Semiconductor device
By employing a silicon carbide substrate and a lattice-matched transition semiconductor layer in vertical GaN power devices, the problems of limited device size and high cost have been solved, enabling mass production and improving performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN SANAN SEMICON CO LTD
- Filing Date
- 2024-12-30
- Publication Date
- 2026-07-10
AI Technical Summary
Vertical GaN power devices are limited in size and expensive due to the use of GaN single-crystal substrates, making mass production difficult.
Using a silicon carbide substrate and a silicon carbide drift layer as the base, a material with a lattice constant between silicon carbide and gallium nitride is selected as a transition semiconductor layer to match the lattice of the epitaxial stack, reduce crystal defects in the gallium nitride layer, and achieve mass production by taking advantage of the silicon carbide substrate.
Mass production of vertical GaN power devices has been achieved, improving device performance and fully utilizing the high thermal conductivity of silicon carbide materials.
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Figure CN122373397A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor and electronic device technology, and in particular to a semiconductor device. Background Technology
[0002] Semiconductor devices include GaN power devices fabricated on gallium nitride (GaN) single-crystal substrates and SiC power devices fabricated on silicon carbide (SiC) single-crystal substrates. Based on device structure, power devices can be categorized into lateral power devices and vertical power devices. Lateral GaN power devices are suitable for high-frequency and medium-power applications; vertical GaN power devices can be used in high-frequency modules, offering advantages such as high voltage withstand capability and small device area. However, vertical GaN power devices typically use GaN single-crystal substrates, and the current mainstream size of GaN single-crystal substrates is 2-4 inches, which is expensive, negatively impacting the mass production and commercialization of vertical GaN power devices. Therefore, how to make semiconductor devices, such as vertical GaN power devices, suitable for mass production remains a technical problem to be solved. Summary of the Invention
[0003] In view of this, embodiments of the present invention provide a semiconductor device that facilitates the mass production of semiconductor devices such as vertical GaN power devices.
[0004] On one hand, an embodiment of the present invention provides a semiconductor device, for example including: a silicon carbide substrate, a silicon carbide drift layer, a transition semiconductor layer, and an epitaxial stack; wherein, the silicon carbide drift layer is disposed on the silicon carbide substrate; the transition semiconductor layer is disposed on the side of the silicon carbide drift layer opposite to the silicon carbide substrate, the lattice constant of the material of the transition semiconductor layer is greater than or equal to the lattice constant of silicon carbide and less than or equal to the lattice constant of gallium nitride; the epitaxial stack is disposed on the side of the transition semiconductor layer opposite to the silicon carbide drift layer, the epitaxial stack includes a gallium nitride buffer layer and a heterostructure having a two-dimensional electron gas, the heterostructure includes a gallium nitride channel layer and a barrier layer, and the gallium nitride buffer layer is located between the transition semiconductor layer and the heterostructure.
[0005] The above embodiments of the present invention can have the following beneficial effects: by using a silicon carbide substrate and a silicon carbide drift layer suitable for mass production as the substrate, and selecting a suitable material, that is, a material with a lattice constant greater than or equal to the lattice constant of silicon carbide and less than or equal to the lattice constant of gallium nitride, the transition semiconductor layer located between the silicon carbide drift layer and the epitaxial stack can be fabricated to achieve lattice matching and reduce the crystal defects of the gallium nitride layer of the epitaxial stack during device fabrication. This enables the realization of semiconductor devices based on silicon carbide substrates, such as GaN power devices. Since the size of silicon carbide substrates can reach 6-8 inches or even larger, the use of silicon carbide substrates and silicon carbide drift layers is beneficial to the mass production of semiconductor devices, such as vertical GaN power devices, and allows semiconductor devices to fully utilize the advantages of silicon carbide material, such as high thermal conductivity, to improve device performance. Attached Figure Description
[0006] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0007] Figure 1 This is a schematic cross-sectional view of a semiconductor device provided in an embodiment of the present invention.
[0008] Figures 2A to 2B These are schematic diagrams of two different embodiments of the transition semiconductor layer provided in this invention.
[0009] Figures 3A to 3C These are schematic diagrams of three different embodiments of the transition semiconductor layer provided in this invention.
[0010] Figures 4A to 4C Schematic diagrams of three other different embodiments of the transition semiconductor layer provided in this invention.
[0011] Figures 5A to 5C These are schematic diagrams of three different embodiments of the transition semiconductor layer provided in this invention.
[0012] Figures 6A to 6C The following are schematic diagrams of three other different embodiments of the transition semiconductor layer provided in this invention.
[0013] Figures 7A to 7C The diagram shows three more different embodiments of the transition semiconductor layer provided in this invention.
[0014] Figures 8A to 8C These are schematic diagrams of three other different embodiments of the transition semiconductor layer provided in this invention.
[0015] Figures 9A to 9C These are schematic diagrams of three other different embodiments of the transition semiconductor layer provided in this invention.
[0016] [Explanation of Key Figure Markings]
[0017] 100, Semiconductor device; 11, Silicon carbide substrate; 13, Silicon carbide drift layer; 20, Transition semiconductor layer; 30, Epitaxial stack; 31, Gallium nitride buffer layer; 33, Heterogeneous structure; 331, Gallium nitride channel layer; 333, Barrier layer; CA, Current aperture; CBL, Current blocking layer; 2DEG, Two-dimensional electron gas; 50, Source; 70, Gate structure; 71, P-type gallium nitride cap layer; 73, Gate; 90, Drain; A1, First direction. Detailed Implementation
[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0019] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0021] It should also be noted that the division of multiple embodiments in this invention is only for the convenience of description and should not constitute a special limitation. Features in various embodiments can be combined and referenced in each other without contradiction.
[0022] See Figure 1An embodiment of the present invention provides a semiconductor device 100, which includes, for example, a silicon carbide substrate 11, a silicon carbide drift layer 13, a transition semiconductor layer 20, and an epitaxial stack 30; wherein, the silicon carbide drift layer 13 is disposed on the silicon carbide substrate 11; the transition semiconductor layer 20 is disposed on the side of the silicon carbide drift layer 13 away from the silicon carbide substrate 11, and the lattice constant of the material of the transition semiconductor layer 20 is greater than or equal to the lattice constant of silicon carbide and less than or equal to the lattice constant of gallium nitride; the epitaxial stack 30 is disposed on the side of the transition semiconductor layer 20 away from the silicon carbide drift layer 13, and the epitaxial stack 30 includes a gallium nitride buffer layer 31 and a heterostructure 33 having a two-dimensional electron gas 2DEG, the heterostructure 33 includes a gallium nitride channel layer 331 and a barrier layer 333, and the gallium nitride buffer layer 31 is located between the transition semiconductor layer 20 and the heterostructure 33.
[0023] This invention employs a silicon carbide substrate 11 and a silicon carbide drift layer 13 suitable for mass production as a substrate, and selects a suitable material, namely a material with a lattice constant greater than or equal to the lattice constant of silicon carbide and less than or equal to the lattice constant of gallium nitride, to fabricate the transition semiconductor layer 20 located between the silicon carbide drift layer 13 and the epitaxial stack 30. This achieves lattice matching and reduces crystal defects in the gallium nitride layer of the epitaxial stack 30 during device fabrication. As a result, semiconductor devices based on silicon carbide substrates, such as GaN power devices, can be realized. Since the size of the silicon carbide substrate can reach 6-8 inches or even larger, the use of silicon carbide substrates and silicon carbide drift layers is beneficial to the mass production of semiconductor devices, such as vertical GaN power devices, and allows the semiconductor devices to fully utilize the advantages of silicon carbide material, such as high thermal conductivity, to improve device performance.
[0024] In some embodiments, the semiconductor device 100 is a vertical device, such as a vertical GaN power device. For example, a source 50 and a gate structure 70 are disposed on the side of the epitaxial stack 30 facing away from the transition semiconductor layer 20, and a drain 90 is disposed on the side of the silicon carbide substrate 11 facing away from the transition semiconductor layer 20. As an enhancement-mode device, the gate structure 70 includes, for example, a P-type gallium nitride (P-GaN) cap layer 71 and a gate 73 located on the side of the P-type gallium nitride cap layer 71 facing away from the epitaxial stack 30. Furthermore, the epitaxial stack 30 also includes, for example, a current aperture CA and a current blocking layer CBL. The current blocking layer CBL is disposed co-layered with the current aperture CA between the gallium nitride channel layer 331 and the gallium nitride buffer layer 31, and the current blocking layer CBL is located on opposite sides of the current aperture CA. It is worth mentioning that, in other embodiments, the semiconductor device 100 may also be a lateral GaN power device, and a high-resistivity gallium nitride layer, such as an iron-doped or carbon-doped gallium nitride layer, may be provided on the side of the epitaxial stack 30 near the transition semiconductor layer 20.
[0025] For example, the silicon carbide substrate 11 has a crystal form of 4H SiC or 6H SiC, and the doping concentration of the silicon carbide substrate 11 is, for example, 1E19-5E20 / cm³. 3 The doping concentration range of the silicon carbide drift layer 13 is, for example, 1E14-5E16 / cm³. 3 That is, the doping concentration of the silicon carbide drift layer 13 is lower than that of the silicon carbide substrate 11. The lower concentration of the silicon carbide drift layer 13 compared to the silicon carbide substrate 11 is mainly to optimize device performance, improve the conversion efficiency from base plane dislocation (BPD) to threading edge dislocation (TED), and reduce structural defects and stacking faults (SFs). The current blocking layer CBL is, for example, a p-type gallium nitride layer, which can be formed by ion implantation or etching processes. Thus, the current aperture CA can be formed during the epitaxial growth of the gallium nitride buffer layer 31 or during the epitaxial growth of the gallium nitride channel layer 331. The barrier layer 333 can be an AlGaN layer, an InGaN layer, an AlGaInN layer, an AlN layer, or an InAlN layer. It is worth mentioning that the heterostructure 33 in this embodiment is not limited to... Figure 1 The two-layer structure shown can also be applied to other suitable epitaxial stacks that include gallium nitride channel layers and barrier layers in the prior art and are suitable for constructing two-dimensional electron gases to provide conductive channels.
[0026] In some embodiments, the bandgap of the material of the transition semiconductor layer 20 is less than or equal to 4.0 eV and greater than 3.4 eV. Specifically, the bandgaps of 4H-SiC and 6H-SiC are about 3.2 eV, and the bandgap of gallium nitride is about 3.47 eV. Therefore, a material with a bandgap less than or equal to 4.0 eV and greater than 3.4 eV is selected, so that the bandgap of the material of the transition semiconductor layer 20 is close to the bandgaps of gallium nitride and SiC, and the conductivity is similar, which is beneficial to achieving better vertical conduction performance of the device.
[0027] In some embodiments, referring to Figure 2A and Figure 2B , the transition semiconductor layer 20 includes a gallium boron nitride layer, and the material of the gallium boron nitride layer is B a Ga 1-a N, where B is boron, Ga is gallium, N is nitrogen, a is the molar fraction and 0 < a ≤ 0.17. For Figure 2A example, the material of the gallium boron nitride layer is, for example, B 0.17 Ga 0.83 N (corresponding to a = 0.17), and its a-axis lattice constant is 3.073 angstroms which is between the a-axis lattice constant of silicon carbide and the a-axis lattice constant of gallium nitride, and its bandgap is about 3.5 eV. Since 0 < a ≤ 0.17, it enables the a-axis lattice constant of the gallium boron nitride layer to remain between the a-axis lattice constant of silicon carbide and the a-axis lattice constant of gallium nitride, so as to achieve a gradual change in the lattice constant from the silicon carbide drift layer 13 to the gallium nitride layer in the epitaxial stack 30 and improve the crystal quality of the gallium nitride layer.
[0028] In some embodiments, referring to Figure 2B , the gallium boron nitride layer includes multiple gallium boron nitride sub-layers B a Ga 1-a N, and in the first direction A1 from the silicon carbide drift layer 13 to the gallium nitride buffer layer 31, the a value of the multiple gallium boron nitride sub-layers B a Ga 1-a N gradually decreases. Since the a value gradually decreases, the molar fraction of boron (B) in the gallium boron nitride sub-layer B a Ga 1-a N gradually decreases, and the molar fraction of gallium (Ga) gradually increases, which can achieve a smoother lattice matching between the silicon carbide drift layer 13 and the gallium nitride buffer layer 31.
[0029] In some embodiments, the lattice constant of the material of the transition semiconductor layer 20 is greater than or equal to 3.07 angstroms and less than or equal to 3.189 angstroms. Specifically, the a-axis lattice constant of 4H-SiC is The a-axis lattice constant of 6H-SiC is The a-axis lattice constant of gallium nitride is Therefore, a lattice constant between 3.07 Å and 3.189 Å is chosen to achieve better lattice matching.
[0030] In some embodiments, see Figure 3A , Figure 4A , Figure 5A , Figure 6A , Figure 7A , Figure 8A and Figure 9A The transition semiconductor layer 20 includes multiple nitride semiconductor layers, each made of a different material, and each nitride semiconductor layer contains at least one of boron (B), aluminum (Al), gallium (Ga), and indium (In). Along the first direction A1, the lattice constant (e.g., the a-axis lattice constant) of the materials of the multiple nitride semiconductor layers gradually increases. In this way, through the gradient design of the lattice constants of the multiple nitride semiconductor layers, a gradient in the lattice constant can be achieved from the silicon carbide drift layer 13 to the gallium nitride layer in the epitaxial stack 30, which helps to reduce lattice defects and improve the crystal quality of the gallium nitride layer.
[0031] As stated above, Figure 3A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially includes B 0.05 Al 0.95 Two nitride semiconductor layers, N and AlN, B 0.05 Al 0.95 The lattice constant of N along the a-axis is approximately The a-axis lattice constant of AlN is
[0032] like Figure 4A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially comprises AlN and Al 0.83 In 0.17 Two nitride semiconductor layers, AlN, have an a-axis lattice constant of... Al 0.83 In 0.17 The lattice constant of N along the a-axis is
[0033] like Figure 5A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially comprises two nitride semiconductor layers, AlN and AlGaN, with the a-axis lattice constant of AlN being... The a-axis lattice constant of AlGaN is between In addition, to achieve a band gap of less than 4.0 eV for AlGaN, the molar percentage of Al in AlGaN can be designed to be less than 0.3; the band gap of AlN is 6.28 eV.
[0034] like Figure 6A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially includes B 0.05 Al 0.95 N, AlN and Al 0.83 In 0.17 N consists of three nitride semiconductor layers, B 0.05 Al 0.95 The lattice constant of N along the a-axis is approximately The a-axis lattice constant of AlN is Al 0.83 In 0.17 The lattice constant of N along the a-axis is
[0035] like Figure 7A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially includes B 0.05 Al 0.95 Three nitride semiconductor layers: N, AlN, and AlGaN; B 0.05 Al 0.95 The lattice constant of N along the a-axis is approximately The a-axis lattice constant of AlN is The a-axis lattice constant of AlGaN is between between.
[0036] like Figure 8A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially includes B 0.05 Al 0.95 N, AlN and B 0.1 Ga 0.9 N consists of three nitride semiconductor layers, B 0.05 Al 0.95 The lattice constant of N along the a-axis is approximately The a-axis lattice constant of AlN is B 0.1 Ga 0.9 The lattice constant of N along the a-axis is approximately
[0037] like Figure 9A As shown, in the first direction A1, the transition semiconductor layer 20 sequentially includes B 0.13 Ga 0.87 Three nitride semiconductor layers: N, AlN, and AlGaN; B 0.13 Ga 0.87 The a-axis lattice constant of N is approximately 3.09 eV, and the a-axis lattice constant of AlN is... The a-axis lattice constant of AlGaN is between them.
[0038] In some embodiments, referring to Figure 3B and Figure 3C and Figure 9B and Figure 9C , the transition semiconductor layer 20 includes a first ternary nitride semiconductor layer and an aluminum nitride layer. The material of the first ternary nitride semiconductor layer is B b X 1-b N, where B is boron, X is aluminum or gallium, N is nitrogen, b is the molar fraction and 0 < b < 1; the first ternary nitride semiconductor layer includes a plurality of first ternary nitride semiconductor sub-layers, and the plurality of first ternary nitride semiconductor sub-layers are all located on the side of the aluminum nitride layer facing the silicon carbide drift layer 13 or are alternately arranged with the aluminum nitride layer in the first direction A1; and, in the first direction A1, the b value of the plurality of first ternary nitride semiconductor sub-layers gradually decreases to achieve a smoother lattice match between the silicon carbide drift layer 13 and the gallium nitride buffer layer 31. It should be noted that the number of the plurality of first ternary nitride semiconductor sub-layers can be two, three or more, and the thickness of a single first ternary nitride semiconductor sub-layer can be dozens of nm or hundreds of nm.
[0039] Specifically, as Figure 3B shown, the transition semiconductor layer 20 includes three B b Al 1-b N sub-layers and an AlN layer, and the three B b Al 1-b N sub-layers are located on the side of the AlN layer facing the silicon carbide drift layer 13; in the first direction A1, the b value of the three B b Al 1-b N sub-layers gradually decreases; further, b ≤ 0.05. Since b ≤ 0.05, it enables the a-axis lattice constant of the B b Al 1-b N sub-layer to remain between the a-axis lattice constant of silicon carbide and the a-axis lattice constant of gallium nitride, so as to achieve a gradual change in the lattice constant from the silicon carbide drift layer 13 to the gallium nitride layer in the epitaxial stack 30 and improve the crystal quality of the gallium nitride layer.
[0040] As Figure 3C shown, the transition semiconductor layer 20 includes three B b Al 1-b N sub-layers and three AlN layers, and in the first direction A1, three B b Al 1-bThe N sublayer and three AlN layers are arranged alternately; in the first direction A1, the three B... b Al 1-b The b value of the N sublayer gradually decreases; furthermore, b ≤ 0.05.
[0041] like Figure 9B As shown, the transition semiconductor layer 20 includes three B... b Ga 1-b The N sublayer and AlN layer also include three Al c Ga 1-c N sublayer, the three B b Ga 1-b The N sublayer is located on the side of the AlN layer facing the silicon carbide drift layer 13; in the first direction A1, the three B... b Ga 1-b The b-value of the N sublayer gradually decreases. Furthermore, the three Al... c Ga 1-c The N sublayer is located on the side of the AlN layer facing the gallium nitride buffer layer 31, and in the first direction A1, the three Al... c Ga 1-c The c value of the N sublayer gradually decreases.
[0042] like Figure 9C As shown, the transition semiconductor layer 20 includes three B... b Ga 1-b The N sublayer and five AlN layers, including three Al layers. c Ga 1-c N sublayer; in the first direction A1, the three B b Ga 1-b The N sublayer and the three AlN layers are arranged alternately, and the three B... b Al 1-b The b-value of the N sublayer gradually decreases. Furthermore, in the first direction A1, the three Al... c Ga 1-c The N sublayer and the three AlN layers are arranged alternately, and the three Al... c Ga 1-c The c value of the N sublayer gradually decreases.
[0043] In some embodiments, see Figure 4B , Figure 4C , Figure 5B , Figure 5C , Figure 6B , Figure 6C , Figure 7B , Figure 7C , Figure 8B and Figure 8C, the transition semiconductor layer 20 includes an aluminum nitride layer and a second ternary nitride semiconductor layer, and the material of the second ternary nitride semiconductor layer is A c Y 1-c N, where A is aluminum or boron, Y is indium or gallium, N is nitrogen, c is the molar fraction and 0 < c < 1; the second ternary nitride semiconductor layer includes a plurality of second ternary nitride semiconductor sub-layers, and the plurality of second ternary nitride semiconductor sub-layers are all located on one side of the aluminum nitride layer facing the gallium nitride buffer layer, or are alternately arranged with the aluminum nitride layer in the first direction A1 from the silicon carbide drift layer 13 to the gallium nitride buffer layer 31; and, in the first direction A1, the c value of the plurality of second ternary nitride semiconductor sub-layers gradually decreases to achieve a smoother lattice match between the silicon carbide drift layer 13 and the gallium nitride buffer layer 31. It should be noted that the number of the plurality of second ternary nitride semiconductor sub-layers can be two, three or more, and the thickness of a single second ternary nitride semiconductor sub-layer can be dozens of nm or hundreds of nm.
[0044] Specifically, as Figure 4B shown, the transition semiconductor layer 20 includes an AlN layer and three Al c In 1-c N sub-layers, and the three Al c In 1-c N sub-layers are located on one side of the AlN layer facing the gallium nitride buffer layer 31; in the first direction A1, the c value of the three Al c In 1-c N sub-layers gradually decreases; further, 0.83 ≤ c < 1. Since 0.83 ≤ c < 1, it enables the a-axis lattice constant of the Al c In 1-c N sub-layer to remain between the a-axis lattice constant of silicon carbide and the a-axis lattice constant of gallium nitride, so as to achieve a gradual change in the lattice constant from the silicon carbide drift layer 13 to the gallium nitride layer in the epitaxial stack 30 and improve the crystal quality of the gallium nitride layer.
[0045] As Figure 4C shown, the transition semiconductor layer 20 includes three AlN layers and three Al c In 1-c N sub-layers; in the first direction A1, the three Al c In 1-c N sub-layers are alternately arranged with the three AlN layers, and the c value of the three Al c In 1-c N sub-layers gradually decreases; further, 0.83 ≤ c < 1.
[0046] As Figure 5BAs shown, the transition semiconductor layer 20 includes an AlN layer and three Al... c Ga 1-c N sublayer, and the three Al c Ga 1-c The N sublayer is located on the side of the AlN layer facing the gallium nitride buffer layer 31; in the first direction A1, the three Al... c Ga 1-c The c value of the N sublayer gradually decreases.
[0047] like Figure 5C As shown, the transition semiconductor layer 20 includes three AlN layers and three Al... c Ga 1-c N sublayer; in the first direction A1, the three Al c Ga 1-c The N sublayer is alternated with the three AlN layers, and the three Al... c In 1-c The c value of the N sublayer gradually decreases.
[0048] like Figure 6B As shown, the transition semiconductor layer 20 includes an AlN layer and three Al... c In 1-c The N sublayer also includes three B layers. b Al 1-b N sublayer; the three Al c In 1-c The N sublayer is located on the side of the AlN layer facing the gallium nitride buffer layer 31, and the three B... b Al 1-b The N sublayer is located on the side of the AlN layer facing the silicon carbide drift layer 13; in the first direction A1, the three Al... c In 1-c The c value of the N sublayer gradually decreases, and the three B... b Al 1-b The b value of the N sublayer gradually decreases.
[0049] like Figure 6C As shown, the transition semiconductor layer 20 includes five AlN layers and three Al... c In 1-c The N sublayer also includes three B layers. b Al 1-b N sublayer; in the first direction A1, the three Al c In 1-c The N sublayer is alternated with three AlN layers, the three B... b Al 1-b The N sublayer is alternately arranged with three AlN layers; in the first direction A1, the three Al... c In1-c The c value of the N sublayer gradually decreases, and the three B... b Al 1-b The b value of the N sublayer gradually decreases.
[0050] like Figure 7B As shown, the transition semiconductor layer 20 includes an AlN layer and three Al... c Ga 1-c The N sublayer also includes three B layers. b Al 1-b N sublayer; the three Al c Ga 1-c The N sublayer is located on the side of the AlN layer facing the gallium nitride buffer layer 31, and the three B... b Al 1-b The N sublayer is located on the side of the AlN layer facing the silicon carbide drift layer 13; in the first direction A1, the three Al... c Ga 1-c The c value of the N sublayer gradually decreases, and the three B... b Al 1-b The b value of the N sublayer gradually decreases.
[0051] like Figure 7C As shown, the transition semiconductor layer 20 includes five AlN layers and three Al... c Ga 1-c The N sublayer also includes three B layers. b Al 1-b N sublayer; in the first direction A1, the three Al c Ga 1-c The N sublayer is alternated with three AlN layers, the three B... b Al 1-b N is arranged alternately with three AlN layers; in the first direction A1, the three Al... c Ga 1-c The c value of the N sublayer gradually decreases, and the three B... b Al 1-b The b value of the N sublayer gradually decreases.
[0052] like Figure 8B As shown, the transition semiconductor layer 20 includes an AlN layer and three B layers. c Ga 1-c The N sublayer also includes three B layers. b Al 1-b N; the three Bs c Ga 1-c The N sublayer is located on the side of the AlN layer facing the gallium nitride buffer layer 31, and the three B... b Al 1-bThe N sublayer is located on the side of the AlN layer facing the silicon carbide drift layer 13; in the first direction A1, the three B... c Ga 1-c The c value of the N sublayer gradually decreases, and the three B... b Al 1-b The b value of the N sublayer gradually decreases.
[0053] like Figure 8C As shown, the transition semiconductor layer 20 includes five AlN layers and three B layers. c Ga 1-c The N sublayer also includes three B layers. b Al 1-b N; in the first direction A1, the three Bs c Ga 1-c The N sublayer is alternated with three AlN layers, the three B... b Al 1- b N is alternately arranged with three AlN layers; in the first direction A1, the three B layers are... c Ga 1-c The c value of the N sublayer gradually decreases, and the three B... b Al 1-b The b value of the N sublayer gradually decreases.
[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A semiconductor device, characterized in that, include: silicon carbide substrate; A silicon carbide drift layer is disposed on the silicon carbide substrate; A transition semiconductor layer is disposed on the side of the silicon carbide drift layer away from the silicon carbide substrate, wherein the lattice constant of the material of the transition semiconductor layer is greater than or equal to the lattice constant of silicon carbide and less than or equal to the lattice constant of gallium nitride. as well as An epitaxial stack is disposed on the side of the transition semiconductor layer away from the silicon carbide drift layer. The epitaxial stack includes a gallium nitride buffer layer and a heterostructure with a two-dimensional electron gas. The heterostructure includes a gallium nitride channel layer and a barrier layer. The gallium nitride buffer layer is located between the transition semiconductor layer and the heterostructure.
2. The semiconductor device according to claim 1, characterized in that, The bandgap of the material of the transition semiconductor layer is less than or equal to 4.0 eV and greater than 3.4 eV.
3. The semiconductor device according to claim 2, characterized in that, The transition semiconductor layer includes a boron gallium nitride layer, and the material of the boron gallium nitride layer is B. a Ga 1-a N, where B is boron, Ga is gallium, N is nitrogen, and a is the molar number and 0 <a≤0.17。 4. The semiconductor device according to claim 3, characterized in that, The boron gallium nitride layer includes a plurality of boron gallium nitride sublayers, and the a value of the plurality of boron gallium nitride sublayers gradually decreases in a first direction from the silicon carbide drift layer to the gallium nitride buffer layer.
5. The semiconductor device according to claim 1, characterized in that, The lattice constant of the material of the transition semiconductor layer is greater than or equal to 3.07 angstroms and less than or equal to 3.189 angstroms.
6. The semiconductor device according to claim 5, characterized in that, The transition semiconductor layer includes a plurality of nitride semiconductor layers, the plurality of nitride semiconductor layers being made of different materials, and each of the nitride semiconductor layers being made of at least one of boron, aluminum, gallium, and indium; in a first direction from the silicon carbide drift layer to the gallium nitride buffer layer, the lattice constant of the materials of the plurality of nitride semiconductor layers gradually increases.
7. The semiconductor device according to claim 5, characterized in that, The transition semiconductor layer includes a first ternary nitride semiconductor layer and an aluminum nitride layer. The material of the first ternary nitride semiconductor layer is B b X 1-b N, where B is boron, X is aluminum or gallium, N is nitrogen, b is the mole fraction and 0 < b < 1; the first ternary nitride semiconductor layer includes a plurality of first ternary nitride semiconductor sub-layers, and the plurality of first ternary nitride semiconductor sub-layers are all located on the side of the aluminum nitride layer facing the silicon carbide drift layer, or are alternately arranged with the aluminum nitride layer in a first direction from the silicon carbide drift layer to the gallium nitride buffer layer; and, in the first direction, the b value of the plurality of first ternary nitride semiconductor sub-layers gradually decreases.
8. The semiconductor device according to claim 7, characterized in that, X is aluminum, and b≤0.
05.
9. The semiconductor device according to claim 5, characterized in that, The transition semiconductor layer includes an aluminum nitride layer and a second ternary nitride semiconductor layer, and the material of the second ternary nitride semiconductor layer is A c Y 1-c N, where A is aluminum or boron, Y is indium or gallium, N is nitrogen, c is the molar fraction and 0 < c < 1; the second ternary nitride semiconductor layer includes a plurality of second ternary nitride semiconductor sub-layers, and the plurality of second ternary nitride semiconductor sub-layers are all located on the side of the aluminum nitride layer facing the gallium nitride buffer layer, or are alternately arranged with the aluminum nitride layer in a first direction from the silicon carbide drift layer to the gallium nitride buffer layer; and, in the first direction, the c values of the plurality of second ternary nitride semiconductor sub-layers gradually decrease.
10. The semiconductor device according to claim 9, characterized in that, A represents aluminum, Y represents indium, and 0.83 ≤ c < 1.
11. The semiconductor device according to any one of claims 1 to 10, characterized in that, The silicon carbide substrate is a 4H silicon carbide or 6H silicon carbide substrate, and the doping concentration of the silicon carbide drift layer is lower than the doping concentration of the silicon carbide substrate; and / or The epitaxial stack also includes a current aperture and a current blocking layer. The current blocking layer is disposed in the same layer as the current aperture between the gallium nitride channel layer and the gallium nitride buffer layer, and the current blocking layer is located on opposite sides of the current aperture.