Power device with shielding protection structure
By introducing shielding protection structures with different conductivity types into silicon carbide power devices, the problem of electric field concentration in trench devices is solved, improving the reliability and conduction performance of the devices while maintaining channel density.
Patent Information
- Application Number
- CN202423322149.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Existing silicon carbide power devices are prone to electric field concentration at the bottom of the trench in trench-type structures, which affects device reliability.
A shielding protection structure is introduced into the semiconductor structure layer, including a shielding protection area and a shielding grounding area. By forming a PN junction with the semiconductor structure layer through shielding protection structures with different conductivity types, the electric field at the bottom of the trench gate is reduced, and grounding connection is achieved through the shielding grounding area to avoid electric field concentration.
It improves the reliability and conduction performance of power devices while maintaining the channel density of the devices. The structure is simple and suitable for practical applications.
Smart Images
Figure CN223872666U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of semiconductor device and manufacturing technology, and relates to a power device with a shielding protection structure.
[0002] This application belongs to the field of semiconductor device and manufacturing technology, and relates to a power device. Background Technology
[0003] Semiconductor power devices are semiconductor devices that operate in high-voltage and high-current environments, and are typically used in applications requiring high-power switching, such as power conversion, power converters, and inverters. Based on the performance requirements of these applications, power semiconductor devices generally need to possess high voltage resistance and high switching speed capabilities.
[0004] Compared to silicon, silicon carbide has a higher band gap and maintains high stability at high temperatures. These characteristics make silicon carbide devices significantly superior to silicon devices in terms of breakdown voltage. Furthermore, to increase the channel density of silicon carbide power semiconductor devices, trench-type silicon carbide power devices with vertical channel structures are widely used. However, in trench-type power devices, electric field concentration is prone to occur in the gate dielectric layer at the bottom of the trench, which adversely affects the reliability of the device.
[0005] Therefore, how to provide a power device with a shielding protection structure to improve the reliability of power devices has become an important technical problem that needs to be solved by those skilled in the art.
[0006] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Utility Model Content
[0007] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a power device with a shielding protection structure to solve the problem that the reliability of power devices in the prior art needs to be improved.
[0008] To achieve the above and other related objectives, this application provides a power device with a shielding protection structure, comprising:
[0009] A semiconductor structure layer, wherein the semiconductor structure layer is of a first conductivity type;
[0010] A cellular structure region is located in the semiconductor structure layer. The cellular structure region includes a plurality of trench gates, each of which includes a trench and a gate filled in the trench.
[0011] A shielding protection structure is located in the semiconductor structure layer, and the shielding protection structure is of a second conductivity type; the shielding protection structure includes at least one shielding protection group, the shielding protection group includes a shielding protection zone and at least one shielding grounding zone, the shielding protection zone extends below the plurality of trench gates, and the extension direction of the shielding protection zone intersects the extension direction of the trench gates, and the shielding grounding zone is electrically connected to the shielding protection zone;
[0012] The source metal is located on the semiconductor structure layer and is electrically connected to the shielding grounding.
[0013] Optionally, the shielding protection structure includes a plurality of shielding protection groups, which are arranged sequentially, and the arrangement direction of the plurality of shielding protection groups intersects with the arrangement direction of the plurality of trench grids.
[0014] Optionally, the shielding protection zone includes multiple main shielding zones and multiple auxiliary shielding zones. In the extending direction of the shielding protection zone, the multiple main shielding zones and the multiple auxiliary shielding zones are alternately connected, and the width of the main shielding zone is greater than the width of the auxiliary shielding zone.
[0015] Optionally, the shielding protection structure includes an adjacent first shielding protection zone and a second sub-shielding protection zone, wherein,
[0016] In the first shielding protection zone: any of the main shielding zones is located at least below the trench grid, any of the auxiliary shielding zones is located between two adjacent trench grids, and the width of the main shielding zone is greater than the width of the trench.
[0017] Optionally, the second shielding protection zone is aligned with the first sub-shielding protection zone; wherein,
[0018] In the second shielding protection zone: any of the main shielding zones is located at least below the trench grid, and any of the auxiliary shielding zones is located between two adjacent trench grids.
[0019] Optionally, the first shielding protection zone and the second sub-shielding protection zone are arranged alternately; wherein,
[0020] In the second shielding protection zone: a portion of the main shielding zone is located at least below the trench grid, and another portion of the main shielding zone extends from between two adjacent trenches to below the bottom corners of the two adjacent trenches facing each other, and the main shielding zone is greater than the distance between two adjacent trench grids.
[0021] Optionally, the shielding grounding unit includes multiple shielding grounding areas, which are arranged along the extension direction of the shielding protection zone, and there is a preset distance between any two adjacent shielding grounding areas; wherein,
[0022] The shielding junction area is electrically connected to the main shielding area; and / or, the shielding junction area is electrically connected to the auxiliary shielding area.
[0023] Optionally, the ratio between the distance between any two adjacent shielding junctions and the cell width of the power device is in the range of 2 to 6.
[0024] Optionally, the doping concentration range of the main shielding region is 1e16 cm⁻¹. -3 ~1e20cm -3 The doping concentration range of the auxiliary shielding region is 1e16 cm⁻¹. -3 ~1e20cm -3 The doping depth of the main shielding region is in the range of 0.1 μm to 1 μm, and the doping depth of the auxiliary shielding region is in the range of 0.1 μm to 1 μm.
[0025] Optionally, the shielding protection zone also covers a portion of the bottom of the plurality of trench grids, and at least one bottom corner of the trench grid is covered by the main shielding zone.
[0026] As described above, the power device with shielding protection structure of this application has at least the following beneficial effects:
[0027] 1. The power device includes a semiconductor structure layer, a cell structure region, a shielding protection structure, and a source metal. The shielding protection structure includes at least one shielding protection group, which includes a shielding protection zone and a shielding grounding zone. The shielding protection zone extends below multiple trench gates in the cell structure region, which can reduce the electric field concentration at the bottom of the multiple trench gates, thereby improving the reliability of the power device. Furthermore, the shielding protection zone and the shielding grounding zone are electrically connected, and the shielding grounding zone is electrically connected to the source metal, enabling grounding of the shielding area and further enhancing the shielding protection effect.
[0028] 2. By designing the structure of the shielding protection zone, which includes multiple alternating main shielding zones and auxiliary shielding zones, and the width (or length) of the main shielding zone is greater than the width (or length) of the auxiliary shielding zone, and the main shielding zone at least covers the bottom corner of the trench gate, the area of the main shielding zone that is mainly used to provide electric field shielding for the trench gate (i.e., the main shielding zone) is larger, while the area of the auxiliary shielding zone that is mainly used to connect multiple main shielding zones is smaller, further improving the conductivity of the device.
[0029] 3. When the shielding protection group includes multiple shielding grounding areas, a preset distance is maintained between two adjacent shielding grounding areas in the same shielding protection group. This ensures good grounding effect of the shielding protection area while avoiding excessive shielding grounding areas that could affect the trench density of the power devices and improve the conductivity of the power devices.
[0030] 4. The overall structure is simple, flexible and versatile, and suitable for practical applications. Attached Figure Description
[0031] Figure 1 A schematic diagram of a first structure of a power device with a shielding protection structure provided in an embodiment of this application;
[0032] Figure 2 This is a schematic diagram of a second structure of a power device with a shielding protection structure provided in an embodiment of this application;
[0033] Figure 3 for Figure 1 and Figure 2 A cross-sectional view of the A-A' section;
[0034] Figure 4 for Figure 1 and Figure 2 A cross-sectional view of the B-B' section;
[0035] Figure 5 for Figure 1 A cross-sectional view of the C-C' section;
[0036] Figure 6 for Figure 2 A cross-sectional view of the middle D-D' section;
[0037] Figure 7 for Figure 1 A schematic diagram showing the arrangement of two adjacent shielding protection groups in the middle;
[0038] Figure 8 for Figure 2 A schematic diagram showing the arrangement of two adjacent shielding protection groups in the middle;
[0039] Figure 9 A schematic diagram of a third structure of a power device with a shielding protection structure provided in an embodiment of this application;
[0040] Figure 10 A schematic diagram of a fourth structure of a power device with a shielding protection structure provided in an embodiment of this application;
[0041] Figure 11 A fifth structural schematic diagram of a power device with a shielding protection structure provided in the embodiments of this application;
[0042] Figure 12 A sixth structural schematic diagram of a power device with a shielding protection structure provided in the embodiments of this application;
[0043] Figure 13A seventh structural schematic diagram of a power device with a shielding protection structure provided in the embodiments of this application;
[0044] Figure 14 A schematic diagram of the eighth structure of a power device with a shielding protection structure provided in the embodiments of this application;
[0045] Explanation of reference numerals in the attached figures:
[0046] 10-Semiconductor structure layer, 11-Substrate, 12-Buffer layer, 13-First epitaxial layer, 14-Second epitaxial layer;
[0047] 20-Shielding protection group, 21-Shielding protection zone, 21a-First shielding protection zone, 21b-Second shielding protection zone, 211-Main shielding zone, 212-Secondary shielding zone, 22-Shielding grounding zone;
[0048] 30 - Cell structure region, 31 - Trench gate, 311 - Trench, 312 - Gate, 313 - Gate dielectric, 32 - Well region, 33 - Source region, 34 - Contact region;
[0049] 40 - Interlayer dielectric; 50 - Source metal; 60 - Drain metal; Y - First direction, X - Second direction. Detailed Implementation
[0050] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.
[0051] Please see Figures 1 to 14 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0052] Regarding the issue mentioned in the background art, where electric field concentration easily occurs in the bottom gate dielectric layer of trench gates, making it difficult to guarantee device reliability, related technologies address this problem. An electric field shielding region is formed in the epitaxial layer below the trench gate. The conductivity type of this shielding region differs from that of the epitaxial layer. This shielding region reduces the electric field strength in the bottom gate dielectric layer of the trench gate, thereby improving the reliability of power devices. For example, a floating electric field shielding region is formed only in the area below the trench gate. However, since this floating electric field shielding region is not grounded, its shielding effect on the bottom of the trench gate is relatively poor. Alternatively, to achieve grounding of the electric field shielding region, a groove is etched after forming the shielding region below the trench gate, and an electrode is placed at the bottom of the groove to achieve grounding of the electric field shielding region. However, this method has high process complexity and is not conducive to practical applications. Alternatively, after forming an electric field shielding region in the area below the trench gate, the electric field shielding region is connected to the well region above to achieve grounding. However, since the electric field shielding region covers the bottom of the trench gate, a local area of the well region above the electric field shielding region cannot form an electron channel, resulting in the channel not being able to open and significantly reducing the channel density of the device.
[0053] This application provides a power device with a shielding protection structure. Please refer to [link / reference]. Figures 1 to 6 ,in, Figure 1 A schematic diagram of the first structure of the power device is shown. Figure 2 A schematic diagram of a second structure for the power device is shown. Figures 3 to 6 It shows Figure 1 and Figure 2 Cross-sectional schematic diagrams of different parts of the device. The power device includes a semiconductor structure layer 10, a cellular structure region 30, a shielding protection structure, and a source metal 50.
[0054] Specifically, the semiconductor structure layer 10 exhibits a first conductivity type. The cell structure region 30 is located within the semiconductor structure layer 10. The cell structure region 30 includes a plurality of trench gates 31, each trench gate 31 including a trench 311 and a gate 312 filled within the trench 311. The shielding protection structure is located within the semiconductor structure layer 10, exhibiting a second conductivity type. The shielding protection structure includes at least one shielding protection group 20, each shielding protection group 20 including a shielding protection zone 21 and at least one shielding grounding zone 22 (i.e., each shielding protection group 20 may include one or more shielding grounding zones 22). The shielding protection zone 21 extends below the plurality of trench gates 31, and the extension direction of the shielding protection zone 21 intersects with the extension direction of the trench gates 31. The shielding grounding zone 22 is electrically connected to the shielding protection zone 21. The source metal 50 is located on the semiconductor structure layer 10, and the source metal 50 is electrically connected to the shielding grounding zone 22. For example, if the extension direction of the trench grid 31 is the first direction Y, and the extension direction of the shielding protection zone 21 is the second direction X, then the first direction Y and the second direction X intersect, for example, perpendicularly.
[0055] It should be noted that, in terms of positional relationship, the shielding protection zone 21 extending beneath the plurality of trench gates 31 includes the following two scenarios: the shielding protection zone 21 directly contacts (can just contact, or cover) the bottom of the plurality of trench gates 31, and the shielding protection zone 21 does not directly contact the bottom of the plurality of trench gates 31. In terms of quantity, the shielding protection zone 21 extending beneath the plurality of trench gates 31 includes the following two scenarios: the shielding protection zone 21 extends beneath a portion of the trench gates 31 included in the cell structure region 30, and the shielding protection zone 21 extends beneath all of the trench gates 31 included in the cell structure region 30.
[0056] Furthermore, in this embodiment of the application, the first direction Y and the second direction X are perpendicularly intersecting as an example. In actual application, the first direction Y and the second direction X may not be perpendicularly intersecting. For example, the first direction Y and the second direction X may form an angle of 30° or 45°.
[0057] In this embodiment, a shielding protection structure with opposite conductivity types is provided in the semiconductor structure layer 10. The shielding protection structure includes at least one shielding protection group 20, which includes a shielding protection zone 21 and at least one shielding grounding zone 22. The shielding protection zone 21 extends below the plurality of trench gates 31, and the shielding grounding zone 22 is electrically connected to the shielding protection zone 21. Since the conductivity type of the shielding protection structure is different from that of the semiconductor structure layer 10, during the reverse blocking period of the power device, the electric field at the bottom of the trench gate 31 is reduced by the electric field extension of the PN junction formed between the shielding protection structure and the semiconductor structure layer 10. This avoids electric field concentration at the bottom of the trench gate 31, which could lead to device reliability issues and improve the long-term reliability of the power device.
[0058] Furthermore, to ensure effective electric field protection of the trench gate 31 by the shielding protection group 20, it is necessary to ground the shielding protection group 20. However, a channel cannot be formed at the location corresponding to the area used for shielding connection in the shielding protection group 20. Therefore, in this embodiment, based on the sequential electrical connection between the shielding protection zone 21, the shielding grounding area 22, and the source metal 50, the trench gate 31 is shielded and protected by the shielding protection zone 21, and the grounding of the shielding protection zone 21 is achieved through the shielding grounding area 22. While improving the shielding protection effect of the shielding protection zone 21 on the trench gate 31, it avoids the large area of the grounding connection area in the shielding protection group 20, which would result in excessive channel loss. This ensures both the reliability of the power device and the channel density of the power device.
[0059] In an optional embodiment, the shielding protection structure includes a plurality of shielding protection groups 20, which are arranged sequentially, and the arrangement direction of the plurality of shielding protection groups 20 intersects (e.g., perpendicularly intersects) the arrangement direction of the plurality of trench gates 31. When the first direction Y intersects perpendicularly with the second direction X, the arrangement direction of the plurality of shielding protection groups 20 is parallel to the length (extension) direction of the trench gates 31.
[0060] In an optional embodiment, please refer to Figure 7 and Figure 8 ,in, Figure 7 It shows Figure 1 A schematic diagram showing the arrangement of two adjacent shielding protection groups 20. Figure 8 It shows Figure 2 A schematic diagram of the arrangement of two adjacent shielding protection groups 20. The shielding protection zone 21 includes multiple main shielding zones 211 and multiple auxiliary shielding zones 212. In the extending direction of the shielding protection zone 21, the multiple main shielding zones 211 and the multiple auxiliary shielding zones 212 are alternately connected, such as... Figure 7As shown, the width a of the main shielding area 211 is greater than the width b of the auxiliary shielding area 212.
[0061] In optional embodiments, such as Figure 3 As shown, the shielding protection zone 21 also covers a portion of the bottom of multiple trench gates 31, and at least one bottom corner of the trench gate 31 is covered by the main shielding zone 211. Compared to a structure where the shielding protection zone 21 is only located below the trench gate 31, or where the shielding protection zone 21 is exactly in contact with the bottom of the trench gate 31, the shielding protection zone 21 covering a portion of the bottom of the trench gate 31 provides more effective protection for the bottom of the trench gate 31, especially improving the electric field concentration effect at the bottom corner of the trench gate 31.
[0062] In an optional embodiment, please refer to Figures 9 to 14 The diagrams show the third to eighth structural schematics of the power device, wherein the shape of the main shielding area 211 includes a square shape (e.g., ...). Figure 1 and Figure 2 As shown), polygons (e.g., as shown) Figure 9 and Figure 10 The hexagon shown, such as Figure 11 and Figure 12 The octagon shown), the circle (as shown) Figure 13 and Figure 14 The auxiliary shielding region 212 includes at least one of the following shapes: (as shown) and ellipse, and its shape includes a rectangle (e.g., a narrow strip). Of course, without considering manufacturing difficulty and yield, in other embodiments, the shape of the main shielding region 211 can also be irregular. In the embodiments of this application, the main shielding region 211 is designed with a regular shape, which makes it easy to ensure the consistency of the power device structure.
[0063] In an optional embodiment, the shielding protection structure includes an adjacent first shielding protection zone 21a and a second sub-shielding protection zone 21, wherein in the first shielding protection zone 21a: any of the main shielding zones 211 is located at least below the trench grid 31, any of the auxiliary shielding zones 212 is located between two adjacent trench grids 31, and the width of the main shielding zone 211 is greater than the width of the trench 311.
[0064] In optional embodiments, the positional relationship between the second shielding protection zone 21b and the first shielding protection zone 21a includes at least two methods: the second shielding protection zone 21b and the first sub-shielding protection zone 21 are aligned, or the first shielding protection zone 21a and the second shielding protection zone 21b are staggered. Alignment means that the plurality of main shielding areas 211 in the first shielding protection zone 21 correspond one-to-one with the plurality of main shielding areas 211 in the second shielding protection zone 21b, and the plurality of auxiliary shielding areas 212 in the first shielding protection zone 21 also correspond one-to-one with the plurality of auxiliary shielding areas 212 in the second shielding protection zone 21b, such as... Figure 1 , Figure 8 , Figure 10 and Figure 11 As shown. When the shielding junction area 22 in the first shielding protection zone 21 and the shielding junction area 22 in the second shielding protection zone 21b are also aligned, then the two shielding protection groups 20 are also aligned. The staggered arrangement means that the multiple main shielding areas 211 in the first shielding protection zone 21 correspond one-to-one with the multiple auxiliary shielding areas 212 in the second shielding protection zone 21b, and correspondingly, the multiple auxiliary shielding areas 212 in the first shielding protection zone 21 correspond one-to-one with the multiple main shielding areas 211 in the second shielding protection zone 21b, as shown. Figure 2 , Figure 9 , Figure 11 and Figure 13 As shown.
[0065] In this embodiment, when the cell spacing is small, the distance between any two adjacent shielding protection zones 21 is also small, and the two arrangement methods have little difference in shielding protection effect on the bottom of the trench gate 31. However, since the current path in the semiconductor structure layer 10 is wider when multiple shielding protection zones 21 are arranged in method one compared to method two, the forward conduction performance of the power device is better when multiple shielding protection zones 21 are arranged in method one.
[0066] In an optional embodiment, when the first direction Y intersects the second direction X perpendicularly, the length d of the main shielding area 211 is greater than the length e of the auxiliary shielding area 212, such as... Figure 7 As shown. That is, on the plane containing the second direction X and the first direction Y, the area of the auxiliary shielding area 212 is smaller than the area of the main shielding area 211, so that the area of the shielding protection area 21 that plays a shielding and protection role for the trench gate 31 (i.e., the main shielding area 211) accounts for a larger proportion, which helps to improve the conduction performance of the power device while ensuring the shielding effect.
[0067] In an optional embodiment, the width a of the main shielding area 211 is greater than the width of the trench 311, and / or the width a of the main shielding area 211 is greater than the distance between two adjacent trenches 311, so as to ensure that the main shielding area 211 can provide good shielding protection for the bottom of the trench 311 (especially the bottom corner).
[0068] In an optional embodiment, the difference between the width of the main shielding region 211 and the width of the trench 311 ranges from 0.1 μm to 0.5 μm (inclusive). For example, the width of the main shielding region 211 is 0.2 μm or 0.4 μm larger than the width of the trench 311. By satisfying this difference range, the electric field shielding effect of the main shielding region 211 on the trench gate 31 can be guaranteed, while avoiding the main shielding region 211 occupying excessive current path area, thus ensuring good operating performance of the power device.
[0069] In optional embodiments, such as Figure 1 , Figure 8 , Figure 10 and Figure 11 As shown, when the second shielding protection zone 21b is aligned with the first sub-shielding protection zone 21, in the second shielding protection zone 21b: any of the main shielding zones 211 is located at least below the trench grid 31, and any of the auxiliary shielding zones 212 is located between two adjacent trench grids 31. In this case, the electric field shielding protection for the bottom of the trench grid 31 is mainly provided by the main shielding zones 211, and the auxiliary shielding zones 212 mainly serve to connect two adjacent first shielding zones.
[0070] In optional embodiments, such as Figure 2 , Figure 9 , Figure 11 and Figure 13 As shown, the first shielding protection zone 21a and the second sub-shielding protection zone 21 are arranged alternately. In the second shielding protection zone 21b: a portion of the main shielding zone 211 is located at least below the trench grid 31, and another portion of the main shielding zone 211 extends from between two adjacent trenches 311 to below the bottom corners of the two adjacent trenches 311 facing each other. The main shielding zone 211 is greater than the distance between two adjacent trench grids 31. In this case, the electric field shielding protection of the bottom corners of a portion of the trench grids 31 in the cell structure region 30 is mainly provided by the main shielding zone 211, and the electric field shielding protection of the bottom areas of these trench grids 31, excluding the corners, is mainly provided by the auxiliary shielding zone 212.
[0071] In this embodiment, since the width and length of the main shielding area 211 are both greater than those of the auxiliary shielding area 212, and the electric field concentration at the corners of the bottom region of the trench grid 31 is higher than in other regions, using a larger main shielding area 211 to provide electric field shielding protection for the corner areas is more conducive to ensuring the overall effectiveness of the electric field shielding protection and guaranteeing the reliability of the power devices. Based on this consideration, the width of the main shielding area 211 also needs to be greater than the distance between two adjacent trenches 311.
[0072] In an optional embodiment, the shielding grounding unit includes a plurality of shielding grounding areas 22, which are arranged in the extension direction of the shielding protection zone 21, and there is a preset distance between any two adjacent shielding grounding areas 22; wherein, the shielding grounding area 22 is electrically connected to the main shielding zone 211; and / or, the shielding grounding area 22 is electrically connected to the auxiliary shielding zone 212.
[0073] It should be noted that although the accompanying drawings of the embodiments of this application illustrate that the shielding grounding area 22 is electrically connected only to the main shielding area 211, in actual applications, the shielding grounding area 22 may also be electrically connected only to the auxiliary shielding area 212, or simultaneously electrically connected to both the main shielding area 211 and the auxiliary shielding area 212. Furthermore, when the shielding grounding area 22 is electrically connected only to the main shielding area 211, and each main shielding area 211 is located below a trench grid 31, such as... Figure 7 As shown, the width c of the shielding junction area 22 is greater than the width a of the main shielding area 211, so as to avoid losing most of the structure of the shielding junction area 22 during the etching process to form the trench 311, thereby affecting the effective electrical connection area and effect between the shielding junction area 22 and the main shielding area 211.
[0074] In optional embodiments, such as Figure 1 As shown, the ratio of the distance f between any two adjacent shielding grounding areas 22 to the cell width g of the power device ranges from 2 to 6 (inclusive), for example, it can be 3, 4, or 5. The cell width g of the power device is the distance (i.e., cell pitch) between any two adjacent trenches 311 on the same side. That is, under the condition of satisfying the good grounding of the shielding protection zone 21, a shielding grounding area 22 can be set at a predetermined number of cell intervals.
[0075] In this embodiment, the relative number of shielding grounding areas 22 is limited by the ratio range between the distance f between any two adjacent shielding grounding areas 22 and the cell width g of the power device. On one hand, this avoids an excessive number of shielding grounding areas 22 included in the same shielding protection group 20 (or even within the power device), which would result in a significant loss of channel density and affect the operating performance of the power device. On the other hand, an insufficient number of shielding grounding areas 22, due to the inherent material resistance, would impair the grounding effect of local areas in the shielding protection zone 21 that are far from the shielding grounding areas 22, thus affecting the overall shielding effect of the shielding protection group 20.
[0076] In an optional embodiment, the doping concentration range of the main shielding region 211 is 1e16 cm⁻¹. -3 ~1e20cm -3 (Including endpoint values), the doping concentration range of the secondary shielding region 212 is 1e16 cm⁻¹. -3 ~1e20cm -3 (Including endpoint values). For example, the doping concentration of the main shielding region 211 can be 1e17 cm⁻¹. -3 1e18cm -3 or 1e19 cm -3 The doping concentration of the auxiliary shielding region 212 can be 5e16 cm⁻¹. -3 5e17cm -3 Or 5e18cm -3 .
[0077] In an optional embodiment, the doping depth of the main shielding region 211 ranges from 0.1 μm to 1 μm (inclusive), and the doping depth of the auxiliary shielding region 212 ranges from 0.1 μm to 1 μm (inclusive). For example, the doping depth of the main shielding region 211 can be 0.3 μm, 0.5 μm, or 0.8 μm, and the doping depth of the auxiliary shielding region 212 can be 0.2 μm, 0.4 μm, or 0.6 μm. The doping concentration of the main shielding region 211 can be the same as or different from that of the auxiliary shielding region 212, and the doping depth of the main shielding region 211 can be the same as or different from that of the auxiliary shielding region 212. For example, if both have the same doping concentration and doping depth, they can be formed in the same step, which helps to save process steps and reduce costs.
[0078] In an optional embodiment, the cell structure region 30 further includes a plurality of well regions 32, any two adjacent well regions 32 being separated by the trench gate 31, the well regions 32 exhibiting the second conductivity type, and the shielding ground region 22 being electrically connected to the source metal 50 based on the well regions 32. Of course, in other embodiments, other suitable methods can also be used to achieve the electrical connection between the shielding ground region 22 and the source metal 50.
[0079] In an optional embodiment, the cell structure region 30 further includes a plurality of source regions 33 located in the well region 32 and adjacent to the trench gate 31 to form a conductive channel in the region of the well region 32 below the source regions 33.
[0080] In an optional embodiment, the cell structure region 30 further includes a plurality of contact regions 34 located within the source region 33. The contact regions 34 are used to improve source contact resistance, and the conductivity type of the source region 33 is the same as that of the well region 32. When the cell structure region 30 includes the contact regions 34, the shielding grounding region 22, the well region 32, the contact regions 34, and the source metal 50 are sequentially electrically connected to achieve the grounding configuration of the shielding protection group 20.
[0081] In an optional embodiment, the semiconductor structure layer 10 includes a first epitaxial layer 13 and a second epitaxial layer 14 stacked together. The shielding protection zone 21 is located in the first epitaxial layer 13, and the grounding region and the second conductivity type well region 32 are both located in the second epitaxial layer 14. The doping concentration of the second epitaxial layer 14 is greater than or equal to the doping concentration of the first epitaxial layer 13. The first epitaxial layer 13 and the second epitaxial layer 14 constitute the drift layer of the power device.
[0082] In this embodiment, since the spacing between any two adjacent shielding protection zones 21 is small, it will affect the current conduction capability of the power device to a certain extent. Setting the doping concentration of the second epitaxial layer 14 to be higher than the doping concentration of the first epitaxial layer 13 can improve the current conduction capability, thereby compensating for the negative impact of the setting and structure of the shielding protection zone 21 on the performance of the power device and ensuring the overall current conduction capability of the power device.
[0083] In an optional embodiment, the thickness of the second epitaxial layer 14 ranges from 1 μm to 3 μm (inclusive). For example, the thickness of the second epitaxial layer 14 can be 1.5 μm, 2 μm, or 2.5 μm.
[0084] In an optional embodiment, the trench gate 31 further includes a gate dielectric 313, which at least covers the inner wall of the trench 311, and the gate electrode is located above the gate dielectric 313. The gate dielectric 313 is made of silicon oxide, and the gate electrode 312 is made of polysilicon.
[0085] In an optional embodiment, the etching depth of the trench 311 ranges from 1 μm to 3 μm (inclusive of endpoints). For example, the thickness of the second epitaxial layer 14 can be 1.5 μm, 2 μm, or 2.5 μm. The etching width of the trench 311 ranges from 0.1 μm to 5 μm (inclusive of endpoints). For example, the etching width of the trench 311 can be 1 μm, 2 μm, or 4 μm. When the shielding protection zone 21 covers a portion of the bottom of the trench gate 31, the etching depth of the trench 311 is set based on the thickness of the second epitaxial layer 14, ensuring that after the gate dielectric 313 is formed by oxidation of the inner wall of the trench 311, the bottom of the gate dielectric 313 is embedded in the shielding protection zone 21 and is covered by the shielding protection zone 21.
[0086] In an optional embodiment, the semiconductor structure layer 10 further includes a substrate 11 and a buffer layer 12. The buffer layer 12 is located between the substrate 11 and the first epitaxial layer 13, and the doping concentration of the buffer layer 12 is lower than that of the substrate 11 (i.e., the substrate 11 is a moderately doped substrate 11, and the buffer layer 12 is a lightly doped buffer layer 12). The materials of the substrate 11 and the buffer layer 12 include silicon carbide, that is, the power device provided in this application embodiment is a trench 311 type silicon carbide power device. This application embodiment uses the semiconductor structure layer 10 including the buffer layer 12 as an example for illustration. In application, whether to provide the buffer layer 12 is selected based on actual needs.
[0087] In an optional embodiment, the power device further includes an interlayer dielectric layer 40 that covers the trench gate 311 to electrically isolate the trench gate 311 from the source metal 50.
[0088] In an optional embodiment, the power device further includes a drain metal 60 located below the semiconductor structure layer 10.
[0089] In an optional embodiment, the semiconductor structure layer 10 and the source region 33 are both N-type conductive, and the shielding protection group 20, the well region 32 and the contact region 34 are all P-type conductive; or, the semiconductor structure layer 10 and the source region 33 are both P-type conductive, and the shielding protection group 20, the well region 32 and the contact region 34 are all N-type conductive.
[0090] The power device with a shielding protection structure provided in this application includes a semiconductor structure layer, a cell structure region, a shielding protection structure, and a source metal. The shielding protection structure includes at least one shielding protection group, which includes a shielding protection area and a shielding grounding area. The shielding protection area extends below multiple trench gates in the cell structure region, which can reduce the electric field concentration at the bottom of the multiple trench gates, thereby improving the reliability of the power device. The shielding protection area and the shielding grounding area are electrically connected, and the shielding grounding area is electrically connected to the source metal, which can realize the grounding of the shielding area and further improve the shielding protection effect. The structure of the shielding protection area is further designed so that the shielding protection area includes multiple alternating main shielding areas and auxiliary shielding areas, and the width (or length) of the main shielding area is greater than the width (or length) of the auxiliary shielding area. The main shielding area at least covers the bottom corner of the trench gate. Through the above structural and dimensional design, the area of the shielding protection area mainly used to provide electric field shielding effect for the trench gate (i.e., the main shielding area) accounts for a larger proportion, while the area of the auxiliary shielding area mainly used to connect multiple main shielding areas accounts for a smaller proportion, further improving the conduction performance of the device. Based on this, when the shielding protection group includes multiple shielding grounding areas, a preset distance is maintained between two adjacent shielding grounding areas within the same shielding protection group. This ensures good grounding performance of the shielding protection zone while avoiding excessive shielding grounding areas that could affect the trench density of power devices, thus improving the conductivity of the power devices. Furthermore, the overall structure is simple, flexible, and versatile, making it suitable for practical applications.
[0091] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.
Claims
1. A power device with a shielding protection structure, characterized in that, include: A semiconductor structure layer, wherein the semiconductor structure layer is of a first conductivity type; A cellular structure region is located in the semiconductor structure layer. The cellular structure region includes a plurality of trench gates, each trench gate including a trench and a gate filling the trench. A shielding protection structure is located in the semiconductor structure layer, and the shielding protection structure is of a second conductivity type; the shielding protection structure includes at least one shielding protection group, the shielding protection group includes a shielding protection zone and at least one shielding grounding zone, the shielding protection zone extends below the plurality of trench gates, and the extension direction of the shielding protection zone intersects the extension direction of the trench gates, and the shielding grounding zone is electrically connected to the shielding protection zone; The source metal is located on the semiconductor structure layer and is electrically connected to the shielding grounding.
2. The power device with a shielding protection structure according to claim 1, characterized in that: The shielding protection structure includes multiple shielding protection groups, which are arranged sequentially, and the arrangement direction of the multiple shielding protection groups intersects with the arrangement direction of the multiple trench grids.
3. The power device with a shielding protection structure according to claim 2, characterized in that: The shielding protection zone includes multiple main shielding zones and multiple auxiliary shielding zones. In the extending direction of the shielding protection zone, the multiple main shielding zones and the multiple auxiliary shielding zones are alternately connected, and the width of the main shielding zone is greater than the width of the auxiliary shielding zone.
4. The power device with a shielding protection structure according to claim 3, characterized in that, The shielding protection structure includes adjacent first sub-shielding protection zones and second sub-shielding protection zones, wherein... In the first sub-shielded protection zone: any of the main shielding zones is located at least below the trench grid, any of the auxiliary shielding zones is located between two adjacent trench grids, and the width of the main shielding zone is greater than the width of the trench.
5. The power device with a shielding protection structure according to claim 4, characterized in that, The second sub-shielded protection zone is aligned with the first sub-shielded protection zone; wherein, In the second sub-shielded protection zone: any of the main shielding zones is located at least below the trench grid, and any of the auxiliary shielding zones is located between two adjacent trench grids.
6. The power device with a shielding protection structure according to claim 4, characterized in that: The first sub-shielded protection zone and the second sub-shielded protection zone are arranged alternately; wherein, In the second sub-shielded protection zone: a portion of the main shielding area is located at least below the trench grid, and another portion of the main shielding area extends from between two adjacent trenches to below the bottom corners of the two adjacent trenches facing each other, and the main shielding area is greater than the distance between two adjacent trench grids.
7. The power device with a shielding protection structure according to claim 3, characterized in that, The shielding protection group includes multiple shielding junction areas, which are arranged along the extension direction of the shielding protection zone, and there is a preset distance between any two adjacent shielding junction areas; wherein, The shielding junction area is electrically connected to the main shielding area; and / or, the shielding junction area is electrically connected to the auxiliary shielding area.
8. The power device with a shielding protection structure according to claim 7, characterized in that: The ratio between the distance between any two adjacent shielding junctions and the cell width of the power device is in the range of 2 to 6.
9. The power device with a shielding protection structure according to claim 3, characterized in that: The doping concentration range of the main shielding region is 1e16 cm⁻¹. -3 ~1e20cm -3 The doping concentration range of the auxiliary shielding region is 1e16 cm⁻¹. -3 ~1e20cm -3 The doping depth of the main shielding region is 0.1 μm to 1 μm, and the doping depth of the auxiliary shielding region is 0.1 μm to 1 μm.
10. The power device with a shielding protection structure according to claim 3, characterized in that: The shielding protection zone also covers a portion of the bottom of the plurality of trench grids, and at least one bottom corner of the trench grid is covered by the main shielding zone.