Terminal structure and power semiconductor device
By introducing field-limiting ring groups with different doping types and junction termination extensions into power semiconductor devices, the problems of electric field concentration in peripheral cells and epitaxial layer charge are solved, resulting in higher breakdown voltage and device stability, and supporting device miniaturization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2026-04-03
AI Technical Summary
The peripheral cells of existing power semiconductor devices are prone to breakdown due to electric field concentration, resulting in a decrease in breakdown voltage. Furthermore, the surface of the epitaxial layer without field limiting rings has charge, which affects the reliability of the device.
By employing field-limiting ring groups and junction termination extensions with high doping concentrations and different types, a PN junction is formed by setting multiple field-limiting rings and junction termination extensions within the epitaxial layer. This reduces the electric field strength, covers the surface charge of the epitaxial layer, and improves the breakdown voltage.
It effectively reduces electric field concentration in the terminal structure, increases breakdown voltage, improves device reliability and stability, and enables miniaturized device design.
Smart Images
Figure CN224083956U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductors, and more specifically, to a terminal structure and a power semiconductor device. Background Technology
[0002] Power semiconductor devices are composed of multiple cells connected in parallel. During reverse breakdown, the transverse electric fields between adjacent cells cancel each other out, so the inner cells generally do not break down. However, the outermost cells will break down due to the concentration of the electric field.
[0003] To reduce the electric field and increase the breakdown voltage, multiple spaced field-limiting rings are typically placed at intervals as termination structures on the outermost ring of the cell. However, the surface of the epitaxial layer without field-limiting rings will have a small amount of charge, which will reduce the voltage that the power semiconductor device can withstand. Summary of the Invention
[0004] This application provides a termination structure and a power semiconductor device that can reduce the electric field strength on the surface of the termination structure and increase the breakdown voltage.
[0005] In a first aspect, this application provides a terminal structure, the terminal structure including a first end and a second end, wherein the first end is closer to the cell of the power semiconductor device than the second end; the terminal structure further includes:
[0006] Epitaxial layer;
[0007] A field limiting ring group is disposed within the epitaxial layer and extends downward from the first end face of the epitaxial layer; the field limiting ring group includes a plurality of field limiting rings spaced apart along a first direction; the first direction is perpendicular to the thickness direction of the epitaxial layer;
[0008] A junction terminal extension is disposed within the epitaxial layer and extends downward from the first end face of the epitaxial layer; the junction terminal extension is attached to the periphery of at least one field limiting ring near the first end and to the periphery of at least one field limiting ring near the second end.
[0009] In this embodiment, at least one of the field limiting rings has a peripheral contact epitaxial layer and extends away from the junction terminal.
[0010] Furthermore, the field limiting ring group includes a first field limiting ring, a second field limiting ring, and a third field limiting ring arranged sequentially from the first end to the second end;
[0011] The junction terminal extension is attached to the side of the first field limiting ring near the first end; and / or, the junction terminal extension is attached to the side of the third field limiting ring near the second end.
[0012] The second field-limiting ring extends peripherally to the epitaxial layer and extends away from the junction terminal.
[0013] In the above configuration, the junction terminal extension is attached to the side of the first field limiting ring near the first end, which can reduce the amount of charge on the surface of the epitaxial layer near the cell and improve the breakdown voltage of the power semiconductor device; the junction terminal extension is attached to the side of the third field limiting ring near the second end, so as to gradually reduce the electric field strength on the terminal surface and reduce or avoid the problem of electric field concentration.
[0014] Furthermore, the knot terminal extension includes a first knot terminal extension unit and a second knot terminal extension unit arranged sequentially from the first end to the second end;
[0015] The first junction terminal extension unit is attached to the side of the first field limiting ring; the second junction terminal extension unit is attached to the side of the third field limiting ring.
[0016] Furthermore, the width of the second junction terminal extension unit is greater than the width of the third field limiting ring.
[0017] With the above settings, the wider second junction terminal extension unit can gradually reduce the electric field strength on the terminal surface, thereby reducing or avoiding the problem of electric field concentration.
[0018] Furthermore, there are multiple first field limiting rings, which are spaced apart along the direction from the first end to the second end, and the sides of the multiple first field limiting rings are extended and covered by the same first junction terminal extension unit, and the thickness of the first junction terminal extension unit is greater than the thickness of the first field limiting ring; and / or,
[0019] The number of the second field-limited loops is multiple; and / or,
[0020] There are multiple third field limiting rings, and the sides of the multiple third field limiting rings are covered by the same second junction terminal extension unit, and the thickness of the second junction terminal extension unit is greater than the thickness of the third field limiting ring.
[0021] In the above configuration, the thicker first junction termination extension unit can simultaneously cover multiple first field limiting rings, effectively covering more surfaces of the epitaxial layer and providing effective shielding to improve the breakdown voltage of the power semiconductor device; a large number of second field limiting rings, independent of the junction termination extension, contact the epitaxial layer and form multiple PN junctions, further reducing the electric field strength on the termination surface; the thicker third field limiting ring can simultaneously cover multiple second field limiting rings, effectively achieving a gradual reduction in the electric field strength on the termination surface and reducing or avoiding the problem of electric field concentration.
[0022] Furthermore, there are multiple first field limiting rings and multiple first junction terminal extension units. The first field limiting rings and the first junction terminal extension units are arranged alternately along the direction from the first end to the second end, and the thickness of the first junction terminal extension unit is less than or equal to the thickness of the first field limiting ring; and / or,
[0023] The number of the third field limiting ring and the second junction terminal extension unit are both multiple. The third field limiting ring and the second junction terminal extension unit are arranged alternately along the first direction, and the thickness of the second junction terminal extension unit is less than or equal to the thickness of the third field limiting ring.
[0024] In the above configuration, multiple first field limiting rings and multiple first junction termination extension units are arranged alternately, which can effectively cover more of the surface of the epitaxial layer, avoid excessive exposure, and improve the breakdown voltage of the power semiconductor device. A large number of second field limiting rings, which exist independently of the junction termination extension, contact the epitaxial layer and form multiple PN junctions, which better reduce the electric field strength on the termination surface. Multiple third field limiting rings and multiple second field limiting rings are arranged alternately, which can effectively achieve a gradual reduction of the electric field strength on the termination surface, reduce or avoid the problem of electric field concentration.
[0025] Furthermore, the junction termination extension also includes a third junction termination extension unit, which is located at one end of the termination structure away from the cell of the power semiconductor device;
[0026] The third junction terminal extension unit is located away from the field limiting ring group.
[0027] With the above settings, the additional third junction terminal extension unit can gradually reduce the electric field strength on the terminal surface, thereby reducing or avoiding the problem of electric field concentration.
[0028] Furthermore, there are multiple third junction terminal extension units, and these multiple third junction terminal extension units are arranged sequentially at intervals along the first direction.
[0029] Furthermore, the thickness of the junction terminal extension is less than the thickness of the field limiting ring assembly.
[0030] Furthermore, the thickness of the junction terminal extension is greater than the thickness of the field limiting ring assembly, and the junction terminal extension covers the bottom surface of at least one of the field limiting rings; and / or,
[0031] The ratio of the thickness of the junction terminal extension to the thickness of the epitaxial layer is less than or equal to 1 / 5.
[0032] In the above configuration, by limiting the ratio of the thickness of the junction terminal extension to the thickness of the epitaxial layer, the epitaxial layer is ensured to have sufficient thickness, thereby ensuring that the terminal structure has sufficient pressure-bearing capacity.
[0033] Furthermore, the terminal structure also includes a transition block, the doping type of which is the same as that of the field-limiting ring group; at least a portion of the junction terminal extension is also attached to the side of the transition block; and / or,
[0034] At least a portion of the terminal extension of the terminal structure is also attached to the sidewall of the cell of the power semiconductor device.
[0035] Secondly, this application provides a power semiconductor device, the power semiconductor device comprising a cell and a terminal structure;
[0036] The terminal structure is arranged around the periphery of the cell.
[0037] The solution provided in this application includes at least the following beneficial effects:
[0038] In this application, a field-limiting ring group with a high doping concentration and a doping type different from that of the epitaxial layer is used to reduce the electric field concentration in the termination region of the power semiconductor device when subjected to reverse bias, thereby achieving a higher breakdown voltage. The junction termination extension with a lower doping concentration and a doping type different from that of the epitaxial layer ensures complete depletion before avalanche breakdown, effectively controlling leakage current and improving the reliability and stability of the power semiconductor device. Simultaneously, the junction termination extension can also cover part of the surface of the epitaxial layer without field-limiting rings, reducing the amount of charge on the epitaxial layer surface and increasing the breakdown voltage of the power semiconductor device. Furthermore, this application also includes a field-limiting ring independent of the junction termination extension, which directly contacts the epitaxial layer to form a PN junction, further reducing the electric field strength on the termination surface, increasing the breakdown voltage, and effectively reducing the size of the termination structure, achieving miniaturization design. Attached Figure Description
[0039] Figure 1 This is a schematic diagram of the structure of a power semiconductor device according to an embodiment;
[0040] Figure 2 This is a cross-sectional structural schematic diagram of a terminal structure shown in one embodiment;
[0041] Figure 3 This is a cross-sectional structural diagram of the terminal structure shown in another embodiment;
[0042] Figure 4 This is a cross-sectional structural diagram of the terminal structure shown in another embodiment;
[0043] Figure 5 This is a cross-sectional structural schematic diagram of the terminal structure shown in another embodiment;
[0044] Figure 6This is a cross-sectional structural schematic diagram of the terminal structure shown in another embodiment;
[0045] Figure 7 This is a cross-sectional structural schematic diagram of the terminal structure shown in another embodiment;
[0046] Figure 8 This is a cross-sectional structural schematic diagram of the terminal structure shown in another embodiment;
[0047] Figure 9 This is a cross-sectional structural diagram of the terminal structure shown in another embodiment.
[0048] Explanation of reference numerals in the attached figures
[0049] Power semiconductor device 1 Termination structure 10 Termination region 11 Transition region 12
[0050] First end 13, Second end 14, Cell region 20, Epitaxial layer 100
[0051] First end face 101 Field limiting ring group 200 Field limiting ring 201 First field limiting ring 210
[0052] Second loop limit 220, third loop limit 230, terminal extension 300
[0053] First terminal expansion unit 310 Second terminal expansion unit 320
[0054] Third junction termination extension unit 330, substrate 400, drain metal layer 500
[0055] Passivation layer 600, protective layer 700, transition block 900
[0056] Source metal layer 800 First direction X Thickness direction H Detailed Implementation
[0057] The technical solutions in the embodiments (or "implementations") of this application will be clearly and completely described herein with reference to the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.
[0058] If the embodiments of this application contain terms relating to directional indications or positional relationships (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationships and movement of the components in a specific posture (as shown in the attached figures); if the specific posture changes, the directional indications or positional relationships will also change accordingly. Furthermore, the terms "first" and "second" used in the embodiments of this application are only for descriptive convenience and should not be construed as indicating or implying relative importance.
[0059] like Figure 1 This application discloses a power semiconductor device 1. The power semiconductor device 1 includes a cell region 20 and a termination structure 10. A plurality of cells are disposed in the cell region 20, and the termination structure 10 is disposed around the outer periphery of the cell region 20; in other words, the termination structure 10 is disposed around the outer periphery of the outermost cell. The termination structure 10 includes a first end 13 and a second end 14, with the first end 13 being closer to the cells of the power semiconductor device 1 than the second end 14.
[0060] By adding a surrounding terminal structure 10 to the outside of the cell region 20, the electric field distribution in the edge region of the power semiconductor device 1 can be effectively optimized to improve the maximum breakdown voltage of the power semiconductor device 1 and ensure reliability and stability under high voltage operation.
[0061] To further improve the optimization effect of the terminal structure 10 on the edge region of the power semiconductor device 1, the inventors made the following design:
[0062] like Figures 2-9 As shown, the terminal structure 10 includes an epitaxial layer 100, a field limiting ring group 200, a junction terminal extension 300, a substrate 400, a drain metal layer 500, a passivation layer 600, and a protective layer 700.
[0063] In this application, the field-limiting ring group 200 and the junction termination extension 300 have the same doping type, but the doping concentration of the field-limiting ring group 200 is greater than that of the junction termination extension 300. Furthermore, their doping types differ from those of the epitaxial layer 100. In this application, both the field-limiting ring group 200 and the junction termination extension 300 are P-type doped, with the field-limiting ring group 200 located in a heavily doped P-type region and the junction termination extension 300 located in a lightly doped P-type region. The epitaxial layer 100 is N-type doped, and the region where the epitaxial layer 100 is located is a lightly doped N-type region.
[0064] Specifically, the epitaxial layer 100 is formed above the substrate 400, and the drain metal layer 500 is formed below the substrate 400. The field limiting ring group 200 and the junction termination extension 300 are both disposed within the epitaxial layer 100 and extend downward from the first end face 101 of the epitaxial layer 100. A passivation layer 600 covers the first end face 101, and a protective layer 700 covers the side of the passivation layer 600 away from the epitaxial layer 100 to protect the internal structure. It should be noted that in actual operation, a thicker substrate 400 is provided first, and then the drain metal layer 500 is fabricated on top of the substrate 400. Then, the entire structure is flipped and inverted, at which point the drain metal layer 500 is located below the substrate 400. The side of the substrate 400 away from the drain metal layer 500 is then thinned. After the thinning is complete, an epitaxial layer 100 and other structures are formed on the thinned substrate 400 away from the drain metal layer 500.
[0065] The field limiting ring group 200 includes a plurality of field limiting rings 201 spaced apart along a first direction X. The portion of the field limiting ring 201 that contacts the epitaxial layer 100 forms a PN junction. By using the field limiting ring group 200 with a higher doping concentration and a doping type different from that of the epitaxial layer 100, the electric field concentration in the terminal region 11 of the power semiconductor device 1 can be reduced when subjected to reverse bias, thereby obtaining a higher breakdown voltage.
[0066] The junction termination extension 300 has a lower doping concentration and a different doping type than the epitaxial layer 100, which can ensure that it is completely depleted before avalanche breakdown, thereby effectively controlling leakage current and improving the reliability and stability of the power semiconductor device 1.
[0067] Simultaneously, the junction termination extension 300 is attached to the side of at least one field limiting ring 201. Through this arrangement, the junction termination extension 300 can cover a portion of the first end face 101 of the epitaxial layer 100 without a field limiting ring. The surface of the junction termination extension 300, belonging to the lightly doped P-type region, is exposed, which can reduce the charge present on the first end face 101 of the epitaxial layer 100 and improve the breakdown voltage of the power semiconductor device 1. Specifically, the junction termination extension 300 is attached to the periphery of at least one field limiting ring 201 near the first end 13 and to the periphery of at least one field limiting ring 201 near the second end 14. The junction terminal extension 300, which is attached to the periphery of at least one field limiting ring 201 near the first end 13, can effectively reduce the amount of charge present on the first end face 101 near the cell region 20 and more effectively improve the breakdown voltage. The junction terminal extension 300, which is attached to the periphery of at least one field limiting ring 201 near the second end 14, can better realize the gradual reduction of the electric field strength of the terminal structure 10 away from the cell region 20, and reduce or avoid the problem of electric field concentration.
[0068] It should be noted that the field limiting ring 201 is a ring structure, which is arranged around the outer side of the cell region 20. Thus, the side of the field limiting ring 201 near the first end 13 should be understood as the inner wall surface of the field limiting ring 201; the side of the field limiting ring 201 near the second end 14 should be understood as the outer wall surface of the field limiting ring 201. In addition, the "ring structure" mentioned above only refers to a structure where the ends are connected, which can be a polygonal ring, a circular ring, an elliptical ring, etc., and should not be understood only as a circular ring structure.
[0069] At least one field-limiting ring 201 has peripheral contact with the epitaxial layer 100 and is located away from the junction termination extension 300. In other words, the surface of the field-limiting ring 201 adjacent to the first end face 101 and its surface away from the first end face 101 are both covered by the epitaxial layer 100 and do not contact the junction termination extension 300, effectively existing independently of the junction termination extension 300. In this configuration, the field-limiting ring 201 directly contacts the epitaxial layer 100 and forms a PN junction with a large concentration difference, thereby better reducing the electric field strength at the termination surface and improving the breakdown voltage.
[0070] With the above settings, among power semiconductor devices 1 with the same breakdown capability, the power semiconductor device 1 using the above-mentioned terminal structure 10 can have a more ideal ability to improve the breakdown voltage with a smaller terminal structure 10, thereby effectively reducing the size of the terminal structure 10 and realizing the miniaturization design of the terminal structure 10 and the power semiconductor device 1.
[0071] It should be noted that the first direction X is perpendicular to the thickness direction H of the epitaxial layer 100, and the first direction X can also be interpreted as parallel to the direction from the first end 13 to the second end 14.
[0072] Continue as Figures 2-9 As shown, the field limiting ring group 200 includes a first field limiting ring 210, a second field limiting ring 220, and a third field limiting ring 230 arranged sequentially from the first end 13 to the second end 14. Alternatively, it can be understood that there are multiple field limiting rings 201, with some field limiting rings 201 closer to the cell region 20 serving as the first field limiting ring 210, some field limiting rings 201 farther from the cell region 20 serving as the third field limiting ring 230, and the remaining field limiting rings 201 located between the first field limiting ring 210 and the third field limiting ring 230 serving as the second field limiting ring 220.
[0073] Continue as Figures 2-9 As shown, in the above embodiment, a junction termination extension 300 is attached to the side of the first field limiting ring 210 near the first end 13. In the above configuration, the junction termination extension 300 attached to the side of the first field limiting ring 210 near the cell region 20 can effectively reduce the amount of charge on the first end face 101 of the epitaxial layer 100 near the cell, thereby better improving the breakdown voltage of the power semiconductor device 1.
[0074] It should be noted that the side of the first field limiting ring 210 away from the first end 13 and the bottom surface of the first field limiting ring 210 away from the passivation layer 600 can also cover the junction terminal extension 300. In other words, any field limiting ring that is fully or partially attached to the side of the first end 13 by the junction terminal extension 300 and is located on the side of the second field limiting ring 220 near the cell region 20 can be used as the first field limiting ring 210.
[0075] A junction termination extension 300 is attached to the side of the third field limiting ring 230 near the second end 14. In the above configuration, the junction termination extension 300 is attached to the side of the third field limiting ring 230 away from the cell region 20 to achieve a gradual reduction in the electric field strength on the terminal surface, thereby reducing or avoiding the problem of electric field concentration. Of course, in other embodiments, the junction termination extension 300 may only be attached to the side of the first field limiting ring 210 near the first end 13.
[0076] Similarly, it should be noted that the side of the third field limiting ring 230 away from the second end 14 and the bottom surface of the third field limiting ring 230 away from the passivation layer 600 can also cover the junction terminal extension 300. In other words, any field limiting ring that is fully or partially attached to the side of the second end 14 by the junction terminal extension 300 and is located on the side of the second field limiting ring 220 away from the cell region 20 can be used as the third field limiting ring 230.
[0077] Continue as Figures 2-9 As shown, in the above embodiment, the peripheral side of the second field limiting ring 220 contacts the epitaxial layer 100 and is far from the junction termination extension 300. In other words, the second field limiting ring 220 is the field limiting ring 201 mentioned above that exists independently of the junction termination extension 300. The surfaces adjacent to its first end face 101 and the surfaces far from its first end face 101 are covered by the epitaxial layer 100 and do not contact the junction termination extension 300. In the above configuration, the second field limiting ring 220 located in the middle region of the termination structure 10 exists independently to better reduce the electric field strength on the termination surface, and at the same time, to better balance the amount of charge on the first end face 101 and the problem of edge electric field concentration, ensuring that the power semiconductor device 1 can have an improved breakdown voltage.
[0078] It should be noted that the number of ring limits 210 in the first round, 220 in the second round, and 230 in the third round can all be one or more. For example, in... Figures 2-9 In the embodiments shown, the number of first field limiting loops 210 is multiple; in Figure 2 , Figure 4 , Figure 6 and Figure 8 In the embodiments shown, there are multiple second field limiting loops 220; such as Figure 3 , Figure 5 , Figure 7 and Figure 9 In the embodiments shown, the number of second field-limiting loops 220 is always one; in Figure 2 , Figure 4 , Figure 6 and Figure 8 In the embodiments shown, the number of third field limiting loops 230 is always one; as Figure 3 , Figure 5 , Figure 7 and Figure 9 In the embodiments shown, there are multiple third field limiting rings 230. Meanwhile, the junction terminal extension 300 may completely cover the periphery of the first field limiting ring 210 and / or the third field limiting ring 230, or may only cover a portion of the periphery of the first field limiting ring 210 and / or the third field limiting ring 230, as will be explained in detail below.
[0079] like Figures 2-9 In the embodiment shown, the junction terminal extension 300 includes a first junction terminal extension unit 310 and a second junction terminal extension unit 320 arranged sequentially from the first end 13 to the second end 14.
[0080] In such Figures 2-9 In the illustrated embodiment, the first junction termination extension unit 310 is attached to the side of the first field limiting ring 210, and the second junction termination extension unit 320 is attached to the side of the third field limiting ring 230. Of course, in other embodiments, the junction termination extension 300 may include only the first junction termination extension unit 310 attached to the side of the first field limiting ring 210, or only the second junction termination extension unit 320 attached to the side of the third field limiting ring 230.
[0081] In the above embodiment, the width K1 of the second junction terminal extension unit 320 is greater than the width K2 of the third field limiting ring 230 (specific references are as follows). Figure 2 (As shown). In the above configuration, the second junction termination extension unit 320, which has a larger width and a lower doping concentration, is arranged on the periphery of the third field limiting ring 230 and directly contacts the epitaxial layer 100. Extensive experiments have demonstrated that the above structure can achieve a gradual reduction in the electric field strength on the surface of the termination structure 10, reducing or avoiding the problem of electric field concentration caused by abrupt changes in electric field strength.
[0082] In such Figure 4 , Figure 5 , Figure 8 and Figure 9In the illustrated embodiment, the junction termination extension 300 further includes a third junction termination extension unit 330, which is located at one end of the termination structure 10 away from the cell of the power semiconductor device 1. The third junction termination extension unit 330 is located away from the field limiting ring group 200. Alternatively, the third junction termination extension unit 330 can be understood as being located at one end of the second junction termination extension unit 320 away from the first junction termination extension unit 310, and the third junction termination extension unit 330 does not contact the aforementioned field limiting ring group 200.
[0083] In the above configuration, the additional third junction termination extension unit 330 can gradually reduce the electric field strength on the surface of the termination structure 10, thereby reducing or avoiding the problem of electric field concentration. The combination of the first junction termination extension unit 310, the second junction termination extension unit 320, and the third junction termination extension unit 330 can better reduce the amount of charge on the surface of the epitaxial layer 100, improve the breakdown voltage of the power semiconductor device 1, and reduce or avoid the problem of electric field concentration.
[0084] exist Figure 4 , Figure 5 , Figure 8 and Figure 9 In the illustrated embodiment, there can be multiple third junction terminal extension units 330, which are arranged sequentially at intervals along the first direction X. By setting multiple spaced-apart third junction terminal extension units 330, the electric field strength on the terminal surface can be reduced in a step-like and gradual manner, thus better reducing or avoiding the problem of electric field concentration. Of course, in other embodiments, only one third junction terminal extension unit 330 with a larger width can be set, or the third junction terminal extension unit 330 can be omitted.
[0085] In the above embodiments, the first junction terminal extension unit 310, the second junction terminal extension unit 320, and the third junction terminal extension unit 330 can be formed simultaneously, and their thicknesses are the same. Of course, in other embodiments, the three units can be formed through different steps, and their thicknesses can also be different. Meanwhile, in this application, the first field limiting ring 210, the second field limiting ring 220, and the third field limiting ring 230 can be formed simultaneously, and their thicknesses are consistent. Of course, in other embodiments, the three units can be formed through different steps, and their thicknesses can also be different. It should be noted that in some embodiments, the thickness of the third junction terminal extension unit 330 can be consistent with the thickness of any one of the field limiting rings 201 (first field limiting ring 210, second field limiting ring 220, third field limiting ring 230) to save process steps. Of course, the thickness of the third junction terminal extension unit 330 can also be different from the thickness of any one of the field limiting rings 201 (first field limiting ring 210, second field limiting ring 220, third field limiting ring 230). In this case, by simply adjusting the width of the third junction terminal extension unit 330, and / or, when there are multiple third junction terminal extension units 330, adjusting the gap between two adjacent third junction terminal extension units 330, the problem of electric field concentration can be effectively reduced or avoided, thereby increasing the flexibility of the design.
[0086] exist Figure 4 and Figure 5 In the illustrated embodiment, the first junction termination extension unit 310, the second junction termination extension unit 320, and the third junction termination extension unit 330 have the same thickness. Furthermore, the thickness of the first junction termination extension unit 310 is greater than the thickness of the first field limiting ring 210, and the thickness of the second junction termination extension unit 320 is greater than the thickness of the third field limiting ring 230. The thickness of the junction termination extension 300 mentioned above can also be understood as its depth; similarly, the thickness of the field limiting ring 201 can also be understood as its depth.
[0087] Meanwhile, there are multiple first field limiting rings 210, which are arranged at intervals along the first direction X, and the sides of the multiple first field limiting rings 210 are covered by the same first junction termination extension 300. In the above configuration, the thicker first junction termination extension unit 310 can simultaneously cover multiple first field limiting rings 210, effectively covering more surfaces of the epitaxial layer 100, providing effective shielding and improving the breakdown voltage of the power semiconductor device 1. This configuration offers high ease of operation and relatively low requirements for process precision.
[0088] Of course, as mentioned above, in other embodiments, the number of first field limiting rings 210 may also be only one.
[0089] exist Figure 3 and Figure 5In the illustrated embodiment, there are multiple third field limiting rings 230, and the sides of multiple third field limiting rings 230 are covered by the same second junction terminal extension unit 320. In the above configuration, the thicker third field limiting rings 230 can simultaneously cover multiple second field limiting rings 220, which can effectively achieve a gradual reduction of the electric field strength on the terminal surface, reducing or avoiding the problem of electric field concentration. This configuration offers high ease of operation and relatively low requirements for process precision.
[0090] Of course, as mentioned above, in other embodiments, the number of third field limiting rings 230 may also be only one.
[0091] exist Figure 2 and Figure 4 In the illustrated embodiment, similarly, there can be multiple second field-limiting rings 220 located away from the junction termination extension 300. A larger number of second field-limiting rings, existing independently of the junction termination extension 300, contact the epitaxial layer 100 and form multiple PN junctions, better reducing the electric field strength at the termination surface. Of course, as mentioned above, in other embodiments, the number of second field-limiting rings 220 can also be only one.
[0092] As can be seen from the above analysis, the thickness of the junction termination extension 300 can be greater than the thickness of the field limiting ring group 200. In this case, the junction termination extension 300 can cover at least the bottom surface of a field limiting ring, so that a termination extension serving as a lightly doped N-type region is provided between the heavily doped P-type field limiting ring and the N-type epitaxial layer 100. Through this arrangement, the electric field concentration in the termination region 11 can be reduced when the power semiconductor device 1 is subjected to reverse bias, thereby obtaining a higher breakdown voltage.
[0093] In the aforementioned terminal structure 10, a sufficiently thick epitaxial layer 100 is required to achieve adequate pressure resistance. The inventors discovered that when the junction termination extension 300 is too thick, it actually reduces the thickness of the epitaxial layer 100, thus affecting the pressure resistance of the terminal structure 10. Through numerous experiments, the inventors found that when the ratio of the thickness H1 of the junction termination extension 300 to the thickness H2 of the epitaxial layer 100 is less than or equal to 1 / 5 (refer to the reference numerals),... Figure 2 As shown), this ensures that the epitaxial layer 100 has a relatively reasonable thickness, thereby ensuring that the terminal structure 10 has sufficient pressure-bearing capacity. In such cases... Figures 2-9 In the embodiment shown, the ratio of the thickness H1 of the junction extension 300 to the thickness H2 of the epitaxial layer 100 is less than or equal to 1 / 10.
[0094] It should be noted that, in Figures 2-9 In order to better illustrate the structure of each component, the diagram is not drawn to scale, but is only a simplified structural illustration.
[0095] Of course, in other embodiments, the thickness of the junction terminal extension 300 may also be less than or equal to the thickness of the field limiting ring assembly 200 (see reference). Figures 6-9 As shown, as long as the junction termination extension 300 extends downward from the first end face 101, it can cover the surface of the epitaxial layer 100 and achieve an effective shielding effect. The following is a more detailed explanation:
[0096] like Figures 6-9 As shown, the first junction terminal extension unit 310, the second junction terminal extension unit 320, and the third junction terminal extension unit 330 have the same thickness. Furthermore, the thickness of the first junction terminal extension unit 310 is less than or equal to the thickness of the first field limiting ring 210, and the thickness of the second junction terminal extension unit 320 is less than or equal to the thickness of the third field limiting ring 230.
[0097] exist Figures 6-9 In the illustrated embodiment, there are multiple first field limiting rings 210 and first junction termination extension units 310, which are arranged alternately along the first direction X. In the above arrangement, the first junction termination extension unit 310 only covers the periphery of the first field limiting ring 210 or only covers a portion of the periphery of the first field limiting ring 210. However, since the first junction termination extension unit 310 extends downward from the first end face 101, it still effectively covers the surface of the epitaxial layer 100, playing an effective shielding role and improving the breakdown voltage of the power semiconductor device 1.
[0098] In actual operation, multiple first junction terminal expansion units 310 can be formed simultaneously. After the first junction terminal expansion units 310 are formed, multiple first field limiting loops 210 are then formed in a designated area. This operation can improve terminal efficiency while increasing the fault tolerance in the process. Of course, in other embodiments, the first field limiting loops 210 can be formed first, followed by the first junction terminal expansion units 310, and multiple first junction terminal expansion units 310 can be formed in different steps.
[0099] In such Figure 7 and Figure 9In the illustrated embodiment, there are multiple third field limiting rings 230 and second junction termination extension units 320, which are arranged alternately along the first direction X. Similarly, in the above arrangement, the second junction termination extension unit 320 only covers the periphery of the third field limiting ring 230 or only covers a portion of the side structure of the first field limiting ring 210. However, since the second junction termination extension unit 320 extends downward from the first end face 101, it still effectively covers the surface of the epitaxial layer 100, avoiding excessive exposure and providing effective shielding, thereby improving the breakdown voltage of the power semiconductor device 1. At the same time, the multiple spaced third field limiting rings 230 and second junction termination extension units 320 can effectively reduce the electric field strength on the terminal surface, reducing or avoiding the problem of electric field concentration.
[0100] In actual operation, multiple second junction terminal expansion units 320 can be formed simultaneously. After the second junction terminal expansion units 320 are formed, multiple third field limiting loops 230 are then formed in a designated area. This operation can improve terminal efficiency while increasing the fault tolerance in the process. Of course, in other embodiments, the third field limiting loops 230 can be formed first, followed by the second junction terminal expansion units 320, and multiple second junction terminal expansion units 320 can be formed in different steps.
[0101] like Figures 2-9 In the embodiment shown, the terminal structure 10 further includes a transition region 12, in which a transition block 900 for routing is disposed in the epitaxial layer 100, and a source metal layer 800 disposed on the epitaxial layer 100 and connected to the transition block 900.
[0102] The doping type of the transition block 900 is the same as that of the field confinement ring group 200. At least a portion of the junction termination extension 300 is also attached to the side of the transition block 900. With the above arrangement, the first end face 101 of the epitaxial layer 100 can be further covered, thereby improving the breakdown voltage of the power semiconductor device 1.
[0103] like Figures 5-9 As shown, when the thickness of the junction terminal extension 300 of the terminal structure 10 is small, the junction terminal extension 300 only fits the peripheral side surface of the transition block 900. Figures 2-5 As shown, when the thickness of the junction terminal extension 300 of the terminal structure 10 is large, the junction terminal extension 300 of the terminal structure 10 not only adheres to the peripheral side of the transition block 900, but also adheres to the bottom surface of the transition block 900 away from the first end face 101. In this case, the area where the field limiting ring group 200 and the junction terminal extension 300 are located can be designated as the terminal region 11. When the junction terminal extension 300 of the terminal structure 10 adheres to the bottom surface of the transition block 900, the terminal region 11 and the transition region 12 have an overlapping portion (see reference). Figures 2-5(As shown).
[0104] Of course, in other embodiments, the transition block 900 may not be provided in the terminal structure 10. In this case, at least a portion of the junction termination extension 300 may be attached to the side of the cell in the cell region 20 of the power semiconductor device 1. With the above arrangement, the first end face 101 of the epitaxial layer 100 can be further covered, thereby improving the breakdown voltage of the power semiconductor device 1.
[0105] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A terminal structure applied to a power semiconductor device, characterized by, The terminal structure comprises a first end and a second end, the first end is closer to the cell of the power semiconductor device than the second end; the terminal structure further comprises: an epitaxial layer; a field limiting ring set arranged in the epitaxial layer and extending downward from a first end surface of the epitaxial layer; the field limiting ring set comprises a plurality of field limiting rings arranged in a direction from the first end to the second end at intervals; a junction terminal extension arranged in the epitaxial layer and extending downward from the first end surface of the epitaxial layer; the junction terminal extension is attached to the circumferential side of at least one of the field limiting rings close to the first end and to the circumferential side of at least one of the field limiting rings close to the second end; wherein the circumferential side of at least one of the field limiting rings contacts the epitaxial layer and is away from the junction terminal extension.
2. The terminal structure of claim 1, wherein The field limiting ring set comprises a first field limiting ring, a second field limiting ring and a third field limiting ring arranged in order from the first end to the second end; the side of the first field limiting ring close to the first end is attached with the junction terminal extension; and / or, the side of the third field limiting ring close to the second end is attached with the junction terminal extension; the circumferential side of the second field limiting ring contacts the epitaxial layer and is away from the junction terminal extension.
3. The terminal structure of claim 2, wherein The junction terminal extension comprises a first junction terminal extension unit and a second junction terminal extension unit arranged in order from the first end to the second end; the first junction terminal extension unit is attached to the side of the first field limiting ring; and the second junction terminal extension unit is attached to the side of the third field limiting ring.
4. The terminal structure of claim 3, wherein The width of the second junction terminal extension unit is greater than the width of the third field limiting ring.
5. The terminal structure of claim 3, wherein The number of the first field limiting rings is a plurality, the plurality of the first field limiting rings are arranged in a direction from the first end to the second end at intervals, the sides of the plurality of the first field limiting rings are covered by the same first junction terminal extension, the thickness of the first junction terminal extension unit is greater than the thickness of the first field limiting ring; and / or, the number of the second field limiting rings is a plurality; and / or, the number of the third field limiting rings is a plurality, the sides of the plurality of the third field limiting rings are covered by the same second junction terminal extension unit, and the thickness of the second junction terminal extension unit is greater than the thickness of the third field limiting ring.
6. The terminal structure of claim 3, wherein The number of the first field limiting rings and the first junction terminal extension unit is a plurality, the first field limiting rings and the first junction terminal extension unit are arranged in order from the first end to the second end at intervals, and the thickness of the first junction terminal extension unit is less than or equal to the thickness of the first field limiting ring; and / or, the number of the second field limiting rings is a plurality; and / or, the number of the third field limiting rings and the second junction terminal extension unit is a plurality, the third field limiting rings and the second junction terminal extension unit are arranged in order from the first end to the second end at intervals, and the thickness of the second junction terminal extension unit is less than or equal to the thickness of the third field limiting ring.
7. The terminal structure of claim 1, wherein The junction terminal extension further comprises a third junction terminal extension unit, the third junction terminal extension unit is located at an end of the terminal structure away from the cell of the power semiconductor device; the third junction terminal extension unit is away from the field limiting ring set.
8. The terminal structure of claim 7, wherein The third junction termination extension unit is multiple in number, and multiple third junction termination extension units are arranged in sequence in the direction from the first end to the second end.
9. The terminal structure of claim 1, wherein The thickness of the junction termination extension is less than or equal to the thickness of the field limiting ring set.
10. The terminal structure of claim 1, wherein The thickness of the junction termination extension is greater than the thickness of the field limiting ring set. The junction termination extension covers the bottom surface of at least one of the field limiting rings; and / or, the ratio of the thickness of the junction termination extension to the thickness of the epitaxial layer is less than or equal to 1 / 5.
11. The terminal structure of claim 1, wherein The terminal structure further comprises a transition block, the doping type of the transition block is the same as the doping type of the field limiting ring set; at least part of the junction termination extension further adheres to the side surface of the transition block; and / or, At least part of the junction termination extension of the terminal structure further adheres to the cell side surface of the power semiconductor device.
12. A power semiconductor device, characterized by The power semiconductor device comprises a cell and a terminal structure as claimed in any one of claims 1-11; The terminal structure is arranged around the periphery of the cell.