Wide bandgap semiconductor device terminal structure and manufacturing method thereof

Abstract

The present application discloses a terminal structure for a wide bandgap semiconductor device and a manufacturing method thereof. The terminal structure includes a main junction and a terminal cutoff region embedded in a sandwich epitaxial structure. The sandwich epitaxial structure includes a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction. The active region, the main junction, and the terminal cutoff region are arranged in sequence along a second direction. The main junction contacts the active region, and the terminal cutoff region is separated from the main junction by a preset distance. The second direction is perpendicular to the first direction. The main junction includes a first P-type ion-doped region that penetrates the second N-type epitaxial layer and the P-type buried layer and is embedded in the first N-type epitaxial layer. The terminal cutoff region includes a first N-type ion-doped region that penetrates the second N-type epitaxial layer and the P-type buried layer and is embedded in the first N-type epitaxial layer. Thus, the terminal cutoff region truncates the P-type buried layer, and the main junction reduces electric field crowding in the active region, providing a highly reliable terminal structure for a wide bandgap semiconductor device with a sandwich epitaxial structure.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a wide bandgap semiconductor device terminal structure and a manufacturing method thereof. Background Art

[0002] In recent years, wide bandgap semiconductor materials such as silicon carbide SiC, gallium nitride GaN, and ultra-wide bandgap semiconductor materials such as gallium oxide Ga2O3 have attracted increasing attention due to their excellent performance in physical properties such as bandgap width, critical breakdown electric field strength, and electron saturation drift velocity. How to use third-generation and fourth-generation semiconductors to manufacture semiconductor devices has attracted increasing attention.

[0003] Currently, wide-bandgap semiconductors are widely used in power electronics due to their lower power loss and higher conversion efficiency in power devices. Furthermore, sandwich epitaxial structures offer excellent results in improving device electrical performance and reducing parasitic effects, making their application in power devices an important optimization direction. In practical applications, field-limiting rings (FLRs) or junction termination extensions (JTEs) are commonly used as terminal structures in semiconductor power devices. However, FLR and JTE structures are sensitive to interface charge and have poor voltage resistance, making device reliability difficult to guarantee. Furthermore, conventional terminal structures are difficult to adapt to power devices based on sandwich epitaxial structures.

[0004] Therefore, how to provide a highly reliable terminal structure for a wide bandgap semiconductor device having a sandwich epitaxial structure becomes a problem that needs to be solved. Summary of the Invention

[0005] Based on the above problems, the present application provides a wide bandgap semiconductor device terminal structure and a manufacturing method thereof, which can provide a high-reliability terminal structure for a wide bandgap semiconductor device with a sandwich epitaxial structure.

[0006] The embodiments of this application disclose the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a terminal structure of a wide bandgap semiconductor device, which matches an active region based on a sandwich epitaxial structure, wherein the terminal structure includes: a main junction embedded in the sandwich epitaxial structure and an end cutoff region;

[0008] The sandwich epitaxial structure comprises a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction; in the sandwich epitaxial structure, the first N-type epitaxial layer is located on a side close to the substrate, and the second N-type epitaxial layer is located on a side away from the substrate;

[0009] The active region, the main junction, and the end cut-off region are arranged in sequence along a second direction; the main junction contacts the active region, and the end cut-off region is spaced a preset distance from the main junction; the second direction is perpendicular to the first direction;

[0010] The main junction includes a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer;

[0011] The end cut-off region includes a first N-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer.

[0012] Optionally, the end cut-off region further includes a first auxiliary trench penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer, and a field oxide layer filled in the first auxiliary trench; the number of the first auxiliary trench is greater than or equal to 1, and is used to assist ion doping to form the first N-type ion doped region.

[0013] Optionally, a field limiting ring region is further provided between the end cut-off region and the main junction;

[0014] The field limiting ring region includes a plurality of separation trenches penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer, and a field oxide layer filled in the separation trenches.

[0015] Optionally, a field limiting ring region is further provided between the end cut-off region and the main junction;

[0016] The field limiting ring region includes a plurality of second N-type ion doped regions penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer.

[0017] Optionally, the field limiting ring region further includes: a plurality of second auxiliary trenches embedded in the sandwich epitaxial structure, and a field oxide layer filled in the plurality of second auxiliary trenches; the second auxiliary trenches are used to assist ion doping to form the second N-type ion doping region.

[0018] Optionally, a second P-type ion doping region is provided between the main junction and the terminal cut-off region.

[0019] Optionally, the second P-type ion doping region has a plurality of regions with different ion doping concentrations.

[0020] Optionally, the second P-type ion doping region is located in the second N-type epitaxial layer between the end cut-off region and the main junction, and is in contact with the first P-type ion doping region and the first N-type ion doping region.

[0021] Optionally, the second P-type ion-doped region is located in the second N-type epitaxial layer between the end cut-off region and the main junction, and includes multiple ion-doped layers with different ion doping concentrations; the ion-doped layers are in contact with the main junction and the length in the second direction decreases layer by layer along the first direction to form an upper stepped structure; the bottom of the upper stepped structure is in contact with the P-type buried layer.

[0022] Optionally, the second P-type ion-doped region is located in the first N-type epitaxial layer between the end cut-off region and the main junction, and includes multiple ion-doped layers with different ion doping concentrations; the ion-doped layers are in contact with the main junction and the length in the second direction increases layer by layer along the first direction to form a lower stepped structure; the top of the lower stepped structure is in contact with the P-type buried layer.

[0023] Optionally, the terminal structure further includes a plurality of third P-type ion-doped regions, and the plurality of third P-type ion-doped regions are spaced apart and distributed along the second direction and penetrate the second N-type epitaxial layer.

[0024] In a second aspect, an embodiment of the present application provides a method for manufacturing a terminal structure of a wide bandgap semiconductor device, wherein the terminal structure matches an active region based on a sandwich epitaxial structure, the method comprising:

[0025] A substrate having a sandwich epitaxial structure is provided; the substrate comprises a substrate, a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction, wherein the second N-type epitaxial layer comprises at least a P-type well region of an active area;

[0026] forming a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer by ion implantation to form a main junction; the first P-type ion-doped region contacts the P-type well region;

[0027] A first N-type ion doped region is formed by ion implantation, penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer, to form a terminal cutoff region; the terminal cutoff region is spaced a preset distance from the main junction.

[0028] Compared with the existing technology, this application has the following beneficial effects:

[0029] An embodiment of the present application provides a terminal structure of a wide bandgap semiconductor device, the terminal structure including a main junction and an end stop region embedded in a sandwich epitaxial structure; the sandwich epitaxial structure includes a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction; in the sandwich epitaxial structure, the first N-type epitaxial layer is located on a side close to a substrate, and the second N-type epitaxial layer is located on a side away from the substrate; the active region, the main junction, and the end stop region are arranged in sequence along a second direction; the main junction contacts the active region, and the end stop region is spaced a preset distance from the main junction; the second direction is perpendicular to the first direction; the main junction includes a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; the end stop region includes a first N-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer. In the embodiments of the present application, on the one hand, the P-type buried layer is cut off by the end cutoff region, thereby preventing leakage current from leaking along the P-type buried layer to the dicing path and causing device failure; on the other hand, the main junction is embedded in the first N-type epitaxial layer, and has a deeper ion doping region, which can better reduce the electric field crowding in the active area and improve the breakdown characteristics of the device; on the other hand, it is highly compatible with the active area based on the sandwich epitaxial structure. The P-type buried layer in the sandwich epitaxial structure between the main junction and the end cutoff region can serve as a JTE structure, which can improve the electric field distribution and enhance the breakdown voltage, thermal stability, and robustness of the device. Therefore, the embodiments of the present application provide a highly reliable terminal structure for a wide bandgap semiconductor device with a sandwich epitaxial structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic diagram of a terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0033] Figure 3 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0034] Figure 4 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0035] Figure 5 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0036] Figure 6 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0037] Figure 7 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0038] Figure 8 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0039] Figure 9 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0040] Figure 10 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0041] Figure 11 A schematic diagram of a terminal structure of another wide bandgap semiconductor device provided in an embodiment of the present application;

[0042] Figure 12 A flow chart of a method for manufacturing a terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application;

[0043] Figure 13 A schematic diagram of the manufacturing process of a wide bandgap semiconductor device terminal structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] The wide bandgap semiconductor device terminal structure and the manufacturing method thereof provided in the present application can be used in the semiconductor field. The above is only an example and does not limit the application field of the wide bandgap semiconductor device terminal structure and the manufacturing method thereof provided in the present application.

[0045] The terms "first", "second", "third" and "fourth" in the specification, claims and drawings of this application are used to distinguish different objects rather than to limit a specific order.

[0046] In the embodiments of this application, words such as "as an example" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described in the embodiments of this application as "as an example" or "for example" should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "as an example" or "for example" is intended to present the relevant concepts in a concrete manner.

[0047] The terms used in the implementation section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application.

[0048] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0049] See also Figure 1 , this figure is a schematic diagram of a terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application. The terminal structure matches the active area 01 based on the sandwich epitaxial structure. The terminal structure includes: a main junction 100 embedded in the sandwich epitaxial structure and an end cut-off region 200.

[0050] Specifically, the sandwich epitaxial structure includes a first N-type epitaxial layer 301 , a P-type buried layer 303 and a second N-type epitaxial layer 302 stacked in sequence along a first direction; wherein the first N-type epitaxial layer 301 is located on a side close to the substrate 304 , and the second N-type epitaxial layer 302 is located on a side away from the substrate 304 .

[0051] Optionally, an N-type buffer layer 305 is further provided between the first N-type epitaxial layer 301 and the substrate 304 to reduce lattice mismatch and improve the quality of the sandwich epitaxial structure.

[0052] Optionally, a metal layer is further provided on a side of the substrate 304 facing away from the second N-type epitaxial layer 302 , serving as a drain electrode 306 of the active region.

[0053] The active area 01, the main junction 100 and the end cut-off area 200 are arranged in sequence along the second direction; the main junction 100 contacts the active area 01, and the end cut-off area 200 is spaced a preset distance from the main junction 100; wherein the second direction is perpendicular to the first direction.

[0054] As an example, the active region 01 may include a drain electrode 306 , a trench gate electrode 307 , a source electrode 308 , a P-type well region 309 , an N-type source region 310 , a P-type source region 311 , an N-type current channel 312 , and a P-type buried layer 303 .

[0055] Specifically, the drain electrode 306, the substrate 304, the N-type buffer layer 305, the first N-type epitaxial layer 301, the P-type buried layer 303 and the second N-type epitaxial layer 302 are stacked in sequence along the first direction; the P-type well region 309 and the N-type source region 310 are sequentially formed on the side of the second N-type epitaxial layer 302 away from the substrate 304, and the P-type well region 309 wraps the N-type source region 310; the P-type source region 311 runs through the P-type well region 309, the N-type source region 310, the second N-type epitaxial layer 302 and the P-type buried layer 303, and is embedded in the first N-type epitaxial layer 301; the trench gate electrode 307 runs through the P-type well region 309 and the N-type The source region 310 is embedded in the second N-type epitaxial layer 302 and may include a gate trench embedded in the second N-type epitaxial layer 302, a gate dielectric layer 3071 located on the sidewalls of the gate trench, a gate polysilicon 3072 filling the gate trench, an interlayer dielectric layer 3073 covering the top of the gate polysilicon 3072, and a masking layer 3074 wrapping the corners of the gate trench; the N-type current channel 312 is located in the P-type buried layer and corresponds to the position of the gate trench in the first direction; the source electrode 308 is a metal layer covering the surface of the structures such as the trench gate electrode 307, the N-type source region 310, and the P-type source region 311.

[0056] Among them, the P-type source region 311 can be formed by source trench assisted ion implantation to reduce high-energy ion implantation; the source trench can be a single-level trench or a multi-level trench, the inner wall of the source trench is covered with a dielectric layer 3111, and the inside of the source trench is filled with source polysilicon 3112.

[0057] It can be understood that the structure of the active area 01 above is only an example provided in the embodiment of the present application, and does not limit the active area matched with the terminal structure provided in the present application.

[0058] Optionally, the active area 01, the main junction 100 and the end cut-off region 200 are arranged laterally along the second direction; the preset distance between the end cut-off region 200 and the main junction 100 is designed based on the actual size of the active area and the terminal structure; the main junction 100 contacts the P-type well region 309 and the N-type source region 310 in the active area 01, penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301.

[0059] The main junction 100 includes a first P-type ion-doped region 101 ; the first P-type ion-doped region 101 penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301 .

[0060] The end stop region 200 includes a first N-type ion-doped region 201 ; the first N-type ion-doped region 201 penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301 .

[0061] Optionally, the width of the end cut-off region 200 may be selected from 10 μm to 20 μm. A wider end cut-off region 200 may better prevent leakage.

[0062] Optionally, ion implantation can be performed directly on the side of the second N-type epitaxial layer 301 facing away from the substrate 304 to form the first P-type ion-doped region 101 and the first N-type ion-doped region 201, respectively. Alternatively, an auxiliary trench can be formed first, and then the first P-type ion-doped region 101 and the first N-type ion-doped region 201 can be formed respectively by ion implantation, thereby making it easier to form deeper ion-doped regions, reducing the energy required for ion implantation, and lowering manufacturing costs.

[0063] Exemplarily, the end cut-off region 200 further includes a first auxiliary trench penetrating the second N-type epitaxial layer 302 and the P-type buried layer 303 and embedded in the first N-type epitaxial layer 301, and a field oxide layer 202 filled in the first auxiliary trench; the first auxiliary trench has a level greater than or equal to 1, and is used to assist ion doping to form the first N-type ion doped region 201.

[0064] Exemplarily, the main junction 100 also includes a main junction auxiliary trench that penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301, and a field oxide layer 102 filled in the main junction auxiliary trench; the number of the main junction auxiliary trenches is greater than or equal to 1, and is used to assist ion doping to form the first P-type ion doping region 101.

[0065] As an example, if the P-type source region 311 is formed by source trench assisted ion implantation, the number of first auxiliary trenches and / or main junction auxiliary trenches can be the same as the number of source trenches, so that in the same etching process, the main junction auxiliary trenches and / or first auxiliary trenches can be formed at the same time as the source trenches are formed, thereby reducing the complexity of the process flow and manufacturing costs.

[0066] In the embodiments of the present application, on the one hand, the P-type buried layer is cut off by the end cutoff region, thereby preventing leakage current from leaking along the P-type buried layer to the dicing path and causing device failure; on the other hand, the main junction is embedded in the first N-type epitaxial layer, and has a deeper ion doping region, which can better reduce the electric field crowding in the active area and improve the breakdown characteristics of the device; on the other hand, it is highly compatible with the active area based on the sandwich epitaxial structure. The P-type buried layer in the sandwich epitaxial structure between the main junction and the end cutoff region can serve as a JTE structure, which can improve the electric field distribution and enhance the breakdown voltage, thermal stability, and robustness of the device. Therefore, the embodiments of the present application provide a highly reliable terminal structure for a wide bandgap semiconductor device with a sandwich epitaxial structure.

[0067] See also Figure 2, this figure is a schematic diagram of another terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application, the terminal structure includes: a main junction 100 and an end cut-off region 200 embedded in a sandwich epitaxial structure, and a field limiting ring region 400 located between the end cut-off region 200 and the main junction 100.

[0068] The field limiting ring region 400 includes a plurality of separation trenches penetrating the second N-type epitaxial layer 302 and the P-type buried layer 303 and embedded in the first N-type epitaxial layer 301 , and a field oxide layer 401 filling the separation trenches.

[0069] Optionally, if the P-type source region 311 is formed by source trench assisted ion implantation, the number of separation trenches can be the same as the number of source trenches, so that the source trench and multiple separation trenches can be formed simultaneously in the same etching process, thereby reducing the complexity of the process flow and manufacturing costs.

[0070] Therefore, by using multiple separation trenches to penetrate the P-type buried layer, the P-type buried layer can be divided into multiple parts to form a field limiting ring FLR structure, so that the electric field can be modulated by the P-type FLR structure and field oxygen, thereby improving the electric field distribution of the device and enhancing the breakdown characteristics of the device.

[0071] See also Figure 3 , this figure is a schematic diagram of another terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application, the terminal structure includes: a main junction 100 and an end cut-off region 200 embedded in a sandwich epitaxial structure, and a field limiting ring region 400 located between the end cut-off region 200 and the main junction 100.

[0072] The field limiting ring region 400 includes a plurality of second N-type ion-doped regions 402 penetrating the second N-type epitaxial layer 302 and the P-type buried layer 303 and embedded in the first N-type epitaxial layer 301 .

[0073] Alternatively, ion implantation can be performed directly to form the second N-type ion-doped region 402. Alternatively, a second auxiliary trench can be formed first, followed by ion implantation to form the second N-type ion-doped region 402, and finally, the field oxide layer 401 can be filled in the second auxiliary trench to reduce the energy required for ion implantation and lower manufacturing costs. The second auxiliary trench is embedded in the sandwich epitaxial structure, specifically, in the second N-type epitaxial layer 302, or through the second N-type epitaxial layer 302 and embedded in the P-type buried layer 303, or through the second N-type epitaxial layer 302 and the P-type buried layer 303 and embedded in the first N-type epitaxial layer 301.

[0074] As an example, if the P-type source region 311 is formed by source trench auxiliary ion implantation, the number of first auxiliary trenches, second auxiliary trenches and / or main junction auxiliary trenches can be the same as that of the source trenches, so that the main junction auxiliary trenches, first auxiliary trenches and / or second auxiliary trenches can be formed at the same time as the source trenches in the same etching process, thereby reducing the complexity of the process flow and the manufacturing cost. Figure 3 As shown, the first auxiliary trench, the second auxiliary trench, the main junction auxiliary trench and the source trench can all be first-level trenches; Figure 4 As shown, the first auxiliary trench, the second auxiliary trench, the main junction auxiliary trench and the source trench can all be secondary trenches.

[0075] Optionally, the top of the field oxide layer may be covered with an interlayer dielectric layer 403 to protect the top surface of the terminal structure.

[0076] Therefore, by using multiple second N-type ion doping regions 402 to penetrate the P-type buried layer, the P-type buried layer can be divided into multiple parts to form an interval block field limiting ring FLR structure, so that the electric field modulation can be performed through the P-type FLR structure, thereby improving the electric field distribution of the device and enhancing the breakdown characteristics of the device.

[0077] Alternatively, see Figure 5 This figure is a schematic diagram of another terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application. In the second N-type epitaxial layer 302 between the main junction 100 and the terminal cut-off region 200, the side thereof facing away from the substrate 304 may also have a P-type well region, thereby better protecting the surface of the terminal structure facing away from the substrate.

[0078] See also Figure 6 , this figure is a schematic diagram of another terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application, the terminal structure includes: a main junction 100 and an end cut-off region 200 embedded in a sandwich epitaxial structure, and a second P-type ion doping region 500 located between the main junction 100 and the end cut-off region 200.

[0079] The second P-type ion-doped region 500 contacts the first P-type ion-doped region 101 and the first N-type ion-doped region 201. Specifically, the second P-type ion-doped region 500 can be located in the second N-type epitaxial layer 302, connecting the first P-type ion-doped region 101 and the first N-type ion-doped region 201. As a result, the second P-type ion-doped region 500 and the P-type buried layer 303 form a double-layer JTE structure with varying ion doping concentrations in the vertical direction, which can further improve the electric field distribution and enhance the breakdown characteristics of the device.

[0080] Optionally, multiple ion implantations may be performed to allow the second P-type ion doping region 500 to have multiple regions with different ion doping concentrations. Figure 7, two ion implantations can be performed. The first ion implantation forms an ion-doped region connecting the first P-type ion-doped region 101 and the first N-type ion-doped region 201. The second ion implantation is performed on the side of the ion-doped region close to the first P-type ion-doped region 101 to form a second P-type ion-doped region 500. Thus, a second P-type ion-doped region 500 is obtained, with a higher ion doping concentration on the side close to the first P-type ion-doped region 101 and a lower ion doping concentration on the side close to the first N-type ion-doped region 201. The second ion implantation can be used to control the doping concentration of the second P-type ion-doped region 500, forming a double-layer JTE structure with adjustable ion doping concentration in both the horizontal and vertical directions, further improving the electric field distribution and enhancing the breakdown characteristics of the device.

[0081] See also Figure 8 , this figure is a schematic diagram of another terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application, the terminal structure includes: a main junction 100 and an end cut-off region 200 embedded in a sandwich epitaxial structure, and a second P-type ion doping region 500 located between the main junction 100 and the end cut-off region 200.

[0082] The second P-type ion-doped region 500 is located in the second N-type epitaxial layer 302 between the terminal cut-off region 200 and the main junction 100 and includes multiple ion-doped layers with different ion doping concentrations, for example, a first ion-doped layer 501 and a second ion-doped layer 502. The ion-doped layers contact the main junction 100 and their lengths in the second direction decrease layer by layer along the first direction, forming an upper stepped structure. Optionally, the lengths of the ion-doped layers in the second direction are all less than the spacing between the main junction 100 and the terminal cut-off region 200. The bottom of the upper stepped structure contacts the P-type buried layer, that is, among the multiple ion-doped layers, the ion-doped layer with the longest length in the second direction contacts the P-type buried layer. Thus, the P-type buried layer and the second P-type ion-doped region 500 together form an upper stepped JTE structure with a longitudinally gradient ion doping concentration. The ion doping concentration of the second P-type ion-doped region 500 is easily adjustable in the first direction, and the ion doping concentrations of each ion-doped layer can be flexibly adjusted according to the actual parameters of the active region, thereby better improving the electric field distribution and enhancing the breakdown characteristics of the device.

[0083] Alternatively, as Figure 9 As shown, the terminal structure may further include a plurality of third P-type ion-doped regions 600, which are spaced apart along the second direction and extend through the second N-type epitaxial layer 302, contacting a side of the second P-type ion-doped region 500 facing away from the substrate 304. Optionally, the ion doping concentration of the third P-type ion-doped region 600 is higher than the ion doping concentration of the second P-type ion-doped region 500.

[0084] Thus, multiple third P-type ion doped regions 600 constitute an FLR structure, and the second P-type ion doped region 500 and the P-type buried layer 303 together constitute a JTE structure, obtaining a terminal structure combining the FLR structure and the JTE structure, which can further improve the electric field distribution, enhance the breakdown characteristics of the device, and improve the reliability of the device.

[0085] See also Figure 10 , this figure is a schematic diagram of another terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application, the terminal structure includes: a main junction 100 and an end cut-off region 200 embedded in a sandwich epitaxial structure, and a second P-type ion doping region 500 located between the main junction 100 and the end cut-off region 200.

[0086] The second P-type ion-doped region 500 is located in the first N-type epitaxial layer 301 between the terminal cut-off region 200 and the main junction 100 and includes multiple ion-doped layers with different ion doping concentrations, for example, a first ion-doped layer 501 and a second ion-doped layer 502. The ion-doped layers contact the main junction 100 and their lengths in the second direction gradually increase along the first direction, forming a lower-stepped structure. Optionally, the lengths of the ion-doped layers in the second direction are all less than the spacing between the main junction 100 and the terminal cut-off region 200. The top of the lower-stepped structure contacts the P-type buried layer, that is, among the multiple ion-doped layers, the ion-doped layer with the longest length in the second direction contacts the P-type buried layer. Thus, the P-type buried layer and the second P-type ion-doped region 500 together form a lower-stepped JTE structure with a longitudinally gradient ion doping concentration. The ion doping concentration of the second P-type ion-doped region 500 is easily adjustable in the first direction, and the ion doping concentrations of each ion-doped layer can be flexibly adjusted according to the actual parameters of the active region, thereby better improving the electric field distribution and enhancing the breakdown characteristics of the device.

[0087] Alternatively, as Figure 11 As shown, the terminal structure may further include a plurality of third P-type ion-doped regions 600, which are spaced apart along the second direction and extend through the second N-type epitaxial layer 302, contacting a side of the P-type buried layer 303 facing away from the substrate 304. Optionally, the ion doping concentration of the third P-type ion-doped regions 600 is higher than the ion doping concentration of the P-type buried layer 303.

[0088] Thus, multiple third P-type ion doped regions 600 constitute an FLR structure, and the second P-type ion doped region 500 and the P-type buried layer 303 together constitute a JTE structure, obtaining a terminal structure combining the FLR structure and the JTE structure, which can further improve the electric field distribution, enhance the breakdown characteristics of the device, and improve the reliability of the device.

[0089] See also Figure 12, which is a flow chart of a method for manufacturing a terminal structure of a wide bandgap semiconductor device provided in an embodiment of the present application. The terminal structure manufactured by this method matches the active region based on the sandwich epitaxial structure. The method includes:

[0090] S121: providing a substrate having a sandwich epitaxial structure.

[0091] like Figure 13 As shown in (a), the base includes a substrate 304, a first N-type epitaxial layer 301, a P-type buried layer 303 and a second N-type epitaxial layer 302 stacked in sequence along a first direction, wherein the second N-type epitaxial layer 302 includes at least a P-type well region 309 of the active region 01.

[0092] For example, a P-type well region 309 can be formed on the side of the second N-type epitaxial layer 302 facing away from the substrate 304 through P-type ion implantation. The P-type well region 309 can be formed only in the active region 01 or in both the active region 01 and the terminal structure. Subsequently, an N-type source region 310 can be formed on the side of the P-type well region 309 facing away from the substrate 304 in the active region 01 through N-type ion implantation. The P-type well region 309 surrounds the N-type source region 310.

[0093] Optionally, an N-type buffer layer 305 may be further provided between the first N-type epitaxial layer 301 and the substrate 304 to reduce lattice mismatch and improve the quality of the sandwich epitaxial structure.

[0094] S122 : forming a first P-type ion-doped region 101 penetrating the second N-type epitaxial layer 302 and the P-type buried layer 303 and embedded in the first N-type epitaxial layer 301 by ion implantation, thereby forming a main junction 100 .

[0095] The first P-type ion-doped region 101 is in contact with the P-type well region 309 .

[0096] Alternatively, see Figure 13 In (b), before ion implantation, source trenches and gate trenches can be formed by dry etching, wherein the gate trench is embedded in the second N-type epitaxial layer 302, and the source trench is used to assist in forming a P-type source region 311 that penetrates the P-type well region 309, the N-type source region 310, the second N-type epitaxial layer 302, and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301. The source trench can be a single-stage trench or a multi-stage trench, for example, Figure 13The secondary trench shown in (b) in FIG. While forming the source trench and the gate trench, one or more of the main junction auxiliary trench, the first auxiliary trench, the separation trench, and the second auxiliary trench may also be formed. The main junction auxiliary trench is used to assist in forming the first P-type ion doping region 101, the first auxiliary trench is used to assist in forming the first N-type ion doping region 201, and the second auxiliary trench is used to assist in forming the second N-type ion doping region 402 that separates the P-type buried layer 303, thereby reducing the energy required for ion implantation and reducing manufacturing costs. The separation trench is used to separate the P-type buried layer 303 to form a field limiting ring. The simultaneous formation of the source trench and the separation trench can reduce process complexity and thus avoid an increase in manufacturing costs. Preferably, the main junction auxiliary trench, the first auxiliary trench, the separation trench, and / or the second auxiliary trench have the same number and depth as the source trench or the same number and depth as the gate trench, thereby unifying process conditions and further avoiding increasing the complexity of the original process.

[0097] Optionally, P-type ion implantation can be performed directly on the side of the second N-type epitaxial layer 302 facing away from the substrate 304 to form a P-type source region 311 and a first P-type ion-doped region 101, wherein the first P-type ion-doped region 101 penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301, with the first P-type ion-doped region 101 serving as the main junction 100; P-type ion implantation can also be performed with the assistance of the source trench and the main junction auxiliary trench to form the P-type source region 311 and the first P-type ion-doped region 101, wherein the first P-type ion-doped region 101 wraps the main junction auxiliary trench, penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301, and after the field oxide layer 102 is filled in the main junction auxiliary trench, the field oxide layer 102 and the first P-type ion-doped region 101 together constitute the main junction 100.

[0098] For example, see Figure 13 In (c), P-type ion implantation may be performed with the assistance of the source trench and the main junction auxiliary trench formed by etching, thereby forming a P-type source region 311 and a first P-type ion doped region 101 .

[0099] S123 : forming a first N-type ion-doped region 201 penetrating the second N-type epitaxial layer 302 and the P-type buried layer 303 and embedded in the first N-type epitaxial layer 301 by ion implantation, thereby forming an end stop region 200 .

[0100] The end cut-off region 200 is spaced apart from the main junction 100 by a preset distance, and the preset distance can be flexibly set based on device size and process parameters.

[0101] Optionally, N-type ion implantation can be performed directly on the side of the second N-type epitaxial layer 302 facing away from the substrate 304 to form a first N-type ion doped region 201 or to form a first N-type ion doped region 201 and a second N-type ion doped region 402, wherein the first N-type ion doped region 201 penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301, and the first N-type ion doped region 201 serves as the end stop region 200, and the second N-type ion doped region 402 separates the P-type buried layer 303, forming a region located between the end stop region 200 and the main junction 100. N-type ion implantation may also be performed with the assistance of the first auxiliary trench or the first auxiliary trench and the second auxiliary trench to form a first N-type ion doped region 201 or to form a first N-type ion doped region 201 and a second N-type ion doped region 402, wherein the first N-type ion doped region 201 wraps the first auxiliary trench, penetrates the second N-type epitaxial layer 302 and the P-type buried layer 303 and is embedded in the first N-type epitaxial layer 301. After the field oxide layer 202 is filled in the first auxiliary trench, the field oxide layer 202 and the first N-type ion doped region 201 together constitute the terminal stop region 200.

[0102] For example, see Figure 13 In (d), N-type ion implantation may be performed with the assistance of the first auxiliary trench and the second auxiliary trench formed by etching, thereby forming the first N-type ion doping region 201 and the second N-type ion doping region 402 .

[0103] Optionally, after forming the second N-type ion doped region 402, a masking layer 3074 that wraps the corner of the gate trench can be formed at the bottom of the gate trench by P-type ion implantation; and then an N-type current channel 312 is formed in the P-type buried layer 303 corresponding to the gate trench position in the first direction by N-type ion implantation, as shown in FIG. Figure 13 (e); then, a field oxide layer is deposited inside the trench existing in the terminal structure region, which may specifically include a field oxide layer 102 filled in the main junction auxiliary trench, a field oxide layer 202 filled in the first auxiliary trench, and a field oxide layer 401 filled in the second auxiliary trench or the separation trench; then, a dielectric layer 3111 covering the sidewalls of the source trench and a dielectric layer 3071 covering the sidewalls of the gate trench are grown; then, polysilicon is filled in the source trench and the gate trench to form a source polysilicon 3112 and a gate polysilicon 3072; then, an interlayer dielectric layer 3073 covering the top of the gate polysilicon 3072 and an interlayer dielectric layer 403 covering the top of the field oxide layer are formed, as shown in FIG. Figure 13 (f); Finally, a source electrode 308 covering the surface of the trench gate electrode 307, the N-type source region 310 and the P-type source region 311 is formed in the active region, and a drain electrode 306 is formed on the surface of the substrate 304, such as Figure 13 Middle (g).

[0104] Alternatively, neither the second N-type ion doping region 402 nor the separation trench may be formed, but one or more P-type ion implantations may be performed between the end stop regions 200 of the main junction 100 to form a P-type ion doping region 402. Figure 6 、 Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 as well as Figure 11 The terminal structure shown in any one of the items.

[0105] In the embodiments of the present application, on the one hand, the P-type buried layer is cut off by the end cutoff region, thereby preventing leakage current from leaking along the P-type buried layer to the dicing path and causing device failure; on the other hand, the main junction is embedded in the first N-type epitaxial layer, and has a deeper ion doping region, which can better reduce the electric field crowding in the active area and improve the breakdown characteristics of the device; on the other hand, it is highly compatible with the active area based on the sandwich epitaxial structure. The P-type buried layer in the sandwich epitaxial structure between the main junction and the end cutoff region can serve as a JTE structure, which can improve the electric field distribution and enhance the breakdown voltage, thermal stability, and robustness of the device. Therefore, the embodiments of the present application provide a highly reliable terminal structure for a wide bandgap semiconductor device with a sandwich epitaxial structure.

[0106] It should be noted that the various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments. For related parts, refer to the partial description of the method embodiment. The terminal structure and method embodiments described above are merely illustrative. Some or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment. Those of ordinary skill in the art can understand and implement them without inventive effort.

[0107] The above is merely one specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A wide bandgap semiconductor device terminal structure, characterized in that: Matching the active region based on the sandwich epitaxial structure, the terminal structure includes: a main junction embedded in the sandwich epitaxial structure and an end cut-off region; The sandwich epitaxial structure comprises a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction; in the sandwich epitaxial structure, the first N-type epitaxial layer is located on a side close to the substrate, and the second N-type epitaxial layer is located on a side away from the substrate; The active region, the main junction, and the end cut-off region are arranged in sequence along a second direction; the main junction contacts the active region, and the end cut-off region is spaced a preset distance from the main junction; the second direction is perpendicular to the first direction; The main junction includes a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; The end stop region includes a first N-type ion doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; There is also a second P-type ion doping region between the main junction and the end cut-off region; the second P-type ion doping region is located in the second N-type epitaxial layer between the end cut-off region and the main junction, and is in contact with the first P-type ion doping region and the first N-type ion doping region; the second P-type ion doping region has multiple regions with different ion doping concentrations.

2. The terminal structure according to claim 1, characterized in that: The end cut-off region also includes a first auxiliary trench penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer, and a field oxide layer filled in the first auxiliary trench; the first auxiliary trench has a level greater than or equal to 1 and is used to assist ion doping to form the first N-type ion doped region.

3. The terminal structure according to claim 1, characterized in that: A field limiting ring region is further provided between the end cut-off region and the main junction; The field limiting ring region includes a plurality of separation trenches penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer, and a field oxide layer filled in the separation trenches.

4. The terminal structure according to claim 1, characterized in that: A field limiting ring region is further provided between the end cut-off region and the main junction; The field limiting ring region includes a plurality of second N-type ion doped regions penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer.

5. The terminal structure according to claim 4, characterized in that: The field limiting ring region further includes: a plurality of second auxiliary trenches embedded in the sandwich epitaxial structure, and a field oxide layer filled in the plurality of second auxiliary trenches; the second auxiliary trenches are used to assist ion doping to form the second N-type ion doped region.

6. A wide bandgap semiconductor device terminal structure, characterized in that: Matching the active region based on the sandwich epitaxial structure, the terminal structure includes: a main junction embedded in the sandwich epitaxial structure and an end cut-off region; The sandwich epitaxial structure comprises a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction; in the sandwich epitaxial structure, the first N-type epitaxial layer is located on a side close to the substrate, and the second N-type epitaxial layer is located on a side away from the substrate; The active region, the main junction, and the end cut-off region are arranged in sequence along a second direction; the main junction contacts the active region, and the end cut-off region is spaced a preset distance from the main junction; the second direction is perpendicular to the first direction; The main junction includes a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; The end stop region includes a first N-type ion doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; There is also a second P-type ion-doped region between the main junction and the end cut-off region; the second P-type ion-doped region is located in the second N-type epitaxial layer between the end cut-off region and the main junction, and includes multiple ion-doped layers with different ion doping concentrations; the ion-doped layers are in contact with the main junction and the length in the second direction decreases layer by layer along the first direction to form an upper stepped structure; the bottom of the upper stepped structure is in contact with the P-type buried layer.

7. The terminal structure according to claim 6, characterized in that: The terminal structure further includes a plurality of third P-type ion-doped regions, which are spaced apart and distributed along the second direction and penetrate the second N-type epitaxial layer.

8. A wide bandgap semiconductor device terminal structure, characterized in that: Matching the active region based on the sandwich epitaxial structure, the terminal structure includes: a main junction embedded in the sandwich epitaxial structure and an end cut-off region; The sandwich epitaxial structure comprises a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction; in the sandwich epitaxial structure, the first N-type epitaxial layer is located on a side close to the substrate, and the second N-type epitaxial layer is located on a side away from the substrate; The active region, the main junction, and the end cut-off region are arranged in sequence along a second direction; the main junction contacts the active region, and the end cut-off region is spaced a preset distance from the main junction; the second direction is perpendicular to the first direction; The main junction includes a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; The end stop region includes a first N-type ion doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer; A second P-type ion-doped region is further provided between the main junction and the end cut-off region; the second P-type ion-doped region is located in the first N-type epitaxial layer between the end cut-off region and the main junction, and includes a plurality of ion-doped layers with different ion doping concentrations; the ion-doped layers are in contact with the main junction, and their lengths in the second direction gradually increase along the first direction, forming a lower stepped structure; the top of the lower stepped structure is in contact with the P-type buried layer; The terminal structure further includes a plurality of third P-type ion-doped regions, which are spaced apart and distributed along the second direction and penetrate the second N-type epitaxial layer.

9. A method for manufacturing a terminal structure of a wide bandgap semiconductor device, characterized in that: The terminal structure is matched to an active region based on a sandwich epitaxial structure, and the method includes: A substrate having a sandwich epitaxial structure is provided; the substrate comprises a substrate, a first N-type epitaxial layer, a P-type buried layer, and a second N-type epitaxial layer stacked in sequence along a first direction, wherein the second N-type epitaxial layer comprises at least a P-type well region of an active area; forming a first P-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer by ion implantation to form a main junction; the first P-type ion-doped region contacts the P-type well region; forming a first N-type ion-doped region penetrating the second N-type epitaxial layer and the P-type buried layer and embedded in the first N-type epitaxial layer by ion implantation, thereby forming an end cutoff region; the end cutoff region is spaced a preset distance from the main junction; A second P-type ion-doped region is formed between the main junction and the end cut-off region by ion implantation; the second P-type ion-doped region is located in the second N-type epitaxial layer between the end cut-off region and the main junction, and is in contact with the first P-type ion-doped region and the first N-type ion-doped region; the second P-type ion-doped region has a plurality of regions with different ion doping concentrations.

Images