A SiC SBD power device terminal structure

Abstract

The present invention discloses a terminal structure of a silicon carbide SBD power device, belonging to the technical field of device design. The N-type doped 4H-SiC epitaxial layer of the terminal structure of the present invention grows on an N-type doped 4H-SiC substrate, and the thickness of the N-type doped 4H-SiC epitaxial layer corresponding to the terminal reserved area is lower than the thickness of the N-type doped 4H-SiC epitaxial layer corresponding to the 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 multiple first trenches etched in the terminal area of the P-type doped 4H-SiC epitaxial layer are all less than the length of the second trench, and the second trench is etched to the edge of the terminal area; the anode metal layer is located in the anode metal layer reserved area of the N-type doped 4H-SiC epitaxial layer; the oxide layer is located on the P-type doped 4H-SiC epitaxial layer. The terminal structure of the present invention does not require an ion implantation process and only needs to form the terminal structure through epitaxial and etching processes, having a high terminal efficiency and a low process cost.

Description

Technical Field

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

[0002] Silicon carbide (SiC) is a wide-bandgap semiconductor material with excellent physical and chemical properties, having advantages such as high working temperature, high breakdown voltage, low on-resistance, high switching frequency, and low switching loss. A 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 an actual silicon carbide SBD power device is relatively steep, and electric field concentration will occur at the junction edge of the device, that is, the electric field concentration effect, resulting in denser electric field lines here than elsewhere, and the edge electric field intensity is significantly greater than the electric field intensity inside the body, causing the device to break down first at the junction edge. At this time, the breakdown voltage will be much smaller than the breakdown voltage of an ideal parallel-plane junction. In order to alleviate the influence of the electric field concentration effect on the power device, terminal structures are widely used.

[0004] Currently, common terminal structures include field plates, junction terminals, and field limiting ring structures. However, each has its own limitations. Among them, field plates are usually made of metal or conductive materials. Due to the sudden change in geometric shape at their edges (especially the ends), electric field lines will be dense here, forming a new electric field peak near the ends of the field plates. Therefore, although field plates can expand the depletion region, they often introduce a new electric field concentration point, leading to premature breakdown. Although the junction terminal has a simple process, it is sensitive to doping concentration, and the silicon carbide junction terminal structure can only be realized through ion implantation technology. The impurity activation level has high requirements for activation conditions. Therefore, the ion implantation window range of the junction terminal corresponding to a certain breakdown 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 junction terminal technologies need to be formed by ion implantation, resulting in a significant increase in the cost of device preparation. Therefore, the present invention proposes a new terminal structure of a silicon carbide SBD power device. Summary of the Invention

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

[0006] The present invention provides a terminal structure of a silicon carbide SBD power device, including:

[0007] A cathode metal layer;

[0008] An N-type doped 4H-SiC substrate, located on the cathode metal layer;

[0009] An N-type doped 4H-SiC epitaxial layer is epitaxially grown on the N-type doped 4H-SiC substrate. The N-type doped 4H-SiC epitaxial layer includes a terminal reserved area and an anode metal layer reserved area. 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;

[0010] A P-type doped 4H-SiC epitaxial layer is located on the N-type doped 4H-SiC epitaxial layer; multiple first trenches and a second trench are etched in the terminal area corresponding to the terminal reserved area of the P-type doped 4H-SiC epitaxial layer, and the length of the first trench is less than the length of the second trench;

[0011] An anode metal layer is located in the anode metal layer reserved area of the N-type doped 4H-SiC epitaxial layer;

[0012] An oxide layer is located on the P-type doped 4H-SiC epitaxial layer.

[0013] Preferably, the second trench is etched to the edge of the terminal area, and multiple first trenches are arranged at intervals in sequence from the side of the second trench away from the edge to the anode metal layer reserved area.

[0014] Preferably, the number of the first trenches is 1 to 10.

[0015] Preferably, the first trench and the second trench have the same depth, and the etching depth is 0.2 μm to 2 μm and less than the thickness of the P-type doped 4H-SiC epitaxial layer.

[0016] Preferably, the number of the first trenches is 4, the distances between the first trenches are 4 μm, 6 μm and 8 μm respectively, the length of the first trench is 1.5 μm, the distance between the second trench and the first trench is 2 μm, and the length of the second trench is greater than 1.5 μm and is etched to the edge of the terminal area.

[0017] Preferably, the doping concentration of the N-type doped 4H-SiC substrate is 5×10 18 cm -3 .

[0018] Preferably, the thickness of the N-type doped 4H-SiC epitaxial layer is 10 μm, and the doping concentration is 6×10 15 cm -3 ~1×10 16 cm -3 .

[0019] 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 。

[0020] Preferably, the reserved area of the anode metal layer 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 reserved area of the anode metal layer contacts the N-type doped 4H-SiC epitaxial layer or is embedded in the N-type doped 4H-SiC epitaxial layer.

[0021] The present invention also discloses a preparation method of the above-mentioned silicon carbide SBD power device terminal structure, including the following steps:

[0022] An N-type doped 4H-SiC epitaxial layer is obtained by epitaxial growth on an N-type doped 4H-SiC substrate;

[0023] Etching is performed on the terminal reserved area of the N-type doped 4H-SiC epitaxial layer, the etching angle is 1° to 90°, and the etching depth is 0.2 μm to 2 μm;

[0024] A P-type doped 4H-SiC epitaxial layer is grown by epitaxial growth on the etched N-type doped 4H-SiC epitaxial layer;

[0025] Etch the P-type doped 4H-SiC epitaxial layer, the etching angle is 1° to 90°, the etching depth is 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 a reserved area for the anode metal layer of the N-type doped 4H-SiC epitaxial layer;

[0026] Perform local etching on the terminal area of the P-type doped 4H-SiC epitaxial layer to etch out a plurality of first trenches and a second trench;

[0027] Finally, an anode metal layer and an oxide layer are sequentially prepared to obtain the silicon carbide SBD power device terminal structure.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] In the silicon carbide SBD power device terminal structure of the present invention, by first etching and then growing a P-type doped 4H-SiC epitaxial layer in the terminal area, and etching an inclined plane, a plurality of first trenches and a second trench on the P-type doped 4H-SiC epitaxial layer, the electric field distribution at the terminal is made uniform, thereby slowing down the edge electric field concentration, enabling the terminal structure to better play the charge modulation role. The terminal efficiency of the silicon carbide SBD power device terminal structure of the present invention is as high as 97.6%, making the actual voltage of the device closer to the breakdown voltage of the ideal parallel plane junction to a large extent.

[0030] The preparation of the terminal structure of the present invention does not require an ion implantation process. Only by means of epitaxial growth and etching processes, a terminal structure is formed on the SiC SBD power device, which can effectively expand the depletion region, make the electric field distribution inside the device uniform, effectively avoid the electric field concentration effect, and has a high terminal efficiency, enabling the actual voltage of the device to approach the breakdown voltage of the ideal parallel plane junction to a large extent, realizing the reduction of the process cost on the basis of improving the terminal efficiency of the terminal structure. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of an N-type doped 4H-SiC epitaxial layer obtained by epitaxial growth on an N-type doped 4H-SiC substrate in an embodiment of the present invention.

[0032] Figure 2 It is a schematic structural diagram of the etched structure in the terminal reserved area of the N-type doped 4H-SiC epitaxial layer in an embodiment of the present invention.

[0033] Figure 3 It is a schematic structural diagram of a P-type doped 4H-SiC epitaxial layer grown epitaxially on the etched N-type doped 4H-SiC epitaxial layer in an embodiment of the present invention.

[0034] Figure 4 It is a schematic structural diagram of the etched structure after forming an anode metal layer reserved area of the N-type doped 4H-SiC epitaxial layer on the P-type doped 4H-SiC epitaxial layer in an embodiment of the present invention.

[0035] Figure 5 It is a schematic structural diagram of the etched structure after etching the first trench and the second trench in the terminal area in an embodiment of the present invention.

[0036] Figure 6 It is a schematic diagram of the terminal structure of the SiC SBD power device in an embodiment of the present invention.

[0037] Figure 7 It is a breakdown voltage test diagram of the terminal structure of the SiC SBD power device in Embodiment 1 of the present invention.

[0038] Figure 8 It is a breakdown voltage test diagram of the terminal structure of the SiC SBD power device in Embodiment 2 of the present invention.

[0039] Figure 9 It is a breakdown voltage test diagram of the terminal structure of the SiC SBD power device in Embodiment 3 of the present invention.

[0040] Description of the Reference Numerals:

[0041] 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 implementation manners

[0042] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are only a part rather than all of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0043] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present disclosure pertains. The "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. The terms "comprising", "including" or the like mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalents, without excluding other elements or items. The terms "connected" or "coupled" or the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationships may also change accordingly.

[0044] This embodiment provides a terminal structure of a silicon carbide SBD power device, including 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. The N-type doped 4H-SiC epitaxial layer 3 includes a terminal reserved area and an anode metal layer reserved area. 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; multiple first trenches and a second trench are etched in the terminal area corresponding to the P-type doped 4H-SiC epitaxial layer 4, and the length of the first trench is less than the length of the second trench; 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, by etching multiple first trenches (i.e., short trenches) and a second trench (i.e., long trench), the electric field concentration is alleviated, so that the electric field distribution in the terminal area is more uniform, and the terminal efficiency is improved.

[0045] As a preferred embodiment, the second trench is etched to the edge of the terminal area, which can avoid introducing new electric field concentration points and effectively improve the terminal efficiency. Multiple first trenches are arranged at intervals in sequence from the side of the second trench far from the edge to the anode metal layer reserved area.

[0046] As a preferred embodiment, the number of the first trenches is 1 to 10.

[0047] 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 less than the thickness of the P-type doped 4H-SiC epitaxial layer 4.

[0048] As a preferred embodiment, the number of the first trenches is 4, the distances between the first trenches are 4 μm, 6 μm, and 8 μm respectively, the length of the first trench is 1.5 μm, the distance between the second trench and the first trench is 2 μm, and the length of the second trench is greater than 1.5 μm and is etched to the edge of the terminal area. Too long or too short trenches will result in uneven electric field distribution, so that the electric field concentration cannot be well alleviated, and the terminal efficiency of the device is low. Too few trenches will not be able to well alleviate the electric field concentration. Too many trenches will not play an obvious role in improving the efficiency, but also waste the device area and increase the manufacturing cost.

[0049] As a preferred embodiment, the doping concentration of the N-type doped 4H-SiC substrate 2 is 5×10 18cm -3 ; The thickness of the N-type doped 4H-SiC epitaxial layer 3 is 10 μm, and the doping concentration is 6×10 15 cm -3 ~1×10 16 cm -3 , and as a preferred embodiment, 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 to 2 μm, and the doping concentration is 3×10 17 cm -3 ~2×10 18 cm -3 .

[0050] The preparation method of the above-mentioned silicon carbide SBD power device terminal structure in this embodiment is as follows:

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

[0052] Etching is performed on the reserved area at the terminal of the N-type doped 4H-SiC epitaxial layer 3, the etching angle is 1° to 90°, and the etching depth is 0.2 μm to 2 μm to obtain the Figure 2 shown structure. It should be noted that the etching angle in this embodiment can be any angle between 1° and 90°. By way of example, the angle can be 1°, 5°, 10°, 15°, 30° or 90°, etc.; similarly, the etching depth can also be any depth between 0.2 μm and 2 μm. By way of example, the depth can be 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.5 μm or 2 μm, etc.

[0053] An epitaxial growth of a P-type doped 4H-SiC epitaxial layer 4 is performed on the etched N-type doped 4H-SiC epitaxial layer 3, with a thickness of 0.2 μm to 2 μm. By way of example, the thickness can 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 to obtain the Figure 3 shown structure. Performing epitaxial growth of the P-type doped 4H-SiC epitaxial layer 4 after etching in advance in the terminal region can enable the depletion region to expand better 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, within the thickness and doping concentration range of the p-type epitaxy, the terminal efficiency shows a Gaussian distribution, resulting in a better terminal electric field distribution and a high terminal efficiency.

[0054] Etch the reserved area of the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3, with an etching angle of 1° to 90°, an etching depth of 0.2 μm to 3 μm and should be greater than or equal to the thickness of the P-type doped 4H-SiC epitaxial layer 4, to obtain Figure 4 the structure shown.

[0055] Then, locally etch the terminal area to etch out a trench structure, which consists of a second trench, i.e., a long trench, and several first trenches, i.e., short trenches, to obtain Figure 5 the structure shown.

[0056] In this embodiment, the long trench and the short trench structures are etched simultaneously, and the etching depths are the same, both being 0.2 μm to 2 μm and less than the thickness of the P-type doped 4H-SiC epitaxial layer 4. As an example, the etching depths of the long trench and the short trenches can be 0.2 μm, 0.3 μm, 0.6 μm, 0.7 μm, 1.5 μm or 2 μm, etc.

[0057] In this embodiment, the number of the first trenches is 1 to 10, and the lengths and spacings of the first trenches can be uniform or non-uniform. The second trench needs to be etched to the device edge. The etched trench structure in this embodiment can help the terminal structure play a better charge modulation role, making the electric field distribution in the terminal area more uniform and improving the terminal efficiency and the device breakdown voltage.

[0058] Successively prepare the anode metal layer 5 and the oxide layer 6 to obtain the final complete device terminal structure, as shown in Figure 6 the figure.

[0059] Example 1

[0060] First, grow an N-type doped 4H-SiC epitaxial layer 3 on the N-type doped 4H-SiC substrate 2 by epitaxial growth to obtain Figure 1 the structure shown.

[0061] Then, etch the reserved area at the terminal of the N-type doped 4H-SiC epitaxial layer 3 with an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 the structure shown.

[0062] Next, grow a P-type doped 4H-SiC epitaxial layer 4 on the etched N-type doped 4H-SiC epitaxial layer 3 by epitaxial growth, with a thickness of 0.4 μm and a doping concentration of 5×10 17 cm -3 , to obtain Figure 3The structure shown. After etching in advance in the terminal region and then growing a P-type doped 4H-SiC epitaxial layer 4, the depletion region can be better expanded in the terminal region.

[0063] Then, etching is performed in the reserved area of the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 the structure shown.

[0064] Next, local etching is performed on the terminal region. The number of short grooves etched is 4, the short groove spacings are 4 μm, 6 μm, and 8 μm respectively, the short groove length is 1.5 μm, the long groove and the short groove spacing is 2 μm, and the length of the second groove is greater than 1.5 μm and etched to the edge of the terminal region to obtain Figure 5 the structure shown.

[0065] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, as Figure 6 shown.

[0066] Please refer to Figure 7 , the device terminal efficiency obtained in this Example 1 can reach 92.5%, Figure 7 where the abscissa in is the breakdown voltage and the ordinate is the breakdown current.

[0067] Example 2

[0068] First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2 to obtain Figure 1 the structure shown.

[0069] Next, etching is performed in the reserved area at the terminal of the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 the structure shown.

[0070] 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 is grown by epitaxial growth on the etched N-type doped 4H-SiC epitaxial layer 3 to obtain Figure 3 the structure shown. After etching in advance in the terminal region and then growing a P-type doped 4H-SiC epitaxial layer 4, the depletion region can be better expanded in the terminal region.

[0071] Then, etching is performed in the reserved area of the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 the structure shown.

[0072] Then, perform local etching on the terminal region. The number of short grooves etched is 4, the short groove spacings are 4 μm, 6 μm, and 8 μm respectively, the length is 1.5 μm, the long groove and short groove spacing is 2 μm, and the length of the second groove is greater than 1.5 μm and etched to the edge of the terminal region, obtaining Figure 5 the structure shown

[0073] Finally, sequentially fabricate the anode metal layer 5 and the oxide layer 6 to obtain the final complete device terminal structure, as shown in Figure 6 the figure

[0074] Please refer to Figure 8 , the device terminal efficiency obtained in this Example 2 can reach 91.2%, Figure 8 where the abscissa is the breakdown voltage and the ordinate is the breakdown current in

[0075] Example 3

[0076] First, grow an N-type doped 4H-SiC epitaxial layer 3 on the N-type doped 4H-SiC substrate 2 by epitaxial growth, obtaining Figure 1 the structure shown

[0077] Next, perform etching on the reserved region at the terminal of the N-type doped 4H-SiC epitaxial layer 3, with an etching angle of 15° and an etching depth of 1.0 μm, obtaining Figure 2 the structure shown

[0078] Next, grow a P-type doped 4H-SiC epitaxial layer 4 on the etched N-type doped 4H-SiC epitaxial layer 3 by epitaxial growth, with a thickness of 0.8 μm and a doping concentration of 9×10 17 cm -3 , obtaining Figure 3 the structure shown. Etching the terminal region in advance and then growing the P-type doped 4H-SiC epitaxial layer 4 can enable the depletion region to better expand in the terminal region

[0079] Then, perform etching on the reserved region for the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3, with an etching angle of 15° and an etching depth of 1.0 μm, obtaining Figure 4 the structure shown

[0080] Then, perform local etching on the terminal region. The number of short grooves etched is 4, the spacings between the short grooves are 4 μm, 6 μm, and 8 μm respectively, the length of the short grooves is 1.5 μm, the long groove and short groove spacing is 2 μm, and the length of the second groove is greater than 1.5 μm and etched to the edge of the terminal region, obtaining Figure 5 the structure shown

[0081] Finally, sequentially fabricate the anode metal layer 5 and the oxide layer 6 to obtain the final complete device terminal structure, as shown in Figure 6 the figure

[0082] Please refer to Figure 9 , the device terminal efficiency obtained in this Example 3 can reach 97.6%, Figure 9 where the abscissa is the breakdown voltage and the ordinate is the breakdown current in

[0083] Example 4

[0084] First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on the N-type doped 4H-SiC substrate 2, obtaining Figure 1 the structure shown in

[0085] Next, etching is performed on the reserved area at the terminal of the N-type doped 4H-SiC epitaxial layer 3 with an etching angle of 20° and an etching depth of 1.5 μm, obtaining Figure 2 the structure shown in

[0086] 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 is grown by epitaxial growth on the etched N-type doped 4H-SiC epitaxial layer 3, obtaining Figure 3 the structure shown in. Performing etching in advance in the terminal area and then growing the P-type doped 4H-SiC epitaxial layer 4 can enable the depletion region to better expand in the terminal area.

[0087] Then, etching is performed on the reserved area of the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3 with an etching angle of 20° and an etching depth of 1.5 μm, obtaining Figure 4 the structure shown in

[0088] Next, local etching is performed on the terminal area, and the number of short grooves etched is 4. The short groove spacings are 4 μm, 6 μm, and 8 μm respectively, the short groove length is 1.5 μm, the long groove and the short groove spacing is 2 μm, and the length of the second groove is greater than 1.5 μm and is etched to the edge of the terminal area, obtaining Figure 5 the structure shown in

[0089] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, as shown in Figure 6

[0090] Example 5

[0091] First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on the N-type doped 4H-SiC substrate 2, obtaining Figure 1 the structure shown in

[0092] Next, etching is performed on the reserved area at the terminal of the N-type doped 4H-SiC epitaxial layer 3 with an etching angle of 10° and an etching depth of 1.0 μm, obtaining Figure 2The structure shown

[0093] 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 is epitaxially grown on the etched N-type doped 4H-SiC epitaxial layer 3 to obtain Figure 3 the structure shown. Etching the terminal region in advance and then growing the P-type doped 4H-SiC epitaxial layer 4 can enable the depletion region to better expand in the terminal region.

[0094] Then, etching is performed in the reserved area of the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 10° and an etching depth of 1.5 μm to obtain Figure 4 the structure shown

[0095] Next, local etching is performed on the terminal region. The number of short grooves etched is 4, the short groove spacings are 4 μm, 6 μm, and 8 μm respectively, the length is 1.5 μm, the long groove and the short groove spacing is 2 μm, and the length of the second groove is greater than 1.5 μm and etched to the edge of the terminal region to obtain Figure 5 the structure shown

[0096] Finally, the anode metal layer 5 and the oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, as shown in Figure 6 the figure

[0097] Example 6

[0098] First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on the N-type doped 4H-SiC substrate 2 to obtain Figure 1 the structure shown

[0099] Next, etching is performed in the reserved area at the terminal of the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 2 the structure shown

[0100] 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 is epitaxially grown on the etched N-type doped 4H-SiC epitaxial layer 3 to obtain Figure 3 the structure shown. Etching the terminal region in advance and then growing the P-type doped 4H-SiC epitaxial layer 4 can enable the depletion region to better expand in the terminal region.

[0101] Then, etching is performed in the reserved area of the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3 at an etching angle of 15° and an etching depth of 1.0 μm to obtain Figure 4 the structure shown

[0102] Then, local etching is performed on the terminal region, and the number of short grooves etched is 3. The short groove spacings are 4 μm and 8 μm respectively, the short groove length is 1.5 μm, the long groove and short groove spacing is 2 μm, and the length of the second groove is greater than 1.5 μm and is etched to the edge of the terminal region, obtaining Figure 5 the structure shown.

[0103] Finally, an anode metal layer 5 and an oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, as Figure 6 shown.

[0104] Example 7

[0105] First, an N-type doped 4H-SiC epitaxial layer 3 is obtained by epitaxial growth on an N-type doped 4H-SiC substrate 2, obtaining Figure 1 the structure shown.

[0106] Next, etching is performed on the reserved region at the terminal of the N-type doped 4H-SiC epitaxial layer 3, with an etching angle of 15° and an etching depth of 1.0 μm, obtaining Figure 2 the structure shown.

[0107] 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 is epitaxially grown on the etched N-type doped 4H-SiC epitaxial layer 3, obtaining Figure 3 the structure shown. Performing epitaxial growth of the P-type doped 4H-SiC epitaxial layer 4 after pre-etching in the terminal region can enable better expansion of the depletion region in the terminal region.

[0108] Then, etching is performed on the reserved region for the anode metal layer of the N-type doped 4H-SiC epitaxial layer 3, with an etching angle of 15° and an etching depth of 1.0 μm, obtaining Figure 4 the structure shown.

[0109] Then, local etching is performed on the terminal region, and the number of short grooves etched is 5. The short groove spacings are 4 μm, 6 μm, 8 μm, 10 μm respectively, the short groove length is 2 μm, the long groove and short groove spacing is 2 μm, and the length of the second groove is greater than 2 μm and is etched to the edge of the terminal region, obtaining Figure 5 the structure shown.

[0110] Finally, an anode metal layer 5 and an oxide layer 6 are sequentially prepared to obtain the final complete device terminal structure, as Figure 6 shown.

[0111] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and 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 corresponding to the terminal reserved region being smaller than the thickness of the N-type doped 4H-SiC epitaxial layer 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); An oxide layer (6) located on the P-type doped 4H-SiC epitaxial layer (4); The method for preparing the above-mentioned silicon carbide SBD power device terminal structure comprises the following steps: 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), with an etching angle of 1° to 90° and an etching depth of 0.2 μm to 2 μm; Growing a P-type doped 4H-SiC epitaxial layer (4) on the etched N-type doped 4H-SiC epitaxial layer (3) by epitaxial growth; 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 area 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 etch out 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.

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 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 .

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).

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