Cell structure of silicon carbide MPS diode and silicon carbide MPS diode
By designing various regular hexagonal cell structures on the silicon carbide epitaxial layer and optimizing the boundaries of the Schottky junction and PN junction regions, the surge resistance and reverse withstand voltage of the silicon carbide MPS diode were improved, the problem of anode metal melting failure was solved, and the process was simplified.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHUZHOU CRRC TIMES SEMICON CO LTD
- Filing Date
- 2025-06-18
- Publication Date
- 2026-06-23
Smart Images
Figure CN224401990U_ABST
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 MPS diodes are power semiconductor devices based on silicon carbide materials. They have excellent electrical performance and are widely used in the field of power electronics, such as in photovoltaic inverters, energy storage systems, and industrial drives.
[0003] In silicon carbide MPS diodes, the existing cell structure mostly adopts the strip cell structure. When subjected to surge current, the PN junction turn-on voltage is high, which makes the anode metal easy to melt and fail when a surge occurs. Utility Model Content
[0004] The purpose of this application is to provide at least one cell structure for a silicon carbide MPS diode and a silicon carbide MPS diode, which can at least solve the problem that the anode metal of the silicon carbide MPS diode is prone to melting and failure when a surge occurs, and at least achieve the effect of improving the surge resistance of the silicon carbide MPS diode while compromising the forward and reverse characteristics.
[0005] In a first aspect, this application provides a cell structure for a silicon carbide MPS diode, comprising:
[0006] silicon carbide substrate;
[0007] A silicon carbide epitaxial layer, wherein the silicon carbide epitaxial layer is located on the silicon carbide substrate;
[0008] Multiple cells are located on the silicon carbide epitaxial layer; the outer contour of the projection area of each cell on the silicon carbide epitaxial layer is a regular hexagon, and the projection area includes a first PN junction region, a Schottky junction region and a second PN junction region arranged concentrically from the inside to the outside;
[0009] The plurality of cells includes at least two of the first cell, the second cell, and the third cell;
[0010] Wherein, the boundary line between the Schottky junction region of the first cell and the first PN junction region is circular, and the boundary line between the Schottky junction region and the second PN junction region is a regular hexagon;
[0011] The boundary between the Schottky junction region of the second cell and the first PN junction region is a regular hexagon, and the boundary between the Schottky junction region and the second PN junction region is a circle;
[0012] The boundary lines between the Schottky junction region of the third cell and the first PN junction region and the second PN junction region are all circular.
[0013] Optionally, the plurality of cells includes 2M-1 cell groups; wherein the number of cells in each cell group from the first cell group to the Mth cell group increases sequentially, and the number of cells in each cell group from the Mth cell group to the 2M-1th cell group decreases sequentially; M is a positive integer greater than 2.
[0014] The cells in the same cell group are of the same type.
[0015] Optionally, from the cell group in column 1 to the cell group in column 2M-1, the first cell and the second cell are alternately arranged.
[0016] Optionally, from the cell group in column 1 to the cell group in column 2M-1, the first cell and the third cell are alternately arranged.
[0017] Optionally, from the cell group in column 1 to the cell group in column 2M-1, the second cell and the third cell are alternately arranged.
[0018] Optionally, the cell groups from column 1 to column 2M-1 are arranged cyclically in the order of the first cell, the second cell, and the third cell.
[0019] Optionally, the cell groups from column 1 to column 2M-1 are arranged cyclically in the order of the first cell, the third cell, and the second cell.
[0020] Optionally, the cell groups from column 1 to column 2M-1 are arranged cyclically in the order of the first cell, the second cell, the third cell, the second cell, and the first cell.
[0021] Optionally, the plurality of cells includes at least two of the following: a first cell array formed by a plurality of the first cells, a second cell array formed by a plurality of the second cells, and a third cell array formed by a plurality of the third cells.
[0022] Secondly, this application provides a silicon carbide MPS diode, including the cell structure of a silicon carbide MPS diode as described in any of the above.
[0023] The advantages of this application compared to the prior art are:
[0024] In the cell structure of the silicon carbide MPS diode of this application, at least two types of regular hexagonal cells are used on the silicon carbide epitaxial layer of the silicon carbide substrate, namely, a first cell, a second cell, and a third cell. Compared with strip cells, regular hexagonal cells can increase the PN junction region to reduce the turn-on voltage of the PN junction without excessively reducing the area of the Schottky junction region, thereby improving the surge resistance of the silicon carbide MPS diode. Furthermore, they provide a good shielding effect against the front electric field of the Schottky junction region during reverse bias, thus improving the reverse breakdown voltage. Moreover, since the boundaries between the Schottky junction region and the first PN junction region of the first and third cells are circular, it is beneficial to increase the shielding distance against the electric field. The boundaries between the Schottky junction region and the first PN junction region of the second cell, and between the Schottky junction region and the second PN junction region of the first cell, are regular hexagonal. The large angles and straight sides of the regular hexagons can effectively avoid electric field concentration, thereby further improving the reverse breakdown voltage through the combination of cells with various characteristics. Thus, by compromising between forward and reverse characteristics, the surge resistance of silicon carbide MPS diodes is improved, solving the problem of easy melting and failure of the anode metal during surges. Furthermore, the manufacturing processes for hexagonal and circular shapes are simpler and easier to implement.
[0025] 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
[0026] 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.
[0027] 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 ;
[0028] 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 ;
[0029] 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 ;
[0030] 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 ;
[0031] Figure 5 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 5 ;
[0032] 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 ;
[0033] 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 ;
[0034] Figure 8 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 8 ;
[0035] Figure 9 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 9 ;
[0036] Figure 10 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 10 ;
[0037] Figure 11 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 10 one;
[0038] Figure 12 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 10 two;
[0039] Figure 13 This is a schematic diagram of the cell structure of a silicon carbide MPS diode provided in another embodiment of this application. Figure 10 three. Detailed Implementation
[0040] 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.
[0041] Embodiments of this application relate to a cell structure of a silicon carbide MPS diode.
[0042] Compared to existing technologies, the embodiments of this application employ at least two types of regular hexagonal cells selected from at least a first cell, a second cell, and a third cell on the silicon carbide epitaxial layer of the silicon carbide substrate. Compared to strip cells, regular hexagonal cells can increase the PN junction region without excessively reducing the area of the Schottky junction region, thereby reducing the turn-on voltage of the PN junction and improving the surge resistance of the silicon carbide MPS diode. Furthermore, they provide a good shielding effect against the front electric field of the Schottky junction region during reverse bias, improving the reverse breakdown voltage. Moreover, since the boundaries between the Schottky junction region and the first PN junction region of the first cell and the third cell are circular, it is beneficial to increase the shielding distance against the electric field. The boundaries between the Schottky junction region and the first PN junction region of the second cell, and between the Schottky junction region and the second PN junction region of the first cell, are regular hexagonal. The large angles and straight sides of the regular hexagons effectively prevent electric field concentration, thereby further improving the reverse breakdown voltage through the combination of cells with various characteristics. By compromising between forward and reverse characteristics, the surge immunity of silicon carbide MPS diodes has been improved, solving the problem of easy melting and failure of the anode metal during surges. Furthermore, the manufacturing processes for hexagonal and circular shapes are simpler and easier to implement.
[0043] 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.
[0044] This embodiment provides a cell structure for a silicon carbide MPS diode, such as... Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, it includes:
[0045] Silicon carbide substrate 110;
[0046] A silicon carbide epitaxial layer 120 is located on a silicon carbide substrate 110;
[0047] Multiple cells are located on the silicon carbide epitaxial layer 120; the outer contour of the projection area of each cell on the silicon carbide epitaxial layer 120 is a regular hexagon, and the projection area includes a first PN junction region PN1, a Schottky junction region SB and a second PN junction region PN2 arranged concentrically from the inside to the outside.
[0048] The plurality of cells includes at least two of the first cell 130, the second cell 140, and the third cell 150;
[0049] Among them, the boundary line between the Schottky junction region SB of the first cell 130 and the first PN junction region PN1 is circular, and the boundary line between the Schottky junction region SB and the second PN junction region PN2 is a regular hexagon.
[0050] The boundary between the Schottky junction region SB of the second cell 140 and the first PN junction region PN1 is a regular hexagon, and the boundary between the Schottky junction region SB and the second PN junction region PN2 is a circle.
[0051] The boundary lines between the Schottky junction region SB of the third cell 150 and the first PN junction region PN1 and the second PN junction region PN2 are both circular.
[0052] In this embodiment, the silicon carbide substrate 110 is an N+ type heavily doped silicon carbide substrate. In practice, an N-type lightly doped drift layer can be grown on the silicon carbide substrate 110 using vapor phase epitaxy to obtain a silicon carbide epitaxial layer 120. A Schottky junction is formed by depositing metal on the silicon carbide epitaxial layer 120. The region containing the Schottky junction is called the Schottky junction region SB. Furthermore, a P-type impurity is implanted on the silicon carbide epitaxial layer 120 to form a PiN junction, thus obtaining the first PN junction region PN1 and the second PN junction region PN2. The Schottky junction region SB surrounds the first PN junction region PN1, and the second PN junction region PN2 surrounds the Schottky junction region SB.
[0053] In practical applications, the cell types in multiple cells can be set as needed. For example, multiple cells can include the first cell 130 and the second cell 140, or include the first cell 130 and the third cell 150, or include the second cell 140 and the third cell 150, or include the first cell 130, the second cell 140 and the third cell 150.
[0054] In this embodiment, at least two types of regular hexagonal cells among the first cell 130, the second cell 140, and the third cell 150, compared with strip cells, can increase the PN junction region to reduce the turn-on voltage of the PN junction without excessively reducing the area of the Schottky junction region SB, thereby improving the surge resistance of the silicon carbide MPS diode. Furthermore, they provide a good shielding effect against the front electric field of the Schottky junction region SB under reverse bias, thereby improving the reverse breakdown voltage. Furthermore, in multiple cells, the boundary lines between the Schottky junction region SB and the first PN junction region PN1 in the first cell 130 and the third cell 150 are circular, which helps to increase the shielding distance for the electric field. The boundary lines between the Schottky junction region SB and the first PN junction region PN1 in the second cell 140, and between the Schottky junction region SB and the second PN junction region PN2 in the first cell 130, are regular hexagons. The large angles and straight sides of the regular hexagons effectively avoid electric field concentration, thus further improving the reverse withstand voltage through the combination of cells with various characteristics. In this way, the surge resistance of the silicon carbide MPS diode is improved while compromising forward and reverse characteristics, solving the problem of easy melting and failure of the anode metal during surges. In addition, the process control of regular hexagons and circles is simple and more convenient to implement.
[0055] In some embodiments, the plurality of cells include 2M-1 cell groups; wherein the number of cells in each cell group from the 1st cell group to the Mth cell group increases sequentially, and the number of cells in each cell group from the Mth cell group to the 2M-1th cell group decreases sequentially; M is a positive integer greater than 2; and the cells in the same cell group are of the same type.
[0056] In practical applications, each cell group includes at least one cell. The cells of each cell group are arranged in columns. The cells in the same cell group are of the same type. For example, each cell group may include at least two of the following: a first cell group formed by at least one first cell 130, a second cell group formed by at least one second cell 140, and a third cell group formed by at least one third cell 150.
[0057] join Figure 5 In the diagram, M is represented by a value of 5, and there are a total of 9 cell groups. The arrows in the diagram indicate the direction from the 1st cell group to the 2M-1st cell group. From the 1st cell group to the 5th cell group, the number of cells increases by 1 each time, and from the 5th cell group to the 9th cell group, the number of cells decreases by 1 each time.
[0058] The increasing and decreasing cell counts within each of the 2M-1 column cell groups can be arranged to form a rhombus matrix. The cells are closely packed, allowing for flexible and efficient use of space and the placement of more cells. Furthermore, cells of the same type within the same column can fully utilize cell characteristics in localized areas, thereby improving the performance of silicon carbide MPS diodes.
[0059] There are several ways to arrange the cells. Some of them are listed below.
[0060] I. In the case of multiple cells, including the first cell 130 and the second cell 140, such as Figure 5 As shown, from the first cell group to the second cell group (2M-1), the first cell 130 and the second cell 140 are alternately arranged. Since the boundary between the Schottky junction region SB of the first cell 130 and the first PN junction region PN1 is circular, and the boundary with the second PN junction region PN2 is a regular hexagon, and the boundary between the Schottky junction region SB of the second cell 140 and the first PN junction region PN1 is a regular hexagon, and the boundary with the second PN junction region PN2 is circular, this not only increases the shielding distance against the electric field, but also effectively avoids electric field concentration through the large angle and straight sides of the regular hexagon. The combination of the first cell 130 and the second cell 140 reduces the turn-on voltage of the PN junction, improves the surge resistance of the silicon carbide MPS diode, and simultaneously increases the reverse withstand voltage.
[0061] II. In the case of multiple cells, including the first cell 130 and the third cell 150, such as Figure 6As shown, from the first column of cells to the second (M-1) column of cells, the first cell 130 and the third cell 150 are alternately arranged. Since the boundary line between the Schottky junction region SB and the first PN junction region PN1 of the first cell 130 is circular, and the boundary line between it and the second PN junction region PN2 is a regular hexagon, and the boundary lines between the Schottky junction region SB and the first PN junction region PN1 and the second PN junction region PN2 of the third cell 150 are both circular, on the one hand, the circular boundary lines help increase the shielding distance for the electric field, and the large angle and straight sides of the regular hexagon effectively prevent electric field concentration. The combination of the first cell 130 and the third cell 150 reduces the turn-on voltage of the PN junction, improves the surge resistance of the silicon carbide MPS diode, and also improves the reverse withstand voltage. On the other hand, the regular hexagonal boundary lines in the first cell 130 reduce the requirements for process precision control and simplify the process.
[0062] III. In the case of multiple cells, including the second cell 140 and the third cell 150, such as Figure 7 As shown, from the first column of cells to the second (2M-1)th column of cells, the second cell 140 and the third cell 150 are alternately arranged. Since the boundary line between the Schottky junction region SB of the second cell 140 and the first PN junction region PN1 is a regular hexagon, and the boundary line between it and the second PN junction region PN2 is circular, and the boundary lines between the Schottky junction region SB of the third cell 150 and the first PN junction regions PN1 and PN2 are both circular, on the one hand, the circular boundary lines can increase the shielding distance for the electric field, and the large angle and straight sides of the regular hexagon can effectively avoid electric field concentration. The combination of the two cell types, second cell 140 and third cell 150, reduces the turn-on voltage of the PN junction, improves the surge resistance of the silicon carbide MPS diode, and also improves the reverse withstand voltage. On the other hand, the regular hexagonal boundary lines in the second cell 140 have lower requirements for process precision control, making the process simpler.
[0063] IV. In the case of multiple cells, including the first cell 130, the second cell 140, and the third cell 150, such as Figure 8 As shown, the cells from the first column to the second M-1 column are arranged in a cyclical manner, following the order of first cell 130, second cell 140, and third cell 150.
[0064] V. In the case of multiple cells, including the first cell 130, the second cell 140, and the third cell 150, such as Figure 9 As shown, the cells from the first column to the second column are arranged in a cyclical manner, following the order of first cell 130, third cell 150, and second cell 140.
[0065] VI. In the case of multiple cells, including the first cell 130, the second cell 140, and the third cell 150, such as Figure 10 As shown, the cells from the first column to the second M-1 column are arranged in a cyclical order of first cell 130, second cell 140, third cell 150, second cell 140 and first cell 130.
[0066] The fourth to sixth arrangement methods mentioned above all include three types of cells: the first cell 130, the second cell 140, and the third cell 150. This allows the entire cell structure to have the advantages of each cell. Furthermore, by cyclically arranging the three types of cells in a certain order, the overall performance of the cell structure is balanced.
[0067] In some embodiments, the plurality of cells includes at least two of the following: a first cell array formed by a plurality of first cells 130, a second cell array formed by a plurality of second cells 140, and a third cell array formed by a plurality of third cells 150.
[0068] like Figure 11 As shown, the first cell array is a rhomboid array formed by multiple first cells 130. Figure 12 As shown, the second cell array is a rhomboid array formed by multiple second cells 140. Figure 13 As shown, the third-cell array is a rhombus array formed by multiple third-cell arrays 150. The rhombus arrays within the multiple cells can be spliced together. In this way, the cells can be arranged closely, thus making flexible and full use of space and accommodating more cells. Furthermore, the characteristics of the rhombus array cells can improve local performance.
[0069] Embodiments of this application also relate to a silicon carbide MPS diode, including the cell structure of a silicon carbide MPS diode as described in any of the above embodiments.
[0070] 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.
[0071] 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 application.
Claims
1. A cell structure of a silicon carbide MPS diode, characterized by, include: silicon carbide substrate; A silicon carbide epitaxial layer, wherein the silicon carbide epitaxial layer is located on the silicon carbide substrate; Multiple cells are located on the silicon carbide epitaxial layer; the outer contour of the projection area of each cell on the silicon carbide epitaxial layer is a regular hexagon, and the projection area includes a first PN junction region, a Schottky junction region and a second PN junction region arranged concentrically from the inside to the outside; The plurality of cells includes at least two of the first cell, the second cell, and the third cell; Wherein, the boundary line between the Schottky junction region of the first cell and the first PN junction region is circular, and the boundary line between the Schottky junction region and the second PN junction region is a regular hexagon; The boundary between the Schottky junction region of the second cell and the first PN junction region is a regular hexagon, and the boundary between the Schottky junction region and the second PN junction region is a circle; The boundary lines between the Schottky junction region of the third cell and the first PN junction region and the second PN junction region are all circular.
2. The cell structure of a silicon carbide MPS diode according to claim 1, wherein The plurality of cells comprises 2M-1 cell groups; wherein the number of cells in each cell group from the first cell group to the Mth cell group increases sequentially, and the number of cells in each cell group from the Mth cell group to the 2M-1th cell group decreases sequentially; M is a positive integer greater than 2; The cell types in the same cell group are the same.
3. The cell structure of a silicon carbide MPS diode according to claim 2, wherein From the cell group in column 1 to the cell group in column 2M-1, the first cell and the second cell are alternately arranged.
4. The cell structure of a silicon carbide MPS diode according to claim 2, wherein From the cell group in column 1 to the cell group in column 2M-1, the first cell and the third cell are alternately arranged.
5. The cell structure of the silicon carbide MPS diode according to claim 2, characterized in that, The second cell and the third cell are alternately arranged from the cell group in column 1 to the cell group in column 2M-1.
6. The cell structure of the silicon carbide MPS diode according to claim 2, characterized in that, The cells from column 1 to column 2M-1 are arranged cyclically in the order of the first cell, the second cell, and the third cell.
7. The cell structure of the silicon carbide MPS diode according to claim 2, characterized in that, The cells from column 1 to column 2M-1 are arranged cyclically in the order of the first cell, the third cell, and the second cell.
8. The cell structure of the silicon carbide MPS diode according to claim 2, characterized in that, The cells from column 1 to column 2M-1 are arranged cyclically in the order of first cell, second cell, third cell, second cell and first cell.
9. The cell structure of the silicon carbide MPS diode according to claim 1, characterized in that, The plurality of cells includes at least two of the following: a first cell array formed by a plurality of the first cells, a second cell array formed by a plurality of the second cells, and a third cell array formed by a plurality of the third cells.
10. A silicon carbide MPS diode, characterized in that, The cell structure includes that of the silicon carbide MPS diode as described in any one of claims 1 to 9.