Silicon carbide SBD power device terminal structure

Abstract

The invention discloses a silicon carbide SBD power device terminal structure, and belongs to the technical field of device design. An N-type doped 4H-SiC epitaxial layer of the terminal structure grows on an N-type doped 4H-SiC substrate, and the thickness of the N-type doped 4H-SiC epitaxial layer corresponding to a terminal reserved area is lower than that of the N-type doped 4H-SiC epitaxial layer corresponding to an anode metal layer reserved area; the P-type doped 4H-SiC epitaxial layer is located on the surface of the N-type doped 4H-SiC epitaxial layer; the lengths of a plurality of first grooves etched in a terminal area of the P-type doped 4H-SiC epitaxial layer are smaller than the length of a second groove, and the second groove is etched to the edge of the terminal area; the anode metal layer is located in an anode metal layer reserved area of the N-type doped 4H-SiC epitaxial layer; according to the terminal structure, an ion implantation process is not needed, the terminal structure only needs to be formed through an epitaxy process and an etching process, the terminal efficiency is high, and the process cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of device design, and in particular to a silicon carbide SBD power device terminal structure. Background Art

[0002] Silicon carbide (SiC) is a wide bandgap semiconductor material with excellent physical and chemical properties, and has the advantages of high operating temperature, high breakdown voltage, low conduction loss, high switching frequency, and low switching loss. Silicon carbide Schottky diode (SBD) is a semiconductor device based on silicon carbide material with high speed, high temperature, and high power characteristics.

[0003] The edge of the actual silicon carbide SBD power device is relatively steep, and the electric field will gather at the junction edge of the device, that is, the electric field concentration effect, causing the electric field lines here to be denser than elsewhere, and the edge electric field strength is significantly greater than the electric field strength in the body, causing the device to first break down at the junction edge. At this time, the breakdown voltage will be much lower than the breakdown voltage of the ideal parallel plane junction. In order to alleviate the impact of the electric field concentration effect on power devices, the terminal structure is widely used.

[0004] Common terminal structures currently include field plates, junction terminals and field limiting ring structures. However, each has its own limitations. The field plate is usually made of metal or conductive material. Its edge (especially the end) will cause the electric field lines to be dense here due to the sudden change in geometric shape, forming a new electric field peak near the field plate, especially the end. Therefore, although the field plate can expand the depletion region, it often introduces a new electric field concentration point, resulting in premature breakdown. Although the junction terminal process is simple, it is sensitive to the doping concentration, and the silicon carbide junction terminal structure can only be achieved through the ion implantation process. The impurity activation level has high requirements on the activation conditions. Therefore, the junction terminal ion implantation window range corresponding to a certain withstand voltage level is generally narrow, and the terminal efficiency is low. The field limiting ring structure is the most commonly used terminal structure, but both the field limiting ring and the junction terminal technology need to be formed by ion implantation, which greatly increases the cost of device preparation. Therefore, the present invention proposes a new silicon carbide SBD power device terminal structure. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems in the prior art and provide a silicon carbide SBD power device terminal structure.

[0006] The present invention provides a silicon carbide SBD power device terminal structure, comprising: cathode metal layer; An N-type doped 4H-SiC substrate is located on the cathode metal layer; An N-type doped 4H-SiC epitaxial layer is epitaxially grown on the N-type doped 4H-SiC substrate, wherein the N-type doped 4H-SiC epitaxial layer includes a terminal reserved area and an anode metal layer reserved area, and the thickness of the N-type doped 4H-SiC epitaxial layer corresponding to the terminal reserved area is less than the thickness of the N-type doped 4H-SiC epitaxial layer corresponding to the anode metal layer reserved area; A P-type doped 4H-SiC epitaxial layer is located on the N-type doped 4H-SiC epitaxial layer; a terminal area of ​​the P-type doped 4H-SiC epitaxial layer corresponding to the terminal reserved area is etched with a plurality of first grooves and a second groove, and the length of the first groove is less than the length of the second groove; An anode metal layer is located in a reserved region of the anode metal layer of the N-type doped 4H-SiC epitaxial layer; The oxide layer is located on the P-type doped 4H-SiC epitaxial layer.

[0007] Preferably, the second groove is etched to the edge of the terminal area, and a plurality of first grooves are sequentially arranged from a side of the second groove away from the edge to the anode metal layer reserved area.

[0008] Preferably, the number of the first grooves is 1 to 10.

[0009] Preferably, the first trench and the second trench have the same depth, and the etching depth is 0.2 μm to 2 μm and is less than the thickness of the P-type doped 4H-SiC epitaxial layer.

[0010] Preferably, the number of the first grooves is 4, the spacing between the first grooves is 4μm, 6μm and 8μm respectively, the length of the first groove is 1.5μm, the spacing between the second groove and the first groove is 2μm, the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area.

[0011] Preferably, the doping concentration of the N-type doped 4H-SiC substrate is 5×10 18 cm -3 .

[0012] Preferably, the N-type doped 4H-SiC epitaxial layer has a thickness of 10 μm and a doping concentration of 6×10 15 cm -3 ~1×10 16 cm -3 .

[0013] Preferably, the thickness of the P-type doped 4H-SiC epitaxial layer is 0.2 μm to 2 μm, and the doping concentration is 3×10 17 cm -3 ~2×10 18 cm -3 .

[0014] Preferably, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer is obtained by etching the P-type doped 4H-SiC epitaxial layer, and the bottom of the anode metal layer reserved area is in contact with the N-type doped 4H-SiC epitaxial layer or embedded in the N-type doped 4H-SiC epitaxial layer.

[0015] The present invention also discloses a method for preparing the above-mentioned silicon carbide SBD power device terminal structure, comprising the following steps: Obtaining an N-type doped 4H-SiC epitaxial layer by epitaxial growth on an N-type doped 4H-SiC substrate; Etching is performed in the terminal reserved area of ​​the N-type doped 4H-SiC epitaxial layer, with an etching angle of 1°~90° and an etching depth of 0.2μm~2μm; Epitaxially growing a P-type doped 4H-SiC epitaxial layer on the etched N-type doped 4H-SiC epitaxial layer; Etching the P-type doped 4H-SiC epitaxial layer, with an etching angle of 1° to 90° and an etching depth of 0.2 μm to 3 μm, and the etching depth is greater than or equal to the thickness of the P-type doped 4H-SiC epitaxial layer, to form an anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer; Partially etching the terminal region of the P-type doped 4H-SiC epitaxial layer to etch a plurality of first trenches and one second trench; Finally, the anode metal layer and the oxide layer are prepared in sequence to obtain the terminal structure of the silicon carbide SBD power device.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The terminal structure of the silicon carbide SBD power device of the present invention etches and then grows a P-type doped 4H-SiC epitaxial layer in the terminal area, and etches a bevel and a plurality of first grooves and a second groove on the P-type doped 4H-SiC epitaxial layer, so that the electric field distribution at the terminal is uniform, thereby alleviating the edge electric field concentration, so that the terminal structure can better play the charge modulation role. The terminal efficiency of the terminal structure of the silicon carbide SBD power device of the present invention is as high as 97.6%, so that the actual voltage of the device is close to the breakdown voltage of the ideal parallel plane junction to a large extent.

[0017] The preparation of the terminal structure of the present invention does not require an ion implantation process, and only requires the formation of the terminal structure on the silicon carbide SBD power device through epitaxy and etching processes, which can effectively expand the depletion region and make the electric field inside the device uniform, effectively avoiding the electric field concentration effect, and having a high terminal efficiency, so that the actual voltage of the device is close to the breakdown voltage of the ideal parallel plane junction to a large extent, thereby reducing the process cost on the basis of improving the terminal efficiency of the terminal structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The schematic diagram is a structural diagram of an N-type doped 4H-SiC epitaxial layer obtained by epitaxial growth on an N-type doped 4H-SiC substrate according to an embodiment of the present invention.

[0019] Figure 2 It is a schematic diagram of the structure after etching the reserved area of ​​the N-type doped 4H-SiC epitaxial layer terminal according to an embodiment of the present invention.

[0020] Figure 3 It is a schematic structural diagram of an embodiment of the present invention in which a P-type doped 4H-SiC epitaxial layer is epitaxially grown on an etched N-type doped 4H-SiC epitaxial layer.

[0021] Figure 4 It is a schematic structural diagram of an embodiment of the present invention after etching a reserved area of ​​an anode metal layer to form an N-type doped 4H-SiC epitaxial layer on a P-type doped 4H-SiC epitaxial layer.

[0022] Figure 5 This is a schematic diagram of the structure after etching the first trench and the second trench in the terminal region according to an embodiment of the present invention.

[0023] Figure 6 Schematic diagram of the terminal structure of a silicon carbide SBD power device according to an embodiment of the present invention.

[0024] Figure 7 This is a breakdown voltage test diagram of the terminal structure of the silicon carbide SBD power device in Example 1 of the present invention.

[0025] Figure 8 This is a breakdown voltage test diagram of the terminal structure of the silicon carbide SBD power device in Example 2 of the present invention.

[0026] Fig. 9 This is a breakdown voltage test diagram of the terminal structure of the silicon carbide SBD power device in Example 3 of the present invention.

[0027] Description of reference numerals: 1. Cathode metal layer, 2. N-type doped 4H-SiC substrate, 3. N-type doped 4H-SiC epitaxial layer, 4. P-type doped 4H-SiC epitaxial layer, 5. Anode metal layer, 6. Oxide layer. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0029] Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with ordinary skills in the field to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of "including" or "comprising" cover the elements or objects listed after "including" or "comprising" and their equivalents, and do not exclude other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] The present embodiment provides a terminal structure of a silicon carbide SBD power device, comprising a cathode metal layer 1, an N-type doped 4H-SiC substrate 2, an N-type doped 4H-SiC epitaxial layer 3, a P-type doped 4H-SiC epitaxial layer 4, an anode metal layer 5 and an oxide layer 6. The N-type doped 4H-SiC substrate 2 is located on the cathode metal layer 1; the N-type doped 4H-SiC epitaxial layer 3 is epitaxially grown on the N-type doped 4H-SiC substrate 2, and the N-type doped 4H-SiC epitaxial layer 3 comprises a terminal reserved area and an anode metal layer reserved area, and the thickness of the N-type doped 4H-SiC epitaxial layer 3 corresponding to the terminal reserved area is less than the thickness of the N-type doped 4H-SiC epitaxial layer 3 corresponding to the anode metal layer reserved area. The P-type doped 4H-SiC epitaxial layer 4 is located on the N-type doped 4H-SiC epitaxial layer 3; the terminal area of ​​the P-type doped 4H-SiC epitaxial layer 4 corresponding to the terminal reserved area is etched with a plurality of first grooves and a second groove, and the length of the first groove is less than the length of the second groove; the anode metal layer 5 is located in the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3; the oxide layer 6 is located on the P-type doped 4H-SiC epitaxial layer 4. In this embodiment, the electric field concentration is alleviated by etching a plurality of first grooves (i.e., short grooves) and a second groove (i.e., long groove), so that the electric field distribution in the terminal area is more uniform, and the terminal efficiency is improved.

[0031] As a preferred embodiment, the second groove is etched to the edge of the terminal area, which can avoid introducing a new electric field concentration point and effectively improve the terminal efficiency. Multiple first grooves are arranged in sequence from the side of the second groove away from the edge to the anode metal layer reserved area.

[0032] As a preferred embodiment, the number of the first grooves is 1 to 10.

[0033] As a preferred embodiment, the first trench and the second trench have the same depth, and the etching depth is 0.2 μm to 2 μm and is smaller than the thickness of the P-type doped 4H-SiC epitaxial layer 4 .

[0034] As a preferred embodiment, the number of the first grooves is 4, the spacing between the first grooves is 4μm, 6μm and 8μm respectively, the length of the first groove is 1.5μm, the spacing between the second groove and the first groove is 2μm, the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area. Grooves that are too long or too short will lead to uneven electric field distribution, so that the electric field concentration cannot be well alleviated, and the device terminal efficiency is low. If the number of grooves is too small, the electric field concentration cannot be well alleviated. If the number of grooves is too large, it will not significantly improve the efficiency, and it will also waste device area and increase manufacturing costs.

[0035] As a preferred embodiment, the doping concentration of the N-type doped 4H-SiC substrate 2 is 5×10 18 cm -3 The N-type doped 4H-SiC epitaxial layer 3 has a thickness of 10 μm and a doping concentration of 6×10 15 cm -3 ~1×10 16 cm -3 As a preferred method, the doping concentration is 8×10 15 cm -3 The thickness of the P-type doped 4H-SiC epitaxial layer 4 is 0.2 μm~2 μm, and the doping concentration is 3×10 17 cm -3 ~2×10 18 cm -3 .

[0036] The method for preparing the above-mentioned silicon carbide SBD power device terminal structure in this embodiment is as follows: First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0037] Etching is performed in the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 1°~90° and an etching depth of 0.2μm~2μm to obtain Figure 2 It should be noted that, in this embodiment, the etching angle can be any angle between 1° and 90°. For example, the angle can be 1°, 5°, 10°, 15°, 30° or 90°, etc.; similarly, the etching depth can also be any depth between 0.2μm and 2μm. For example, the depth can be 0.2μm, 0.4μm, 0.6μm, 0.8μm, 1.5μm or 2μm, etc.

[0038] A P-type doped 4H-SiC epitaxial layer 4 is epitaxially grown on the etched N-type doped 4H-SiC epitaxial layer 3, with a thickness of 0.2 μm to 2 μm. For example, the thickness may be 0.2 μm, 0.5 μm, 0.6 μm, 0.8 μm, 1.2 μm or 2 μm, etc. The doping concentration is 3×10 17 cm~2×10 18 cm -3 ,get Figure 3 The structure shown in FIG. After the terminal region is etched in advance and then the P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region. In this embodiment, the thickness of the P-type doped 4H-SiC epitaxial layer 4 is 0.2 μm to 2 μm, and the doping concentration is 3×10 17 cm -3 ~2×10 18 cm -3 The terminal efficiency is Gaussian distributed within the thickness and doping concentration range of the p-type epitaxy, and the obtained terminal electric field distribution is good and the terminal efficiency is high.

[0039] Etching is performed in the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3, the etching angle is 1°~90°, the etching depth is 0.2μm~3μm and should be greater than or equal to the thickness of the P-type doped 4H-SiC epitaxial layer 4, and the Figure 4 The structure shown.

[0040] Then the terminal area is locally etched to form a groove structure, which is composed of a second groove, i.e., a long groove, and a plurality of first grooves, i.e., short grooves. Figure 5 The structure shown.

[0041] The long trench and short trench structures in this embodiment are etched simultaneously, and the etching depth is the same, and the etching depth is 0.2 μm to 2 μm and is less than the thickness of the P-type doped 4H-SiC epitaxial layer 4. As an example, the etching depth of the long trench and the short trench can be 0.2 μm, 0.3 μm, 0.6 μm, 0.7 μm, 1.5 μm or 2 μm, etc.

[0042] In this embodiment, the number of first grooves is 1 to 10, the length and spacing of the first grooves can be uniform or non-uniform, and the second grooves need to be etched to the edge of the device. The groove structure etched in this embodiment can help the terminal structure to better play a charge modulation role, making the electric field distribution in the terminal area more uniform, and improving the terminal efficiency and device breakdown voltage.

[0043] The anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0044] Example 1 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0045] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 The structure shown.

[0046] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.4 μm and a doping concentration of 5×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0047] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 The structure shown.

[0048] Then the terminal area is partially etched, and the number of short grooves etched is 4, the short groove spacing is 4μm, 6μm, and 8μm respectively, the short groove length is 1.5μm, the spacing between the long groove and the short groove is 2μm, the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area, and the Figure 5 The structure shown.

[0049] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0050] See also Figure 7 The device terminal efficiency obtained in this embodiment 1 can reach 92.5%, Figure 7 The horizontal axis is the breakdown voltage and the vertical axis is the breakdown current.

[0051] Example 2 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0052] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 The structure shown.

[0053] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.8 μm and a doping concentration of 5×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0054] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 The structure shown.

[0055] Then the terminal area is partially etched, and the number of short grooves etched is 4, the short groove spacing is 4μm, 6μm, 8μm, and the length is 1.5μm. The spacing between the long groove and the short groove is 2μm. The length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area. Figure 5 The structure shown.

[0056] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0057] See also Figure 8 The device terminal efficiency obtained in this embodiment 2 can reach 91.2%. Figure 8 The horizontal axis is the breakdown voltage and the vertical axis is the breakdown current.

[0058] Example 3 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0059] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 The structure shown.

[0060] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.8 μm and a doping concentration of 9×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0061] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 The structure shown.

[0062] Then the terminal area is partially etched, and the number of short grooves etched is 4, the spacing between the short grooves is 4μm, 6μm, and 8μm, the length of the short groove is 1.5μm, the spacing between the long groove and the short groove is 2μm, the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area, and the Figure 5 The structure shown.

[0063] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0064] See also Fig. 9 The device terminal efficiency obtained in this embodiment 3 can reach 97.6%. Fig. 9 The horizontal axis is the breakdown voltage and the vertical axis is the breakdown current.

[0065] Example 4 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0066] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 20° and an etching depth of 1.5 μm to obtain Figure 2 The structure shown.

[0067] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.8 μm and a doping concentration of 9×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0068] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 20° and an etching depth of 1.5 μm to obtain Figure 4 The structure shown.

[0069] Then the terminal area is partially etched, and the number of short grooves etched is 4, the short groove spacing is 4μm, 6μm, and 8μm respectively, the short groove length is 1.5μm, the spacing between the long groove and the short groove is 2μm, the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area, and the Figure 5The structure shown.

[0070] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0071] Example 5 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0072] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 10° and an etching depth of 1.0 μm to obtain Figure 2 The structure shown.

[0073] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.8 μm and a doping concentration of 9×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0074] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 10° and an etching depth of 1.5 μm to obtain Figure 4 The structure shown.

[0075] Then the terminal area is partially etched, and the number of short grooves etched is 4, the short groove spacing is 4μm, 6μm, 8μm, and the length is 1.5μm. The spacing between the long groove and the short groove is 2μm. The length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area. Figure 5 The structure shown.

[0076] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0077] Example 6 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0078] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 The structure shown.

[0079] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.8 μm and a doping concentration of 9×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0080] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 The structure shown.

[0081] Then the terminal area is partially etched, and the number of short grooves etched is 3, the short groove spacing is 4μm and 8μm respectively, the short groove length is 1.5μm, the spacing between the long groove and the short groove is 2μm, and the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area, and the Figure 5 The structure shown.

[0082] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0083] Example 7 First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2. Figure 1 The structure shown.

[0084] Then, the reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 The structure shown.

[0085] Next, a P-type doped 4H-SiC epitaxial layer 4 with a thickness of 0.8 μm and a doping concentration of 9×10 17 cm -3 ,get Figure 3 After the terminal region is etched in advance and then a P-type doped 4H-SiC epitaxial layer 4 is grown, the depletion region can be better expanded in the terminal region.

[0086] Then, the anode metal layer reserved area of ​​the N-type doped 4H-SiC epitaxial layer 3 is etched at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 The structure shown.

[0087] The terminal area is then partially etched, and the number of short grooves etched is 5, the short groove spacing is 4μm, 6μm, 8μm, 10μm, the short groove length is 2μm, the long groove and the short groove spacing is 2μm, the length of the second groove is greater than 2μm and is etched to the edge of the terminal area, and the Figure 5 The structure shown.

[0088] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, such as Figure 6 shown.

[0089] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A silicon carbide SBD power device terminal structure, characterized in that: include: Cathode metal layer (1); An N-type doped 4H-SiC substrate (2) located on the cathode metal layer (1); An N-type doped 4H-SiC epitaxial layer (3) epitaxially grown on the N-type doped 4H-SiC substrate (2), the N-type doped 4H-SiC epitaxial layer (3) comprising a terminal reserved region and an anode metal layer reserved region, the thickness of the N-type doped 4H-SiC epitaxial layer (3) corresponding to the terminal reserved region being smaller than the thickness of the N-type doped 4H-SiC epitaxial layer (3) corresponding to the anode metal layer reserved region; A P-type doped 4H-SiC epitaxial layer (4) is located on the N-type doped 4H-SiC epitaxial layer (3); a terminal area of ​​the P-type doped 4H-SiC epitaxial layer (4) corresponding to the terminal reserved area is etched with a plurality of first grooves and a second groove, and the length of the first groove is less than the length of the second groove; An anode metal layer (5) is located in an anode metal layer reserved region of the N-type doped 4H-SiC epitaxial layer (3); The oxide layer (6) is located on the P-type doped 4H-SiC epitaxial layer (4).

2. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The second groove is etched to the edge of the terminal area, and a plurality of first grooves are sequentially arranged from a side of the second groove away from the edge to the anode metal layer reserved area.

3. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The number of the first grooves is 1 to 10.

4. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The first trench and the second trench have the same depth, and the etching depth is 0.2 μm to 2 μm and is less than the thickness of the P-type doped 4H-SiC epitaxial layer (4).

5. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The number of the first grooves is 4, the spacing between the first grooves is 4μm, 6μm and 8μm respectively, the length of the first groove is 1.5μm, the spacing between the second groove and the first groove is 2μm, the length of the second groove is greater than 1.5μm and is etched to the edge of the terminal area.

6. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The doping concentration of the N-type doped 4H-SiC substrate (2) is 5×10 18 cm -3 .

7. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The N-type doped 4H-SiC epitaxial layer (3) has a thickness of 10 μm and a doping concentration of 6×10 15 cm -3 ~1×10 16 cm -3 .

8. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The P-type doped 4H-SiC epitaxial layer (4) has a thickness of 0.2 μm to 2 μm and a doping concentration of 3×10 17 cm -3 ~2×10 18 cm -3 .

9. The silicon carbide SBD power device terminal structure according to claim 1, characterized in that: The anode metal layer reserved region of the N-type doped 4H-SiC epitaxial layer (3) is obtained by etching the P-type doped 4H-SiC epitaxial layer (4), and the bottom of the anode metal layer reserved region is in contact with the N-type doped 4H-SiC epitaxial layer (3) or is embedded in the N-type doped 4H-SiC epitaxial layer (3).

10. The method for preparing a terminal structure of a silicon carbide SBD power device according to claim 1, characterized in that: The following steps are involved: Obtaining an N-type doped 4H-SiC epitaxial layer (3) by epitaxial growth on an N-type doped 4H-SiC substrate (2); Etching is performed on the terminal reserved area of ​​the N-type doped 4H-SiC epitaxial layer (3) at an etching angle of 1° to 90° and an etching depth of 0.2 μm to 2 μm; epitaxially growing a P-type doped 4H-SiC epitaxial layer (4) on the etched N-type doped 4H-SiC epitaxial layer (3); Etching the P-type doped 4H-SiC epitaxial layer (4) at an etching angle of 1° to 90° and an etching depth of 0.2 μm to 3 μm; and the etching depth is greater than or equal to the thickness of the P-type doped 4H-SiC epitaxial layer (4), to form an anode metal layer reserved region of the N-type doped 4H-SiC epitaxial layer (3); Locally etching the terminal region of the P-type doped 4H-SiC epitaxial layer (4) to form a plurality of first grooves and one second groove; Finally, an anode metal layer (5) and an oxide layer (6) are prepared in sequence to obtain a silicon carbide SBD power device terminal structure.

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