Silicon carbide Schottky diode device
By providing a trap area on the SiC epitaxial layer of the silicon carbide Schottky diode device and setting an inner and outer protective ring, the problem of increasing the outermost main junction edge electric field in the prior art is solved, and the effect of reducing the main junction edge electric field and avoiding breakdown is achieved.
Patent Information
- Application Number
- CN202421644943.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-12
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2034-07-12
AI Technical Summary
There are multiple P+ regions at the upper end of the epitaxial layer of the existing silicon carbide Schottky diode device, which leads to an increase in the electric field at the edge of the outermost main junction and easily leads to breakdown.
A plurality of trap areas are provided on the SiC epitaxial layer, and an inner protection ring and an outer protection ring are provided outside the trap area. The inner protection ring is not connected to any electrode. The depletion zone formed by the pn junction in the equilibrium state is connected to the depletion zone formed by the main junction, widening the width of the depletion zone at the edge position of the main junction, thereby reducing the electric field at the edge of the main junction.
By setting the inner protection ring and the outer protection ring, the electric field at the edge of the main junction is reduced, breakdown of the main junction is avoided, and the protection effect is further improved.
Smart Images
Figure CN222954304U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductors, in particular to a silicon carbide Schottky diode device. Background Art
[0002] Silicon carbide (SiC) is a third-generation wide bandgap semiconductor material. Compared with silicon (Si), silicon carbide has a greater dielectric breakdown strength, a faster saturated electron drift velocity, and a higher thermal conductivity. Therefore, when used in semiconductor devices, silicon carbide devices have the characteristics of high withstand voltage, high-speed switching, low on-resistance, and high efficiency, which helps to reduce energy consumption and reduce system size. Compared with silicon diodes, silicon carbide diodes have higher voltage tolerance, with a withstand voltage level of more than 3300V, and are suitable for a wider range of occasions. At the same power, the size of SiC can be made smaller. In addition, the on-resistance of the device is smaller and the high-voltage loss is low. The bandgap width of SiC diodes is three times that of silicon tubes, and they have a higher operating temperature. After 150-175°C, the reliability and performance indicators of silicon tubes drop significantly. Moreover, the performance of SiC diodes is basically not affected by the junction temperature, and they can still operate reliably at a maximum operating temperature of 175°C. It is not difficult to see that the SiC diode plays the role of a rectifier switch at the input or output end of the circuit module, mainly by using a large number of Schottky diode dies in parallel to increase the breakdown voltage of the entire device chip.
[0003] The existing silicon carbide Schottky diode device has multiple P+ regions on the top of its epitaxial layer, and multiple equal-width guard rings are equidistantly arranged outside the P+ region to avoid current breakdown. However, because the existing guard ring is set to wrap a single P+ region, this leads to an increase in the electric field at the edge of the outermost main junction, which is prone to breakdown. Utility Model Content
[0004] The utility model aims to provide a silicon carbide Schottky diode device in view of the problems existing in the background technology.
[0005] The technical solution of the utility model is: a silicon carbide Schottky diode device, comprising an N-type substrate, a SiC epitaxial layer is arranged on the N-type substrate, a plurality of trap areas are opened on the SiC epitaxial layer, an inner guard ring is arranged around each of the trap areas, and outer guard rings are arranged around the plurality of trap areas, and the inner guard rings are surrounded by the outer guard rings.
[0006] Preferably, a plurality of the trap regions are equidistantly distributed on the SiC epitaxial layer, and the trap regions are square P+ regions.
[0007] Preferably, the trap region is formed by shallow trench etching followed by ion implantation.
[0008] Preferably, a metal layer is disposed on the SiC epitaxial layer, the SiC epitaxial layer forms a Schottky contact with the metal layer, and the metal layer forms an ohmic contact with a portion of the trap region.
[0009] Compared with the existing technology, the beneficial effects of the utility model are: through the arrangement of the inner guard ring and the outer guard ring, the inner guard ring is not connected to any electrode, and it mainly utilizes the depletion region formed by the pn junction in the equilibrium state. When the depletion region formed by the field ring is connected to the depletion region formed by the main junction, the width of the depletion region at the edge of the main junction is widened, thereby reducing the electric field at the edge of the main junction, avoiding the breakdown of the main junction to a certain extent, and a separate depletion region is arranged on the periphery, the depletion region is formed by shallow groove corrosion, and another circle of outer guard ring is arranged at this location, thereby further improving the protection effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 This is a schematic diagram of the cross-sectional structure of a silicon carbide Schottky diode device proposed in the utility model;
[0011] Figure 2 The utility model provides a schematic diagram of the top view structure of the inner and outer guard rings of a silicon carbide Schottky diode device.
[0012] Figure numerals: 1, N-type substrate; 3, SiC epitaxial layer; 4, trap area; 5, inner guard ring; 6, outer guard ring; 7, metal layer. DETAILED DESCRIPTION
[0013] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.
[0014] Refer to the attached Figure 1-2 A silicon carbide Schottky diode device comprises an N-type substrate 1, a SiC epitaxial layer 3 is provided on the N-type substrate 1, a plurality of trap regions 4 are provided on the SiC epitaxial layer 3, an inner guard ring 5 is provided on the periphery of each trap region 4, an outer guard ring 6 is provided on the periphery of the plurality of trap regions 4, and the inner guard ring 5 is surrounded by the outer guard ring 6. It should be noted that the inner guard ring 5 is not connected to any electrode, and mainly utilizes the depletion region formed by the pn junction in the equilibrium state. When the depletion region formed by the field ring is connected to the depletion region formed by the main junction, the width of the depletion region at the edge of the main junction is widened, thereby reducing the electric field at the edge of the main junction, and avoiding the breakdown of the main junction to a certain extent, and a separate depletion region is provided on the periphery, the depletion region is formed by shallow groove corrosion, and a circle of outer guard ring 6 is provided at the location, thereby further improving the protection effect, and when an inner guard ring 5 is broken down, the guard ring 6 can prevent the escape of the current.
[0015] It should be noted that, in this embodiment, a plurality of trap regions 4 are equidistantly distributed on the SiC epitaxial layer 3 , and the trap region 4 is a square P+ region. Specifically, the square P+ region is a P-type heavily doped P+ region 4 domain, and in this embodiment, the square is a square.
[0016] Specifically, the trap area 4 is formed by an ion implantation process after shallow groove etching. During the manufacturing process, in the p-trap structure, the metal layer 7 is connected to the highest potential silicon bit, the p-trap has the lowest potential, and a reverse pn junction bias voltage is formed between the p-trap and the metal layer 7, so that the p-trap and the metal layer 7 are naturally isolated. Specifically, a shallow groove etching process is used to form a groove, and a P-type well area is formed on both sides and the bottom of the groove by injecting boron ions. When the device is reverse biased, unidirectional depletion is achieved with the SiC epitaxial layer, so that the epitaxial layer concentration can be further increased to a certain extent, thereby ensuring the device on-state voltage drop requirement without excessively weakening the resistance to increase the current, thereby increasing the device breakdown voltage.
[0017] It should also be noted that, in the present embodiment, a metal layer 7 is provided on the SiC epitaxial layer 3, the SiC epitaxial layer 3 and the metal layer 7 form a Schottky contact, and the metal layer 7 forms an ohmic contact with a portion of the trap region 4. Specifically, in the present embodiment, the doping concentration of the SiC epitaxial layer 3 should generally be higher than 1x1019cm-3.
[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0020] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A silicon carbide Schottky diode device, comprising an N-type substrate (1), on which a SiC epitaxial layer (3) is provided, characterized in that: A plurality of trap areas (4) are provided on the SiC epitaxial layer (3), an inner protection ring (5) is provided on the periphery of each of the trap areas (4), an outer protection ring (6) is provided on the periphery of the plurality of trap areas (4), and the inner protection ring (5) is surrounded by the outer protection ring (6).
2. A silicon carbide Schottky diode device according to claim 1, characterized in that: The plurality of trap regions (4) are equidistantly distributed on the SiC epitaxial layer (3), and the trap regions (4) are square P+ regions.
3. A silicon carbide Schottky diode device according to claim 2, characterized in that: The trap area (4) is formed by a shallow groove etching followed by an ion implantation process.
4. A silicon carbide Schottky diode device according to claim 3, characterized in that: A metal layer (7) is provided on the SiC epitaxial layer (3), the SiC epitaxial layer (3) and the metal layer (7) form a Schottky contact, and the metal layer (7) forms an ohmic contact with a portion of the trap region (4).