layer 200 is also divided into the first channel step layer 210 on the left side and the second channel step layer 220 on the right side that has not been etched.

[0060] In step S300, an insulating material is deposited on the barrier layer 400 and the channel layer 200 to form an insulating layer 700. The insulating layer 700 has an L-shaped structure. Figure 6 As shown, in one example, after step S300 is performed, the top of the first channel step layer 210 is filled with the insulating layer 700, and the entire front side of the barrier layer 400 is also covered with the insulating layer 700.

[0061] In step S400, the edge of the first side of the insulating layer 700 is etched until the channel layer 200 is exposed to form a cathode-filled trench 910. The edge of the second side of the insulating layer 700 is then etched until the barrier layer 400 is exposed to form an anode-filled trench 920. The first side and the second side are opposite each other. Figure 7 As shown, in one example, the first side corresponds to the left side and the second side corresponds to the right side. After performing step S300, the formed cathode filling trench 910 is located above the first channel step layer 210, and the formed anode filling trench 920 is located above the barrier layer 400.

[0062] In step S500, ohmic metal material is deposited at the bottom of the cathode filling trench 910 to form an ohmic metal cathode 300, and ohmic metal material is deposited in the anode filling trench 920 to form an ohmic metal anode 500. Figure 8 As shown, in one example, after performing step S500, the thickness of the formed ohmic metal cathode 300 is less than the depth of the cathode filling trench 910, thereby forming a trench with the ohmic metal cathode 300 as the bottom and the insulating layer as the sidewall, and the thickness of the formed ohmic metal anode 500 is equal to the depth of the anode filling trench 920.

[0063] In step S600, the edge of the second side of the insulating layer 700 is etched until a portion of the barrier layer 400 is etched to form a Schottky-filled trench 930. The Schottky-filled trench 930 is located between the insulating layer 700 and the ohmic metal anode 500. Figure 9 As shown, in one example, after step S600 is performed, a Schottky-filled trench 930 is formed on the left side of the ohmic metal anode 500 (that is, on the right side of the insulating layer 700), and the Schottky-filled trench 930 is located between the insulating layer 700 and the ohmic metal anode 500.

[0064] In step S700, Schottky metal material is deposited within the Schottky filled trench 930 to form a Schottky metal anode 600. The Schottky metal anode 600 has a convex structure, with the protrusion located within the Schottky filled trench 930, and the horizontal portion of the Schottky metal anode 600 positioned on the horizontal portion of the insulating layer 700. Figure 10 As shown, in one example, after performing step S700, the Schottky metal anode 600 has a T-shaped structure. The thickness of the protrusion of the Schottky metal anode 600 is equal to the depth of the Schottky filling trench 930. The protrusion of the Schottky metal anode 600 is located between the insulating layer 700 and the ohmic metal anode 500, and contacts both the insulating layer 700 and the ohmic metal anode 500 respectively. Step S700 can be performed in two steps: first, the protrusion of the Schottky metal anode 600 can be deposited, and then the horizontal portion of the Schottky metal anode 600 can be deposited.

[0065] In step S800, a cathode metal layer 800 is formed on the ohmic metal cathode 300. For example... Figure 1 As shown, in one example, after step S800, the cathode metal layer 800 has an L-shaped structure. The vertical portion of the cathode metal layer 800 is disposed on the front side of the ohmic metal cathode 300 and contacts the insulating layer 700. The horizontal portion of the cathode metal layer 800 is disposed on the front side of both the vertical portion and the front side of the insulating layer 700. Step S800 can be performed in two steps: first, the vertical portion of the cathode metal layer 800 can be deposited, and then the horizontal portion of the cathode metal layer 800 can be deposited.

[0066] In one embodiment, the horizontal portion of the Schottky metal anode 600 and the horizontal portion of the cathode metal layer 800 are the same size and do not contact each other, and are used to connect to an external circuit to receive voltage. Since the horizontal portions of the Schottky metal anode 600 and the cathode metal layer 800 are located on the same horizontal plane, they can be fabricated using the same mask to simplify the manufacturing process.

[0067] Steps S800 and S700 can be performed simultaneously to reduce the overall production time.

[0068] When a high forward bias voltage is applied to the Schottky metal anode 600 and the ohmic metal cathode 300, the high voltage can open the Schottky contact formed between the Schottky metal anode 600 and the barrier layer 400. Therefore, current can be transferred to the two-dimensional electron gas through both the Schottky metal anode 600 and the ohmic metal anode 500, thereby significantly increasing the conduction current and exhibiting high voltage resistance.

[0069] In one embodiment, the barrier layer 400 is etched to a depth less than half the thickness of the barrier layer 400. By embedding a Schottky metal anode 600 into the barrier layer 400 in a Schottky contact with the barrier layer 400, the on / off state of the two-dimensional electron gas can be controlled by applying a voltage to the Schottky metal anode 600, thereby forming a diode.

[0070] In one embodiment, in steps S100 and S300, known methods such as chemical vapor deposition (CVD) can be used to deposit the channel layer 200, barrier layer 400 and insulating layer 700. This embodiment does not limit the deposition method of the channel layer 200, barrier layer 400 and insulating layer 700.

[0071] In one embodiment, in steps S200, 400 and S600, known methods such as inductively coupled plasma (ICP) can be used to etch the channel layer 200, barrier layer 400 and insulating layer 700. This embodiment does not limit the etching methods of the channel layer 200, barrier layer 400 and insulating layer 700.

[0072] In one embodiment, in steps S500 and S700, the ohmic metal cathode 300, ohmic metal anode 500, Schottky metal anode 600, and cathode metal layer 800 can be constructed using known methods such as vacuum evaporation or sputtering. This embodiment does not limit the specific construction methods of the ohmic metal cathode 300, ohmic metal anode 500, Schottky metal anode 600, and cathode metal layer 800. In one example, the ohmic metal cathode 300 and ohmic metal anode 500 can be constructed using sputtering, and the Schottky metal anode 600 and cathode metal layer 800 can be constructed using vacuum evaporation.

[0073] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0074] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0075] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0076] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A gallium nitride Schottky diode, characterized in that, include: Semiconductor substrate; The channel layer includes a first channel step layer and a second channel step layer that are in contact with each other. Both the first channel step layer and the second channel step layer are disposed on the front side of the semiconductor substrate. The thickness of the first channel step layer is less than the thickness of the second channel step layer. An ohmic metal cathode is in contact with the first channel stepped layer; A barrier layer is disposed on the front of the second channel step layer; An insulating layer has an L-shaped structure, with its vertical portion disposed between the ohmic metal cathode and the second channel step layer, and its horizontal portion disposed on the barrier layer. The Schottky metal anode has a convex structure, with the convex portion of the Schottky metal anode embedded in the barrier layer, and the horizontal portion of the Schottky metal anode disposed on the horizontal portion of the insulating layer; An ohmic metal anode is disposed on the front side of the barrier layer and in contact with the Schottky metal anode; wherein the protrusion of the Schottky metal anode is disposed between the ohmic metal anode and the horizontal portion of the insulating layer; A cathode metal layer is disposed on the ohmic metal cathode.

2. The gallium nitride Schottky diode as described in claim 1, characterized in that, The cathode metal layer has an L-shaped structure. The vertical portion of the cathode metal layer is disposed on the ohmic metal cathode and in contact with the insulating layer; the horizontal portion of the cathode metal layer is disposed above the insulating layer.

3. The gallium nitride Schottky diode as described in claim 1, characterized in that, The cathode metal layer is made of Schottky metal.

4. The gallium nitride Schottky diode as described in claim 1, characterized in that, The protrusions of the Schottky metal anode penetrate into the barrier layer to a depth less than half the thickness of the barrier layer.

5. The gallium nitride Schottky diode as described in any one of claims 2-4, characterized in that, The ohmic metal cathode is disposed on the front side of the first channel stepped layer.

6. The gallium nitride Schottky diode as described in any one of claims 2-4, characterized in that, The ohmic metal cathode is disposed on the front side of the semiconductor substrate and contacts the side of the first channel step layer.

7. The gallium nitride Schottky diode as described in any one of claims 2-4, characterized in that, The semiconductor substrate is made of silicon carbide, the channel layer is made of N-type gallium nitride, the barrier layer is made of aluminum gallium nitride, and the insulating layer is made of a high-dielectric material.

8. The gallium nitride Schottky diode as described in any one of claims 2-4, characterized in that, The dielectric constant of the horizontal portion of the insulating layer is greater than the dielectric constant of the vertical portion of the insulating layer.

9. A method for fabricating a gallium nitride Schottky diode, characterized in that, include: A channel layer and a barrier layer are sequentially formed on a semiconductor substrate; The barrier layer is etched and the edge of the first side of the channel layer is etched to divide the channel layer into a first channel step layer and a second channel step layer; wherein the thickness of the first channel step layer is less than the thickness of the second channel step layer. An insulating layer is formed by depositing insulating material on the barrier layer and the channel layer; wherein the insulating layer has an L-shaped structure. The edge of the first side of the insulating layer is etched until the channel layer is exposed to form a cathode-filled trench, and the edge of the second side of the insulating layer is etched until the barrier layer is exposed to form an anode-filled trench; the first side and the second side are opposite to each other. An ohmic metal material is deposited at the bottom of the cathode filling trench to form an ohmic metal cathode, and an ohmic metal material is deposited in the anode filling trench to form an ohmic metal anode; The edge of the second side of the insulating layer is etched until a portion of the barrier layer is etched to form a Schottky-filled trench; the Schottky-filled trench is located between the insulating layer and the ohmic metal anode; Schottky metal material is deposited in the Schottky filling trench to form a Schottky metal anode; wherein the Schottky metal anode has a convex structure, the convex portion of the Schottky metal anode is located in the Schottky filling trench, and the horizontal portion of the Schottky metal anode is disposed on the horizontal portion of the insulating layer; A cathode metal layer is formed on the ohmic metal cathode.

10. The method for fabricating a gallium nitride Schottky diode as described in claim 9, characterized in that, The barrier layer is etched to a depth less than half the thickness of the barrier layer.

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