Terminal structure of high-voltage MOSFET device

Abstract

The utility model is applicable to the technical field of semiconductors, and provides a terminal structure of a high-voltage MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) device, which comprises a highly-doped N-type substrate, a lowly-doped N-type drift region and a cellular region, and a core assembly is arranged in the cellular region; the terminal protection area surrounds the periphery of the cellular area; a plurality of grooves are formed in the terminal protection area, the grooves are filled with insulating materials, and the insulating materials are of gradient structures which are gradually thickened from the bottoms of the grooves to the tops of the grooves; according to the utility model, the optimization of electric field distribution and the double improvement of high-efficiency current transmission are realized, the low-doped N-type drift region is combined with the insulating material groove with the gradually thickened gradient structure in the terminal protection region, the electric field concentration is effectively reduced, the breakdown risk is avoided, and in addition, the service life of the terminal protection region is prolonged. The arrangement of the slowly changing junction P-type well region ensures the efficient transmission of current in the device, and through the smooth change of the doping concentration and the junction depth, the smooth transition electric field distribution is formed at the edge of the device, and the breakdown possibility is further reduced.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor technology, and in particular relates to a termination structure for a high-voltage MOSFET device. Background Technology

[0002] With the rapid development of power electronics technology, high-voltage MOSFETs (metal-oxide-semiconductor field-effect transistors) have shown great application potential and value in key areas such as power conversion systems, motor drive devices, and energy management systems as core components of modern power electronic systems. However, in practical applications, especially when these devices are placed in high-voltage and high-current operating environments, a series of challenges have emerged, posing a severe test to the overall performance and long-term reliability of the devices.

[0003] Specifically, traditional high-voltage MOSFET devices are often difficult to perfectly handle high voltage stress in their design. Under the influence of high electric field strength, the electric field tends to concentrate in certain specific areas of the device (such as edges or corners). This uneven electric field distribution not only exacerbates the electric stress inside the device, but also significantly increases the risk of breakdown due to excessive electric field concentration. Once breakdown occurs, the device will not be able to work properly and may even suffer permanent damage, which undoubtedly poses a huge threat to the stable operation of the system.

[0004] Meanwhile, insufficient breakdown voltage is another major challenge faced by traditional high-voltage MOSFET devices. Breakdown voltage is an important indicator of a device's ability to withstand high voltage, and it is directly related to the device's operational stability and safety in high-voltage environments. However, due to design limitations and material properties, the breakdown voltage of many traditional devices often fails to meet the requirements of practical applications, which limits their application range in high-voltage fields.

[0005] In addition, poor stability is also an important reason why traditional high-voltage MOSFET devices perform poorly under high voltage and high current conditions. When the device is working under high stress, its internal structure and performance are prone to change, leading to a decrease in stability. This instability not only affects the normal operation of the device, but may also trigger a series of chain reactions, posing a potential threat to the stable operation of the entire power electronic system. Utility Model Content

[0006] This invention provides a termination structure for a high-voltage MOSFET device, aiming to solve the problems of electric field concentration, insufficient breakdown voltage, and poor stability faced by traditional high-voltage MOSFET devices under high voltage and high current operating conditions.

[0007] This invention is implemented as follows: a termination structure for a high-voltage MOSFET device includes a highly doped N-type substrate; a lightly doped N-type drift region disposed on the highly doped N-type substrate; a cell region disposed on the lightly doped N-type drift region, wherein a core assembly is disposed within the cell region; the core assembly includes: a gate, wherein an insulating layer is disposed on the outer surface of the gate, the insulating layer separating the gate and the lightly doped N-type drift region, forming an insulating barrier controlling the current path between the gate and the drift region; a source, wherein the input terminal of the source is connected to the lightly doped N-type drift region, forming a current input port; a drain, wherein the output terminal of the drain is connected to the other end of the lightly doped N-type drift region, forming a current output port; and a termination protection zone surrounding the cell region; wherein a plurality of trenches arranged in parallel are disposed within the termination protection zone, the trenches being filled with an insulating material, the insulating material having a gradually thickening gradient structure from the bottom to the top of the trench.

[0008] Preferably, the sidewalls of the trench are roughened at the nanoscale, and the spacing between two adjacent trenches is in the range of 0.7-1 micrometer.

[0009] Preferably, a gradually changing junction P-type well region is provided in the terminal protection zone. The doping concentration of the gradually changing junction P-type well region gradually increases from the edge to the inside, and its junction depth also shows a gradual trend from shallow to deep.

[0010] Preferably, the outer surface of the terminal protection zone is covered with multiple layers of insulating medium, wherein at least one layer of the insulating medium is silicon dioxide.

[0011] Preferably, the doping concentration of the low-doped N-type drift region is lower than the doping concentration of the high-doped N-type substrate.

[0012] Preferably, the edge of the terminal protection zone is provided with a metallized layer.

[0013] Compared with the prior art, the embodiments of this application have the following main advantages:

[0014] Firstly, by setting up a low-doped N-type drift region and filling the terminal protection zone with trenches containing gradually thickened gradient insulating material, this device successfully optimizes the electric field distribution. This design effectively reduces the concentration of the electric field inside and at the edges of the device, avoiding the risk of breakdown due to excessive electric field concentration. At the same time, the nanoscale roughening treatment further homogenizes the electric field distribution on the trench sidewalls, reducing the risk of electric field concentration. These measures work together to significantly improve the breakdown voltage and high-voltage withstand capability of the device, ensuring the stability and reliability of the device in high-voltage applications.

[0015] Secondly, this device achieves efficient current transmission, which not only ensures efficient current transmission within the device, but also further reduces the possibility of device breakdown under high voltage by setting the gradually changing junction P-type well region. The doping concentration and junction depth of the gradually changing junction P-type well region exhibit a smooth change. This change helps to form a smooth transition electric field distribution at the edge of the device, thereby reducing the risk of electric field concentration and improving the breakdown voltage of the device. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0017] Figure 2 This is a three-dimensional structural schematic diagram of the present invention;

[0018] Figure 3 This is a front sectional view of the structure of this utility model;

[0019] Figure 4 This is a side sectional view of the present invention.

[0020] Figure 5 This is a side sectional view of the present invention.

[0021] In the figure: 1. Highly doped N-type substrate; 2. Lowly doped N-type drift region; 3. Cell region; 4. Gate; 5. Insulating layer; 6. Source; 7. Drain; 8. Termination protection zone; 9. Trench; 10. Metallization layer; 11. Gradually changing junction P-type well region. Detailed Implementation

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] This utility model embodiment provides a termination structure for a high-voltage MOSFET device, such as... Figure 1-5 As shown, the system includes a highly doped N-type substrate 1; a lightly doped N-type drift region 2 disposed on the highly doped N-type substrate 1; a cell region 3 disposed on the lightly doped N-type drift region 2, wherein a core assembly is disposed within the cell region 3; the core assembly includes: a gate 4, wherein an insulating layer 5 is disposed on the outer surface of the gate 4, the insulating layer 5 separating the gate 4 and the lightly doped N-type drift region 2, forming an insulating barrier controlling the current path between the gate 4 and the drift region; a source 6, wherein the input terminal of the source 6 is connected to the lightly doped N-type drift region 2, forming a current input port; a drain 7, wherein the output terminal of the drain 7 is connected to the other end of the lightly doped N-type drift region 2, forming a current output port; and a terminal protection zone 8 surrounding the cell region 3; wherein a plurality of parallel trenches 9 are disposed within the terminal protection zone 8, the trenches 9 being filled with insulating material, the insulating material having a gradient structure that gradually thickens from the bottom to the top of the trenches 9.

[0025] It should be noted that, due to the problems of electric field concentration, insufficient breakdown voltage, and poor stability faced by traditional high-voltage MOSFET devices under high-voltage and high-current operating conditions, this solution achieves a dual improvement in electric field distribution and efficient current transmission. The combination of the low-doped N-type drift region 2 and the gradually thickening gradient structure of the insulating material trench 9 within the terminal protection zone 8 effectively reduces electric field concentration and avoids the risk of breakdown. At the same time, the nanoscale roughening treatment further homogenizes the electric field distribution, significantly improving the breakdown voltage and high-voltage withstand capability of the device. In addition, the setting of the gradually changing junction P-type well region 11 ensures efficient current transmission within the device, and through the smooth change of doping concentration and junction depth, a smooth transition electric field distribution is formed at the edge of the device, further reducing the possibility of breakdown. This not only enhances the stability and reliability of the device in high-voltage applications but also achieves a significant improvement in current transmission efficiency, providing a strong guarantee for the high-performance operation of the device.

[0026] Specifically, in this embodiment, the solution mainly includes a highly doped N-type substrate 1; the highly doped N-type substrate 1 provides the conductivity required by the device; on this basis, a low-doped N-type drift region 2 is provided, which, through its low doping concentration, helps to withstand higher voltages when the device is working, and at the same time serves as a channel for current transmission.

[0027] Next, cell region 3 is located above the lightly doped N-type drift region 2. Cell region 3 contains a core assembly, including gate 4, source 6, and drain 7. The outer surface of gate 4 is covered with an insulating layer 5, which not only physically separates gate 4 from the lightly doped N-type drift region 2, but also forms an insulating barrier to control the current path between gate 4 and lightly doped N-type drift region 2. When a sufficiently high positive voltage is applied to gate 4, an inversion layer is formed at the interface of lightly doped N-type drift region 2 near gate 4, thereby allowing current to flow from source 6 through lightly doped N-type drift region 2 to drain 7.

[0028] Source 6 serves as the current input port, with its input terminal connected to the low-doped N-type drift region 2, while drain 7 serves as the current output port, with its output terminal connected to the other end of the low-doped N-type drift region 2. Thus, when the gate 4 voltage controls the channel to turn on, current can flow in from source 6, pass through the low-doped N-type drift region 2, and finally flow out from drain 7.

[0029] In addition, to enhance the stability and reliability of the device, a terminal protection zone 8 is designed around the cell region 3. Multiple parallel trenches 9 are provided in the protection zone, and these trenches 9 are filled with insulating material. The insulating material has a gradient structure that gradually thickens from the bottom to the top of the trenches 9. This design helps to optimize the electric field distribution, reduce electric field concentration, and thus improve the breakdown voltage and high voltage withstand capability of the device.

[0030] In a further preferred embodiment of this utility model, such as Figure 1-5 As shown, the sidewalls of the groove 9 are roughened at the nanoscale, and the spacing between two adjacent grooves 9 is in the range of 0.7-1 micrometers.

[0031] In this embodiment, the nanoscale roughening treatment can change the surface morphology of the sidewall of the trench 9, making the electric field distribution on the sidewall more uniform. This helps to reduce electric field concentration, improve the breakdown voltage and high voltage withstand capability of the device. In addition, by optimizing the spacing, the electric field concentration can be further reduced, the breakdown voltage of the device can be improved, and the current transmission efficiency in the drift region can be ensured.

[0032] In a further preferred embodiment of this utility model, such as Figure 1-5 As shown, a gradually changing junction P-type well region 11 is provided in the terminal protection zone 8. The doping concentration of the gradually changing junction P-type well region 11 gradually increases from the edge to the inside, and its junction depth also shows a gradual trend from shallow to deep.

[0033] In this embodiment, the doping concentration of the P-type well region 11 of the gradual transition junction gradually increases from the edge to the inside. This design helps to form a gradually transitioning electric field distribution at the edge of the device. Due to the change in doping concentration, the electric field at the interface between the P-type well region and the N-type drift region no longer changes abruptly, but presents a smooth transition region. This smooth electric field distribution helps to reduce electric field concentration, thereby reducing the risk of device breakdown under high voltage.

[0034] Meanwhile, the junction depth of the gradually changing P-type well region 11 also shows a gradual trend from shallow to deep; the change in junction depth further enhances the flexibility of electric field control; in the region near the edge of the device, the shallower junction depth helps to reduce the impact of the electric field on the device surface and reduce the risk of surface leakage current; while in the internal region, the deeper junction depth helps to better constrain the electric field and improve the breakdown voltage of the device.

[0035] In a further preferred embodiment of this utility model, such as Figure 1-5 As shown, the outer surface of the terminal protection zone 8 is covered with multiple layers of insulating medium, of which at least one layer of the insulating medium is silicon dioxide.

[0036] In this embodiment, a multilayer insulating medium is used to provide electrical isolation, ensuring that no electrical short circuits occur between the components. Silica is chemically stable, does not easily react with other materials, and can maintain its insulating properties in various environments.

[0037] In a further preferred embodiment of this utility model, such as Figure 1-5 As shown, the doping concentration of the low-doped N-type drift region 2 is lower than that of the high-doped N-type substrate 1.

[0038] In this embodiment, by rationally designing the difference in doping concentration between the highly doped N-type substrate 1 and the low-doped N-type drift region 2, the ability to efficiently transmit and regulate current is achieved while withstanding high voltage.

[0039] In a further preferred embodiment of this utility model, such as Figure 1-5 As shown, a metallization layer 10 is provided at the edge of the terminal protection zone 8.

[0040] In this embodiment, the metallization layer 10 can serve as an electric field shielding layer, reducing the interference of external electric fields on sensitive areas inside the device. In high-voltage applications, this helps prevent the concentration of electric fields at the device edges, thereby reducing the risk of breakdown.

[0041] Working principle: The highly doped N-type substrate 1 of this device provides the conductivity required by the device; on this basis, a low-doped N-type drift region 2 is set. The doping concentration of this region is much lower than that of the highly doped N-type substrate 1, so that it can withstand higher voltage when the device is working; at the same time, the low-doped N-type drift region 2 also serves as the main channel for current transmission, ensuring the smooth flow of current inside the device.

[0042] Next, cell region 3 is placed on top of low-doped N-type drift region 2. Cell region 3 contains a core assembly, including gate 4, source 6 and drain 7. The outer surface of gate 4 is tightly wrapped by insulating layer 5. This insulating layer 5 not only physically separates gate 4 from low-doped N-type drift region 2, but also forms an insulating barrier. When a sufficiently high positive voltage is applied to gate 4, the insulating barrier will form an inversion layer at the interface of the drift region near gate 4, thereby opening the current path and allowing current to flow from source 6 through the drift region to drain 7.

[0043] The source 6 serves as the starting point of the current, with its input terminal closely connected to the low-doped N-type drift region 2; while the drain 7 serves as the ending point of the current, with its output terminal connected to the other end of the low-doped N-type drift region 2; thus, when the gate 4 voltage controls the channel to open, the current can smoothly flow from the source 6, pass through the low-doped N-type drift region 2, and finally flow out from the drain 7.

[0044] To further improve the stability and reliability of the device, a terminal protection zone 8 is added around the cell region 3. Multiple parallel trenches 9 are set in this protection zone and filled with insulating material. The insulating material has a gradient structure that gradually thickens from the bottom to the top of the trenches 9. This design helps to optimize the electric field distribution, significantly reduce the electric field concentration phenomenon, and thus greatly improve the breakdown voltage and high voltage withstand capability of the device.

[0045] In addition, nanoscale roughening is applied to the sidewalls of trench 9, making the electric field distribution on the sidewalls more uniform. This treatment further reduces the risk of electric field concentration and improves the breakdown voltage of the device. At the same time, by optimizing the spacing between trenches 9, electric field concentration can be further reduced, ensuring efficient current transmission in the drift region.

[0046] In the edge region of the device, the doping concentration of the P-type well region 11 of the gradual transition junction gradually increases from the edge to the interior. This change helps to form a smooth transition electric field distribution at the edge of the device. Due to the smooth change in doping concentration, the electric field no longer changes abruptly at the interface between the P-type well region and the N-type drift region, but presents a smooth transition region. This design significantly reduces the risk of electric field concentration, thereby reducing the possibility of device breakdown under high voltage.

[0047] Meanwhile, the junction depth of the gradually changing P-type well region 11 also exhibits a gradual trend from shallow to deep; this change in junction depth further enhances the flexibility of electric field control; in the region near the edge of the device, the shallower junction depth helps to reduce the impact of the electric field on the device surface and reduce the risk of surface leakage current; while in the internal region, the deeper junction depth helps to better confine the electric field and further improve the breakdown voltage of the device.

[0048] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0049] It should be understood that the disclosed apparatus can be implemented in other ways, given the several embodiments provided in this application. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units described above may be implemented in other ways in practice. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or communication connections shown or discussed may be through some interfaces; indirect coupling or communication connections between devices or units may be telecommunications or other forms.

[0050] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0051] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Although this utility model has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of this utility model according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of this utility model. These technical solutions are also within the scope of protection of this utility model.

Claims

1. A termination structure for a high voltage MOSFET device, characterized by, include: Including highly doped N-type substrates (1); A low-doped N-type drift region (2) is provided on the highly doped N-type substrate (1); A cell region (3) is provided on a low-doped N-type drift region (2), and a core assembly is provided in the cell region (3); The core assembly includes: Gate (4), an insulating layer (5) is provided on the outer surface of the gate (4), the insulating layer (5) separates the gate (4) and the low-doped N-type drift region (2) to form an insulating barrier that controls the current path between the gate (4) and the drift region; Source (6), the input terminal of which is connected to the low-doped N-type drift region (2) to form a current input port; Drain (7), the output terminal of the drain (7) is connected to the other end of the low-doped N-type drift region (2) to form a current output port; Terminal protection zone (8) surrounding the cell region (3); The terminal protection zone (8) is provided with multiple parallel trenches (9), the trenches (9) are filled with insulating material, and the insulating material has a gradient structure that gradually thickens from the bottom to the top of the trenches (9).

2. The termination structure of a high voltage MOSFET device of claim 1, wherein, The sidewalls of the trench (9) are roughened at the nanoscale, and the spacing between two adjacent trenches (9) is in the range of 0.7-1 micrometer.

3. The termination structure of a high voltage MOSFET device of claim 1, wherein, The terminal protection zone (8) is provided with a gradually changing junction P-type well region (11). The doping concentration of the gradually changing junction P-type well region (11) gradually increases from the edge to the inside, and its junction depth also shows a gradual trend from shallow to deep.

4. The termination structure of a high voltage MOSFET device of claim 3, wherein, The outer surface of the terminal protection zone (8) is covered with multiple layers of insulating medium, wherein at least one layer of the insulating medium is silicon dioxide.

5. The termination structure of a high voltage MOSFET device of claim 1, wherein, The doping concentration of the low-doped N-type drift region (2) is lower than that of the high-doped N-type substrate (1).

6. The termination structure of a high voltage MOSFET device of claim 4, wherein, The edge of the terminal protection zone (8) is provided with a metallized layer (10).

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