Silicon carbide Schottky diode with groove structure and preparation method thereof
By introducing a trench structure into the hole-type semiconductor region of the silicon carbide Schottky diode, increasing the contact area and deepening the p-n junction, the large resistance and local temperature rise problems caused by the small contact area of the anode p-region are solved, and the conduction ability, voltage withstand capacity and switching speed are improved.
Patent Information
- Application Number
- CN202510110764.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-06-10
AI Technical Summary
When the silicon carbide Schottky diode is switched frequently, due to the small contact area between the anode p-region and the metal electrode, the ohmic contact resistance is large, resulting in a local temperature rise, increasing the forward voltage drop and reverse leakage current, limiting the voltage change rate withstandability, and accelerating material aging and reducing reliability.
The trench structure is introduced in the hole-type semiconductor region of the silicon carbide SBD, which increases the contact area of the hole-type semiconductor region and the anode metal layer, reduces the contact resistance of the ohmic contact, and deepens the junction depth of the p-n junction without changing the width and spacing of the hole-type semiconductor region.
It effectively reduces the local heating of the hole-type semiconductor region, improves the conduction ability and voltage resistance of the silicon carbide SBD, and accelerates the switching speed and improves the overall reliability.
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Figure CN120129255A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a silicon carbide Schottky diode with a trench structure and a preparation method thereof. Background Art
[0002] A silicon carbide Schottky diode (SiC SBD) is a Schottky diode using silicon carbide as a semiconductor material, mainly used for freewheeling in high-frequency switching circuits, and its cell structure is as Figure 1 shown. When the SiC SBD conducts forward, holes in the anode p-region are injected into the drift region and form a plasma with electrons in the drift region, reducing the conduction loss of the SiC SBD; when the SiC SBD withstands reverse voltage, the drift region extracts holes from the anode p-region and electrons from the cathode under the action of the reverse voltage to form a displacement current, realizing reverse blocking.
[0003] However, due to the small contact area between the anode p-region and the metal electrode, the ohmic contact resistance of the p-region is often relatively large (greater than 1×10 -4 Ωcm 2 ). When the SiC SBD switches frequently, a large amount of hole current will be drawn away by the anode p-region, resulting in an increase in the voltage change rate (dv / dt) across the SiC SBD and generating a large displacement current. This displacement current is locally concentrated in the anode p-region under the action of the electric field and acts with the contact resistance of the ohmic contact in the anode p-region, generating local temperature rise, resulting in an increase in the forward voltage drop and an increase in the reverse leakage current of the SiC SBD, limiting the voltage change rate tolerance of the SiC SBD, and accelerating the aging of the SiC SBD material, resulting in a reduction in the reliability of the SiC SBD.
[0004] As Figure 2 shown, currently, mainly by adding a p+ region with a larger size and higher concentration to the SiC SBD cell structure, a larger flow area is provided for the displacement current to reduce the local concentration problem of the displacement current. However, this structure greatly reduces the Schottky contact area, increasing the conduction voltage drop and conduction loss of the SiC SBD, resulting in a serious impact on the function of the SiC SBD. Summary of the Invention
[0005] The object of the present invention is to provide a silicon carbide Schottky diode with a trench structure and a preparation method thereof in view of the deficiencies of the corresponding prior art. By introducing a trench structure (such as a square trench, a stepped trench, etc.) into the p-type semiconductor region of the silicon carbide SBD, not only can the contact area of the p-type semiconductor region with the anode metal layer be increased without changing the width of the p-type semiconductor region and the pitch of the p-type semiconductor regions, thereby reducing the contact resistance of the ohmic contact of the p-type semiconductor region, effectively reducing the local temperature rise of the p-type semiconductor region, and improving the conduction ability of the silicon carbide SBD; but also the junction depth of the p-n junction (p junction) of the silicon carbide Schottky diode is deepened, thereby improving the breakdown voltage ability of the silicon carbide Schottky diode and the switching speed of the silicon carbide SBD.
[0006] The object of the present invention is achieved by the following solution:
[0007] A preparation method of a silicon carbide Schottky diode with a trench structure, characterized by comprising the following steps:
[0008] 1) An n+Sub substrate layer is disposed on the cathode metal contact layer;
[0009] 2) An n-Epi epitaxial layer is epitaxially grown on the n+Sub substrate layer;
[0010] 3) A plurality of p-type semiconductor regions are disposed on the n-Epi epitaxial layer as required;
[0011] 4) Corresponding trenches are disposed on each p-type semiconductor region, and metal electrodes are disposed in each trench, so that each metal electrode is connected to the anode metal contact layer disposed on the n-Epi epitaxial layer.
[0012] Preferably, the trench is located inside the p-type semiconductor region, so that the metal electrode disposed in the trench is only in contact with the anode metal contact layer and the p-type semiconductor region.
[0013] Preferably, the trench is composed of a groove A and a groove B, the groove A is located in the n-Epi epitaxial layer, and the groove B is located in the p-type semiconductor region.
[0014] Preferably, the trench is a square trench or a stepped trench.
[0015] Preferably, when the trench is a square trench, the depth of the square trench satisfies the following mathematical expression:
[0016] H≤h
[0017] In the formula, H is the depth of the square trench, and h is the depth of the p-type semiconductor region.
[0018] Preferably, when the groove is a square groove, the width of the square groove satisfies the following mathematical expression:
[0019] 0 < L3 ≤ (L1 / 2 + L2) / 2
[0020] In the formula, L1 is the distance between two hole-type semiconductor regions, L2 is the width of the hole-type semiconductor region, and L3 is the width of the square groove.
[0021] The silicon carbide Schottky diode prepared by the above method includes an anode metal contact layer, an n+Sub substrate layer, an n-Epi epitaxial layer, a cathode metal contact layer, and a plurality of hole-type semiconductor regions. The cathode metal contact layer, the n+Sub substrate layer, the n-Epi epitaxial layer, and the anode metal contact layer are arranged in sequence from bottom to top. Each hole-type semiconductor region is arranged between the n-Epi epitaxial layer and the anode metal contact layer, and a plurality of metal electrodes are fixedly arranged on the anode metal contact layer. Each metal electrode is arranged in an alternating manner corresponding to each hole-type semiconductor region one by one.
[0022] Preferably, the metal electrode is arranged in the groove, and the groove is a square groove or a stepped groove.
[0023] Preferably, the groove is located inside the hole-type semiconductor region, so that the metal electrode arranged in the groove only contacts the anode metal contact layer and the hole-type semiconductor region.
[0024] Preferably, the groove is composed of groove A and groove B. Groove A is located in the n-Epi epitaxial layer, and groove B is located in the hole-type semiconductor region.
[0025] The beneficial effects of the present invention include that a plurality of metal electrodes are fixedly arranged on the anode metal contact layer, and each metal electrode is arranged in an alternating manner corresponding to each hole-type semiconductor region one by one. Without changing the width of the hole-type semiconductor region and the distance between each hole-type semiconductor region, the contact area of the ohmic contact between the hole-type semiconductor region and the anode metal layer can be increased, thereby reducing the contact resistance of the ohmic contact of the hole-type semiconductor region, effectively reducing the local temperature rise of the hole-type semiconductor region, and improving the conduction ability of the silicon carbide SBD;
[0026] Preferably, when the groove is a square groove, the depth of the square groove satisfies the following mathematical expression:
[0027] H ≤ h
[0028] In the formula, H is the depth of the square groove, and h is the depth of the hole-type semiconductor region.
[0029] In this way, the size between the depth of the square groove and the depth of the hole-type semiconductor region is limited within a reasonable range to ensure that the length of the metal electrode extending downward does not exceed the depth of the hole-type semiconductor region, avoiding changing the structure of the silicon carbide Schottky diode while ensuring that the bottom of the groove does not affect the P-N junction of the silicon carbide Schottky diode, resulting in uneven electric field distribution inside the silicon carbide Schottky diode and damage to the structure of the P-N junction. In other words, if the depth of the square groove is greater than the depth of the hole-type semiconductor region, the bottom of the groove will affect the P-N junction of the silicon carbide Schottky diode, resulting in uneven electric field distribution inside the silicon carbide Schottky diode and damage to the structure of the P-N junction.
[0030] Preferably, when the groove is a square groove, the width of the square groove satisfies the following mathematical expression:
[0031] 0 < L3 ≤ (L1 / 2 + L2) / 2
[0032] In the formula, L1 is the distance between two hole-type semiconductor regions, L2 is the width of the hole-type semiconductor region, and L3 is the width of the square groove.
[0033] In this way, by restricting the width of the square groove, it is possible to ensure uniform electric field distribution inside the silicon carbide Schottky diode, avoid excessive electric field concentration at the bottom of the groove, affect the performance of the P-N junction, and ensure good contact quality and structural stability, which helps to improve the breakdown voltage and overall reliability of the silicon carbide Schottky diode.
[0034] The advantages of the present invention are that by introducing a groove structure (such as a square groove, a stepped groove, etc.) into the hole-type semiconductor region of the silicon carbide Schottky diode, it is possible to increase the contact area of the ohmic contact between the hole-type semiconductor region and the anode metal layer without changing the width of the hole-type semiconductor region and the distance between the hole-type semiconductor regions, thereby reducing the contact resistance of the ohmic contact in the hole-type semiconductor region, effectively reducing the local temperature rise in the hole-type semiconductor region, and improving the conduction ability of the silicon carbide Schottky diode; it also deepens the junction depth of the p-n junction (p junction) of the silicon carbide Schottky diode, thereby improving the breakdown voltage ability of the silicon carbide Schottky diode and the switching speed of the silicon carbide SBD.
[0035] Glossary:
[0036] Rate of voltage change: That is, dv / dt, which refers to the amount of voltage change per unit time. The voltage change rate tolerance of a device refers to the ability of the device to withstand the maximum voltage change rate without experiencing abnormal conditions such as mis-conduction or damage.
[0037] Hole: Also known as electron hole, in solid state physics, it refers to the phenomenon where a covalent bond loses an electron and finally leaves a vacancy in the covalent bond. That is, some valence electrons in the covalent bond gain some energy due to thermal motion, thus breaking away from the constraint of the covalent bond to become free electrons, and at the same time leaving vacancies in the covalent bond, and these vacancies are called holes. For example, the first p-region, the second p-region, the third p-region, the fourth p-region, etc. in the present invention are hole-type semiconductor regions (p-regions), and the anode p-region refers to the hole-type semiconductor region close to the anode metal contact layer.
[0038] Displacement current: It refers to the time rate of change of the electric displacement flux passing through a certain surface. Essentially, it is the rate of change of the electric displacement vector with time, which reflects the dynamic change of the electric field. That is, when the electric field strength in a certain region changes, a displacement current will be generated, and the faster the change, the greater the displacement current.
[0039] Junction depth: In power semiconductors, the junction depth usually refers to the distance from the semiconductor surface to the place where the diffusion layer concentration is equal to the substrate concentration. Specifically for the p-region junction depth, it is the vertical distance from the semiconductor surface to the pn junction interface formed by the p-type semiconductor and the n-type semiconductor, generally measured in micrometers.
[0040] Reverse blocking: It refers to a characteristic of a semiconductor diode (such as a silicon carbide SBD) that blocks the current from flowing from the cathode to the anode under a reverse bias voltage. When a reverse voltage is applied across the diode, ideally, the diode should completely block the current, just like an open switch, making the circuit in an open state under the action of the reverse voltage.
[0041] p-base ions: The p-base ions in the present invention refer to acceptor impurity ions used for implantation to form the P-type base region (P-base), such as aluminum ions, boron ions, etc. Description of the Drawings
[0042] Figure 1 is a schematic diagram of the cell structure of a conventional silicon carbide SBD;
[0043] Figure 2 is a schematic diagram of the cell structure of a conventional silicon carbide SBD improved by using existing improvement techniques;
[0044] Figure 3 is a flowchart of the present invention;
[0045] Figure 4 is a schematic diagram of the position of the metal electrode (square) in the present invention, where Figure 4 a is a schematic diagram of the semi-wrapped structure of the metal electrode (square), Figure 4 b is a schematic diagram of the fully wrapped structure of the metal electrode (square);
[0046] Figure 5 This is a schematic diagram of the structure of the metal electrode (stepped) in the present invention, where Figure 5 a is a schematic diagram of the semi-encapsulated structure of the metal electrode (stepped), Figure 5 b is a schematic diagram of the fully encapsulated structure of the metal electrode (stepped);
[0047] Figure 6 This is a schematic diagram of the size marking of the square groove in the present invention;
[0048] Figure 7 This is a schematic diagram of the SiC SBD structure of Example 1 in the present invention;
[0049] Figure 8 This is Schematic Diagram A of the square groove in the present invention;
[0050] Figure 9 This is Schematic Diagram B of the square groove in the present invention;
[0051] Figure 10 This is a schematic diagram of the SiC SBD structure of Example 2 in the present invention;
[0052] Figure 11 This is Schematic Diagram A of the stepped groove in the present invention;
[0053] Figure 12 This is Schematic Diagram B of the stepped groove in the present invention. Detailed implementation manners
[0054] As Figures 1 to 12 shown, a preparation method of a silicon carbide Schottky diode provided with a groove structure includes the following steps:
[0055] 1) Set an n+Sub substrate layer on the cathode metal contact layer;
[0056] 2) Epitaxially grow an n-Epi epitaxial layer on the n+Sub substrate layer;
[0057] 3) Set a plurality of hole-type semiconductor regions on the n-Epi epitaxial layer as required;
[0058] 4) Set corresponding grooves on each hole-type semiconductor region, and set metal electrodes in each groove, so that each metal electrode is connected to the anode metal contact layer provided on the n-Epi epitaxial layer.
[0059] In the present invention, Metal is the identifier of the metal contact layer, n+Sub is the identifier of the substrate region with high-concentration n-type doping, n-Epi is the identifier of the n-Epi epitaxial layer region, and p is the identifier of the p-base ion implantation region. An ohmic contact refers to the contact between a metal and a semiconductor. For example, the contact between the metal contact layer and the p+ region, or the contact between the metal contact layer and the p region (usually, the contact resistance of the ohmic contact with the p region is relatively large). The contact between the metal contact layer and the n-Epi region is a Schottky contact.
[0060] As Figure 4 、 Figure 5 shown, in the present invention, the trench provided can be a square trench or a stepped trench, and there are the following two setting methods:
[0061] ① Full-wrap structure: This kind of trench can be directly set inside the hole-type semiconductor region, which is a full-wrap structure (that is, the entire metal electrode is completely inserted into the hole-type semiconductor region and does not contact the n-Epi epitaxial layer), so that the metal electrode set in the trench only contacts the anode metal contact layer and the hole-type semiconductor region, as Figure 4 shown in Figs. 5b and 5b;
[0062] ② Half-wrap structure: This kind of trench can also be composed of groove A and groove B, which is a half-wrap structure (that is, a part of the metal electrode is inserted into the hole-type semiconductor region and the other part is inserted into the n-Epi epitaxial layer region). The groove A is located in the n-Epi epitaxial layer, and the groove B is located in the hole-type semiconductor region, as Figure 4 shown in Figs. 5a and 5a.
[0063] As Figure 6 shown, in the present invention, when the trench is a square trench, the silicon carbide Schottky diode (such as the depth of the square trench, the width of the square trench, etc.) satisfies the following mathematical expressions:
[0064] H ≤ h
[0065] In the formula, H is the depth of the square trench, and h is the depth of the hole-type semiconductor region.
[0066] 0 < L3 ≤ (L1 / 2 + L2) / 2
[0067] In the formula, L1 is the distance between two hole-type semiconductor regions, L2 is the width of the hole-type semiconductor region, and L3 is the width of the square trench.
[0068] Actually, in the present invention, the width of the metal electrode is the same as the width of the square trench, and the depth of the metal electrode is the same as the depth of the square trench. The additional square trenches not only increase the contact area between the hole-type semiconductor region and the anode metal layer, thereby reducing the contact resistance of the ohmic contact in the hole-type semiconductor region, effectively reducing the local temperature rise in the hole-type semiconductor region, and improving the conduction ability of the silicon carbide Schottky diode; but also deepen the junction depth of the p-n junction (p-junction) of the silicon carbide Schottky diode, thereby improving the breakdown voltage ability of the silicon carbide Schottky diode and the switching speed of the silicon carbide SBD.
[0069] The silicon carbide Schottky diode prepared by the above method includes an anode metal contact layer, an n+Sub substrate layer, an n-Epi epitaxial layer, a cathode metal contact layer, and a plurality of hole-type semiconductor regions. The cathode metal contact layer, the n+Sub substrate layer, the n-Epi epitaxial layer, and the anode metal contact layer are sequentially arranged from bottom to top. Each hole-type semiconductor region is disposed between the n-Epi epitaxial layer and the anode metal contact layer, and a plurality of metal electrodes are fixedly arranged on the anode metal contact layer, and each metal electrode is alternately arranged in one-to-one correspondence with the hole-type semiconductor region.
[0070] It should be noted that in the present invention, "each metal electrode is alternately arranged in one-to-one correspondence with the hole-type semiconductor region" means that each metal electrode is respectively located in the trench formed on the corresponding hole-type semiconductor region and presents a fully wrapped structure or a semi-wrapped structure.
[0071] According to the above method, Examples 1 and 2 are made to construct a silicon carbide Schottky diode with a square trench structure and a silicon carbide Schottky diode with a stepped trench structure:
[0072] Example 1 (Silicon Carbide Schottky Diode with Square Trench Structure):
[0073] 1) An n+Sub substrate layer 2 is disposed on the cathode metal contact layer 1;
[0074] 2) An n-Epi epitaxial layer 3 is epitaxially grown on the n+Sub substrate layer 2;
[0075] 3) Aluminum ions are implanted into the n-Epi epitaxial layer 3 to form a first p-region 4, a second p-region 5, a third p-region 6, and a fourth p-region 7;
[0076] 4) Square trenches are etched on the first p-region 4, the second p-region 5, the third p-region 6, the fourth p-region 7, and the n-Epi epitaxial layer 3 respectively;
[0077] 5) A metal layer is deposited on each square trench to form a metal electrode, and each metal electrode is connected to the anode metal contact layer 8 disposed on the n-Epi epitaxial layer 3.
[0078] In this embodiment, the first p-region 4, the second p-region 5, the third p-region 6, and the fourth p-region 7 are p-base ion implantation regions with the same size. The metal electrode forms an ohmic contact with the first p-region 4, the second p-region 5, the third p-region 6, and the fourth p-region 7, and the metal electrode forms a Schottky contact with the n-Epi epitaxial layer 3.
[0079] As Figure 7 shown, the silicon carbide Schottky diode with a square trench structure in this embodiment includes a cathode metal contact layer 1, an n+Sub substrate layer 2, an n-Epi epitaxial layer 3, an anode metal contact layer 8, a first p-region 4, a second p-region 5, a third p-region 6, and a fourth p-region 7. The cathode metal contact layer 1, the n+Sub substrate layer 2, the n-Epi epitaxial layer 3, and the anode metal contact layer 8 are arranged in sequence from bottom to top. The first p-region 4, the second p-region 5, the third p-region 6, and the fourth p-region 7 are all arranged between the n-Epi epitaxial layer 3 and the anode metal contact layer 8. A plurality of metal electrodes are fixedly arranged on the anode metal contact layer 8, and each metal electrode is arranged in an alternating manner corresponding to the hole-type semiconductor region one by one.
[0080] It should be noted that, as Figures 8 to 9 shown, the square trench is composed of a first rectangular groove 20 arranged in the p-region and a second rectangular groove 19 arranged on the n-Epi epitaxial layer 3 to form a larger third rectangular groove 18. This trench structure can increase the contact area between each p-region and the second metal contact layer 8, thereby reducing the contact resistance of the anode p-region ohmic contact.
[0081] Embodiment 2 (Silicon Carbide Schottky Diode with a Stepped Trench Structure):
[0082] 1) An n+Sub substrate layer 10 is arranged on the cathode metal contact layer 9;
[0083] 2) An n-Epi epitaxial layer 11 is epitaxially grown on the n+Sub substrate layer 10;
[0084] 3) Aluminum ions are implanted into the n-Epi epitaxial layer 11 to form a fifth p-region 13, a sixth p-region 14, a seventh p-region 15, an eighth p-region 16, and a ninth p-region 17;
[0085] 4) Stepped first square trenches are etched on the fifth p-region 13, the sixth p-region 14, the seventh p-region 15, the eighth p-region 16, and the ninth p-region 17 respectively;
[0086] 5) Stepped second square trenches are etched on the fifth p-region 13, the sixth p-region 14, the seventh p-region 15, the eighth p-region 16, and the ninth p-region 17 respectively;
[0087] 6) Deposit metal layers on the first square groove and the second square groove respectively to form metal electrodes, and each metal electrode is connected to the anode metal contact layer 12 provided on the n-Epi epitaxial layer 11.
[0088] In this embodiment, the fifth p-region 13, the sixth p-region 14, the seventh p-region 15, the eighth p-region 16, and the ninth p-region 17 are p-base ion implantation regions with the same size. The metal electrode forms an ohmic contact with the fifth p-region 13, the sixth p-region 14, the seventh p-region 15, the eighth p-region 16, and the ninth p-region 17, and the metal electrode forms a Schottky contact with the n-Epi epitaxial layer 11.
[0089] As Figure 10 shown, the silicon carbide Schottky diode with a stepped groove structure in this embodiment includes a cathode metal contact layer 9, an n+Sub substrate layer 10, an n-Epi epitaxial layer 11, an anode metal contact layer 12, and a fifth p-region 13, a sixth p-region 14, a seventh p-region 15, an eighth p-region 16, and a ninth p-region 17. The cathode metal contact layer 9, the n+Sub substrate layer 10, the n-Epi epitaxial layer 11, and the anode metal contact layer 12 are arranged in sequence from bottom to top. The fifth p-region 13, the sixth p-region 14, the seventh p-region 15, the eighth p-region 16, and the ninth p-region 17 are all arranged between the n-Epi epitaxial layer 11 and the anode metal contact layer 12, and a plurality of metal electrodes are fixedly arranged on the anode metal contact layer 12, and each metal electrode is arranged in one-to-one correspondence and alternately with the hole-type semiconductor region.
[0090] It should be noted that the stepped groove is located in the center of the anode p-region and is composed of a first square groove and a second square groove. The widths and depths of the first and second square grooves are adjusted according to the width and depth of the anode p-region, the chip breakdown voltage, and the actual situation of the on-state voltage drop, and the stepped depth exceeds the p-region depth: the width of the first square groove is less than or equal to the width of the p-region, and the depth is greater than or equal to 1 / 2 of the p-region depth; the width of the second square groove is less than or equal to the width of the first square groove, and the depth of the second square groove is greater than 1 / 10 of the p-region depth. When the depth of the second groove appropriately exceeds the depth of the p-region (not exceeding 1 / 10 of the p-region depth), this stepped groove structure can increase the junction depth of the p-region of the silicon carbide Schottky diode, thereby improving the breakdown voltage capability of the silicon carbide Schottky diode.
[0091] As Figures 11 to 12 shown, the stepped groove can also be regarded as a stepped groove 21 composed of a first groove 22 provided in the p-region and a second groove 23 provided on the n-Epi epitaxial layer 11. This groove structure can increase the contact area between each p-region and the second metal contact layer 12, thereby reducing the contact resistance of the ohmic contact of the anode p-region.
[0092] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention fall within the protection scope of the present invention.
Claims
1. A method for preparing a silicon carbide Schottky diode having a trench structure, characterized in that: The following steps are involved: 1) Arranging an n+Sub substrate layer on the cathode metal contact layer; 2) epitaxially growing an n-Epi epitaxial layer on the n+Sub substrate layer; 3) Arrange multiple hole-type semiconductor regions in the n-Epi epitaxial layer as required; 4) A corresponding groove is arranged on each hole-type semiconductor region, and a metal electrode is arranged in each groove, so that each metal electrode is connected to the anode metal contact layer arranged on the n-Epi epitaxial layer.
2. The preparation method according to claim 1, characterized in that: The trench is located inside the hole-type semiconductor region, so that the metal electrode disposed in the trench is in contact only with the anode metal contact layer and the hole-type semiconductor region.
3. The preparation method according to claim 1, characterized in that: The trench consists of a trench A and a trench B. The trench A is located in the n-Epi epitaxial layer, and the trench B is located in the hole-type semiconductor region.
4. The preparation method according to claim 1, characterized in that: The groove is a square groove or a stepped groove.
5. The preparation method according to claim 1, characterized in that: When the groove is a square groove, the depth of the square groove satisfies the following mathematical expression: H≤h Wherein, H is the depth of the square trench, and h is the depth of the hole-type semiconductor region.
6. The preparation method according to claim 1, characterized in that: When the groove is a square groove, the width of the square groove satisfies the following mathematical expression: 0<L3≤(L1 / 2+L2) / 2 Wherein, L1 is the distance between two hole-type semiconductor regions, L2 is the width of the hole-type semiconductor region, and L3 is the width of the square trench.
7. A silicon carbide Schottky diode prepared by the method of claim 1, characterized in that: It includes an anode metal contact layer, an n+Sub substrate layer, an n-Epi epitaxial layer, a cathode metal contact layer, and a plurality of hole-type semiconductor regions. The cathode metal contact layer, the n+Sub substrate layer, the n-Epi epitaxial layer, and the anode metal contact layer are arranged in sequence from bottom to top, and each hole-type semiconductor region is arranged between the n-Epi epitaxial layer and the anode metal contact layer. A plurality of metal electrodes are fixedly arranged on the anode metal contact layer, and each metal electrode is arranged alternately with the hole-type semiconductor region in a one-to-one correspondence.
8. The silicon carbide Schottky diode according to claim 7, characterized in that: The metal electrode is arranged in a groove, and the groove is a square groove or a stepped groove.
9. The silicon carbide Schottky diode according to claim 8, characterized in that: The trench is located inside the hole-type semiconductor region, so that the metal electrode disposed in the trench is in contact only with the anode metal contact layer and the hole-type semiconductor region.
10. The silicon carbide Schottky diode according to claim 8, characterized in that: The trench consists of a trench A and a trench B. The trench A is located in the n-Epi epitaxial layer, and the trench B is located in the hole-type semiconductor region.