Diode and method of manufacturing the same

Abstract

The application provides a diode and a preparation method thereof. The diode comprises an N-type substrate, an N-type epitaxial layer arranged on one side of the N-type substrate, a plurality of grooves arranged in the N-type epitaxial layer along the length direction of the N-type epitaxial layer, one end of each groove being arranged away from the N-type substrate, and the other end of each groove being in communication with the side of the N-type epitaxial layer away from the N-type substrate, the plurality of grooves comprising a first groove, a second groove and a third groove arranged in sequence, the depth of the first groove and the depth of the third groove being greater than the depth of the second groove, a plurality of P-type epitaxial regions arranged in the plurality of grooves one by one, and a first metal filling region, wherein the P-type epitaxial region in the second groove forms an open groove, and the first metal filling region is arranged in the open groove, thereby solving the problem of poor high-voltage resistance per unit area of the SIC diode device in the prior art.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a diode and a method for its fabrication. Background Technology

[0002] Power diodes are key components of circuit systems and are widely used in civilian products such as high-frequency inverters, digital products, generators, and televisions, as well as in military applications such as satellite receivers, missiles, and aircraft control systems and instruments. Power diodes are expanding in two important directions: (1) towards tens of millions or even tens of thousands of amperes, which can be applied to high-temperature arc wind tunnels, resistance welding machines, and other applications; (2) towards shorter and shorter reverse recovery times, exhibiting a trend towards ultra-fast, ultra-soft, and ultra-durable characteristics, enabling them to play different roles not only in rectification applications but also in various switching circuits. In order to meet the application requirements of low power consumption, high frequency, high temperature, and miniaturization, their withstand voltage, on-resistance, turn-on voltage drop, reverse recovery characteristics, and high-temperature characteristics are becoming increasingly demanding.

[0003] Commonly used power diodes include ordinary rectifier diodes, Schottky rectifier diodes, and PIN rectifier diodes. Each has its own characteristics: Schottky rectifier diodes have a lower on-state voltage drop, a larger leakage current, and a near-zero reverse recovery time. While PIN fast recovery rectifier diodes have a faster reverse recovery time, their on-state voltage drop is very high.

[0004] Currently, with the development of microelectronic devices towards low power consumption, high voltage resistance, and high reliability, the requirements for semiconductor materials are also gradually increasing. Microelectronic devices are increasingly being used in special environments such as high temperature, high radiation, high frequency, and high power. To meet the application requirements of microelectronic devices in areas such as high temperature resistance and radiation resistance, it is necessary to develop new semiconductor materials to maximize the performance of microelectronic devices. Existing silicon and gallium arsenide devices limit the improvement of device and system performance. Third-generation semiconductor materials, represented by silicon carbide (SiC) and gallium nitride (GaN), have become ideal semiconductor materials for fabricating high-temperature, high-power, and radiation-resistant electronic devices due to their wide bandgap and high critical breakdown electric field.

[0005] Currently, the critical breakdown field strength of SiC-based devices (such as high-temperature and power SiC devices, microwave and high-frequency SiC devices, SiC optoelectronic devices, and radiation-resistant devices) is 10 times that of Si materials. The bandgap and thermal conductivity of SiC-based devices are both 3 times that of Si materials, and the intrinsic carrier concentration of SiC-based devices is only one-tenth that of silicon materials. These superior physical properties give SiC-based semiconductor power devices significant advantages in high-frequency, high-temperature, high-power, and high-irradiation environments. SiC can form different crystal structures under different environments, with 3C-SiC, 4H-SiC, and 6H-SiC being the most commonly used. 4H-SiC, with its high bandgap, high hole mobility, and low intrinsic carrier concentration, has become the mainstream material for manufacturing semiconductor devices.

[0006] In existing technologies, the structure of diodes mainly adopts a trench structure. However, the electrical performance of existing trench structure diodes still has significant room for improvement. Because SiC diodes do not have structural optimizations tailored to the material properties of SiC, their performance advantages over Si diodes are not significant in some parameters. Furthermore, the depletion region of SiC diodes during reverse operation is a semi-circular shape, high in the middle and low at both ends, resulting in poor high-voltage withstand performance per unit area. In addition, the manufacturing process for SiC diodes follows the traditional process for Si diodes. Due to the characteristics of SiC material, the manufacturing process is relatively complex, requiring specialized equipment (Al ion implantation, which requires dedicated implantation equipment), leading to higher production costs. Summary of the Invention

[0007] The main objective of this invention is to provide a diode and its fabrication method to solve the problem of poor high voltage withstand performance per unit area in existing SiC diode devices.

[0008] To achieve the above objectives, according to one aspect of the present invention, a diode is provided, comprising: an N-type substrate; an N-type epitaxial layer disposed on one side of the N-type substrate; a plurality of trenches spaced apart along the length direction of the N-type epitaxial layer, one end of each trench being spaced apart from the N-type substrate, and the other end of each trench communicating with the side of the N-type epitaxial layer away from the N-type substrate; the plurality of trenches including a first trench, a second trench, and a third trench disposed sequentially, the depth of the first trench and the depth of the third trench being greater than the depth of the second trench; a plurality of P-type epitaxial regions correspondingly disposed in the plurality of trenches; and a first metal filling region, wherein the P-type epitaxial regions in the second trench form an open groove, and the first metal filling region is disposed in the open groove.

[0009] Furthermore, each groove is a rectangular groove, the depth of the first groove is equal to the depth of the third groove, the width of the first groove is equal to the width of the third groove and both are less than the width of the second groove.

[0010] Furthermore, the diode includes a P-type ion implantation region disposed on an N-type epitaxial layer.

[0011] Furthermore, the doping concentration of the P-type ion implantation region is lower than that of the P-type epitaxial region.

[0012] Furthermore, a P-type ion implantation region is provided on the side of the first trench closer to the second trench, and no P-type ion implantation region is provided on the side of the first trench away from the second trench; and / or P-type ion implantation regions are provided on both opposite sides of the second trench; and / or a P-type ion implantation region is provided on the side of the third trench closer to the second trench, and no P-type ion implantation region is provided on the side of the third trench away from the second trench.

[0013] Furthermore, the depth of the P-type ion implantation region is less than the depth of the trench; and / or the width of the P-type ion implantation region is greater than the width of the first trench and greater than the width of the third trench; and / or the width of the P-type ion implantation region is less than the width of the second trench.

[0014] Furthermore, the material used to fabricate the first metal-filled region includes nickel; and / or an ohmic contact is formed between the first metal-filled region and the P-type epitaxial region.

[0015] Furthermore, the diode includes: a second metal layer disposed on the side of the N-type epitaxial layer away from the N-type substrate; a third metal layer disposed on the side of the second metal layer away from the N-type epitaxial layer; and a back metal layer disposed on the side of the N-type substrate away from the N-type epitaxial layer.

[0016] Furthermore, a Schottky contact is formed between the second metal layer and the N-type epitaxial layer and the P-type epitaxial region; and / or an ohmic contact is formed between the back metal layer and the N-type epitaxial layer.

[0017] Furthermore, the second metal layer includes a titanium metal layer; and / or the third metal layer includes an aluminum metal layer; and / or the back metal layer includes a titanium metal layer, a nickel metal layer, and a silver metal layer disposed sequentially in a direction away from the N-type substrate.

[0018] According to another aspect of the present invention, a diode fabrication method is provided for fabricating the aforementioned diode. The diode fabrication method includes: setting an N-type substrate; setting an N-type epitaxial layer on the N-type substrate; forming a plurality of trenches including a first trench, a second trench, and a third trench on the N-type epitaxial layer by dry etching; filling each trench with P-type epitaxial material to form a plurality of P-type epitaxial regions; removing a portion of the P-type epitaxial region in a second trench by dry etching to form an open groove; and filling the open groove with a first metal to form a first metal-filled region.

[0019] Furthermore, in performing the step of filling the opening groove with the first metal to form the first metal filling region, the diode fabrication method includes: thermally annealing the first metal filling region to form an ohmic contact between the first metal filling region and the corresponding P-type epitaxial region.

[0020] Furthermore, the diode fabrication method includes implanting P-type ions onto an N-type epitaxial layer to form a P-type ion implantation region.

[0021] Furthermore, the diode fabrication method includes: depositing a second metal layer on the side of the N-type epitaxial layer away from the N-type substrate; depositing a third metal layer on the side of the second metal layer away from the N-type epitaxial layer; and depositing a back metal layer on the side of the N-type substrate away from the N-type epitaxial layer.

[0022] Furthermore, when performing the step of setting a third metal layer on the side of the second metal layer away from the N-type epitaxial layer, the diode fabrication method includes: fabricating the third metal layer at a high temperature and thermally annealing the second metal layer to form a Schottky contact between the second metal layer and the N-type epitaxial layer and the P-type epitaxial region.

[0023] According to the technical solution of this invention, the diode of this invention includes: an N-type substrate; an N-type epitaxial layer disposed on one side of the N-type substrate; a plurality of trenches disposed at intervals along the length direction of the N-type epitaxial layer, one end of each trench being spaced apart from the N-type substrate, and the other end of each trench being connected to the side of the N-type epitaxial layer away from the N-type substrate; the plurality of trenches including a first trench, a second trench, and a third trench disposed sequentially, the depth of the first trench and the depth of the third trench being greater than the depth of the second trench; a plurality of P-type epitaxial regions disposed one-to-one in the plurality of trenches; and a first metal filling region, wherein the P-type epitaxial region in the second trench forms an open groove, and the first metal filling region is disposed in the open groove. Thus, the diode of the present invention achieves high performance and high reliability by setting trenches of different depths in the N-type epitaxial layer, setting P-type epitaxial regions in each trench, and forming a first metal-filled region in the opening groove of the P-type epitaxial region in the second trench. This improves the overall electrical performance and application range of the diode, optimizes the shape of the depletion region when the diode device is operating in reverse, making its shape closer to a rectangle, and improves the high voltage withstand performance per unit area of ​​the diode. It solves the problem of poor high voltage withstand performance per unit area of ​​existing SiC diode devices, and can significantly improve the efficiency and stability of power electronic devices. It is particularly suitable for applications in high-power, high-frequency and high-temperature environments, bringing significant benefits to the development of power electronics technology. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 A schematic diagram of the first state during the fabrication process of an embodiment of the diode according to the present invention is shown;

[0026] Figure 2 It shows Figure 1 The diagram shows the second state of the diode during the fabrication process.

[0027] Figure 3 It shows Figure 2 The diagram shows the third state of the diode during its fabrication process.

[0028] Figure 4 It shows Figure 3 The diagram shows the fourth state of the diode during its fabrication process.

[0029] Figure 5 It shows Figure 4 The diagram shows the fifth state of the diode during its fabrication process.

[0030] Figure 6 It shows Figure 5 The diagram shows the sixth state of the diode during its fabrication process.

[0031] Figure 7 It shows Figure 6 The diagram shows the seventh state of the diode during its fabrication process.

[0032] Figure 8 It shows Figure 7 The diagram shows the final state of the diode during the fabrication process.

[0033] Figure 9 It shows Figure 8 The diagram shows the shape of the depletion region of the diode when it is operating in reverse.

[0034] Figure 10 A flowchart illustrating an embodiment of the diode fabrication method according to the present invention is shown.

[0035] The above figures include the following reference numerals:

[0036] 1. N-type substrate;

[0037] 2. N-type epitaxial layer;

[0038] 3. Trench; 31. First trench; 32. Second trench; 33. Third trench;

[0039] 4. P-type extension region; 41. Opening groove;

[0040] 5. First metal filling area;

[0041] 6. P-type ion implantation region;

[0042] 7. Second metal layer;

[0043] 8. Third metal layer;

[0044] 9. Back metal layer. Detailed Implementation

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] like Figures 1 to 9As shown, the present invention provides a diode, comprising: an N-type substrate 1; an N-type epitaxial layer 2 disposed on one side of the N-type substrate 1; a plurality of trenches 3, which are spaced apart along the length of the N-type epitaxial layer 2, one end of each trench 3 being spaced apart from the N-type substrate 1, and the other end of each trench 3 being connected to the side of the N-type epitaxial layer 2 away from the N-type substrate 1; the plurality of trenches 3 including a first trench 31, a second trench 32, and a third trench 33 disposed sequentially, wherein the depth of the first trench 31 and the depth of the third trench 33 are both greater than the depth of the second trench 32; a plurality of P-type epitaxial regions 4, which are disposed one-to-one in the plurality of trenches 3; and a first metal filling region 5, wherein the P-type epitaxial regions 4 in the second trench 32 form an opening groove 41, and the first metal filling region 5 is disposed in the opening groove 41.

[0047] Thus, the diode of the present invention achieves high performance and high reliability by setting trenches 3 of different depths in the N-type epitaxial layer 2, setting P-type epitaxial regions 4 in each trench 3, and forming a first metal filling region 5 in the opening groove 41 of the P-type epitaxial region 4 in the second trench 32. This improves the overall electrical performance and application range of the diode, optimizes the shape of the depletion region when the diode device is working in reverse, making the shape of its depletion region closer to a rectangle, and improves the high voltage withstand performance per unit area of ​​the diode. It solves the problem of poor high voltage withstand performance per unit area of ​​existing SiC diode devices, and can significantly improve the efficiency and stability of power electronic devices. It is particularly suitable for applications in high power, high frequency and high temperature environments, bringing significant benefits to the development of power electronics technology.

[0048] Specifically, the N-type substrate 1 is an N-type silicon carbide substrate, and the N-type epitaxial layer 2 is an N-type silicon carbide epitaxial layer.

[0049] like Figure 2 As shown, each trench 3 is a rectangular trench. The depth of the first trench 31 is equal to the depth of the third trench 33, and the width of the first trench 31 is equal to the width of the third trench 33 and both are less than the width of the second trench 32. This makes the formation of the P-type epitaxial region 4 more uniform, improves the breakdown voltage and current carrying capacity of the diode, and is suitable for high-voltage power transmission and high-current switching applications.

[0050] like Figures 3 to 9 As shown, the diode includes a P-type ion implantation region 6, which is disposed on the N-type epitaxial layer 2. This further optimizes the characteristics of the PN junction, improves the switching speed and efficiency of the diode, and is suitable for high-frequency power conversion and high-speed switching circuits.

[0051] Specifically, the doping concentration of the P-type ion implantation region 6 is lower than that of the P-type epitaxial region 4. By controlling the doping concentration of the P-type ion implantation region 6, the breakdown voltage of the diode can be increased without significantly increasing the leakage current, thereby reducing the diode chip area and manufacturing costs.

[0052] like Figures 3 to 9 As shown, a P-type ion implantation region 6 is provided on the side of the first trench 31 closest to the second trench 32, while no P-type ion implantation region 6 is provided on the side of the first trench 31 furthest from the second trench 32; and / or P-type ion implantation regions 6 are provided on both opposite sides of the second trench 32; and / or a P-type ion implantation region 6 is provided on the side of the third trench 33 closest to the second trench 32, while no P-type ion implantation region 6 is provided on the side of the third trench 33 furthest from the second trench 32. This precise arrangement of the P-type ion implantation region 6 effectively controls the electric field distribution of the diode, reduces electric field concentration, and is suitable for power electronic devices requiring high reliability and long lifespan.

[0053] Specifically, the P-type ion implantation region 6 is rectangular in shape; wherein the depth of the P-type ion implantation region 6 is less than the depth of the trench 3; and / or the width of the P-type ion implantation region 6 is greater than the width of the first trench 31 and greater than the width of the third trench 33; and / or the width of the P-type ion implantation region 6 is less than the width of the second trench 32. This control over the size of the P-type ion implantation region allows for precise adjustment of the diode's electrical performance, improving its adaptability to complex power environments, and making it suitable for various rectification and protection circuits in power systems.

[0054] In the diode of the present invention, the material of the first metal filling region 5 includes nickel, which can form a stable ohmic contact with the P-type epitaxial region, increasing the contact area, improving the ability to handle large currents, and improving the current transmission efficiency of the diode. It is suitable for high-frequency, high-current power electronic applications, such as high-speed switching circuits and high-power rectifiers; and / or the first metal filling region 5 forms an ohmic contact with the P-type epitaxial region 4, which can improve the surge capability, reduce the forward voltage drop, reduce the contact resistance of the diode, and improve its current transmission efficiency while ensuring the withstand voltage performance. It is suitable for power conversion systems that require low loss and high efficiency.

[0055] like Figures 5 to 9As shown, the diode includes: a second metal layer 7, which is disposed on the side of the N-type epitaxial layer 2 away from the N-type substrate 1, suitable for high-frequency, high-power power electronic applications; a third metal layer 8, which is disposed on the side of the second metal layer 7 away from the N-type epitaxial layer 2, improving the diode's heat dissipation capacity and mechanical strength, suitable for power electronic devices requiring good heat dissipation and durability; and a back metal layer 9, which is disposed on the side of the N-type substrate 1 away from the N-type epitaxial layer 2, serving as a heat dissipation path for the diode, suitable for applications in high-power, high-temperature environments.

[0056] In the diode of the present invention, a Schottky contact is formed between the second metal layer 7 and the N-type epitaxial layer 2, the P-type epitaxial region 4, and the P-type ion implantation region 6. This reduces the leakage current of the diode, improves its voltage withstand performance, significantly reduces the switching loss of the diode, and improves its performance in high-frequency switching circuits, making it suitable for high-speed switching power supplies and power electronic converters. And / or an ohmic contact is formed between the back metal layer 9 and the N-type epitaxial layer 2. This improves the surge capability, reduces the forward voltage drop, increases the contact discharge area, reduces the on-resistance of the diode, and improves its ability to handle large currents, making it suitable for high-current, high-power power electronic applications, such as high-voltage direct current transmission and high-power motor drives.

[0057] In the diode of the present invention, the second metal layer 7 includes a titanium metal layer. The introduction of the titanium metal layer enables the formation of a good Schottky contact with the N-type epitaxial layer, reducing the leakage current of the diode, improving the diode's withstand voltage performance, and reducing the diode's switching losses. It is suitable for high-frequency, high-power power electronic devices, such as power inverters and frequency converters. And / or the third metal layer 8 includes an aluminum metal layer. The use of the aluminum metal layer not only improves the diode's heat dissipation capacity but also enhances its mechanical strength. It is suitable for power electronic devices that require good heat dissipation and durability, such as electric vehicle battery management systems and industrial motor drives. And / or the back metal layer 9 includes a titanium metal layer, a nickel metal layer, and a silver metal layer arranged sequentially in a direction away from the N-type substrate 1. Such a multilayer structure can provide stable connection and good heat dissipation performance, making it suitable for applications in high-power, high-temperature environments.

[0058] like Figure 10As shown, the present invention also provides a diode fabrication method for fabricating the aforementioned diode. The diode fabrication method includes: setting an N-type substrate 1; setting an N-type epitaxial layer 2 on the N-type substrate 1; forming a plurality of trenches 3 including a first trench 31, a second trench 32, and a third trench 33 on the N-type epitaxial layer 2 by dry etching; filling each trench 3 with P-type epitaxial material to form a plurality of P-type epitaxial regions 4; removing a portion of the P-type epitaxial region 4 in the second trench 32 by dry etching to form an opening groove 41; and filling the opening groove 41 with a first metal to form a first metal filling region 5.

[0059] When performing the step of filling the first metal into the opening groove 41 to form the first metal filling region 5, the diode fabrication method includes: thermally annealing the first metal filling region 5 to form an ohmic contact between the first metal filling region 5 and the corresponding P-type epitaxial region 4.

[0060] Among them, the temperature of hot annealing is greater than 900℃.

[0061] Specifically, the thermal annealing process can optimize the interface between the metal and the semiconductor (i.e., the first metal filling region 5 and the corresponding P-type epitaxial region 4) so ​​that a low-resistance ohmic contact is formed between the first metal filling region 5 and the corresponding P-type epitaxial region 4, which can significantly improve the current transmission efficiency and reliability of the diode.

[0062] like Figure 10 As shown, the diode fabrication method includes implanting P-type ions into the N-type epitaxial layer 2 to form a P-type ion implantation region 6.

[0063] like Figure 10 As shown, the diode fabrication method includes: depositing a second metal layer 7 on the side of the N-type epitaxial layer 2 away from the N-type substrate 1; depositing a third metal layer 8 on the side of the second metal layer 7 away from the N-type epitaxial layer 2; and depositing a back metal layer 9 on the side of the N-type substrate 1 away from the N-type epitaxial layer 2.

[0064] Specifically, the back metal layer 9 is manufactured using conventional processes and does not undergo high-temperature or heat annealing treatment.

[0065] When performing the step of setting a third metal layer 8 on the side of the second metal layer 7 away from the N-type epitaxial layer 2, the diode fabrication method includes: fabricating the third metal layer 8 at a high temperature and thermally annealing the second metal layer 7 so that Schottky contacts are formed between the second metal layer 7 and the N-type epitaxial layer 2, the P-type epitaxial region 4 and the P-type ion implantation region 6.

[0066] High temperature refers to a temperature greater than 400℃.

[0067] Specifically, high-temperature preparation and thermal annealing can ensure the stability and low-loss characteristics of the Schottky contact between the second metal layer 7 and the N-type epitaxial layer 2, the P-type epitaxial region 4 and the P-type ion implantation region 6, making it suitable for high-frequency, high-power power electronic equipment. It can significantly reduce diode losses and further improve the current transmission efficiency and reliability of the diode.

[0068] The diodes fabricated by the method of this invention not only exhibit excellent electrical performance, such as high breakdown voltage, low on-resistance, and high current carrying capacity, but also possess significant advantages in thermal and mechanical properties, such as good heat dissipation, the use of high-melting-point materials, and enhanced mechanical strength. These characteristics enable the diodes of this invention to be widely used in various power electronic devices, particularly in new energy vehicles, solar inverters, high-voltage direct current transmission, high-power motor drives, aerospace power systems, high-temperature industrial power supplies, and power supplies for large data centers, resulting in significant economic and social benefits. Furthermore, the stability and reliability exhibited by the diodes of this invention under high-frequency, high-current, high-temperature, and high-voltage environments open up new possibilities for the development and application of power electronics technology, contributing to the advancement of power electronic devices towards higher performance, higher efficiency, and wider application areas.

[0069] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0070] The diode of the present invention includes: an N-type substrate 1; an N-type epitaxial layer 2 disposed on one side of the N-type substrate 1; a plurality of trenches 3, which are spaced apart along the length of the N-type epitaxial layer 2, with one end of each trench 3 spaced apart from the N-type substrate 1 and the other end of each trench 3 connected to the side of the N-type epitaxial layer 2 away from the N-type substrate 1; the plurality of trenches 3 include a first trench 31, a second trench 32, and a third trench 33 disposed sequentially, the depth of the first trench 31 and the depth of the third trench 33 being greater than the depth of the second trench 32; a plurality of P-type epitaxial regions 4, which are disposed one-to-one in the plurality of trenches 3; and a first metal filling region 5, in which the P-type epitaxial regions 4 in the second trench 32 form an opening groove 41, and the first metal filling region 5 is disposed in the opening groove 41. Thus, the diode of the present invention achieves high performance and high reliability by setting trenches 3 of different depths in the N-type epitaxial layer 2, setting P-type epitaxial regions 4 in each trench 3, and forming a first metal filling region 5 in the opening groove 41 of the P-type epitaxial region 4 in the second trench 32. This improves the overall electrical performance and application range of the diode, optimizes the shape of the depletion region when the diode device is working in reverse, making the shape of its depletion region closer to a rectangle, and improves the high voltage withstand performance per unit area of ​​the diode. It solves the problem of poor high voltage withstand performance per unit area of ​​existing SiC diode devices, and can significantly improve the efficiency and stability of power electronic devices. It is particularly suitable for applications in high power, high frequency and high temperature environments, bringing significant benefits to the development of power electronics technology.

[0071] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0072] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0073] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0074] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0075] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A diode, characterized in that, include: N-type substrate (1); An N-type epitaxial layer (2) is disposed on one side of the N-type substrate (1); Multiple trenches (3) are spaced apart along the length of the N-type epitaxial layer (2). One end of each trench (3) is spaced apart from the N-type substrate (1), and the other end of each trench (3) is connected to the side of the N-type epitaxial layer (2) away from the N-type substrate (1). The multiple trenches (3) include a first trench (31), a second trench (32), and a third trench (33) arranged sequentially. The depth of the first trench (31) and the depth of the third trench (33) are both greater than the depth of the second trench (32). Multiple P-type epitaxial regions (4) are provided in the multiple trenches (3) in a one-to-one correspondence. Each trench (3) is provided with one P-type epitaxial region (4). The first trench (31) and the third trench (33) are filled with the P-type epitaxial regions (4). The first metal filling area (5) and the P-type extension area (4) in the second groove (32) form an opening groove (41), and the first metal filling area (5) is disposed in the opening groove (41). The diode includes a P-type ion implantation region (6) disposed on the N-type epitaxial layer (2), and the doping concentration of the P-type ion implantation region (6) is less than the doping concentration of the P-type epitaxial region (4); the P-type ion implantation region (6) is disposed on the side of the first trench (31) near the second trench (32), and the P-type ion implantation region (6) is not disposed on the side of the first trench (31) away from the second trench (32); and / or the P-type ion implantation region (6) is disposed on both opposite sides of the second trench (32); and / or the P-type ion implantation region (6) is disposed on the side of the third trench (33) near the second trench (32), and the P-type ion implantation region (6) is not disposed on the side of the third trench (33) away from the second trench (32).

2. The diode according to claim 1, characterized in that, Each of the grooves (3) is a rectangular groove. The depth of the first groove (31) is equal to the depth of the third groove (33). The width of the first groove (31) is equal to the width of the third groove (33) and both are less than the width of the second groove (32).

3. The diode according to claim 1, characterized in that, The depth of the P-type ion implantation region (6) is less than the depth of the trench (3); and / or The width of the P-type ion implantation region (6) is greater than the width of the first trench (31) and greater than the width of the third trench (33); and / or The width of the P-type ion implantation region (6) is smaller than the width of the second trench (32).

4. The diode according to claim 1, characterized in that, The material used to fabricate the first metal-filled region (5) includes nickel; and / or An ohmic contact is formed between the first metal filling region (5) and the P-type epitaxial region (4).

5. The diode according to claim 1, characterized in that, The diode includes: A second metal layer (7) is disposed on the side of the N-type epitaxial layer (2) away from the N-type substrate (1); A third metal layer (8) is disposed on the side of the second metal layer (7) away from the N-type epitaxial layer (2); A back metal layer (9) is disposed on the side of the N-type substrate (1) away from the N-type epitaxial layer (2).

6. The diode according to claim 5, characterized in that, The second metal layer (7) forms a Schottky contact with the N-type epitaxial layer (2) and the P-type epitaxial region (4).

7. The diode according to claim 5, characterized in that, The second metal layer (7) includes a titanium metal layer; and / or The third metal layer (8) includes an aluminum metal layer; and / or The back metal layer (9) includes a titanium metal layer, a nickel metal layer and a silver metal layer arranged sequentially in a direction away from the N-type substrate (1).

8. A method for fabricating a diode, characterized in that, The method for preparing the diode according to any one of claims 1 to 7 comprises: Set an N-type substrate (1); An N-type epitaxial layer (2) is disposed on the N-type substrate (1); Multiple trenches (3) including a first trench (31), a second trench (32) and a third trench (33) are formed on the N-type epitaxial layer (2) by dry etching. P-type epitaxial material is filled into each of the trenches (3) to form multiple P-type epitaxial regions (4). A portion of the P-type epitaxial region (4) within the second trench (32) is removed by dry etching to form an opening groove (41). The first metal is filled into the opening groove (41) to form the first metal filling area (5).

9. The diode fabrication method according to claim 8, characterized in that, When performing the step of filling the opening groove (41) with the first metal to form the first metal filling region (5), the diode fabrication method includes: The first metal filling region (5) is thermally annealed to form an ohmic contact between the first metal filling region (5) and the corresponding P-type epitaxial region (4).

10. The diode fabrication method according to claim 8, characterized in that, The diode fabrication method includes: P-type ions are implanted into the N-type epitaxial layer (2) to form a P-type ion implantation region (6).

11. The diode fabrication method according to claim 8, characterized in that, The diode fabrication method includes: A second metal layer (7) is provided on the side of the N-type epitaxial layer (2) away from the N-type substrate (1); A third metal layer (8) is provided on the side of the second metal layer (7) away from the N-type epitaxial layer (2); A back metal layer (9) is provided on the side of the N-type substrate (1) away from the N-type epitaxial layer (2).

12. The diode fabrication method according to claim 11, characterized in that, When performing the step of setting a third metal layer (8) on the side of the second metal layer (7) away from the N-type epitaxial layer (2), the diode fabrication method includes: The third metal layer (8) is prepared at high temperature, and the second metal layer (7) is thermally annealed to form a Schottky contact between the second metal layer (7) and the N-type epitaxial layer (2) and the P-type epitaxial region (4).

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