Cell structure of silicon carbide MPS diode and silicon carbide MPS diode
Patent Information
- Application Number
- CN202521259768.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-18
- Publication Date
- 2026-08-18
- Estimated Expiration
- 2035-06-18
AI Technical Summary
[0004]本申请的目的在于至少提供一种碳化硅MPS二极管的元胞结构及碳化硅MPS二极管，至少可以解决键合点附近在大的浪涌电流下容易发热导致金属融化和器件失效的问题，至少可以达到提升碳化硅MPS二极管的抗浪涌能力的效果
[0027]本申请的碳化硅MPS二极管的元胞结构中，采用键合区域与非键合区域对应设置不同的元胞，其中，碳化硅衬底的碳化硅外延层上与键合区域对应的第一区域包括第一元胞和第二元胞两种元胞，与非键合区域对应的第二区域包括第一元胞这一种元胞，由于第一元胞包括肖特基结和PN结，第二元胞全部区域都是PN结，第二元胞的流通区域比第一元胞的流通区域更少，因此，碳化硅MPS二极管工作时，与第二元胞相比，电流会更多的流过第一元胞，如此，可以减少第一区域对应键合区域的电流，进而减缓键合区域附近的金属发热，减少碳化硅MPS二极管的失效情况，从而提升碳化硅MPS二极管的抗浪涌能力。
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Abstract
Description
Technical Field
[0001] This application relates to the semiconductor field, and more particularly to a cell structure of a silicon carbide merged PiN Schottky (MPS) diode and a silicon carbide MPS diode. Background Technology
[0002] Silicon carbide (SiC) materials possess advantages such as wide bandgap, high thermal conductivity, high breakdown field strength, and high saturation velocity, making them ideal for fabricating high-temperature, high-power semiconductor devices. Silicon carbide-based power devices can fully leverage their high-temperature, high-frequency, and low-loss characteristics, making them highly promising for applications in high-voltage, high-temperature, high-frequency, high-power, and high-radiation fields.
[0003] In practical applications, the anode pads on the front side of silicon carbide MPS diodes are bonded by welding. Under large surge currents, the area near the bonding point is prone to overheating, which can lead to metal melting and device failure. Utility Model Content
[0004] The purpose of this application is to provide at least one cell structure of a silicon carbide MPS diode and a silicon carbide MPS diode, which can at least solve the problem that the bonding point is prone to overheating under large surge current, leading to metal melting and device failure, and can at least improve the surge resistance of the silicon carbide MPS diode.
[0005] In a first aspect, this application provides a cell structure for a silicon carbide MPS diode, wherein the front side of the silicon carbide MPS diode has a bonding region and a non-bonded region adjacent to the bonding region, and the cell structure of the silicon carbide MPS diode includes:
[0006] silicon carbide substrate;
[0007] A silicon carbide epitaxial layer is located on the silicon carbide substrate and includes a first region and a second region, wherein the first region corresponds to the bonding region and the second region corresponds to the non-bonding region;
[0008] Multiple cells, located on the silicon carbide epitaxial layer, including a first cell and a second cell;
[0009] Wherein, a portion of the projection region of the first cell in the silicon carbide epitaxial layer is a Schottky junction, and another portion is a PN junction; both the first region and the second region include the first cell;
[0010] The entire projection region of the second cell in the silicon carbide epitaxial layer is a PN junction; the first region also includes the second cell.
[0011] Optionally, in the first region, multiple first cell groups and multiple second cell groups are arranged in parallel;
[0012] The first cell group and the second cell group have the same number of cells;
[0013] Multiple second cell groups are evenly distributed within multiple first cell groups;
[0014] The first cell group includes the first cell;
[0015] The second cell group includes the second cell and the first cell.
[0016] Optionally, in the second cell group, the second cells are evenly distributed among a plurality of the first cells.
[0017] Optionally, in the first region, starting from the second cell group, N first cell groups are set between every two second cell groups, where N is a positive integer;
[0018] In the second cell group, starting from the second cell, N first cells are set between every two second cells.
[0019] Optionally, in the second region, multiple third cell groups are arranged in parallel;
[0020] Each of the third cell groups contains the same number of the first cells.
[0021] Optionally, the projection region of the first cell in the silicon carbide epitaxial layer includes a first sub-region, a second sub-region surrounding the first sub-region, and a third sub-region surrounding the second sub-region; the partial region includes the second sub-region, and the other partial region includes the first sub-region and the third sub-region.
[0022] Optionally, the boundary line between the second sub-region and the first sub-region is circular, and the boundary line between the second sub-region and the third sub-region is also circular.
[0023] Optionally, the outer contours of the projection regions of the first cell and the second cell in the silicon carbide epitaxial layer are both regular hexagons.
[0024] Secondly, this application provides a silicon carbide MPS diode, the front side of which includes a bonding region and a non-bonded region adjacent to the bonding region, and the silicon carbide MPS diode further includes the cell structure of the silicon carbide MPS diode as described in any of the above.
[0025] Optionally, the non-bonded region surrounds the bonded region.
[0026] The advantages of this application compared to the prior art are:
[0027] In the cell structure of the silicon carbide MPS diode of this application, different cells are set for the bonding region and the non-bonded region. The first region on the silicon carbide epitaxial layer of the silicon carbide substrate corresponding to the bonding region includes two types of cells: first cells and second cells. The second region corresponding to the non-bonded region includes only one type of cell: the first cell. Since the first cell includes a Schottky junction and a PN junction, and the entire area of the second cell is a PN junction, the current flow area of the second cell is smaller than that of the first cell. Therefore, when the silicon carbide MPS diode is working, more current flows through the first cell compared to the second cell. This reduces the current in the bonding region corresponding to the first region, thereby mitigating the heating of the metal near the bonding region, reducing the failure of the silicon carbide MPS diode, and improving the surge resistance of the silicon carbide MPS diode.
[0028] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description
[0029] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.
[0030] Figure 1 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in one embodiment of this application. Figure 1 ;
[0031] Figure 2 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in one embodiment of this application. Figure 2 ;
[0032] Figure 3 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in one embodiment of this application. Figure 3 ;
[0033] Figure 4 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in one embodiment of this application. Figure 4 ;
[0034] Figure 5 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in one embodiment of this application. Figure 5 ;
[0035] Figure 6 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 6 ;
[0036] Figure 7 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 7 . Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this application to help readers better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.
[0038] Embodiments of this application relate to a cell structure of a silicon carbide MPS diode.
[0039] Compared to the prior art, the embodiments of this application employ different cells corresponding to the bonding region and the non-bonded region. Specifically, the first region on the silicon carbide epitaxial layer of the silicon carbide substrate corresponding to the bonding region includes both first cells and second cells, while the second region corresponding to the non-bonded region includes only the first cell. Since the first cell includes both a Schottky junction and a PN junction, and the entire area of the second cell is a PN junction, the current flow area of the second cell is smaller than that of the first cell. Therefore, when the silicon carbide MPS diode is operating, more current flows through the first cell compared to the second cell. This reduces the current in the bonding region corresponding to the first region, thereby mitigating metal heating near the bonding region, reducing the failure rate of the silicon carbide MPS diode, and improving its surge protection capability.
[0040] This application provides a detailed description of the implementation details of the silicon carbide MPS diode of this embodiment. The following details are provided for ease of understanding and are not necessary for implementing this solution.
[0041] This application provides a cell structure for a silicon carbide MPS diode, see [link to relevant documentation]. Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The silicon carbide MPS diode 100 has a bonding region 110 on its front side and a non-bonded region 120 adjacent to the bonding region 110. The cell structure of the silicon carbide MPS diode includes:
[0042] Silicon carbide substrate 180;
[0043] A silicon carbide epitaxial layer 190 is located on a silicon carbide substrate 180 and includes a first region 191 and a second region 192. The first region 191 corresponds to the bonding region 110 and the second region 192 corresponds to the non-bonded region 120.
[0044] Multiple cells are located on the silicon carbide epitaxial layer 190, including the first cell 130 and the second cell 140;
[0045] Among them, a portion of the projection region of the first cell 130 onto the silicon carbide epitaxial layer 190 is a Schottky junction, and another portion is a PN junction; both the first region 191 and the second region 192 include the first cell 130.
[0046] The entire projection region of the second cell 140 onto the silicon carbide epitaxial layer 190 is a PN junction; the first region 191 also includes the second cell 140.
[0047] The front side of the silicon carbide MPS diode is the anode side.
[0048] In practical applications, during the packaging process of silicon carbide MPS diodes, such as Figure 1 As shown, the front side of the silicon carbide MPS diode has a bonding region 110 for setting bonding points 111. Metal pads can be provided in the bonding region 110 to achieve bonding of the bonding points 111. The other areas on the front side of the silicon carbide MPS diode besides the bonding region 110 are non-bonding regions 120.
[0049] The silicon carbide substrate 180 is an N+ type heavily doped silicon carbide substrate. An N-type lightly doped drift layer is grown on the silicon carbide substrate 180 by vapor phase epitaxy to obtain a silicon carbide epitaxial layer 190. A metal is deposited on the silicon carbide epitaxial layer 190 to form a Schottky junction, and a P-type impurity is implanted on the silicon carbide epitaxial layer 190 to form a PiN junction, thus obtaining a PN junction.
[0050] The outer contour shape and size of the projection regions of multiple cells on the silicon carbide epitaxial layer 190 are the same.
[0051] The first cell 130 includes Schottky junctions and PN junctions, while the second cell 140 consists entirely of PN junctions, i.e., P-island structures. Therefore, the flow area of the first cell 130 is larger than that of the second cell 140.
[0052] To address the issue of overheating near the bonding point under large surge currents, leading to metal melting and device failure, the cell layout is configured differently in the bonding region 110 and the non-bonding region 120. The second region 192 corresponding to the non-bonding region 120 has a first cell 130, while the first region 191 corresponding to the bonding region 110 has a second cell 140 in addition to the first cell 130. This reduces the flow area in the bonding region 110, thereby increasing the voltage drop (VF) in and around the bonding region 110 and improving current sharing in different regions. This allows the silicon carbide MPS diode to withstand larger surge currents in surge mode, improving its surge resistance.
[0053] The non-bonded region 120 can surround the bonded region 110, thus the heat generation of the surrounding bonded region 110 can be sufficiently mitigated by the cell layout of the second region 192 corresponding to the non-bonded region 120. For example, the bonded region 110 is located in the central region of the front side of the silicon carbide MPS diode.
[0054] like Figure 4 and Figure 5 As shown, the outer contours of the projection regions of the first cell 130 and the second cell 140 onto the silicon carbide epitaxial layer 190 are both regular hexagons. The geometric symmetry of the regular hexagonal cells allows for a close arrangement of the cells.
[0055] For example, such as Figure 4 As shown, the projection region of the first cell 130 onto the silicon carbide epitaxial layer 190 includes a first sub-region 131, a second sub-region 132 surrounding the first sub-region 131, and a third sub-region 133 surrounding the second sub-region 132; a portion of the region includes the second sub-region 132, and another portion includes the first sub-region 131 and the third sub-region 133. The first sub-region 131, the second sub-region 132, and the third sub-region 133 are concentrically arranged. Based on this, the second sub-region 132 is a Schottky junction, and the first sub-region 131 and the third sub-region 133 are PN junctions. The PN junctions on both sides of the Schottky junction effectively block the diffusion of minority carriers and suppress the reverse leakage current of the Schottky junction.
[0056] The boundary lines between the second sub-region 132 and the first sub-region 131 are circular, and the boundary line between the second sub-region 132 and the third sub-region 133 is also circular. The circular boundary lines between the second sub-region 132 and both the first and third sub-regions 131 and 133 optimize the electric field distribution. Of course, the boundary lines can also have other shapes, which are not listed here.
[0057] In this embodiment, different cells are set corresponding to the bonding region 110 and the non-bonded region 120. The first region 191 on the silicon carbide epitaxial layer 190 of the silicon carbide substrate 180, corresponding to the bonding region 110, includes two types of cells: first cell 130 and second cell 140. The second region 192, corresponding to the non-bonded region 120, includes only one type of cell: first cell 130. Since the first cell 130 includes both Schottky junctions and PN junctions, and the entire area of the second cell 140 is a PN junction, the current flow area of the second cell 140 is smaller than that of the first cell 130. Therefore, when the silicon carbide MPS diode is working, more current flows through the first cell 130 compared to the second cell 140. This reduces the current in the bonding region 110 corresponding to the first region 191, thereby mitigating the metal heating near the bonding region 110, reducing the failure of the silicon carbide MPS diode, and improving the surge resistance of the silicon carbide MPS diode.
[0058] In some embodiments, in the first region 191, a plurality of first cell groups 150 and a plurality of second cell groups 160 are evenly arranged.
[0059] Among them, the number of cells in the first cell group 150 and the second cell group 160 is the same;
[0060] Multiple second-cell groups 160 are evenly distributed within multiple first-cell groups 150;
[0061] The first cell group 150 includes the first cell 130;
[0062] The second cell group 160 includes the second cell 140 and the first cell 130.
[0063] The number of cells in the first cell group 150 and the second cell group 160 can be set according to actual needs, and no specific limit is made here.
[0064] In practical applications, the number of first cell groups 150 and second cell groups 160 can be reasonably set according to the bonding points 111 in the bonding region 110. In this embodiment, in the first region 191, the current distribution can be optimized by evenly arranging multiple second cell groups 160 in multiple first cell groups 150.
[0065] In some embodiments, in the second cell group 160, the second cells 140 are uniformly distributed among a plurality of first cells 130. The number of second cells 140 in the second cell group 160 can be one or more. In this embodiment, by uniformly distributing the second cells 140 among each of the first cells 130 in the second cell group 160, the local current distribution can be further optimized.
[0066] In some embodiments, such as Figure 6As shown, in the first region 191, starting from the second cell group 160, N first cell groups 150 are set between every two second cell groups 160, where N is a positive integer;
[0067] In the second cell group 160, starting from the second cell 140, N first cells 130 are set between every two second cells 140.
[0068] For example, N is set to 1, and the figure illustrates N with a value of 1. In the second cell group 160, one first cell 130 is set between every two second cells 140.
[0069] In this embodiment, the second cell 140 can be uniformly arranged in the first region 191, so that the current in the bonding region 110 is more balanced.
[0070] It should be noted that the arrangement of the first cell 130 and the second cell 140 in the first region 191 above is only an example, and other arrangements can also be used, which will not be listed here.
[0071] In some embodiments, such as Figure 7 As shown, in the second region 192, multiple third cell groups 170 are arranged in parallel; each third cell group 170 contains the same number of first cells 130.
[0072] Multiple sets of third cells 170 containing the same number of first cells 130 are arranged in parallel, so that the first cells 130 form a periodic and uniform arrangement in the second region 192, which can improve the current uniformity of the non-bonded region 120.
[0073] Embodiments of this application also relate to a silicon carbide MPS diode, the front side of which includes a bonding region and a non-bonding region adjacent to the bonding region, and the silicon carbide MPS diode further includes the cell structure of the silicon carbide MPS diode as described in any of the above embodiments.
[0074] In some embodiments, the non-bonded region surrounds the bonded region.
[0075] It should be understood that the terms "mechanism," "device," "component," etc., used in this application are merely one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they can be replaced by other expressions.
[0076] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application. In practical applications, the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification, and various changes can be made to them in form and detail without departing from the spirit and scope of this utility model.
Claims
1. A cell structure for a silicon carbide MPS diode, characterized in that, The front side of the silicon carbide MPS diode has a bonding region and an adjacent non-bonded region. The cell structure of the silicon carbide MPS diode includes: silicon carbide substrate; A silicon carbide epitaxial layer is located on the silicon carbide substrate and includes a first region and a second region, wherein the first region corresponds to the bonding region and the second region corresponds to the non-bonding region; Multiple cells, located on the silicon carbide epitaxial layer, including a first cell and a second cell; Wherein, a portion of the projection region of the first cell in the silicon carbide epitaxial layer is a Schottky junction, and another portion is a PN junction; both the first region and the second region include the first cell; The entire projection region of the second cell in the silicon carbide epitaxial layer is a PN junction; the first region also includes the second cell.
2. The cell structure of the silicon carbide MPS diode according to claim 1, characterized in that, In the first region, multiple first cell groups and multiple second cell groups are arranged in parallel; The first cell group and the second cell group have the same number of cells; Multiple second cell groups are evenly distributed within multiple first cell groups; The first cell group includes the first cell; The second cell group includes the second cell and the first cell.
3. The cell structure of the silicon carbide MPS diode according to claim 2, characterized in that, In the second cell group, the second cells are evenly distributed among a plurality of the first cells.
4. The cell structure of the silicon carbide MPS diode according to claim 3, characterized in that, In the first region, starting from the second cell group, N first cell groups are set between every two second cell groups, where N is a positive integer; In the second cell group, starting from the second cell, N first cells are set between every two second cells.
5. The cell structure of the silicon carbide MPS diode according to claim 1, characterized in that, In the second region, multiple third-cell groups are arranged in parallel; Each of the third cell groups contains the same number of the first cells.
6. The cell structure of the silicon carbide MPS diode according to claim 1, characterized in that, The projection region of the first cell in the silicon carbide epitaxial layer includes a first sub-region, a second sub-region surrounding the first sub-region, and a third sub-region surrounding the second sub-region; the partial region includes the second sub-region, and the other partial region includes the first sub-region and the third sub-region.
7. The cell structure of the silicon carbide MPS diode according to claim 6, characterized in that, The boundary line between the second sub-region and the first sub-region is circular, and the boundary line between the second sub-region and the third sub-region is also circular.
8. The cell structure of the silicon carbide MPS diode according to claim 1 or 7, characterized in that, The outer contours of the projection regions of the first cell and the second cell in the silicon carbide epitaxial layer are both regular hexagons.
9. A silicon carbide MPS diode, characterized in that, The front side of the silicon carbide MPS diode includes a bonding region and an unbonded region adjacent to the bonding region, and the silicon carbide MPS diode further includes the cell structure of the silicon carbide MPS diode as described in any one of claims 1 to 8.
10. The silicon carbide MPS diode according to claim 9, characterized in that, The non-bonded region surrounds the bonded region.