A low-loss sapphire-based gallium nitride power device
By setting up micro-trench arrays, optimizing epitaxial layer structure and electrode design in sapphire-based GaN power devices, the problems of heat dissipation and uneven current distribution were solved, realizing low-loss and high-reliability GaN power devices.
Patent Information
- Application Number
- CN202521104885.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2026-11-06
- Estimated Expiration
- 2035-05-30
AI Technical Summary
Existing sapphire-based GaN power devices suffer from problems such as insufficient heat dissipation of the substrate, high contact resistance between the electrodes and the semiconductor layer, and uneven current distribution leading to localized overheating, resulting in high losses and poor reliability.
By setting a micro-trench array on the back of a sapphire substrate and filling it with highly thermally conductive materials such as diamond or graphene, the structure of the GaN epitaxial layer is optimized, including a GaN buffer layer, an unintentionally doped GaN layer, and an AlGaN barrier layer. A periodically distributed p-type GaN columnar array is embedded in the unintentionally doped GaN layer, and the electrodes adopt a Ti/Al/Ni/Au multilayer metal stacked structure.
It significantly improves thermal conductivity and mechanical stability, optimizes current transmission path, reduces resistance loss, enhances the thermal stability and reliability of the device, extends service life, and improves performance under high frequency and high voltage.
Smart Images
Figure CN224948033U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor device technology, and in particular to a low-loss sapphire-based gallium nitride power device. Background Technology
[0002] Sapphire-based gallium nitride (GaN) power devices are a type of GaN power device, and their main characteristics and advantages are as follows: Sapphire-based GaN power devices use sapphire as the substrate material. Sapphire substrates offer numerous advantages, such as: the widespread availability of 8-inch substrates, which helps reduce production costs; low substrate cost, with 8-inch sapphire substrates being relatively inexpensive, facilitating the widespread application of GaN power devices; low requirements for epitaxial equipment, and high mechanical strength and insulation properties, making them suitable for high-voltage applications above 650V; overcoming heat dissipation challenges, and being thinner to 50μm, which is beneficial for achieving high-power output; high voltage resistance, substrate insulation, absence of parasitic channels, and ultra-thin epitaxy, giving them significant advantages in high-voltage applications.
[0003] Traditional silicon-based power devices suffer from problems such as high conduction loss and slow switching speed under high frequency and high voltage. Sapphire substrates are used for GaN epitaxial growth due to their good insulation and low cost. However, existing sapphire-based GaN devices still have the following problems: insufficient heat dissipation capacity of the substrate leads to heat loss, high contact resistance between the electrode and the semiconductor layer, and uneven current distribution causes local overheating. Therefore, a low-loss sapphire-based gallium nitride power device is needed. Utility Model Content
[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a low-loss sapphire-based GaN power device by optimizing the electrode structure, heat dissipation path, and material combination.
[0005] To achieve the above objectives, this utility model is implemented through the following technical solution: a low-loss sapphire-based gallium nitride power device, comprising a sapphire substrate, a GaN epitaxial layer and electrodes, wherein a micro-trench array is provided on the back side of the sapphire substrate.
[0006] Furthermore, the microgrooves are filled with a high thermal conductivity material, which is diamond or graphene.
[0007] Furthermore, the GaN epitaxial layer comprises a GaN buffer layer, an unintentionally doped GaN layer, and an AlGaN barrier layer grown sequentially from bottom to top.
[0008] Furthermore, a periodically distributed array of p-type GaN pillars is embedded in the unintentionally doped GaN layer.
[0009] Furthermore, the diameter of the p-type GaN columnar array is 1-5 μm, and the spacing is 10-20 μm.
[0010] Furthermore, the electrode includes a source and a drain, which are Ti / Al / Ni / Au multilayer metal stacks.
[0011] Furthermore, the sapphire substrate has a thickness of 200-500 μm, the microtrench depth is 50-100 μm, and the spacing of the microtrench array is ≤10 μm.
[0012] The beneficial effects of this utility model are: 1. This utility model can significantly improve the heat conduction efficiency and enhance the heat dissipation performance of the device by setting a micro-groove array on the back of the sapphire substrate, effectively preventing performance degradation or damage caused by high temperature. The micro-groove array can also increase the bonding force between the substrate and the packaging material, improve the mechanical stability and reliability of the device. The GaN epitaxial layer has excellent electrical properties and high breakdown voltage, which makes the device perform well in high-frequency and high-power applications.
[0013] 2. This utility model significantly improves the thermal conductivity of the structure by filling the micro-grooves with a high thermal conductivity material, such as diamond or graphene. As high thermal conductivity materials, diamond and graphene can quickly conduct heat away from the heat source, effectively dissipating heat and avoiding performance degradation or damage caused by high temperature, thereby improving the stability and durability of the overall structure. This design also helps to optimize thermal management and improve the operating efficiency and reliability of the equipment.
[0014] 3. This invention significantly improves the performance of GaN devices by growing a GaN buffer layer, an unintentionally doped GaN layer, and an AlGaN barrier layer sequentially from bottom to top. The GaN buffer layer, as the bottom layer, effectively reduces lattice mismatch and stress accumulation during epitaxial growth, providing a stable substrate for the high-quality growth of the upper layers. The unintentionally doped GaN layer has a low defect density and excellent electrical properties. As an electron transport channel, it ensures the stability and reliability of the device under high-speed and high-power operating conditions. The AlGaN barrier layer, due to the band difference between itself and the unintentionally doped GaN layer, forms an effective electron barrier, thereby restricting the movement of electrons in the vertical direction and increasing the concentration and mobility of electrons in the two-dimensional plane. This not only enhances the current driving capability of the device but also optimizes key parameters such as the threshold voltage and transconductance of the device.
[0015] 4. This invention significantly improves the performance of GaN-based electronic devices by embedding a periodically distributed p-type GaN columnar array within an unintentionally doped GaN layer. The periodically distributed p-type GaN columnar array serves as an effective channel for charge carriers, optimizing the carrier transport path, reducing resistance, and thus improving the device's conductivity. This structure also helps improve the device's thermal stability. The p-type GaN columnar array forms a good thermal interface with the surrounding unintentionally doped GaN layer, effectively improving heat dissipation efficiency and reducing the risk of performance degradation due to overheating during operation. This structure also improves the device's reliability. The periodic distribution of the p-type GaN columnar array reduces the generation of crystal defects such as defects and dislocations, lowering the degradation rate of the device under long-term operation and extending its lifespan.
[0016] 5. By setting a p-type GaN columnar array with a diameter of 1-5μm and a spacing of 10-20μm, this utility model can significantly improve the photoelectric conversion efficiency of the device, while optimizing the current transmission path and reducing resistance loss. This structure also helps to improve the thermal stability and mechanical strength of the device, extend its service life, and facilitate integration and packaging with other electronic components.
[0017] 6. This invention utilizes a Ti / Al / Ni / Au multilayer metal stacked structure for the source and drain electrodes. This multilayer metal stacked structure exhibits excellent conductivity and stability. The Ti layer, acting as an adhesion layer, enhances the adhesion between the metal and semiconductors or other materials. The Al layer, as the primary conductive layer, possesses low resistivity. The Ni layer, acting as a barrier layer, effectively prevents the Au layer from diffusing to other layers while improving the structure's heat resistance. The Au layer, as a surface layer, exhibits excellent oxidation resistance and chemical stability, protecting the internal structure from external environmental influences. This multilayer metal stacked structure not only improves the conductivity and stability of the electrodes but also extends their lifespan, enhancing the overall reliability and performance of the device.
[0018] 7. By setting the sapphire substrate thickness to 200-500μm, the microtrench depth to 50-100μm, and the spacing of the microtrench array to ≤10μm, this invention can significantly improve the thermal conductivity and mechanical strength of the device. The choice of sapphire substrate thickness ensures the stability and durability of the device, while the depth and spacing design of the microtrench effectively increases the heat dissipation area and improves the heat dissipation efficiency. At the same time, it optimizes the light extraction effect, which is conducive to improving the overall performance of the device. Attached Figure Description
[0019] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1This is a schematic diagram of the structure of this utility model; Figure 2 This is a diagram of the layered structure of a GaN epitaxial layer. Figure 3 This is a three-dimensional view of the bottom of a sapphire substrate.
[0020] In the figure: 1. Sapphire substrate; 2. GaN epitaxial layer; 21. GaN buffer layer; 22. Unintentionally doped GaN layer; 23. AlGaN barrier layer; 3. Electrode. Detailed Implementation
[0021] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.
[0022] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of this utility model.
[0023] A low-loss sapphire-based gallium nitride power device includes a sapphire substrate 1, a GaN epitaxial layer 2, and an electrode 3. The back side of the sapphire substrate 1 is provided with a micro-trench array.
[0024] Please see Figure 2 and Figure 3 , Figure 2 This is a diagram of the layered structure of a GaN epitaxial layer. Figure 3 This is a three-dimensional view of the bottom of a sapphire substrate.
[0025] The microgrooves are filled with high thermal conductivity materials, such as diamond or graphene, which can significantly improve the thermal conductivity of the structure. As high thermal conductivity materials, diamond and graphene can quickly conduct heat away from the heat source, effectively dissipate heat, and avoid performance degradation or damage caused by high temperature, thereby improving the stability and durability of the overall structure. This design also helps to optimize thermal management and improve the operating efficiency and reliability of the equipment.
[0026] The GaN epitaxial layer 2 comprises a GaN buffer layer 21, an unintentionally doped GaN layer 22, and an AlGaN barrier layer 23 grown sequentially from bottom to top. This structure can significantly improve the performance of GaN devices. The GaN buffer layer 21, as the bottom layer, can effectively reduce lattice mismatch and stress accumulation during epitaxial growth, providing a stable substrate for the high-quality growth of the upper layers. The unintentionally doped GaN layer 22 has a low defect density and excellent electrical properties. As an electron transport channel, it can ensure the stability and reliability of the device under high-speed and high-power operating conditions. The AlGaN barrier layer 23, due to the band difference between itself and the unintentionally doped GaN layer, can form an effective electron barrier, thereby restricting the movement of electrons in the vertical direction and increasing the concentration and mobility of electrons in the two-dimensional plane. This not only enhances the current driving capability of the device but also optimizes key parameters such as the threshold voltage and transconductance of the device.
[0027] Embedding a periodically distributed array of p-type GaN pillars within an unintentionally doped GaN layer 22 can significantly improve the performance of GaN-based electronic devices. The periodically distributed p-type GaN pillars serve as effective channels for charge carriers, optimizing their transport paths, reducing resistance, and thus improving the device's conductivity. This structure also helps improve the device's thermal stability; the p-type GaN pillars form a good thermal interface with the surrounding unintentionally doped GaN layer 22, effectively improving heat dissipation efficiency and reducing the risk of performance degradation due to overheating during operation. Furthermore, this structure is beneficial for improving device reliability; the periodic distribution of the p-type GaN pillars reduces the generation of crystal defects such as defects and dislocations, lowering the degradation rate of the device under long-term operation and extending its lifespan.
[0028] The p-type GaN columnar array has a diameter of 1-5 μm and a spacing of 10-20 μm, which can significantly improve the photoelectric conversion efficiency of the device, while optimizing the current transmission path and reducing resistance loss. This structure also helps to improve the thermal stability and mechanical strength of the device, extend its service life, and facilitate integration and packaging with other electronic components.
[0029] Electrode 3 includes a source and a drain, which are Ti / Al / Ni / Au multilayer metal stacks. The multilayer metal stack structure has good conductivity and stability. The Ti layer acts as an adhesion layer, which can enhance the adhesion between the metal and the semiconductor or other materials. The Al layer acts as the main conductive layer, which has low resistivity. The Ni layer acts as a barrier layer, which can effectively prevent the Au layer from diffusing to other layers and improve the heat resistance of the structure. The Au layer acts as a surface layer, which has good oxidation resistance and chemical stability, and can protect the internal structure from the influence of the external environment. This multilayer metal stack structure can not only improve the conductivity and stability of electrode 3, but also extend the service life of electrode 3 and improve the reliability and performance of the entire device.
[0030] The sapphire substrate 1 has a thickness of 200-500μm, a microtrench depth of 50-100μm, and a microtrench array spacing of ≤10μm, which can significantly improve the thermal conductivity and mechanical strength of the device. The thickness of the sapphire substrate 1 ensures the stability and durability of the device, while the depth and spacing design of the microtrench effectively increases the heat dissipation area and improves the heat dissipation efficiency. At the same time, it optimizes the light extraction effect, which is conducive to improving the overall performance of the device.
[0031] Working Principle: This invention achieves efficient thermal management and optimized electron transport through a carefully designed structure. During operation, heat is primarily conducted through the micro-trench array on the back side of the sapphire substrate 1. These micro-trenches are filled with highly thermally conductive materials, such as diamond or graphene, which can rapidly conduct heat away from the heat source, effectively preventing performance degradation or damage caused by high temperatures. This design significantly improves the stability and durability of the overall structure, optimizes thermal management, and enhances the operating efficiency and reliability of the equipment. In terms of electron transport, the GaN epitaxial layer 2 plays a crucial role. It consists of a GaN buffer layer 21, an unintentionally doped GaN layer 22, and an AlGaN barrier layer 23 grown sequentially from bottom to top. The GaN buffer layer 21 reduces lattice mismatch and stress accumulation during epitaxial growth, providing a stable substrate for the high-quality growth of the unintentionally doped GaN layer 22. The unintentionally doped GaN layer 22, as an electron transport channel, has low defects. The high density and excellent electrical performance ensure the stability and reliability of the device under high-speed and high-power operation. The AlGaN barrier layer 23 forms an effective electronic barrier, restricting the movement of electrons in the vertical direction, increasing the concentration and mobility of electrons in the two-dimensional plane, thereby enhancing the current driving capability of the device and optimizing key parameters such as the threshold voltage and transconductance. The periodically distributed p-type GaN columnar array embedded in the unintentionally doped GaN layer 22 further optimizes the carrier transport path, reduces resistance, and improves the conductivity and thermal stability of the device. This structure also helps to improve the reliability of the device and extend its service life. The electrode 3 adopts a Ti / Al / Ni / Au multilayer metal stack structure, which has good conductivity and stability. This multilayer metal stack structure not only improves the conductivity and stability of electrode 3, but also extends the service life of electrode 3, further improving the reliability and performance of the entire device. The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A low-loss sapphire-based gallium nitride power device, characterized in that: It includes a sapphire substrate (1), a GaN epitaxial layer (2) and an electrode (3), wherein the back side of the sapphire substrate (1) is provided with a micro-trench array; The GaN epitaxial layer (2) includes a GaN buffer layer (21), an unintentionally doped GaN layer (22), and an AlGaN barrier layer (23) grown sequentially from bottom to top. The unintentionally doped GaN layer (22) contains a periodically distributed p-type GaN columnar array.
2. The low-loss sapphire-based gallium nitride power device according to claim 1, characterized in that: The microgrooves are filled with a high thermal conductivity material, which is diamond or graphene.
3. The low-loss sapphire-based gallium nitride power device according to claim 1, characterized in that: The diameter of the p-type GaN columnar array is 1-5 μm, and the spacing is 10-20 μm.
4. The low-loss sapphire-based gallium nitride power device according to claim 1, characterized in that: The electrode (3) includes a source and a drain, which are Ti / Al / Ni / Au multilayer metal stacks.
5. A low-loss sapphire-based gallium nitride power device according to claim 1, characterized in that: The sapphire substrate (1) has a thickness of 200-500 μm, the micro trench has a depth of 50-100 μm, and the spacing of the micro trench array is ≤10 μm.