Gallium nitride diode device structure and manufacturing method

Abstract

The invention relates to a gallium nitride diode device structure and a manufacturing method. The AlGaN / GaN heterojunction field effect transistor comprises a substrate, an AlN layer, a GaN buffer layer, a GaN channel layer, an AlN space layer, an AlGaN barrier layer, a p-GaN layer, an ohmic contact structure and a Schottky structure, the Schottky structure is respectively contacted with the p-GaN surface and the ohmic contact structure; the bonding pad structure is in contact with the ohmic contact structure and / or the Schottky structure, or part of the bonding pad structure serves as a part of the Schottky structure and is in contact with the p-GaN layer; each of the first ohmic contact layer and the second ohmic contact layer comprises a bottom layer, an upper layer and a plurality of intermediate layers arranged between the bottom layer and the upper layer, the bottom layer is of a porous Ti structure, the upper layer is of a first metal structure, and the plurality of intermediate layers are respectively of a second metal structure and / or a porous Ti structure. The turn-on voltage range of the device can be flexibly adjusted.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a gallium nitride diode device structure and a manufacturing method thereof. Background Art

[0002] Gallium nitride (GaN) has excellent electron transmission capability, high breakdown electric field and electron saturation velocity, and has great potential in microwave / millimeter wave high-power devices and power electronics. This is because the electron mobility of GaN materials is high, and the transmission speed of electrons in them is much faster than that of traditional silicon-based materials. The breakdown electric field of GaN is about ten times that of silicon, and it can maintain stable operation under high voltage conditions. This material can work effectively at extremely high frequencies and is suitable for high-frequency application scenarios.

[0003] At present, GaN-based devices have been used in various power amplifiers, radio frequency devices and high-power power electronic equipment. However, the existing technology still has the following defects in the preparation and structural design of GaN devices: Ohmic contact is the key part of power devices to introduce current into GaN materials from the outside. The traditional ohmic contact design has the problem of unstable interface between metal and GaN, which leads to high contact resistance and affects the overall performance of the device.

[0004] Due to the hardness and high temperature stability of GaN materials, it is relatively difficult to form ohmic contact metal with stable low contact resistance, especially in high temperature and high voltage applications. The stability of ohmic contact directly affects the performance and life of the device.

[0005] The contact control between the Schottky contact metal and p-GaN in the prior art is not precise enough, which makes it difficult to accurately adjust the turn-on voltage, affecting the adjustability and response speed of the device.

[0006] In the high-temperature alloy process, the thermal stability of the ohmic contact metal and Schottky metal stack is poor, especially in the high-temperature alloy process, metal diffusion is prone to occur, which in turn affects the stability and performance of the device.

[0007] The formation process of existing Ohmic contacts and Schottky contacts is complicated, and it is difficult to achieve low-cost, mass production on a large scale. Summary of the invention

[0008] To overcome at least one technical problem in the prior art, the present invention provides a gallium nitride diode device structure and a manufacturing method.

[0009] In order to solve the above technical problems, the present invention provides a gallium nitride diode device structure, comprising: substrate; An AlN layer is disposed on the substrate; A GaN buffer layer is disposed on the AlN layer, wherein step structures are disposed on both sides of the GaN buffer layer; A GaN channel layer is disposed on a high step surface of the step structure; An AlN space layer is disposed on the GaN channel layer; An AlGaN barrier layer is disposed on the AlN space layer; A p-GaN layer, disposed on the AlGaN barrier layer; An ohmic contact structure, comprising a first ohmic contact layer and a second ohmic contact layer; wherein the first ohmic contact layer extends from a low step surface of the step structure on one side to the surface of the p-GaN layer, and the second ohmic contact layer extends from a low step surface of the step structure on the other side to the surface of the p-GaN layer or is directly disposed on the surface of the p-GaN layer; A Schottky structure, contacting the p-GaN surface and the ohmic contact structure respectively; A pad structure, contacting the ohmic contact structure and / or the Schottky structure, or a portion of the pad structure as a part of the Schottky structure and contacting the p-GaN layer; Among them, the first ohmic contact layer and the second ohmic contact layer each include a bottom layer, an upper layer and a plurality of intermediate layers arranged between the bottom layer and the upper layer, the bottom layer is a porous Ti structure, the upper layer is a first metal structure, and the plurality of intermediate layers are respectively a second metal structure and / or a porous Ti structure.

[0010] In one embodiment of the present invention, the Schottky structure adopts a multi-layer high-stress metal stacking structure, and each layer of metal of the multi-layer high-stress metal stacking structure includes Ni, Cr, Pt, Rh or Ru.

[0011] In one embodiment of the present invention, at least one of the following features is also included: The width of the contact surface between the Schottky structure and the surface of the p-GaN layer is in the range of 2 to 20 um; The height of the step structure is 0.1-2 um.

[0012] In one embodiment of the present invention, two intermediate layers are provided, including a first intermediate layer and a second intermediate layer arranged in sequence along the bottom layer, the first intermediate layer is made of Al, the second intermediate layer is made of a porous Ti structure, and the upper layer is made of the metal structure including Al or Au.

[0013] In one embodiment of the present invention, two intermediate layers are provided, including a first intermediate layer and a second intermediate layer arranged in sequence along the bottom layer, the second intermediate layer is made of Al, and the material of the second intermediate layer includes Ti, Ni, Pt, Rh or Ru, and the upper layer uses the material of the metal structure including Al or Au.

[0014] In one embodiment of the present invention, the first ohmic contact layer and the second ohmic contact layer both extend from the corresponding low step surface of the step structure to the surface of the p-GaN layer; The pad structure includes a first pad and a second pad; wherein the first pad and the second pad are respectively in contact with the first ohmic contact layer and the second ohmic contact layer corresponding to the p-GaN layer.

[0015] In one embodiment of the present invention, the first ohmic contact layer and the second ohmic contact layer both extend from the corresponding low step surface of the step structure to the surface of the p-GaN layer; The pad structure includes a first pad and a second pad; wherein the first pad is in contact with the Schottky structure and the first ohmic contact layer located above the p-GaN layer, respectively; The second pad contacts the second ohmic contact layer located above the p-GaN layer.

[0016] In one embodiment of the present invention, the first ohmic contact layer extends from the corresponding low step surface of the step structure to the surface of the p-GaN layer, and the second ohmic contact layer is directly disposed on the surface of the p-GaN layer; The pad structure includes a first pad and a second pad; wherein the first pad is in contact with the Schottky structure and the first ohmic contact layer located above the p-GaN layer, respectively, or the first pad serves as a part of the Schottky structure; The second pad contacts the second ohmic contact layer.

[0017] In one embodiment of the present invention, the first ohmic contact layer extends from the corresponding low step surface of the step structure to the surface of the p-GaN layer, and the second ohmic contact layer is directly disposed on the surface of the p-GaN layer; The pad structure includes a first pad and a second pad; wherein the first ohmic contact layer and the second ohmic contact layer located above the p-GaN layer are both provided with openings, and the Schottky structure includes a first Schottky structure and a second Schottky structure, the first Schottky structure contacts the first ohmic contact layer and extends to contact the p-GaN surface corresponding to the opening; the second Schottky structure contacts the second ohmic contact layer and extends to contact the p-GaN surface corresponding to the opening; The surfaces of the first Schottky structure and the second Schottky structure are both provided with grooves, the first pad extends into the groove of the first Schottky structure and contacts the surface of the first Schottky structure, and the second pad extends into the groove of the first Schottky structure and contacts the surface of the first Schottky structure.

[0018] The present invention also provides a method for manufacturing a gallium nitride diode device structure, comprising: providing a substrate; Growing a multilayer epitaxial structure in sequence on the surface of the substrate, the epitaxial structure comprising an AlN layer, a GaN buffer layer, a GaN channel layer, an AlN space layer, an AlGaN barrier layer and a p-GaN layer arranged in sequence along the surface of the substrate; Grooving is respectively performed on both sides of the epitaxial structure so that a step structure is formed on both sides of the GaN buffer layer, and the GaN channel layer, the AlN space layer, the AlGaN barrier layer and the p-GaN layer are sequentially arranged along the high step surface of the step structure; A first ohmic contact layer and a second ohmic contact layer are manufactured, and an ohmic contact is formed by a high-temperature alloy at a temperature of 600-900°C and a duration of 10-120s under an atmospheric environment; wherein the first ohmic contact layer extends from a low step surface of the step structure on one side to the surface of the p-GaN layer, and the second ohmic contact layer extends from a low step surface of the step structure on the other side to the surface of the p-GaN layer or is directly disposed on the surface of the p-GaN layer, and the first ohmic contact layer and the second ohmic contact layer both include a bottom layer, an upper layer, and a plurality of intermediate layers disposed between the bottom layer and the upper layer, wherein the bottom layer is a porous Ti structure, the upper layer is a first metal structure, and the plurality of intermediate layers are respectively a second metal structure and / or a porous Ti structure, and the porous Ti structure is formed by a porous template or by a high-speed coating method with a coating rate of 5-20A / s; A Schottky structure is manufactured by a multi-layer metal stacking method, wherein the Schottky structure is in contact with the p-GaN surface and the ohmic contact structure respectively; A pad structure is manufactured, wherein the pad structure is in contact with the ohmic contact structure and / or the Schottky structure, or a portion of the pad structure serves as a part of the Schottky structure and is in contact with the p-GaN layer.

[0019] The above technical solution of the present invention has the following advantages compared with the prior art: The gallium nitride diode device structure and manufacturing method described in the present invention can flexibly adjust the turn-on voltage range of the device by controlling the contact area between the Schottky structure and the surface of the p-GaN layer, and is suitable for different application scenarios.

[0020] The present invention adopts a porous Ti structure as the bottom layer of the ohmic contact, combined with multiple intermediate layers and an upper metal structure, which effectively reduces the contact resistance, solves the problem of metal and GaN interface instability in the ohmic contact design, improves the overall performance of the device, and is particularly suitable for operation under high temperature and high pressure conditions.

[0021] The present invention enhances the thermal stability and electric field control capability of the device by forming a Schottky structure through a multi-layer metal stack. The high stress metal stack in the multi-layer metal can increase the built-in electric field, making it easier to adjust the turn-on voltage of the Schottky contact. The turn-on voltage can be accurately controlled by adjusting the width of the Schottky contact surface according to demand, thereby improving the response speed and adjustability of the device.

[0022] The pad structure of the present invention can contact the ohmic contact layer and the Schottky structure, and some pads can even be combined with the Schottky structure, which simplifies the packaging process and enhances the stability and reliability of the device. In addition, the welding is not affected by the surface morphology through the hole design of the ohmic contact, which is conducive to the implementation of the subsequent wire bonding packaging process.

[0023] The ohmic contact production of the present invention adopts a high-temperature alloy process of 600~900℃, controls the heating rate and oxidation process, especially generates a TiO2 barrier layer by combining the porous Ti structure with oxygen, effectively improves the thermal stability of the ohmic contact metal layer, reduces the problem of metal diffusion in the high-temperature alloy process, and ensures the long-term stability of the device.

[0024] The present invention simplifies the manufacturing process and is conducive to achieving low-cost and mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0026] Figure 1 It is a schematic diagram of the structure of the gallium nitride diode device in Example 1 of the present invention.

[0027] Figure 1 (a) is a schematic diagram of the ohmic contact structure in Example 1 of the present invention.

[0028] Figure 2 It is a schematic diagram of the ohmic contact structure in Example 2 of the present invention.

[0029] Figure 3 It is a schematic diagram of the structure of the gallium nitride diode device in Example 3 of the present invention.

[0030] Figure 4 It is a schematic diagram of the structure of a gallium nitride diode device in Example 4 of the present invention.

[0031] Figure 5 It is a schematic diagram of the structure of the gallium nitride diode device in Example 5 of the present invention.

[0032] Figure 6 It is a schematic diagram of the structure of the gallium nitride diode device in Example 6 of the present invention.

[0033] Figure 7 4 is a diode VI curve corresponding to different widths Ls of the contact surface between the Schottky structure of the present invention and the surface of the p-GaN layer (5 μm, 7 μm, and 9 μm, respectively).

[0034] Description of the Figures in the Specification: 1. Substrate; 2. Epitaxial structure; 21. AlN layer; 22. GaN buffer layer; 221. Step structure; 23. GaN channel layer; 24. AlN space layer; 25. AlGaN barrier layer; 26. p-GaN layer; 3a, first ohmic contact layer; 3b, second ohmic contact layer; 31, bottom layer; 32, first intermediate layer; 33, second intermediate layer; 34, upper layer; 4. Schottky structure; 4a. first Schottky structure; 4b. second Schottky structure; 5. Pad structure; 5a. First pad; 5b. Second pad. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0036] In the present invention, if directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solution of the present invention, and does not indicate or imply that the technical features referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention.

[0037] In the present invention, "several" means one or more, "multiple" means more than two, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself. In the description of the present invention, if there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0038] In the present invention, unless otherwise clearly defined, the words "set", "install", "connect" and the like should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium; they can be fixedly connected or detachably connected or integrally formed; they can be mechanically connected or electrically connected or able to communicate with each other; they can be the internal connection of two elements or the interaction relationship between two elements. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0039] Example 1 Reference Figure 1 As shown, a gallium nitride diode device structure of this embodiment includes: Substrate 1; An AlN layer 21 is disposed on the substrate 1; A GaN buffer layer 22 is disposed on the AlN layer 21, wherein step structures 221 are disposed on both sides of the GaN buffer layer 22; The GaN channel layer 23 is disposed on the high step surface of the step structure 221; An AlN space layer 24 is disposed on the GaN channel layer 23; An AlGaN barrier layer 25 is disposed on the AlN space layer 24; A p-GaN layer 26, disposed on the AlGaN barrier layer 25; An ohmic contact structure, comprising a first ohmic contact layer 3a and a second ohmic contact layer 3b; wherein the first ohmic contact layer 3a and the second ohmic contact layer 3b are symmetrically arranged and both extend from the corresponding low step surface of the step structure 221 to the surface of the p-GaN layer 26; A Schottky structure 4, contacting the p-GaN surface and the first ohmic contact layer 3a respectively; The pad structure 5 includes a first pad 5a and a second pad 5b; wherein the first pad 5a and the second pad 5b are respectively in contact with the first ohmic contact layer 3a and the second ohmic contact layer 3b corresponding to the p-GaN layer 26.

[0040] Reference Figure 1 As shown in (a), the first ohmic contact layer 3a and the second ohmic contact layer 3b each include four layers, namely a bottom layer 31, a first intermediate layer 32, a second intermediate layer 33, and an upper layer 34. The bottom layer 31 is a porous Ti structure, the first intermediate layer 32 is Al, the second intermediate layer 33 is a porous Ti structure, and the upper layer 34 is Au.

[0041] Specifically, the pore size of the porous Ti structure may be between 0.5 and 10 nm. The thicknesses of the bottom layer 31 to the top layer are 10-50 nm, 50-300 nm, 50-500 nm, and 10-300 nm, respectively.

[0042] Specifically, the Schottky structure 4 adopts a multi-layer high stress metal stack structure, and each layer of metal of the multi-layer high stress metal stack structure includes Ni, Cr, Pt, Rh or Ru, etc., and the bottom layer can be Ni, Cr, Rh, Ru. The high stress metal stack can increase the built-in electric field of the epitaxial, which is conducive to more effective regulation of the turn-on voltage.

[0043] Specifically, the width of the contact surface between the Schottky structure 4 and the surface of the p-GaN layer 26 ( LS ) ranges from 2 to 20 um, and the turn-on voltage is adjusted by controlling the contact area between the Schottky structure 4 and the p-GaN layer 26 surface, and the turn-on voltage is between 0.5 and 10 V. Figure 7 As shown, the width of the contact surface between different Schottky structures 4 and the surface of the p-GaN layer 26 LS The diode VI curves corresponding to the 5μm, 7μm, and 9μm diameters are shown in Figure 1, where the horizontal axis is the forward voltage (VF) and the vertical axis is the current (I). As can be seen in the figure, as LS As the turn-on voltage of the device (the position where the curve starts to rise significantly) increases, the turn-on voltage of the device decreases. LS =5μm starts to conduct at a lower voltage (about 5V), while the curve with 𝐿𝑠=9𝜇𝑚 turns on at a higher voltage (about 7V). This is because a larger area of ​​Schottky contact can reduce the resistance of the interface, thereby reducing the turn-on voltage.

[0044] By controlling LS The size of 𝐿𝑠 can adjust the turn-on voltage of the device (i.e. the conduction voltage of the Schottky diode). A larger 𝐿𝑠 provides a larger contact area, making it easier for current to pass, thereby reducing the turn-on voltage.

[0045] Specifically, the height (D) of the step structure 221 is between 0.1 and 2 um.

[0046] Example 2 Reference Figure 2As shown, in this embodiment, different from Embodiment 1, the first ohmic contact layer 3a and the second ohmic contact layer 3b each include four layers, namely a bottom layer 31, a first intermediate layer 32, a second intermediate layer 33, and an upper layer 34. The bottom layer 31 is a porous Ti structure, the first intermediate layer 32 is made of Al, the second intermediate layer 33 is made of Ti, Ni, Pt, Rh or Ru, and the upper layer 34 is made of Al or Au.

[0047] The rest of the structure is the same as that of Example 1.

[0048] The gallium nitride diode device of this embodiment is bonded to the metal layer through the second intermediate layer 33 (Ti, Ni, Pt, Rh or Ru), and the plating rate is between 0.5 and 2 A / s, which is conducive to a smoother ohmic contact metal surface morphology.

[0049] Example 3 Reference Figure 3 As shown, in this embodiment, different from Embodiment 1, the first ohmic contact layer 3a and the second ohmic contact layer 3b both extend from the corresponding low step surface of the step structure 221 to the surface of the p-GaN layer 26; The pad structure 5 includes a first pad 5a and a second pad 5b; wherein the first pad 5a is in contact with the Schottky structure 4 and the first ohmic contact layer 3a located above the p-GaN layer 26 respectively; The second pad 5 b contacts the second ohmic contact layer 3 b located above the p-GaN layer 26 .

[0050] The rest of the structure is the same as that of Example 1.

[0051] The gallium nitride diode device of this embodiment is in partial contact with the Schottky structure 4 through the first pad 5a, which is beneficial to adjust the constant current characteristic.

[0052] Example 4 Reference Figure 4 As shown, in this embodiment, different from Embodiment 1, the first ohmic contact layer 3a extends from the corresponding low step surface of the step structure 221 to the surface of the p-GaN layer 26, and the second ohmic contact layer 3b is directly disposed on the surface of the p-GaN layer 26; The pad structure 5 includes a first pad 5a and a second pad 5b; wherein the first pad 5a is in contact with the Schottky structure 4 and the first ohmic contact layer 3a located above the p-GaN layer 26 respectively; The second pad 5b contacts the second ohmic contact layer 3b.

[0053] The rest of the structure is the same as that of Example 1.

[0054] The gallium nitride diode device of this embodiment has a unidirectional switching characteristic.

[0055] Example 5 Reference Figure 5 As shown, in this embodiment, different from Embodiment 1, the first ohmic contact layer 3a extends from the corresponding low step surface of the step structure 221 to the surface of the p-GaN layer 26, and the second ohmic contact layer 3b is directly disposed on the surface of the p-GaN layer 26; The pad structure 5 includes a first pad 5a and a second pad 5b; wherein the first pad 5a is a part of (merged with) the Schottky structure 4; The second pad 5b contacts the second ohmic contact layer 3b.

[0056] The rest of the structure is the same as that of Example 1.

[0057] The gallium nitride diode device of this embodiment is combined with the Schottky structure 4 through the first pad 5 a and partially contacts the surface of the p-GaN layer 26 for adjusting the turn-on voltage.

[0058] Example 6 Reference Figure 6 As shown, in this embodiment, different from Embodiment 1, the first ohmic contact layer 3a extends from the corresponding low step surface of the step structure 221 to the surface of the p-GaN layer 26, and the second ohmic contact layer 3b is directly disposed on the surface of the p-GaN layer 26; The pad structure 5 includes a first pad 5a and a second pad 5b; wherein the first ohmic contact layer 3a and the second ohmic contact layer 3b located above the p-GaN layer 26 are both provided with openings, and the Schottky structure 4 includes a first Schottky structure 4a and a second Schottky structure 4b, wherein the first Schottky structure 4a contacts the first ohmic contact layer 3a and extends to contact the p-GaN surface corresponding to the opening; and the second Schottky structure 4b contacts the second ohmic contact layer 3b and extends to contact the p-GaN surface corresponding to the opening; The surfaces of the first Schottky structure 4a and the second Schottky structure 4b are both provided with grooves, the first pad 5a extends into the groove of the first Schottky structure 4a and contacts the surface of the first Schottky structure 4a, and the second pad 5b extends into the groove of the first Schottky structure 4b and contacts the surface of the first Schottky structure 4b.

[0059] The rest of the structure is the same as that of Example 1.

[0060] The gallium nitride diode device of this embodiment has an ohmic contact hole dug under the pad area, which is not affected by the ohmic contact metal surface morphology and is conducive to subsequent wire bonding packaging.

[0061] Example 7 This embodiment provides a method for manufacturing a gallium nitride diode device structure, including: S1, providing a substrate 1; S2, sequentially growing a multilayer epitaxial structure 2 on the surface of the substrate 1, wherein the epitaxial structure 2 includes an AlN layer 21, a GaN buffer layer 22, a GaN channel layer 23, an AlN space layer 24, an AlGaN barrier layer 25 and a p-GaN layer 26 sequentially arranged along the surface of the substrate 1; S3, respectively grooves are formed on both sides of the epitaxial structure 2, so that a step structure 221 is formed on both sides of the GaN buffer layer 22, and the GaN channel layer 23, the AlN space layer 24, the AlGaN barrier layer 25 and the p-GaN layer 26 are sequentially arranged along the high step surface of the step structure 221; S4, making an ohmic contact structure including a first ohmic contact layer 3a and a second ohmic contact layer 3b, in an atmospheric environment, through a high temperature alloy with a temperature of 600-900°C and a duration of 10-120s, forming an ohmic contact and a bottom barrier, wherein a small amount of oxygen can pass through the porous morphology and combine with Ti to form a TiO2 barrier, and the high temperature alloy condition also includes a heating rate of 5-15°C / s; wherein the first ohmic contact layer 3a extends from the low step surface of the step structure 221 on one side to the surface of the p-GaN layer 26, and the second ohmic contact layer 3b extends from the other side The low step surface of the step structure 221 extends to the surface of the p-GaN layer 26 or is directly arranged on the surface of the p-GaN layer 26, the first ohmic contact layer 3a and the second ohmic contact layer 3b each include a bottom layer 31, an upper layer 34 and a plurality of intermediate layers arranged between the bottom layer 31 and the upper layer 34, the bottom layer 31 is a porous Ti structure, the upper layer 34 is a first metal structure, the plurality of intermediate layers are respectively a second metal structure and / or a porous Ti structure, and the porous Ti structure is formed by a porous template or by a high-speed coating method with a coating rate of 5-20A / s; S5, manufacturing a Schottky structure 4 by a multi-layer metal stacking method, wherein the Schottky structure 4 is in contact with the p-GaN surface and the ohmic contact structure respectively; S6 , manufacturing a pad structure 5 , wherein the pad structure 5 is in contact with the ohmic contact structure and / or the Schottky structure 4 , or a portion of the pad structure 5 serves as a portion of the Schottky structure 4 and is in contact with the p-GaN layer 26 .

[0062] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A gallium nitride diode device structure, characterized in that: include: Substrate (1); An AlN layer (21) is disposed on the substrate (1); A GaN buffer layer (22) is disposed on the AlN layer (21), wherein step structures (221) are disposed on both sides of the GaN buffer layer (22); A GaN channel layer (23) is arranged on a high step surface of the step structure (221); An AlN space layer (24) is disposed on the GaN channel layer (23); An AlGaN barrier layer (25) is disposed on the AlN space layer (24); A p-GaN layer (26) is disposed on the AlGaN barrier layer (25); An ohmic contact structure, comprising a first ohmic contact layer (3a) and a second ohmic contact layer (3b); wherein the first ohmic contact layer (3a) extends from a low step surface of the step structure (221) on one side to the surface of the p-GaN layer (26), and the second ohmic contact layer (3b) extends from a low step surface of the step structure (221) on the other side to the surface of the p-GaN layer (26) or is directly arranged on the surface of the p-GaN layer (26); A Schottky structure (4) is in contact with the p-GaN surface and the ohmic contact structure respectively; A pad structure (5) in contact with the ohmic contact structure and / or the Schottky structure (4), or a portion of the pad structure (5) serves as a portion of the Schottky structure (4) and in contact with the p-GaN layer (26); The first ohmic contact layer (3a) and the second ohmic contact layer (3b) each comprise a bottom layer (31), an upper layer (34), and a plurality of intermediate layers arranged between the bottom layer (31) and the upper layer (34), the bottom layer (31) being a porous Ti structure, the upper layer (34) being a first metal structure, and the plurality of intermediate layers being a second metal structure and / or a porous Ti structure.

2. A gallium nitride diode device structure according to claim 1, characterized in that: The Schottky structure (4) adopts a multi-layer high-stress metal stacking structure, and each layer of metal in the multi-layer high-stress metal stacking structure includes Ni, Cr, Pt, Rh and / or Ru.

3. A gallium nitride diode device structure according to claim 1, characterized in that: Also includes at least one of the following features: The width of the contact surface between the Schottky structure (4) and the surface of the p-GaN layer (26) is in the range of 2 to 20 μm; The height of the step structure (221) is between 0.1 and 2 um.

4. The gallium nitride diode device structure according to claim 1, characterized in that: The intermediate layers are provided with two, including a first intermediate layer (32) and a second intermediate layer (33) which are sequentially provided along the bottom layer (31); the first intermediate layer (32) is made of Al, the second intermediate layer (33) is made of a porous Ti structure, and the upper layer (34) is made of the metal structure including Al or Au.

5. The gallium nitride diode device structure according to claim 1, characterized in that: The intermediate layers are provided with two, including a first intermediate layer (32) and a second intermediate layer (33) which are sequentially provided along the bottom layer (31); the material of the second intermediate layer (33) is Al; the material of the second intermediate layer (33) includes Ti, Ni, Pt, Rh or Ru; the material of the metal structure used by the upper layer (34) includes Al or Au.

6. A gallium nitride diode device structure according to claim 1, characterized in that: The first ohmic contact layer (3a) and the second ohmic contact layer (3b) both extend from the corresponding low step surface of the step structure (221) to the surface of the p-GaN layer (26); The pad structure (5) comprises a first pad (5a) and a second pad (5b); wherein the first pad (5a) and the second pad (5b) are respectively in contact with the first ohmic contact layer (3a) and the second ohmic contact layer (3b) corresponding to the p-GaN layer (26).

7. The gallium nitride diode device structure according to claim 1, characterized in that: The first ohmic contact layer (3a) and the second ohmic contact layer (3b) both extend from the corresponding low step surface of the step structure (221) to the surface of the p-GaN layer (26); The pad structure (5) comprises a first pad (5a) and a second pad (5b); wherein the first pad (5a) is in contact with the Schottky structure (4) and the first ohmic contact layer (3a) located above the p-GaN layer (26), respectively; The second pad (5b) contacts the second ohmic contact layer (3b) located above the p-GaN layer (26).

8. The gallium nitride diode device structure according to claim 1, characterized in that: The first ohmic contact layer (3a) extends from the corresponding low step surface of the step structure (221) to the surface of the p-GaN layer (26), and the second ohmic contact layer (3b) is directly arranged on the surface of the p-GaN layer (26); The pad structure (5) comprises a first pad (5a) and a second pad (5b); wherein the first pad (5a) is in contact with the Schottky structure (4) and the first ohmic contact layer (3a) located above the p-GaN layer (26), respectively, or the first pad (5a) serves as a part of the Schottky structure (4); The second pad (5b) contacts the second ohmic contact layer (3b).

9. The gallium nitride diode device structure according to claim 1, characterized in that: The first ohmic contact layer (3a) extends from the corresponding low step surface of the step structure (221) to the surface of the p-GaN layer (26), and the second ohmic contact layer (3b) is directly arranged on the surface of the p-GaN layer (26); The pad structure (5) comprises a first pad (5a) and a second pad (5b); wherein the first ohmic contact layer (3a) and the second ohmic contact layer (3b) located above the p-GaN layer (26) are both provided with openings, and the Schottky structure (4) comprises a first Schottky structure (4a) and a second Schottky structure (4b), wherein the first Schottky structure (4a) contacts the first ohmic contact layer (3a) and extends to contact the p-GaN surface corresponding to the opening; and the second Schottky structure (4b) contacts the second ohmic contact layer (3b) and extends to contact the p-GaN surface corresponding to the opening; The surfaces of the first Schottky structure (4a) and the second Schottky structure (4b) are both provided with grooves, the first pad (5a) extends into the groove of the first Schottky structure (4a) and contacts the surface of the first Schottky structure (4a), and the second pad (5b) extends into the groove of the first Schottky structure (4b) and contacts the surface of the first Schottky structure (4b).

10. A method for manufacturing a gallium nitride diode device structure, characterized in that: include: Providing a substrate (1); A multilayer epitaxial structure (2) is sequentially grown on the surface of the substrate (1), wherein the epitaxial structure (2) comprises an AlN layer (21), a GaN buffer layer (22), a GaN channel layer (23), an AlN space layer (24), an AlGaN barrier layer (25), and a p-GaN layer (26) which are sequentially arranged along the surface of the substrate (1); Grooves are respectively formed on both sides of the epitaxial structure (2), so that a step structure (221) is formed on both sides of the GaN buffer layer (22), and the GaN channel layer (23), the AlN space layer (24), the AlGaN barrier layer (25) and the p-GaN layer (26) are sequentially arranged along the high step surface of the step structure (221); A first ohmic contact layer (3a) and a second ohmic contact layer (3b) are manufactured, and an ohmic contact is formed in an atmospheric environment by using a high-temperature alloy at a temperature of 600 to 900°C and a duration of 10 to 120 seconds; wherein the first ohmic contact layer (3a) extends from a low step surface of the step structure (221) on one side to the surface of the p-GaN layer (26), and the second ohmic contact layer (3b) extends from a low step surface of the step structure (221) on the other side to the surface of the p-GaN layer (26) or is directly arranged on the step structure (221). On the surface of the p-GaN layer (26), the first ohmic contact layer (3a) and the second ohmic contact layer (3b) both comprise a bottom layer (31), an upper layer (34), and a plurality of intermediate layers arranged between the bottom layer (31) and the upper layer (34), the bottom layer (31) being a porous Ti structure, the upper layer (34) being a first metal structure, the plurality of intermediate layers being a second metal structure and / or a porous Ti structure, respectively, the porous Ti structure being formed by a porous template or by a high-speed coating method with a coating rate of 5 to 20 A / s; A Schottky structure (4) is manufactured by a multi-layer metal stacking method, wherein the Schottky structure (4) is in contact with the p-GaN surface and the ohmic contact structure respectively; A pad structure (5) is manufactured, wherein the pad structure (5) contacts the ohmic contact structure and / or the Schottky structure (4), or a portion of the pad structure (5) serves as a portion of the Schottky structure (4) and contacts the p-GaN layer (26).

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