Silicon carbide device and forming method thereof
By forming a protective doping region and a body doping region in the silicon carbide epitaxial layer to cover the bottom and corners of the trench gate structure, the problem of unstable reliability in silicon carbide power devices is solved and the electric field shielding effect is improved.
Patent Information
- Application Number
- CN202510789116.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-09-19
AI Technical Summary
The reliability of the bottom corners of the trench gate structure in silicon carbide power devices is unstable, especially under high current and high electric field.
A protective doping region and a body doping region are formed in the silicon carbide epitaxial layer to cover the bottom and corners of the trench gate structure. A buried doping region and a protective doping region are formed through an ion implantation process to improve the electric field shielding effect.
The reliability of the bottom corner of the trench gate structure in the silicon carbide power device is improved, and the influence of the electric field on the structure is reduced.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a silicon carbide device and a method for forming the same. Background Art
[0002] The insulating gate of the semiconductor power device is set as a vertical trench gate device, which has the advantages of small cell pitch, high channel density, and high current density. It is gradually replacing planar structure devices and is widely used.
[0003] In existing trench-structured devices, the insulating film beneath the gate serves to isolate the gate from the trench and also stores charge when a gate voltage is applied. However, the gate oxide layer at the bottom of the trench is prone to reliability issues, especially when silicon carbide is used as the semiconductor material. High currents and high electric fields increase the electric field strength applied to the insulating layer, leading to unstable reliability at the bottom corners. Further improvements are needed to shield the high electric field at the bottom corners and improve gate reliability.
[0004] Therefore, it is necessary to provide a more effective and reliable technical solution to improve the reliability of the bottom corner position of the trench gate structure in silicon carbide power devices. Summary of the Invention
[0005] The present application provides a silicon carbide device and a method for forming the same, which can improve the reliability of the bottom corner position of the trench gate structure in the silicon carbide power device.
[0006] One aspect of the present application provides a method for forming a silicon carbide device, comprising: providing a silicon carbide substrate, a silicon carbide epitaxial layer formed on the surface of the silicon carbide substrate, a plurality of buried doped regions formed in the silicon carbide epitaxial layer, the top surface of the buried doped region being lower than the top surface of the silicon carbide epitaxial layer; forming protective doped regions connected to the buried doped regions on both sides of the buried doped regions, the doping type of the protective doped regions being opposite to the doping type of the silicon carbide epitaxial layer; forming a body doped region in the silicon carbide epitaxial layer that is higher than the top surface of the protective doped region by an ion implantation process; and forming a plurality of trench gate structures in the silicon carbide epitaxial layer, the trench gate structures being located at positions where the two sides of the buried doped region are connected to the protective doped regions, and the bottoms of the trench gate structures being respectively covered by the buried doped regions and the protective doped regions.
[0007] In some embodiments of the present application, the doping concentration of the protective doping region is greater than the doping concentration of the silicon carbide epitaxial layer.
[0008] In some embodiments of the present application, the doping concentration of the protective doping region is 5E16 to 5E20 cm -3 .
[0009] In some embodiments of the present application, the bottom of the trench gate structure is higher than the bottom of the protective doping region.
[0010] In some embodiments of the present application, the width of the protection doping region is smaller than the width of the buried doping region.
[0011] Another aspect of the present application also provides a silicon carbide device, comprising: a silicon carbide substrate, a silicon carbide epitaxial layer formed on the surface of the silicon carbide substrate, a plurality of buried doped regions formed in the silicon carbide epitaxial layer, the top surface of the buried doped region being lower than the top surface of the silicon carbide epitaxial layer; protective doped regions located on both sides of the buried doped region and connected to the buried doped region, the doping type of the protective doped region being opposite to the doping type of the silicon carbide epitaxial layer; a body doped region located in the silicon carbide epitaxial layer above the top surface of the protective doped region; and a plurality of trench gate structures located in the silicon carbide epitaxial layer, the trench gate structures located at positions where both sides of the buried doped region are connected to the protective doped region, and the bottoms of the trench gate structures are respectively covered by the buried doped region and the protective doped region.
[0012] In some embodiments of the present application, the doping concentration of the protective doping region is greater than the doping concentration of the silicon carbide epitaxial layer.
[0013] In some embodiments of the present application, the doping concentration of the protective doping region is 5E16 to 5E20 cm -3 .
[0014] In some embodiments of the present application, the bottom of the trench gate structure is higher than the bottom of the protective doping region.
[0015] In some embodiments of the present application, the width of the protection doping region is smaller than the width of the buried doping region.
[0016] The present application provides a silicon carbide device and a method for forming the same, which forms a protective doping region at the bottom corner of the trench gate structure, thereby improving the reliability of the bottom corner of the trench gate structure in the silicon carbide power device. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The following figures describe in detail exemplary embodiments disclosed in this application. Like reference numerals denote similar structures throughout the several views of the drawings. Those skilled in the art will appreciate that these embodiments are non-limiting, exemplary embodiments, and that the drawings are provided for illustration and description purposes only and are not intended to limit the scope of this application. Other embodiments may also achieve the inventive intent of this application. It should be understood that the drawings are not drawn to scale.
[0018] in:
[0019] Figures 1 to 6 This is a schematic structural diagram of each step in the method for forming a silicon carbide device described in an embodiment of the present application. DETAILED DESCRIPTION
[0020] The following description provides specific application scenarios and requirements of the present application, with the purpose of enabling those skilled in the art to make and use the content of this application. Various local modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but is intended to be of the widest scope consistent with the claims.
[0021] The technical solution of the present invention is described in detail below with reference to the embodiments and drawings.
[0022] Figures 1 to 6 The following is a structural diagram of each step in the method for forming a silicon carbide device according to an embodiment of the present application. The method for forming a silicon carbide device according to an embodiment of the present application is described in detail with reference to the accompanying drawings.
[0023] refer to Figure 1 As shown, a silicon carbide substrate 100 is provided, a silicon carbide epitaxial layer 110 is formed on the surface of the silicon carbide substrate 100 , a plurality of buried doped regions 120 are formed in the silicon carbide epitaxial layer 110 , and a top surface of the buried doped region 120 is lower than a top surface of the silicon carbide epitaxial layer 110 .
[0024] The semiconductor structure described in the embodiment of the present application is a silicon carbide power device MOSFET. The material of the silicon carbide substrate 100 is silicon carbide material, and the material of the silicon carbide epitaxial layer 110 is also silicon carbide material. In some embodiments of the present application, the silicon carbide substrate 100 and the silicon carbide epitaxial layer 110 may have doping ions, such as N-type doping ions. The buried doping region 120 may be formed by an ion implantation process in the silicon carbide epitaxial layer 110. The doping type of the buried doping region 120 is opposite to that of the silicon carbide epitaxial layer 110, for example, P-type. The doping concentration of the buried doping region 120 is higher than the doping concentration of the silicon carbide epitaxial layer 110. The number of the buried doping regions 120 can be arbitrary, and the present application only shows two here as a demonstration.
[0025] refer to Figure 2As shown, protective doped regions 130 are formed on both sides of each buried doped region 120 to connect to the buried doped region 120. The doping type of the protective doped region 130 is opposite to the doping type of the silicon carbide epitaxial layer 110, for example, P-type. The top surface of the protective doped region 130 is lower than the top surface of the buried doped region 120, and the bottom surface of the protective doped region 130 is not lower than the bottom surface of the buried doped region 120.
[0026] In some embodiments of the present application, the doping concentration of the protective doping region 130 is greater than the doping concentration of the silicon carbide epitaxial layer 110 .
[0027] In some embodiments of the present application, the doping concentration of the protective doping region 130 is 5E16 to 5E20 cm -3 .
[0028] In some embodiments of the present application, the width of the protection doping region 130 is smaller than the width of the buried doping region 120 .
[0029] refer to Figure 3 As shown, an ion implantation process is used to form a body doped region 140 connected to the buried doped region 120 in the silicon carbide epitaxial layer 110 above the top surface of the protective doped region 130. The body doped region 140 has the same doping type as the buried doped region 120, for example, P-type. The body doped region 140 is higher than the buried doped region 120 and is not connected to the buried doped region 120.
[0030] refer to Figure 4 As shown, a source region 150 is formed in the body doping region 140 between adjacent buried doping regions 120. The doping type of the source region 150 is, for example, N-type. The method of forming the source region 150 includes an ion implantation process.
[0031] refer to Figure 5 As shown, a contact region 160 is formed in the source region 150 and extends through the source region 150 into the body doped region 140 . The doping type of the contact region 160 is, for example, P-type. The contact region 160 is used to form an ohmic contact with the source region 150 .
[0032] refer to Figure 6 As shown, a plurality of trench gate structures 170 are formed in the silicon carbide epitaxial layer 110. The trench gate structures 170 are located at positions where the buried doped region 120 and the protective doped region 130 are connected on both sides of the buried doped region 120. The bottoms of the trench gate structures 170 are respectively covered by the buried doped region 120 and the protective doped region 130. The trench gate structure includes a gate dielectric layer located at the bottom and sidewalls of the trench and a gate layer filling the trench.
[0033] In some embodiments of the present application, the bottom of the trench gate structure 170 is higher than the bottom of the buried doped region 120 .
[0034] In the technical solution of the present application, the bottom and corners of the trench gate structure 170 are respectively covered by the buried doping region 120 and the protective doping region 130, so that the bottom and corners of the trench gate structure 170 are less affected by the electric field of the silicon carbide epitaxial layer 110, thereby improving the reliability of the bottom corner position of the trench gate structure in the silicon carbide power device.
[0035] The embodiment of the present application also provides a silicon carbide device, referring to Figure 6 As shown, it includes: a silicon carbide substrate 100, a silicon carbide epitaxial layer 110 is formed on the surface of the silicon carbide substrate 100, and a plurality of buried doped regions 120 are formed in the silicon carbide epitaxial layer 110, and the top surface of the buried doped region 120 is lower than the top surface of the silicon carbide epitaxial layer 110; a protective doped region 130, which is located on both sides of the buried doped region 120 and connected to the buried doped region 120, and the doping type of the protective doped region 130 is the same as that of the silicon carbide epitaxial layer 110 has an opposite doping type; a body doping region 140 is located in the silicon carbide epitaxial layer 110 above the top surface of the protective doping region 130; a plurality of trench gate structures 170 are located in the silicon carbide epitaxial layer 110, and the trench gate structures 170 are located at positions where the two sides of the buried doping region 120 are connected to the protective doping region 130, and the bottoms of the trench gate structures 170 are respectively covered by the buried doping region 120 and the protective doping region 130.
[0036] The semiconductor structure described in the embodiment of the present application is a silicon carbide power device MOSFET. The material of the silicon carbide substrate 100 is silicon carbide material, and the material of the silicon carbide epitaxial layer 110 is also silicon carbide material. In some embodiments of the present application, the silicon carbide substrate 100 and the silicon carbide epitaxial layer 110 may have doping ions, such as N-type doping ions. The buried doping region 120 may be formed by an ion implantation process in the silicon carbide epitaxial layer 110. The doping type of the buried doping region 120 is opposite to that of the silicon carbide epitaxial layer 110, for example, P-type. The doping concentration of the buried doping region 120 is higher than the doping concentration of the silicon carbide epitaxial layer 110. The number of the buried doping regions 120 can be arbitrary, and the present application only shows two here as a demonstration.
[0037] refer to Figure 6 As shown, in some embodiments of the present application, the top surface of the protective doping region 130 is lower than the top surface of the buried doping region 120 , and the bottom surface of the protective doping region 130 is not lower than the bottom surface of the buried doping region 120 .
[0038] In some embodiments of the present application, the doping concentration of the protective doping region 130 is greater than the doping concentration of the silicon carbide epitaxial layer 110 .
[0039] In some embodiments of the present application, the doping concentration of the protective doping region 130 is 5E16 to 5E20 cm -3 .
[0040] In some embodiments of the present application, the width of the protection doping region 130 is smaller than the width of the buried doping region 120 .
[0041] refer to Figure 6 As shown, in some embodiments of the present application, the doping type of the body doping region 140 is the same as that of the buried doping region 120 , for example, P-type. The body doping region 140 is higher than the buried doping region 120 and is not connected to the buried doping region 120 .
[0042] refer to Figure 6 As shown, an active region 150 is further formed in the body doping region 140 between adjacent buried doping regions 120. The doping type of the source region 150 is, for example, N-type. The method of forming the source region 150 includes an ion implantation process.
[0043] refer to Figure 6 As shown, a contact region 160 is formed in the source region 150 and extends through the source region 150 into the body doped region 140 . The doping type of the contact region 160 is, for example, P-type. The contact region 160 is used to form an ohmic contact with the source region 150 .
[0044] refer to Figure 6 As shown, a plurality of trench gate structures 170 are formed in the silicon carbide epitaxial layer 110. The trench gate structures 170 are located at positions where the buried doped region 120 and the protective doped region 130 are connected on both sides of the buried doped region 120. The bottoms of the trench gate structures 170 are respectively covered by the buried doped region 120 and the protective doped region 130. The trench gate structure includes a gate dielectric layer located at the bottom and sidewalls of the trench and a gate layer filling the trench.
[0045] In some embodiments of the present application, the bottom of the trench gate structure 170 is higher than the bottom of the buried doped region 120 .
[0046] In the technical solution of the present application, the bottom and corners of the trench gate structure 170 are respectively covered by the buried doping region 120 and the protective doping region 130, so that the bottom and corners of the trench gate structure 170 are less affected by the electric field of the silicon carbide epitaxial layer 110, thereby improving the reliability of the bottom corner position of the trench gate structure in the silicon carbide power device.
[0047] The present application provides a silicon carbide device and a method for forming the same, which forms a protective doping region at the bottom corner of the trench gate structure, thereby improving the reliability of the bottom corner of the trench gate structure in the silicon carbide power device.
[0048] In summary, after reading the contents of this application, those skilled in the art will understand that the foregoing contents are presented by way of example only and are not intended to be limiting. Although not expressly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are within the spirit and scope of the exemplary embodiments of this application.
[0049] It should be understood that the term "and / or" used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may also be present.
[0050] Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may be present. In contrast, the term "directly" indicates that there are no intervening elements. It should also be understood that the terms "comprising," "including," "include," or "comprising," when used in this specification, indicate the presence of recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.
[0051] It should also be understood that although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of the present application, the first element in some embodiments may be referred to as the second element in other embodiments. The same reference numerals or the same reference designators represent the same elements throughout the specification.
[0052] In addition, this specification describes exemplary embodiments by reference to idealized exemplary cross-sectional views and / or plan views and / or stereograms. Therefore, differences from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are foreseeable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but should include deviations in shapes due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have rounded or curved features. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the actual shape of the region of the device nor to limit the scope of the exemplary embodiments.
Claims
1. A method for forming a silicon carbide device, characterized in that: include: Providing a silicon carbide substrate, wherein a silicon carbide epitaxial layer is formed on a surface of the silicon carbide substrate, wherein a plurality of buried doped regions are formed in the silicon carbide epitaxial layer, and wherein a top surface of the buried doped region is lower than a top surface of the silicon carbide epitaxial layer; forming protective doping regions connected to the buried doping regions on both sides of the buried doping regions, wherein the doping type of the protective doping regions is opposite to the doping type of the silicon carbide epitaxial layer; forming a body doping region in the silicon carbide epitaxial layer above a top surface of the protective doping region by an ion implantation process; A plurality of trench gate structures are formed in the silicon carbide epitaxial layer. The trench gate structures are located at positions where both sides of the buried doping region are connected to the protective doping region. The bottoms of the trench gate structures are respectively covered by the buried doping region and the protective doping region.
2. The method for forming a silicon carbide device according to claim 1, wherein: The doping concentration of the protective doping region is greater than the doping concentration of the silicon carbide epitaxial layer.
3. The method for forming a silicon carbide device according to claim 1, wherein: The doping concentration of the protective doping region is 5E16 to 5E20 cm -3 .
4. The method for forming a silicon carbide device according to claim 1, wherein: The bottom of the trench gate structure is higher than the bottom of the protective doping region.
5. The method for forming a silicon carbide device according to claim 1, wherein: The width of the protection doping region is smaller than the width of the buried doping region.
6. A silicon carbide device, characterized in that: include: A silicon carbide substrate, wherein a silicon carbide epitaxial layer is formed on a surface of the silicon carbide substrate, wherein a plurality of buried doped regions are formed in the silicon carbide epitaxial layer, and a top surface of the buried doped regions is lower than a top surface of the silicon carbide epitaxial layer; a protective doping region, located on both sides of the buried doping region and connected to the buried doping region, wherein the doping type of the protective doping region is opposite to the doping type of the silicon carbide epitaxial layer; a body doping region, located in the silicon carbide epitaxial layer above a top surface of the protective doping region; A plurality of trench gate structures are located in the silicon carbide epitaxial layer, the trench gate structures are located at positions where both sides of the buried doping region are connected to the protective doping region, and the bottoms of the trench gate structures are respectively covered by the buried doping region and the protective doping region.
7. The silicon carbide device according to claim 6, wherein: The doping concentration of the protective doping region is greater than the doping concentration of the silicon carbide epitaxial layer.
8. The silicon carbide device according to claim 6, wherein: The doping concentration of the protective doping region is 5E16 to 5E20 cm -3 .
9. The silicon carbide device according to claim 6, wherein: The bottom of the trench gate structure is higher than the bottom of the protective doping region.
10. The silicon carbide device according to claim 6, wherein: The width of the protection doping region is smaller than the width of the buried doping region.