Epitaxial method of silicon-based gallium nitride heterojunction material

Abstract

The invention provides an epitaxial method of a silicon-based gallium nitride heterojunction material, and relates to the technical field of semiconductors, and the method comprises the steps: carrying out the pretreatment of a Si substrate; growing an AIN nucleating layer on the pretreated Si substrate; growing an AlGaN buffer layer according to the content of an inverted stepped Al component; growing a semi-insulating GaN buffer layer with a preset distance on the AlGaN buffer layer; growing an AlGaN back barrier layer on the semi-insulating GaN buffer layer; the thickness of a GaN channel layer, the thickness of an AlGaN barrier layer and the expected Al component content in the AlGaN barrier layer are determined with the purpose that the electron mobility of 2DEG is maximized and the expected breakdown voltage is met; and sequentially growing a GaN channel layer and an AlGaN barrier layer in the heterojunction to obtain the silicon-based gallium nitride heterojunction. The electron mobility of the silicon-based gallium nitride heterojunction material is greatly improved, and the quality defect is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to an epitaxial method for silicon-based gallium nitride heterojunction materials. Background Art

[0002] Silicon-based gallium nitride heterojunction is a technology that grows gallium nitride (GaN) material on a silicon substrate. This heterojunction structure can combine the excellent properties of gallium nitride with the cost advantage of the silicon substrate to achieve ideal performance. Gallium nitride is a wide-bandgap semiconductor with excellent high-temperature, high-frequency, and high-power characteristics, while silicon-based materials are widely used in integrated circuit manufacturing and have a relatively low cost.

[0003] The research and application of silicon-based gallium nitride heterojunction are of great significance. Gallium nitride has excellent electronic properties and high-temperature resistance, which can effectively improve the performance in the fields of power electronics, LEDs, lasers, etc. Growing gallium nitride on a silicon substrate can significantly reduce production costs and improve the economic efficiency of devices. In addition, silicon-based gallium nitride heterojunction can achieve more efficient thermal management, promoting the development of next-generation high-performance electronic and optoelectronic devices, and has important application prospects.

[0004] However, in the design process of existing silicon-based gallium nitride heterojunction materials, although a buffer layer is used to address the leakage caused by lattice mismatch of the heterojunction, the thicknesses of the buffer layer and the heterojunction are usually set based on experience, which is easily affected by subjective factors. Unreasonable designs often lead to a large deviation between the electron mobility of the silicon-based gallium nitride heterojunction material and the expected electron mobility, affecting the production quality of the silicon-based gallium nitride heterojunction material. Summary of the Invention

[0005] In order to solve the technical problem that in the design process of existing silicon-based gallium nitride heterojunction materials, although a buffer layer is used to address the leakage caused by lattice mismatch of the heterojunction, the thicknesses of the buffer layer and the heterojunction are usually set based on experience, which is easily affected by subjective factors. Unreasonable designs often lead to a large deviation between the electron mobility of the silicon-based gallium nitride heterojunction material and the expected electron mobility, affecting the production quality of the silicon-based gallium nitride heterojunction material, the present invention provides an epitaxial method and system for silicon-based gallium nitride heterojunction materials.

[0006] The technical solutions provided by the embodiments of the present invention are as follows: An epitaxial method for a silicon-based gallium nitride heterojunction material provided by an embodiment of the present invention is applied to a silicon-based gallium nitride epitaxial structure. The silicon-based gallium nitride epitaxial structure includes an Si substrate, an AlN nucleation layer, an AlGaN buffer layer, a semi-insulating GaN buffer layer, an AlGaN back barrier layer, and a heterojunction formed by a GaN channel layer and an AlGaN barrier layer that are stacked in sequence. Among them, the GaN channel layer is in contact with the AlGaN back barrier layer, and 2DEG is formed in the GaN channel layer. The method includes: S1: Pretreat the Si substrate; S2: Grow an AIN nucleation layer on the pretreated Si substrate by MOCVD; S3: Grow an AlGaN buffer layer with an inverted stepped Al component content, where the Al component content in the AlGaN buffer layer is positively correlated with the distance from the AlN nucleation layer; S4: Grow a semi-insulating GaN buffer layer with a preset distance on the AlGaN buffer layer; S5: Grow an AlGaN back barrier layer on the semi-insulating GaN buffer layer; S6: Based on the principle of bandgap engineering, with the goal of maximizing the electron mobility of 2DEG and meeting the desired breakdown voltage, determine the thickness of the GaN channel layer, the thickness of the AlGaN barrier layer, and the desired Al component content in the AlGaN barrier layer; S7: According to the thickness of the GaN channel layer and the AlGaN barrier layer and the desired Al component content in the AlGaN barrier layer, grow the GaN channel layer and the AlGaN barrier layer in the heterojunction in sequence at the first temperature to obtain a silicon-based gallium nitride heterojunction.

[0007] The beneficial effects brought by the technical solution provided by the embodiment of the present invention at least include: In the embodiment of the present invention, by precisely controlling the growth process and component content of each layer, the problem of electron mobility deviation caused by experience limitation in traditional designs is overcome. The method reduces the leakage phenomenon caused by lattice mismatch in the heterojunction by gradually optimizing the lattice matching through the inverted stepped AlGaN buffer layer growth technology. By precisely regulating the thickness and Al component content of the GaN channel layer and the AlGaN barrier layer based on the principle of bandgap engineering, the electron mobility in 2DEG (two-dimensional electron gas) is maximized, and the desired breakdown voltage is ensured, greatly improving the performance and production quality of the silicon-based gallium nitride heterojunction material. The interference of subjective factors in traditional methods is avoided, making the silicon-based gallium nitride heterojunction material more stable and reliable in performance. Description of the Drawings

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0009] Figure 1 It is a schematic flow chart of an epitaxial method for a silicon-based gallium nitride heterojunction material provided by an embodiment of the present invention; Figure 2 It is a schematic structural diagram of a silicon-based gallium nitride heterojunction provided by an embodiment of the present invention. Detailed implementation manners

[0010] The following will describe the technical solutions in the present invention with reference to the accompanying drawings.

[0011] Referring to the attached Figure 1 illustrates a schematic flow chart of an epitaxial method for a silicon-based gallium nitride heterojunction material provided by an embodiment of the present invention.

[0012] Referring to the attached Figure 2 illustrates a schematic structural diagram of a silicon-based gallium nitride heterojunction provided by an embodiment of the present invention.

[0013] Figure 2 The silicon-based gallium nitride heterojunction structure is shown. The silicon-based gallium nitride epitaxial structure is composed of multiple layers stacked in sequence. The bottom layer is the Si substrate, which provides support. Above it is the AlN nucleation layer, which plays a good lattice matching role and reduces the influence of lattice mismatch. Then there are multiple buffer layers, including the AlGaN buffer layer, semi-insulating GaN buffer layer, and AlGaN back barrier layer, which optimize the crystal quality and electron performance. The GaN channel layer and the AlGaN barrier layer form the heterojunction, and a 2DEG (two-dimensional electron gas) is formed in the GaN channel layer. This layer is the key to maximizing the electron mobility and optimizes the electrical performance of the device. Improve the performance of the silicon-based gallium nitride heterojunction, reduce leakage current and increase electron mobility.

[0014] An embodiment of the present invention provides an epitaxial method for a silicon-based gallium nitride heterojunction material, which is applied to a silicon-based gallium nitride epitaxial structure. The silicon-based gallium nitride epitaxial structure includes a Si substrate, an AlN nucleation layer, an AlGaN buffer layer, a semi-insulating GaN buffer layer, an AlGaN back barrier layer, and a heterojunction formed by a GaN channel layer and an AlGaN barrier layer, which are stacked in sequence. Among them, the GaN channel layer is in contact with the AlGaN back barrier layer, and a 2DEG is formed in the GaN channel layer.

[0015] Among them, the heterojunction belongs to a part of the epitaxial layer. The semi-insulating GaN buffer layer is grown on the optimized stepped AlGaN buffer layer with a 2-μm semi-insulating buffer layer. This layer has better crystals and better semi-insulating characteristics compared with the traditional C-doped GaN buffer layer. An AlGaN back barrier layer is inserted between the semi-insulating C-doped GaN buffer layer and the GaN channel layer. The main purpose is to improve the carrier confinement in the 2-DEG channel and reduce the buffer trapping effect. The AlGaN back barrier layer can effectively prevent electrons in the GaN channel layer from transferring to the buffer layer, thereby reducing the leakage current and increasing the breakdown voltage. In addition, the back barrier layer can also suppress the propagation of dislocations in the buffer layer, thereby improving the quality of the GaN channel layer.

[0016] The processing flow of the epitaxial method for silicon-based gallium nitride heterojunction materials may include the following steps: S1: Pretreat the Si substrate.

[0017] It can be understood that the purpose of pretreating the Si substrate is to remove surface impurities and oxides, ensure the surface of the substrate is clean and tidy, provide a good foundation for the subsequent growth of the AlN nucleation layer, and thus improve the adhesion and growth quality of the material.

[0018] In a possible implementation manner, S1 is specifically: Perform a pretreatment on the Si substrate based on chemical cleaning, where the cleaning agent is an HF cleaning agent or a DHF cleaning agent.

[0019] It should be noted that by treating the Si substrate through a chemical cleaning-based method and using an HF or DHF cleaning agent to remove the native oxide on the substrate surface. This cleaning process can effectively clean the Si substrate, ensure its surface is clean and tidy, and provide a high-quality substrate for the subsequent growth of the AlN nucleation layer. The cleaned surface enhances the material adhesion and avoids the interference of oxides on the subsequent growth process, thereby improving the overall material quality and growth effect.

[0020] S2: Grow an AIN nucleation layer on the pretreated Si substrate by MOCVD.

[0021] It should be noted that the metalorganic chemical vapor deposition (MOCVD) technique is used to grow the AlN nucleation layer on the pretreated Si substrate. By introducing TMGa, TMAI, and NH3 as the precursor substances for Ga, Al, and N, and H2 as the carrier gas, the uniform growth of the AlN nucleation layer is ensured. This process provides an excellent substrate for the subsequent growth of the gallium nitride layer.

[0022] In a possible implementation manner, S2 is specifically: The AlN nucleation layer is grown on the pre-treated Si substrate by MOCVD at 1100°C, where the thickness of the AlN nucleation layer is 285 nm.

[0023] It should be noted that using the MOCVD technique at 1100°C, a 285-nm-thick AlN nucleation layer is grown on the pre-treated Si substrate. The role of this nucleation layer is to provide a good growth foundation for the subsequent gallium nitride material, optimize the lattice matching between the substrate and the epitaxial layer, and reduce the stress and defects caused by lattice mismatch. By controlling the growth temperature and the thickness of the nucleation layer, the quality and uniformity of the AlN layer can be ensured, providing good preconditions for the subsequent growth of high-quality gallium nitride heterojunction materials.

[0024] S3: Grow the AlGaN buffer layer with an inverted stepped Al component content, where the Al component content in the AlGaN buffer layer is positively correlated with the distance from the AlN nucleation layer.

[0025] It should be noted that the inverted stepped structure makes the Al component content of the AlGaN buffer layer gradually increase with the increase in the distance from the AlN nucleation layer, optimizing the lattice matching. This gradient design can effectively alleviate the stress concentration problem caused by lattice mismatch. Traditional buffer layers may be difficult to increase in thickness due to excessive stress, limiting the application of devices at high voltages. With the inverted stepped structure, the buffer layer can be grown thicker while maintaining stress balance, effectively improving the stability of the structure and the performance of the device, especially ensuring better performance during high-voltage operation. In addition, the inverted stepped method can be stacked for use to further optimize the bending effect of the wafer and improve the overall quality of the material.

[0026] In a possible implementation, the AlGaN buffer layer includes four sub-AlGaN buffer layers, and the sum of the thicknesses of each sub-AlGaN buffer layer is 2400 nm.

[0027] It should be noted that by growing buffer layers with different thicknesses in layers, the lattice matching can be gradually optimized, and the stress caused by the lattice mismatch between the Si substrate and the nitride material can be alleviated. This layered structure can effectively control the stress distribution of each layer, improve the crystallization quality of each layer, and avoid the generation of defects caused by excessive stress, thereby providing a more stable foundation for the subsequent growth of the GaN channel layer and other structures.

[0028] In a possible implementation, S3 specifically includes: S301: With the goal of minimizing the epitaxial stress of each sub-AlGaN buffer layer, determine the thickness of each sub-AlGaN buffer layer through the Laplace stress balance theorem: ; Where represents the thickness of the i-th sub-AlGaN buffer layer, , represents the lower limit value of the thickness, represents the vertical distance between the lower surface of the i-th sub-AlGaN buffer layer and the lower surface of the AlN nucleation layer, and D represents the maximum thickness of the AlGaN buffer layer.

[0029] Optionally, the lower limit value of the thickness can be set to 658 nm.

[0030] It should be noted that in the initial layer (i.e., when approaching the AlN nucleation layer), the stress is relatively large. Therefore, a thinner AlGaN layer is required to avoid excessive stress. As the distance increases, the epitaxial stress gradually decreases. Therefore, the thickness of each layer gradually increases, avoiding stress concentration. A smooth transition of the epitaxial stress is achieved, thus minimizing material defects caused by excessive stress.

[0031] S302: Calculate the Al composition content in each sub-AlGaN buffer layer according to the distance between the sub-AlGaN buffer layer and the AlN nucleation layer: ; wherein, represents the vertical distance between the upper surface of the i-th sub-AlGaN buffer layer and the upper surface of the AlN nucleation layer, represents the Al composition content of the i-th sub-AlGaN buffer layer, represents the lower limit value of the Al composition content in the sub-AlGaN buffer layer, e represents the natural constant, represents the dynamic growth rate of the Al composition content related to the layer number i, and ln represents the natural logarithm.

[0032] Optionally, the lower limit value of the Al composition content can be set to 23.8%.

[0033] It should be noted that the design of the dynamic change rate can effectively control the stress distribution during the epitaxial growth process by considering the change of the aluminum content in each AlGaN layer with the layer thickness. The gradual increase of the aluminum content layer by layer can help gradually reduce the stress generated by lattice mismatch, thus avoiding excessive stress accumulation and defect generation. In addition, the dynamic adjustment of the aluminum content growth rate provides flexibility for the epitaxial growth process, which can be optimized according to the layer thickness and aluminum content to ensure the stability and consistency of the material quality. By setting the lower limit of the aluminum content, the performance degradation caused by too low aluminum content is avoided, further optimizing the electronic performance and reliability of the material.

[0034] S303: Grow the AlGaN buffer layer at a growth temperature of 1100 °C according to the thickness and Al composition content of each sub-AlGaN buffer layer.

[0035] It should be noted that the sub-steps (S301 to S303) are mainly used to optimize the thickness and Al composition content of the AlGaN buffer layer, so as to minimize the material defects caused by excessive stress. In S301, based on the Laplace stress balance theorem, the goal is to minimize the epitaxial stress of each sub-AlGaN buffer layer. The control of stress is achieved by gradually increasing the thickness of the buffer layer layer by layer. The initial layer is thinner to avoid excessive stress, and the thickness of each subsequent layer gradually increases to smoothly transition the stress, thereby reducing the stress concentration problem. In S302, according to the distance between each sub-AlGaN buffer layer and the AlN nucleation layer, the Al composition content of each layer is calculated. By adjusting the Al composition content through the dynamic growth rate, the stress caused by lattice mismatch can be gradually reduced during the epitaxial process, optimizing the material quality and ensuring the performance consistency of each layer. Finally, in S303, according to the determined thickness and Al composition content above, growth is carried out at 1100 °C to ensure that the quality of the buffer layer meets the design requirements. The entire process optimizes the electronic properties and structural stability of the material by precisely controlling the growth conditions of each layer.

[0036] S4: Grow a semi-insulating GaN buffer layer with a preset distance on the AlGaN buffer layer.

[0037] It can be understood that a semi-insulating GaN buffer layer with a preset distance is grown on the AlGaN buffer layer. The growth of this layer helps to further improve the crystal quality and enhance the electrical properties of the material. The semi-insulating GaN buffer layer has low conductivity, which can effectively reduce the scattering during the electron migration process, improve the stability of the device, especially reduce the leakage current, and provide a good growth foundation for the subsequent AlGaN back barrier layer.

[0038] Optionally, the preset distance can be 2 μm.

[0039] It should be noted that those skilled in the art can set the size of the preset distance according to actual needs, and the present invention does not limit this here.

[0040] In a possible implementation manner, the semi-insulating GaN buffer layer is a C-doped semi-insulating GaN buffer layer.

[0041] Among them, the role of C doping is to control the carrier concentration by adding carbon elements to GaN, so that the material has semi-insulating characteristics. The C-doped semi-insulating GaN buffer layer is mainly used to provide a low free carrier concentration, thereby reducing the influence on the channel layer, enabling the subsequent GaN channel layer to obtain better electron mobility and enhanced current control.

[0042] S5: Grow an AlGaN back barrier layer on the semi-insulating GaN buffer layer.

[0043] Among them, the main function of the AlGaN back barrier layer is to improve the carrier confinement in the 2DEG (two-dimensional electron gas) channel, prevent electrons from migrating from the GaN channel layer to the buffer layer, thereby effectively reducing the leakage current. The AlGaN back barrier layer can also inhibit the propagation of dislocations, enhance the structural stability, increase the breakdown voltage and overall performance of the device, and ensure the efficient operation of the gallium nitride heterojunction material.

[0044] In a possible implementation, the thickness of the AlGaN back barrier layer is 30 nm. The Al component content of the AlGaN back barrier layer is 5%.

[0045] It should be noted that the thickness of the AlGaN back barrier layer is 30 nm and the Al component content is 5%. This design ensures that the back barrier layer has sufficient thickness to effectively prevent electrons in the 2DEG channel from transferring to the lower layer. At the same time, by having a relatively low aluminum content (5%), it maintains the appropriate bandgap and conductivity characteristics of the material, optimizes the electron confinement effect, reduces the leakage current, and improves the performance and stability of the overall device.

[0046] S6: Based on the principle of bandgap engineering, with the goal of maximizing the electron mobility of 2DEG and meeting the desired breakdown voltage, determine the thickness of the GaN channel layer, the thickness of the AlGaN barrier layer, and the desired Al component content in the AlGaN barrier layer.

[0047] Among them, the principle of bandgap engineering is to change the band structure of the material by regulating the ratio or composition of different elements in the material to optimize its electrical, optical and other properties. In the silicon-based gallium nitride heterojunction, by adjusting the Al component in the AlGaN layer, the bandgap size can be controlled, thereby increasing the electron mobility in 2DEG. Electron mobility refers to the migration ability of carriers under the action of an electric field. High electron mobility means a faster current response speed and higher device performance. The desired breakdown voltage refers to the maximum voltage that the material can withstand without breakdown.

[0048] It should be noted that by optimizing the design of the GaN channel layer and the AlGaN barrier layer through the principle of bandgap engineering, the electron mobility in 2DEG can be maximized while ensuring that the device can withstand the desired breakdown voltage. By precisely controlling the thickness of the GaN channel layer, the thickness of the AlGaN barrier layer, and the Al component content in the AlGaN barrier layer, efficient electron transport and a higher operating voltage can be achieved, thereby improving the overall performance of the silicon-based gallium nitride heterojunction and meeting the requirements of high-voltage and high-frequency applications.

[0049] In a possible implementation, S6 specifically includes: S601: Establish a correlation relationship between the electron mobility of 2DEG and the thickness of the GaN channel layer: ; Among them, represents the electron mobility of 2DEG, q represents the electron charge, and n represents the exponential factor describing the relationship between the electron mobility and the thickness of the GaN channel layer. represents the thickness of the GaN channel layer related to n. represents the scattering duration of electrons in the GaN channel layer. represents the effective mass of the electron migration process in the GaN channel layer.

[0050] Among them, the exponential factor reflects the sensitivity of the electron mobility to the thickness of the GaN channel layer, and n can take the value of 1.6.

[0051] S602: Establish the correlation relational expressions between the thickness of the AlGaN barrier layer and the Al component content of the AlGaN barrier layer and the breakdown voltage respectively: ; Among them, represents the breakdown voltage. represents the AlGaN bandgap width. represents the thickness of the AlGaN barrier layer. represents the bandgap width of AlN. represents the bandgap width of GaN. represents the Al component content of the AlGaN barrier layer. represents the bandgap width difference value caused by the Al component content.

[0052] Among them, the AlGaN bandgap width refers to the energy difference required for electrons to transition from the valence band to the conduction band in this material. The bandgap width is an important characteristic of semiconductor materials, which determines the conductivity, optical properties, and energy band structure of the material at different temperatures. The bandgap width of AlN is about 6.2 eV, and the bandgap width of GaN is about 3.4 eV.

[0053] S603: Under the condition of meeting the desired breakdown voltage, with the goal of maximizing the electron mobility of 2DEG, optimize the thickness of the GaN channel layer, the thickness of the AlGaN barrier layer, and the desired Al component content in the AlGaN barrier layer. The optimization constraint conditions are specifically: ; where max represents taking the maximum value of . represents the desired breakdown voltage.

[0054] Experimental findings show that when the thickness ratio of the GaN channel layer to the AlGaN barrier layer is approximately in the range of 2 to 3, the optimal electron mobility and breakdown voltage can be achieved while avoiding excessive stress accumulation.

[0055] It should be noted that by introducing a mathematical model and optimizing the constraint conditions, it is ensured that within the thickness ratio range of 2 to 3 for the GaN channel layer to the AlGaN barrier layer, excessive stress accumulation can be avoided, the electron mobility of the 2DEG can be maximized, and on this basis, the breakdown voltage can meet the requirements. This optimization not only improves the stability of the device, avoids material defects caused by excessive stress, but also provides a flexible and adjustable design space, making this solution have stronger advantages and competitiveness in high-voltage and high-frequency applications. By precisely optimizing the thickness of the GaN channel layer and the AlGaN barrier layer, and the Al composition content of the AlGaN barrier layer, it is ensured to maximize the electron mobility in the 2DEG and meet the desired breakdown voltage. This solution not only avoids defects caused by excessive stress accumulation, but also can effectively balance the electron mobility and the breakdown voltage while ensuring high performance. By adjusting the thickness ratio of the GaN channel layer to the AlGaN barrier layer (in the range of 2 to 3), this solution provides a more stable and reliable design, which can significantly improve the overall performance of the device, especially in high-voltage and high-frequency applications, ensuring higher efficiency and long-term stability.

[0056] S7: According to the thickness of the GaN channel layer and the AlGaN barrier layer, and the desired Al composition content in the AlGaN barrier layer, grow the GaN channel layer and the AlGaN barrier layer in the heterojunction successively at the first temperature to obtain a gallium nitride on silicon heterojunction.

[0057] In a possible implementation, the first temperature is 1070 °C.

[0058] It should be noted that according to the previously determined thickness of the GaN channel layer and the AlGaN barrier layer, and the desired Al composition content in the AlGaN barrier layer, grow the GaN channel layer and the AlGaN barrier layer successively at the set first temperature. The key to this process is to ensure that the structures of the two layers meet the design requirements by precisely controlling the growth conditions, so as to obtain a gallium nitride on silicon heterojunction with excellent electron mobility and high breakdown voltage, providing a high-quality basis for subsequent high-efficiency electronic devices.

[0059] In the actual application process, the performance of the gallium nitride on silicon heterojunction is optimized by precisely controlling the growth process and component content of each layer. In step S1, the Si substrate is pre-treated to remove surface impurities, providing a good foundation for the growth of the AlN nucleation layer in the subsequent steps. In step S2, the AlN nucleation layer is grown on the Si substrate using MOCVD technology to create a suitable environment for the growth of the gallium nitride layer. In step S3, through the growth of an inverted stepped AlGaN buffer layer, the lattice matching is effectively optimized, and the stress caused by lattice mismatch is alleviated. In steps S4 and S5, by growing a semi-insulating GaN buffer layer and an AlGaN back barrier layer, the electron transport characteristics are further improved, the leakage current is reduced, and the device stability is enhanced. In step S6, the design of the GaN channel layer and the AlGaN barrier layer is precisely adjusted using the principle of bandgap engineering to maximize the electron mobility in the 2DEG (two-dimensional electron gas) and ensure that the device can withstand the desired breakdown voltage. Finally, in step S7, by precisely controlling the growth conditions, the GaN channel layer and the AlGaN barrier layer are grown in sequence, and finally a high-performance gallium nitride on silicon heterojunction is formed, providing a reliable foundation for high-efficiency electronic devices. The entire process ensures the high quality and high performance of the final device by precisely controlling the material structure and growth parameters.

[0060] The beneficial effects brought by the technical solution provided by the embodiments of the present invention at least include: In the embodiments of the present invention, by precisely controlling the growth process and component content of each layer, the problem of electron mobility deviation caused by experience limitations in traditional designs is overcome. The method gradually optimizes the lattice matching through the growth technology of the inverted stepped AlGaN buffer layer, reducing the leakage phenomenon in the heterojunction caused by lattice mismatch. By precisely controlling the thickness and Al component content of the GaN channel layer and the AlGaN barrier layer using the principle of bandgap engineering, the electron mobility in the 2DEG (two-dimensional electron gas) is maximized, and the desired breakdown voltage is ensured, greatly improving the performance and production quality of the gallium nitride on silicon heterojunction material. The interference of subjective factors in traditional methods is avoided, making the gallium nitride on silicon heterojunction material more stable and reliable in performance.

[0061] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto.

Claims

1. An epitaxial method for silicon-based gallium nitride heterojunction material, characterized in that: Applied to a silicon-based gallium nitride epitaxial structure, the silicon-based gallium nitride epitaxial structure comprises a Si substrate, an AlN nucleation layer, an AlGaN buffer layer, a semi-insulating GaN buffer layer, an AlGaN back barrier layer, and a heterojunction formed by a GaN channel layer and an AlGaN barrier layer, wherein the GaN channel layer contacts the AlGaN back barrier layer, and a 2DEG is formed in the GaN channel layer; the method comprises: S1: pre-treating the Si substrate; S2: growing the AlN nucleation layer on the pretreated Si substrate using MOCVD; S3: growing the AlGaN buffer layer with an inverted step-like Al component content, wherein the Al component content in the AlGaN buffer layer is positively correlated with the distance away from the AlN nucleation layer; S4: growing the semi-insulating GaN buffer layer with a preset distance on the AlGaN buffer layer; S5: growing the AlGaN back barrier layer on the semi-insulating GaN buffer layer; S6: Based on the principle of bandgap engineering, with the goal of maximizing the electron mobility of the 2DEG and satisfying the desired breakdown voltage, determining the thickness of the GaN channel layer, the thickness of the AlGaN barrier layer, and the desired Al component content in the AlGaN barrier layer; S7: According to the thicknesses of the GaN channel layer and the AlGaN barrier layer and the desired Al component content in the AlGaN barrier layer, sequentially growing the GaN channel layer and the AlGaN barrier layer in the heterojunction at a first temperature to obtain a silicon-based gallium nitride heterojunction.

2. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The silicon-based gallium nitride epitaxial structure also includes a GaN capping layer.

3. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The S1 is specifically: The Si substrate is pre-treated by chemical cleaning, wherein the cleaning agent is HF cleaning agent or DHF cleaning agent.

4. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The S2 is specifically: The AlN nucleation layer is grown on the pretreated Si substrate by MOCVD at 1100° C., wherein the thickness of the AlN nucleation layer is 285 nm.

5. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The AlGaN buffer layer includes four sub-layers of AlGaN buffer layers, and the sum of the thicknesses of the sub-layers of AlGaN buffer layers is 2400 nm.

6. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 5, characterized in that: The S3 specifically includes: S301: With the goal of minimizing the epitaxial stress of each sub-layer AlGaN buffer layer, the thickness of each sub-layer AlGaN buffer layer is determined by Laplace stress equilibrium theorem: ； in, represents the thickness of the i-th AlGaN buffer layer, , Indicates the lower limit of thickness, represents the vertical distance between the lower surface of the i-th sub-AlGaN buffer layer and the lower surface of the AlN nucleation layer, and D represents the maximum thickness of the AlGaN buffer layer; S302: Calculate the Al component content in each sub-AlGaN buffer layer according to the distance between the sub-AlGaN buffer layer and the AlN nucleation layer: ； in, represents the vertical distance between the upper surface of the i-th sub-AlGaN buffer layer and the upper surface of the AlN nucleation layer, represents the Al content of the i-th AlGaN buffer layer, represents the lower limit of Al content in the sub-AlGaN buffer layer, e represents a natural constant, represents the dynamic growth rate of Al component content related to layer number i, and ln represents the natural logarithm; S303: growing the AlGaN buffer layer at a growth temperature of 1100° C. according to the thickness of each sub-AlGaN buffer layer and the Al component content.

7. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The semi-insulating GaN buffer layer is a C-doped semi-insulating GaN buffer layer.

8. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The thickness of the AlGaN back barrier layer is 30 nm; the Al component content of the AlGaN back barrier layer is 5%.

9. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The S6 specifically includes: S601: Establishing a correlation equation between the electron mobility of the 2DEG and the thickness of the GaN channel layer: ； in, represents the electron mobility of 2DEG, q represents the electron charge, and n represents the exponential factor describing the relationship between the electron mobility and the thickness of the GaN channel layer. represents the thickness of the GaN channel layer related to n, Indicates the scattering time of electrons in the GaN channel layer, Represents the equivalent mass of electron migration in the GaN channel layer; S602: Establishing the correlation equations of the thickness of the AlGaN barrier layer and the Al component content of the AlGaN barrier layer and the breakdown voltage respectively: ； in, represents the breakdown voltage, represents the AlGaN bandgap width, represents the thickness of the AlGaN barrier layer, represents the band gap width of AlN, represents the band gap width of GaN, represents the Al content of the AlGaN barrier layer, represents the difference in band gap width caused by Al component content; S603: Under the condition of satisfying the expected breakdown voltage, with the goal of maximizing the electron mobility of the 2DEG, optimizing the thickness of the GaN channel layer, the thickness of the AlGaN barrier layer, and the expected Al component content in the AlGaN barrier layer, wherein the optimization constraints are specifically as follows: ； Among them, max Express Take the maximum value, Indicates the expected breakdown voltage.

10. The epitaxial growth method of silicon-based gallium nitride heterojunction material according to claim 1, characterized in that: The first temperature is 1070°C.

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