A buried P+SiC JBS structure to improve single-particle resistance
By introducing three N-type buffer layers and a P+ buried layer into the SiC JBS structure, the problem of SiC JBS structure being easily burned under single-event irradiation is solved, and the device achieves high-efficiency single-event resistance performance, which is suitable for aerospace electric propulsion systems and power systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN MICROELECTRONICS TECH INST
- Filing Date
- 2022-12-30
- Publication Date
- 2026-06-26
AI Technical Summary
The SiC JBS structure is prone to micro-burning marks under single-particle irradiation, which can lead to excessive reverse leakage current or even burn-out of the device, limiting its application in the military and aerospace fields.
By adding three N-type buffer layers and a P+ buried layer to the SiC JBS structure, a buried P+ SiC JBS structure is formed. The buffer layer is used to balance the electron-hole pairs generated by the single-particle incident track, and the P+ buried layer blocks the electron-hole pair tracks, preventing leakage and burn-out.
Without changing the chip area, the single-event immunity of the SiC JBS structure is effectively improved, preventing excessive leakage current and burn-out, and enhancing the device's radiation resistance.
Smart Images
Figure CN116314143B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor discrete devices, specifically to a buried P+SiC JBS structure for improving single-event immunity. Background Technology
[0002] Third-generation semiconductor silicon carbide (SiC) materials have advantages such as large bandgap, high critical breakdown field strength, high temperature resistance, high thermal conductivity, and fast saturated electron drift velocity, making them particularly suitable for fabricating high-voltage power devices.
[0003] Power devices made of SiC have advantages such as high breakdown voltage, small parasitic capacitance, fast switching speed, no reverse recovery, and better thermal stability. Replacing Si power devices with SiC power devices can effectively simplify circuit structure, improve efficiency, reduce weight, and shrink size. In military applications, especially in the aerospace field, there is an urgent need for their use, such as new generation of long-life satellites, solar cell power supplies and power distribution systems for space stations, electric propulsion systems and high power density power supplies for new rockets.
[0004] While SiC power devices possess excellent performance characteristics, making them well-suited for the high-voltage, high-frequency, high-efficiency, high-temperature, and high-power applications required in the military and aerospace fields, their poor radiation resistance has been a persistent technical bottleneck hindering their widespread application in radiation-hardened military and aerospace applications. The blocking voltage of SiC Schottky diodes under single-event irradiation is approximately 200V, far from meeting the requirements for high-voltage applications. Therefore, research on single-event radiation hardening of SiC Schottky diodes is urgently needed.
[0005] Currently, such as Figure 1 As shown, the internal chips of mass-produced SiC Schottky diodes mainly adopt a JBS (Junction Barrier Schottky) structure. This structure combines the advantages of SBD and PiN diodes by introducing heavily doped P+ ions into the device and arranging them at a certain spacing. It features low forward voltage drop and low reverse leakage current. However, under single-particle irradiation, micro-burn-out marks easily form on the Schottky contact surface, leading to excessive reverse leakage current or even burn-out, severely limiting the application of SiC Schottky diodes in military and aerospace fields.
[0006] Therefore, there is an urgent need for a new SiC JBS structure with single-particle resistance. Summary of the Invention
[0007] To address the problem in existing technologies where SiC JBS structures are prone to micro-burning marks under single-particle irradiation, leading to excessive reverse leakage current or even burnout, this invention provides a buried P+SiC JBS structure with improved single-particle resistance. By improving the SiC JBS structure, the advantages of low forward voltage drop and low reverse leakage current of the original SiC JBS structure are maintained. At the same time, it can ensure that the collection of holes to the anode metal and electrons to the cathode metal is reduced during single-particle irradiation, and prevent excessive leakage current and burnout.
[0008] This invention is achieved through the following technical solution: a buried P+SiC JBS structure for improving single-particle rejection performance, comprising a cathode metal, an anode metal, a SiC N+ substrate, an N-type buffer layer, an N-epitaxial layer, a P+ buried layer, and a JBS contact P+. The N-type buffer layer and the N-epitaxial layer are disposed above the SiC N+ substrate, and the JBS contact P+ is connected above the N-epitaxial layer. The JBS contact P+ is disposed between the cathode metal and the N-epitaxial layer, and an N-type buffer layer is disposed between the N-epitaxial layer and the SiC N+ substrate. The cathode metal is disposed below the SiC N+ substrate, and the anode metal is connected above the JBS contact P+. The P+ buried layer is disposed between the N-epitaxial layer and the JBS contact P+.
[0009] Furthermore, the JBS contact P+ is configured with multiple contacts.
[0010] Furthermore, the buffer layer is provided with multiple layers.
[0011] Furthermore, the multilayer buffer layers are arranged sequentially according to the concentration gradient, with the buffer layer closest to the SiC N+ substrate having the highest concentration, and the buffer layer closest to the N- epitaxial layer having a higher concentration than the N- epitaxial layer.
[0012] Furthermore, the concentration difference between adjacent buffer layers is about an order of magnitude.
[0013] Furthermore, the concentration and thickness of the N-epitaxial layer are determined based on the breakdown voltage of the device.
[0014] Furthermore, the concentration of the P+ buried layer is determined based on the spacing between two adjacent P+ buried layers above and the distance between the P+ buried layer and the JBS contacting the P+.
[0015] Furthermore, the concentration of P+ in the JBS contact is determined by the type of the connected anode metal.
[0016] Compared with the prior art, the present invention has the following beneficial technical effects:
[0017] The technical solution provided by this invention improves the SiC JBS structure by adding three N-type buffer layers to the typical SiC JBS structure and implanting a P+ buried layer in the N-epitaxial layer. This structure can maintain the advantages of the original SiC JBS structure, such as low forward voltage drop and low reverse leakage current. At the same time, it can ensure that during single-particle irradiation, the three buffer layers balance and redistribute the electron-hole pairs generated by the single-particle incident tracks, reducing the collection of holes to the anode metal and electrons to the cathode metal. Meanwhile, the P+ buried layer blocks the electron-hole pair tracks generated by single-particle incident, preventing the accumulation of holes at the contact surface between the anode metal and the N-epitaxial layer, thus preventing excessive leakage current and burnout.
[0018] Furthermore, by forming a buried P+ region under the Schottky barrier region, the structure can effectively block the trajectory of a single particle during high-voltage reverse bias, prevent the accumulation of electron-hole pairs at the Schottky barrier, and improve the device's single-particle rejection performance.
[0019] Furthermore, the radiation-resistant SiC power devices provided by this invention have an urgent application demand in the electric propulsion and power systems of aerospace vehicles. This solution can effectively improve the single-event immunity of SiC Schottky diodes, has a broad aerospace application market, and brings extremely high economic benefits. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a typical SiC JBS Schottky diode structure in the existing technology;
[0022] Figure 2 This invention proposes a buried P+SiC JBS structure to improve single-particle rejection performance. Detailed Implementation
[0023] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.
[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0025] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0026] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0027] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0028] Example 1:
[0029] In a specific embodiment of the present invention, an improved buried P+SiC JBS structure with three N-type buffer layers is provided, including cathode metal, SiC N+ substrate, N-type buffer layer 1, N-type buffer layer 2, N-type buffer layer 3, N- epitaxial layer, P+ buried layer, JBS contact P+, and anode metal.
[0030] Three N-type buffer layers are sequentially formed on a SiC N+ substrate. The three N-type buffer layers include N-type buffer layer 1, N-type buffer layer 2 and N-type buffer layer 3. The N-type buffer layer 1 has the highest concentration and the N-type buffer layer 3 has the lowest concentration. The three N-type buffer layers are arranged in sequence according to the concentration gradient, and the concentration difference between adjacent buffer layers is about one order of magnitude.
[0031] An N-epitaxial layer is formed on the N-type buffer layer 3. The concentration of the N-type buffer layer 3 is greater than that of the N-epitaxial layer. The concentration and thickness of the N-epitaxial layer are determined according to the breakdown voltage of the device.
[0032] P+ buried layer implantation and JBS contact P+ implantation are performed on the N-epitaxial layer. The P+ buried layer and JBS contact P+ are implanted once or multiple times depending on their respective depths. The P+ buried layer concentration is determined based on the spacing between two adjacent P+ buried layers and the distance between the P+ buried layer and the JBS contact P+. The JBS contact P+ concentration is determined based on the type of anode metal, ensuring a good ohmic contact between the JBS contact P+ and the anode metal, and forming a Schottky contact with the N-epitaxial layer.
[0033] An anode metal is formed on the N- epitaxial layer and P+, ensuring good ohmic contact between the metal and P+, and good Schottky contact between the metal and the N- epitaxial layer. A cathode metal is formed under the SiC N+ substrate, ensuring good ohmic contact with the SiC N+ substrate.
[0034] When the anode metal is connected to a low level and the cathode metal is connected to a high level, the space charge region formed by the JBS contact P+, the P+ buried layer and the N- epitaxial layer, as well as the N- epitaxial layer, can withstand high voltage while reducing reverse leakage current to less than the μA level.
[0035] When the anode metal is connected to a high level and the cathode metal is connected to a low level, the PN junction formed by the P+, anode metal and N- epitaxial layer and the Schottky diode are simultaneously forward-biased.
[0036] Under single-particle irradiation, a typical SiC JBS structure will cause an increase in leakage current or even burn out. The P+ SiC JBS structure with three N-type buffer layers first uses the three buffer layers to balance and redistribute the electron-hole pairs generated by the single-particle incident tracks, reducing the collection of holes to the anode metal and electrons to the cathode metal. Then, the P+ buried layer simultaneously blocks the electron-hole pair tracks generated by the single-particle incident, suppressing the accumulation of holes at the contact surface between the anode metal and the N-epitaxial layer, preventing excessive leakage current and burn-out, and effectively enhancing the device's resistance to single-particle irradiation.
[0037] Example 2:
[0038] like Figure 2As shown, in a preferred embodiment of the present invention, an improved buried P+SiC JBS structure with three N-type buffer layers is provided.
[0039] It mainly includes cathode metal, SiC N+ substrate, N-type buffer layer 1, N-type buffer layer 2, N-type buffer layer 3, N- epitaxial layer, P+ buried layer, JBS contact P+, and anode metal.
[0040] N-type buffer layer 1, N-type buffer layer 2 and N-type buffer layer 3 are sequentially formed on SiC N+ substrate. These three N-type buffer layers need to have a certain concentration gradient. The concentration of N-type buffer layer 1 is the highest and the concentration of N-type buffer layer 3 is the lowest. The concentration difference between adjacent buffer layers is about one order of magnitude. The concentration of N-type buffer layer 3 is greater than that of N- epitaxial layer.
[0041] In this embodiment, when a single particle irradiates the device, if the device is in a forward conduction state with the anode metal connected to a high level and the cathode metal connected to a low level, it will not affect the normal operation of the device.
[0042] When the device is in a reverse cutoff state with the anode metal connected to a low level and the cathode metal connected to a high level, the improved buried P+SiC JBS structure with three N-type buffer layers first uses the three buffer layers to balance and redistribute the electron-hole pairs generated by the single-particle incident track, reducing the collection of holes to the anode metal and the collection of electrons to the cathode metal. Then, the P+ buried layer is used to block the electron-hole pair tracks generated by the single-particle incident, blocking the accumulation of holes in the anode metal and the N-epitaxial layer, preventing excessive leakage current and burnout, and effectively enhancing the device's resistance to single-particle irradiation.
[0043] This improved buried P+SiC JBS structure with three N-type buffer layers effectively blocks the collection of holes in the anode metal and electrons in the cathode metal generated by single-particle incident by adding three N-type buffer layers and an N-epitaxial layer buried P+ structure, preventing excessive leakage current and burnout. It greatly enhances the device's single-particle rejection capability without changing the chip area.
[0044] Without departing from the spirit of this invention, the number of N-type buffer layers and other similar P+ buried layer structures can also be changed.
[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0046] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.
Claims
1. A buried P+ SiC JBS structure for improved single-particle rejection, characterized in that, The device includes a cathode metal, an anode metal, a SiC N+ substrate, an N-type buffer layer, an N-epitaxial layer, a P+ buried layer, and a JBS contact P+. The N-type buffer layer and the N-epitaxial layer are disposed above the SiC N+ substrate, and the JBS contact P+ is connected above the N-epitaxial layer. The JBS contact P+ is positioned between the anode metal and the N-epitaxial layer, and the N-type buffer layer is disposed between the N-epitaxial layer and the SiC N+ substrate. The cathode metal is disposed below the SiC N+ substrate, and the anode metal is connected above the JBS contact P+. The P+ buried layer is disposed between the N-epitaxial layer and the JBS contact P+. The multilayer buffer layers are arranged sequentially according to the concentration gradient, with the buffer layer closest to the SiC N+ substrate having the highest concentration, and the buffer layer closest to the N- epitaxial layer having a higher concentration than the N- epitaxial layer. The concentration difference between adjacent buffer layers is about an order of magnitude; The concentration of the P+ buried layer is determined based on the spacing between two adjacent P+ buried layers above and the distance between the P+ buried layer and the JBS contacting the P+.
2. The buried P+ SiC JBS structure for improving single-particle resistance according to claim 1, characterized in that, The JBS contact P+ is configured in multiple ways.
3. The buried P+ SiC JBS structure for improving single-particle resistance according to claim 1, characterized in that, The buffer layer has multiple layers.
4. The buried P+ SiC JBS structure for improving single-particle resistance according to claim 1, characterized in that, The concentration and thickness of the N-epitaxial layer are determined based on the breakdown voltage of the device.
5. The buried P+ SiC JBS structure for improving single-particle resistance according to claim 1, characterized in that, The concentration of P+ in the JBS contact is determined by the type of the connected anode metal.