Novel defect control layer HEMT epitaxial structure and preparation method thereof
The introduction of a defect control layer with a multi-layer superlattice structure in GaN HEMT devices addresses the issue of high defect densities, enhancing the performance and reliability of these high-frequency electronic devices by reducing defects and improving structural integrity.
Patent Information
- Application Number
- CN202411838747.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-28
AI Technical Summary
The existing technologies for preparing HEMT (High Electron Mobility Transistor) devices, such as those based on gallium nitride (GaN) and silicon or diamond substrates, face challenges due to high defect densities during the epitaxial growth process, which negatively impact the performance of these high-frequency and high-speed electronic devices.
A new epitaxial structure for HEMT devices is proposed, incorporating a defect control layer with a multi-layer superlattice structure, comprising AlxGa1-xN/AlyGa1-yN sublayers, optimized to reduce defect density by adjusting the bandgap width and thickness, and grown using techniques like molecular beam epitaxy or metalorganic chemical vapor deposition, to enhance the structural integrity and reduce defects.
This approach effectively lowers defect density, thereby improving the reliability and high-frequency performance of GaN HEMT devices, making them suitable for high-speed electronic applications.
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Figure CN119730299A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a novel defect control layer HEMT epitaxial structure and a preparation method thereof. Background Art
[0002] Gallium nitride HEMT devices have been widely used in the field of high-frequency and high-speed electronic devices due to their high electron mobility, low power consumption and excellent high-frequency characteristics.
[0003] However, GaN homogeneous substrates are too expensive to be commercially available, and silicon-based and sapphire-based HEMT epitaxy is prone to defects during the preparation process, which can affect device performance.
[0004] In order to improve the performance of GaN HEMT devices, the defect density in the epitaxial layer needs to be reduced.
[0005] Therefore, a novel defect control layer HEMT epitaxial structure and a preparation method are proposed. Summary of the invention
[0006] The object of the present invention is to provide a novel defect control layer HEMT epitaxial structure and a preparation method thereof, so as to solve the problems raised in the above background technology.
[0007] To achieve the above-mentioned object, the present invention provides the following technical solution: a novel defect-controlled layer HEMT epitaxial structure, comprising a substrate layer, a gallium nitride buffer layer is provided on the substrate layer, a defect control layer is provided on the gallium nitride buffer layer, a high-resistance gallium nitride layer is provided on the defect control layer, a gallium nitride electron transport layer is provided on the high-resistance gallium nitride layer, a barrier layer is provided on the gallium nitride electron transport layer, and a Cap layer is provided on the barrier layer; the defect control layer is an inserted multi-layer superlattice structure, which is used to reduce the defect density in the gallium nitride layer.
[0008] Preferably: the multilayer superlattice structure of the defect control layer is divided into 3 to 10 sublayers, each sublayer is a superlattice structure, the bandgap width of the sublayer along the growth direction tends to be rhombus, first increasing and then decreasing, and the total thickness is 60 to 3000 nm.
[0009] Preferably: each sublayer structure of the defect control layer is AlxGa1-xN / AlyGa1-yN, with a period range of 5 to 10; x<y, 0≤x<100%, 0<y≤100%; AlxGa1-xN thickness>AlyGa1-yN; the thickness of a single heterojunction is 4 to 30 nm, and the thickness of a single sublayer is 20 to 300 nm.
[0010] A method for preparing a novel defect-controlled layer HEMT epitaxial structure according to any one of the above items comprises the following steps:
[0011] S1. Select a semiconductor substrate and grow a gallium nitride buffer layer on the semiconductor substrate;
[0012] S2, inserting a defect control layer on the gallium nitride buffer layer, and reducing the defect density in the gallium nitride layer by optimizing the structure of the defect control layer;
[0013] S3, growing a high-resistance gallium nitride layer on the defect-controlling layer;
[0014] S4, growing a gallium nitride electron transport layer on the high-resistance gallium nitride layer;
[0015] S5, growing a barrier layer on the gallium nitride electron transport layer;
[0016] S6. Growing a Cap layer on the barrier layer.
[0017] Preferably: in step S2, by optimizing the composition and proportion of different materials in each sublayer of the defect control layer, the band gap width is adjusted by periodic composition and thickness changes, the bottom threading dislocation is turned at the wide band gap of the heterojunction, and the design of different thicknesses brings about a buffer area.
[0018] Preferably: by first raising and then lowering the bandgap structure, when approaching the upper semiconductor gallium nitride layer, the defect density of the bottom layer decreases while reducing the bandgap of the sub-layer to reduce the introduction of new defects, and the defect state is engineered on the quantum scale to reduce the unfavorable defect state density.
[0019] Preferably: in step S2, the optimized layer structure includes a multi-quantum well structure, a superlattice structure or a strain balance structure.
[0020] Preferably, in step S2, the process of growing the optimized defect control layer includes molecular beam epitaxy, metal organic chemical vapor deposition or chemical vapor deposition.
[0021] Compared with the prior art, the beneficial effects of the present invention are: by setting an optimized defect control layer and introducing a multi-layer superlattice structure, the defect density of the device is effectively reduced, the voltage resistance and reliability of the device are improved, and it is suitable for the field of high-frequency and high-speed electronic devices and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a structural schematic diagram of the present invention;
[0023] Figure 2 A schematic diagram of the growth direction trend of each sub-layer of the present invention;
[0024] Figure 3 The present invention is a flow chart of the preparation method.
[0025] In the figure: 1. substrate layer; 2. gallium nitride buffer layer; 3. defect control layer; 4. high-resistance gallium nitride layer; 5. gallium nitride electron transport layer; 6. barrier layer; 7. cap layer. DETAILED DESCRIPTION
[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.
[0027] See also Figure 1-3 The present invention provides a technical solution: comprising a semiconductor substrate layer 1, a gallium nitride buffer layer 2 arranged on the semiconductor substrate layer 1, an insertion defect control layer 3 arranged on the gallium nitride buffer layer 2, the defect density in the gallium nitride layer is reduced by optimizing the structure of the defect control layer 3, a high-resistance gallium nitride layer 4 arranged on the defect control layer 3, a gallium nitride electron transport layer 5 arranged on the high-resistance gallium nitride layer 4, a barrier layer 6 arranged on the gallium nitride electron transport layer 5, and a Cap layer 7 arranged on the barrier layer,
[0028] The defect control layer 3 is an inserted multi-layer superlattice structure. The multi-layer superlattice structure is divided into 3-10 sub-layers, each sub-layer is a superlattice structure, and the bandgap width of the sub-layer from the growth direction tends to be rhombus, such as Figure 2 As shown in the figure, the trend of increasing first and then decreasing, compared with the traditional technology, the multilayer superlattice heterojunction technology can make the bottom extended screw dislocation turn to the horizontal direction; the diamond frame design can reasonably control the point defects introduced by the heterojunction mismatch while achieving enhanced blocking ability; the optimal bottom defect blocking ability is achieved at the highest point of the heterojunction bandwidth, and the point defects introduced by the mismatch are reduced while the heterojunction bandwidth changes slowly. The total thickness of the overall structure design is 60 to 3000nm.
[0029] The structure of each sublayer is AlxGa1-xN / AlyGa1-yN, and the period range is 5 to 10; x<y, 0≤x<100%, 0<y≤100%; the thickness of AlxGa1-xN>AlyGa1-yN; the thickness of a single heterojunction is 4 to 30nm, and the thickness of a single sublayer is 20 to 300nm.
[0030] Example 1
[0031] The defect control layer 3 is an inserted multi-layer superlattice structure. The multi-layer superlattice structure is divided into three sub-layers, each sub-layer is a superlattice structure, and the bandgap width of the sub-layer from the growth direction tends to be rhombus.
[0032] Compared with traditional technologies, multilayer superlattice heterojunction technology can transform the underlying extended screw dislocations into a horizontal direction; the diamond frame design can achieve enhanced blocking capability while reasonably controlling point defects introduced by heterojunction mismatch.
[0033] The optimal bottom layer defect blocking capability is achieved at the highest point of the heterojunction bandwidth, and the point defects introduced by the mismatch are reduced while the heterojunction bandwidth is slowly changing. The total thickness of the overall structure design is 60nm.
[0034] The structure of each sublayer is AlxGa1-xN / AlyGa1-yN, and the period range is 5; x<y, x=20%, y=30%; the thickness of AlxGa1-xN>AlyGa1-yN; the thickness of a single heterojunction is 4nm, and the thickness of a single sublayer is 20nm.
[0035] Example 2
[0036] The defect control layer 3 is an inserted multi-layer superlattice structure. The multi-layer superlattice structure is divided into 5 sub-layers, each of which is a superlattice structure, and the bandgap width of the sub-layer from the growth direction tends to be rhombus.
[0037] Compared with traditional technologies, multilayer superlattice heterojunction technology can transform the underlying extended screw dislocations into a horizontal direction; the diamond frame design can achieve enhanced blocking capability while reasonably controlling point defects introduced by heterojunction mismatch.
[0038] The optimal bottom layer defect blocking capability is achieved at the highest point of the heterojunction bandwidth, and the point defects introduced by the mismatch are reduced while the heterojunction bandwidth is slowly changing. The total thickness of the overall structure design is 500nm.
[0039] The structure of each sublayer is AlxGa1-xN / AlyGa1-yN, and the period range is 6; x<y, x=40%, y=50%; the thickness of AlxGa1-xN>AlyGa1-yN; the thickness of a single heterojunction is 8nm, and the thickness of a single sublayer is 80nm.
[0040] Example 3
[0041] The defect control layer 3 is an inserted multi-layer superlattice structure. The multi-layer superlattice structure is divided into 7 sub-layers, each of which is a superlattice structure, and the bandgap width of the sub-layer from the growth direction tends to be rhombus.
[0042] Compared with traditional technologies, multilayer superlattice heterojunction technology can transform the underlying extended screw dislocations into a horizontal direction; the diamond frame design can achieve enhanced blocking capability while reasonably controlling point defects introduced by heterojunction mismatch.
[0043] The optimal bottom layer defect blocking capability is achieved at the highest point of the heterojunction bandwidth, and the point defects introduced by the mismatch are reduced while the heterojunction bandwidth is slowly changing. The total thickness of the overall structure design is 900nm.
[0044] The structure of each sublayer is AlxGa1-xN / AlyGa1-yN, and the period range is 6; x<y, x=50%, y=65%; the thickness of AlxGa1-xN>AlyGa1-yN; the thickness of a single heterojunction is 12nm, and the thickness of a single sublayer is 150nm.
[0045] Example 4
[0046] The defect control layer 3 is an inserted multi-layer superlattice structure. The multi-layer superlattice structure is divided into 9 sub-layers, each of which is a superlattice structure, and the bandgap width of the sub-layer from the growth direction tends to be rhombus.
[0047] Compared with traditional technologies, multilayer superlattice heterojunction technology can transform the underlying extended screw dislocations into a horizontal direction; the diamond frame design can achieve enhanced blocking capability while reasonably controlling point defects introduced by heterojunction mismatch.
[0048] The optimal bottom layer defect blocking capability is achieved at the highest point of the heterojunction bandwidth, and the point defects introduced by the mismatch are reduced while the heterojunction bandwidth is slowly changing. The total thickness of the overall structure design is 1500nm.
[0049] The structure of each sublayer is AlxGa1-xN / AlyGa1-yN, and the period range is 6; x<y, x=70%, y=80%; the thickness of AlxGa1-xN>AlyGa1-yN; the thickness of a single heterojunction is 20nm, and the thickness of a single sublayer is 200nm.
[0050] Example 5
[0051] The defect control layer 3 is an inserted multi-layer superlattice structure. The multi-layer superlattice structure is divided into 10 sub-layers, each of which is a superlattice structure, and the bandgap width of the sub-layer from the growth direction tends to be rhombus.
[0052] Compared with traditional technologies, multilayer superlattice heterojunction technology can transform the underlying extended screw dislocations into a horizontal direction; the diamond frame design can achieve enhanced blocking capability while reasonably controlling point defects introduced by heterojunction mismatch.
[0053] The optimal bottom layer defect blocking capability is achieved at the highest point of the heterojunction bandwidth, and the point defects introduced by the mismatch are reduced while the heterojunction bandwidth is slowly changing. The total thickness of the overall structure design is 3000nm.
[0054] The structure of each sublayer is AlxGa1-xN / AlyGa1-yN, and the period range is 6; x<y, x=90%, y=100%; the thickness of AlxGa1-xN>AlyGa1-yN; the thickness of a single heterojunction is 30nm, and the thickness of a single sublayer is 300nm.
[0055]
[0056] Through the design of multi-layer superlattice structure in defect control layer 3, the composition and proportion of different materials in each sub-layer can adjust the band gap width through periodic composition and thickness changes. The bottom layer threading dislocation is turned at the wide band gap of the heterojunction, and the design of different thicknesses brings a buffer area.
[0057] The structure of first raising and then lowering the bandgap, when approaching the upper semiconductor gallium nitride layer, the defect density of the bottom layer decreases while reducing the bandgap of the sub-layer to reduce the introduction of new defects. The defect state is engineered at the quantum scale to reduce the density of unfavorable defect states.
[0058] Meanwhile, the optimized layer structure includes a multi-quantum well structure, a superlattice structure or a strain balance structure, and the process of growing the optimized defect control layer 3 includes molecular beam epitaxy and metal organic chemical vapor deposition.
[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A novel defect-controlled layer HEMT epitaxial structure, comprising a substrate layer (1), characterized in that: A gallium nitride buffer layer (2) is provided above the substrate layer (1), a defect control layer (3) is provided above the gallium nitride buffer layer (2), a high-resistance gallium nitride layer (4) is provided on the defect control layer (3), a gallium nitride electron transport layer (5) is provided on the high-resistance gallium nitride layer (4), a barrier layer (6) is provided on the gallium nitride electron transport layer (5), and a Cap layer (7) is provided on the barrier layer (6); The defect control layer (3) is an inserted multi-layer superlattice structure, and is used to reduce the defect density in the gallium nitride layer.
2. A novel defect-controlled layer HEMT epitaxial structure according to claim 1, characterized in that: The multilayer superlattice structure of the defect control layer (3) is divided into 3 to 10 sublayers, each sublayer is a superlattice structure, the bandgap width of the sublayer tends to be rhombus in the growth direction, first increases and then decreases, and the total thickness is 60 to 3000nm.
3. The novel defect-controlled layer HEMT epitaxial structure according to claim 2, characterized in that: Each sublayer structure of the defect control layer (3) is AlxGa1-xN / AlyGa1-yN, with a period range of 5 to 10; x<y, 0≤x<100%, 0<y≤100%; AlxGa1-xN thickness>AlyGa1-yN; a single heterojunction thickness is 4 to 30 nm, and a single sublayer thickness is 20 to 300 nm.
4. A method for preparing a novel defect-controlled layer HEMT epitaxial structure according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, selecting a semiconductor substrate, and growing a gallium nitride buffer layer (2) on the semiconductor substrate; S2, inserting a defect control layer (3) on the gallium nitride buffer layer (2), and reducing the defect density in the gallium nitride layer by optimizing the structure of the defect control layer (3); S3, growing a high-resistance gallium nitride layer (4) on the defect-controlling layer (3); S4, growing a gallium nitride electron transport layer (5) on the high-resistance gallium nitride layer (4); S5, growing a barrier layer (6) on the gallium nitride electron transport layer (5); S6. Growing a Cap layer (7) on the barrier layer (6).
5. The method for preparing a novel defect-controlled layer HEMT epitaxial structure according to claim 4, characterized in that: In step S2, by optimizing the composition and proportion of different materials in each sublayer of the defect control layer (3), the band gap width is adjusted by periodic composition and thickness changes, the bottom threading dislocation is turned at the wide band gap of the heterojunction, and the design of different thicknesses brings about a buffer area.
6. The method for preparing a novel defect-controlled layer HEMT epitaxial structure according to claim 5, characterized in that: By first raising and then lowering the bandgap structure, when approaching the upper semiconductor gallium nitride layer, the defect density in the bottom layer tends to decrease while reducing the bandgap of the sub-layer to reduce the introduction of new defects, the defect state is engineered at the quantum scale and the unfavorable defect state density is reduced.
7. The method for preparing a novel defect-controlled layer HEMT epitaxial structure according to claim 4, characterized in that: In step S2, the optimized layer structure includes a multi-quantum well structure, a superlattice structure or a strain balance structure.
8. The method for preparing a novel defect-controlled layer HEMT epitaxial structure according to claim 4, characterized in that: In the step S2, the process of growing the optimized defect control layer (3) includes molecular beam epitaxy, metal organic chemical vapor deposition or chemical vapor deposition.
Citation Information
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