Epitaxial wafer structure and method for producing an epitaxial wafer structure
By doping an aluminum gallium nitride layer with indium in the buffer layer of the epitaxial wafer structure, the growth temperature is reduced to 700-850 degrees Celsius, which solves the problem of substrate loss in the epitaxial structure and improves the quality of the epitaxial wafer structure and the high-frequency signal transmission performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN SANAN SEMICON CO LTD
- Filing Date
- 2024-12-31
- Publication Date
- 2026-07-10
AI Technical Summary
The epitaxial structures prepared in the prior art suffer from substrate loss, which affects the transmission of high-frequency signals and leads to a decline in the quality of the epitaxial structure.
An aluminum gallium nitride layer doped with indium is used in the buffer layer, and the growth temperature is controlled at 700-850 degrees Celsius. The substrate loss is reduced by lattice matching, thereby improving the quality of the epitaxial wafer structure.
It effectively reduces substrate loss in epitaxial wafer structures, improving the quality of epitaxial wafer structures and high-frequency signal transmission performance.
Smart Images
Figure CN122373426A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to an epitaxial wafer structure and a method for fabricating the epitaxial wafer structure. Background Technology
[0002] With the development of science and technology, high-frequency devices and radio frequency devices are playing an increasingly indispensable role in modern electronic technology in the field of wireless communication.
[0003] These devices are manufactured by first preparing an epitaxial structure and then using the epitaxial structure to create high-frequency and radio-frequency devices. However, the epitaxial structure prepared in the existing technology will generate substrate loss, which will affect the transmission of high-frequency signals and thus affect the quality of the epitaxial structure, resulting in defects in the epitaxial structure. Summary of the Invention
[0004] Therefore, in order to overcome at least some of the defects and deficiencies of the prior art, the present invention proposes an epitaxial wafer structure.
[0005] On one hand, an epitaxial wafer structure proposed in an embodiment of the present invention includes: a silicon substrate layer; a nucleation layer disposed on the silicon substrate layer and the nucleation layer including an aluminum nitride layer; a buffer layer disposed on the nucleation layer and the buffer layer including an indium-doped aluminum gallium nitride layer; a gallium nitride channel layer disposed on the buffer layer; and an aluminum gallium nitride barrier layer disposed above the gallium nitride channel layer.
[0006] Secondly, another embodiment of the present invention provides a method for fabricating an epitaxial wafer structure, comprising: epitaxially growing a nucleation layer on a silicon substrate; wherein the nucleation layer comprises an aluminum nitride layer; epitaxially growing a buffer layer on the nucleation layer at a first preset temperature; the buffer layer is an indium-doped aluminum gallium nitride layer, and the first preset temperature is 700-850 degrees Celsius; growing a gallium nitride channel layer on the buffer layer; and growing an aluminum gallium nitride barrier layer on the gallium nitride channel layer.
[0007] As can be seen from the above, the above-mentioned technical features of the present invention can have the following beneficial effects: by doping indium in the buffer layer of the epitaxial wafer structure, the present application can reduce the occurrence of substrate loss in the epitaxial wafer structure, thereby improving the quality of the epitaxial wafer structure. Attached Figure Description
[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0009] Figure 1 This is a schematic diagram of an epitaxial wafer structure provided in the first embodiment of the present invention.
[0010] Figure 2 for Figure 1 The diagram shows the relationship between the crystal constants and band gaps of the layers grown on a silicon substrate.
[0011] Figure 3 This is a schematic diagram of an epitaxial wafer structure provided in the second embodiment of the present invention.
[0012] Figure 4 for Figure 3 The diagram shows the relationship between the crystal constants and band gaps of the layers grown on a silicon substrate.
[0013] Figure 5 This is a schematic diagram of an epitaxial wafer structure provided in the third embodiment of the present invention.
[0014] Figure 6 for Figure 5 The diagram shows the relationship between the crystal constants and band gaps of the layers grown on a silicon substrate.
[0015] Figure 7 This is a flowchart of a method for preparing an epitaxial wafer structure according to the fourth embodiment of the present invention.
[0016] Figure 8 for Figure 7 The flowchart showing the specific steps of step S101 is shown.
[0017] [Explanation of Labels in the Attached Image]
[0018] S101-S104, S1011: Steps in the fabrication method of epitaxial wafer structure; 1: Epitaxial wafer structure; 10: Silicon substrate; 20: Nucleation layer; 30: Buffer layer; 40: Gallium nitride channel layer; 50: Al gallium nitride barrier layer; 31: First buffer layer; 32: Second buffer layer. Detailed Implementation
[0019] 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 are within the scope of protection of the present invention.
[0020] [First Embodiment]
[0021] like Figures 1-2As shown, this embodiment provides an epitaxial wafer structure 1, which includes, for example, a silicon substrate layer 10, a nucleation layer 20, a buffer layer 30, a gallium nitride channel layer 40, and an aluminum gallium nitride barrier layer 50.
[0022] Specifically, the nucleation layer 20 is disposed on the silicon substrate layer 10, and the nucleation layer 20 includes an aluminum nitride layer. The buffer layer 30 is disposed on the nucleation layer 20, and the buffer layer 30 includes an indium-doped aluminum gallium nitride layer. The gallium nitride channel layer 40 is disposed on the buffer layer 30; and the aluminum gallium nitride barrier layer 50 is disposed above the gallium nitride channel layer 40.
[0023] The silicon substrate 10 can be, for example, a silicon carbide substrate. The nucleation layer 20 is a thin film deposited on the silicon substrate 10. The nucleation layer 20 can provide nucleation centers, promote the growth of epitaxial structures, help adjust stress, and reduce the growth of defects such as dislocations on the substrate. Because aluminum nitride and gallium nitride have good lattice matching, the aluminum nitride nucleation layer can provide compressive stress, which can compensate for the tensile stress caused by thermal mismatch. Since the buffer layer 30 is doped with indium, the growth temperature of the buffer layer can be between 700-850 degrees Celsius. This temperature allows the buffer layer grown on the silicon substrate 10 to reduce substrate loss.
[0024] To alleviate the stress problem caused by lattice constant mismatch, a buffer layer is grown on the nucleation layer 20. This buffer layer 30 includes an indium-doped aluminum gallium nitride (AGaN) layer; that is, by doping indium into the buffer layer 30, the AGaN layer becomes an indium aluminum gallium nitride (IAGaN) layer. Multiple different materials, such as indium nitride, aluminum nitride, indium aluminum nitride, and indium gallium nitride, can be obtained through arbitrary combinations of indium, aluminum, gallium, and nitrogen elements in the IGaN layer. These materials are matched by their respective lattice constants, forming the buffer layer 30. This gradual variation in lattice constants helps alleviate the stress problem caused by lattice constant mismatch. By setting the buffer layer, the quality of the nucleation layer and the gallium nitride channel layer can be improved, thereby improving the crystal quality of the epitaxial layer and ultimately the quality of the epitaxial wafer structure. In this application, the buffer layer 30 can be, for example, any one or a combination of InAlN, InN, InGaN, and InAlGaN.
[0025] In existing technologies, while an aluminum nitride nucleation layer is also present on the epitaxial wafer structure, the buffer layer used to adjust the stress of the nucleation layer is an aluminum gallium nitride buffer layer. The growth temperature of this nucleation layer and buffer layer exceeds 1000 degrees Celsius. This growth temperature causes losses in the silicon substrate, which in turn affects the epitaxial wafer structure, leading to transmission difficulties during high-frequency signal transmission and ultimately reducing the device's quality. In order to reduce or minimize substrate loss, this application incorporates indium doping into the aluminum gallium nitride layer included in the buffer layer 30. This allows the buffer layer 30 to grow and achieve lattice matching. More importantly, the growth temperature of the indium-doped aluminum gallium nitride layer is also lower. Compared to the prior art, the temperature required to grow the nucleation layer 20 and the buffer layer 30 on the silicon substrate 10 is lower. The temperature of 700-850 degrees Celsius, compared to the previous temperature of over 1000 degrees Celsius, can further reduce the loss of the silicon substrate 10. Therefore, by doping the buffer layer 30 of the epitaxial wafer structure 1 with indium, this application can reduce the occurrence of loss in the silicon substrate 10 of the epitaxial wafer structure 1, thereby improving the quality and performance of the epitaxial wafer structure 1 and reducing the generation of defects.
[0026] Furthermore, such as Figures 1-2 As shown, the nucleation layer 20 includes an indium-doped aluminum nitride layer. The band gap of the nucleation layer 20 is higher than that of the buffer layer 30, and the lattice constant of the nucleation layer 20 is the same as that of the buffer layer 30. The nucleation layer 20 is, for example, an indium aluminum nitride (InAlN) layer, while the buffer layer 30 is an indium aluminum gallium nitride (InAlGaN) layer. Figure 2 It is known that the lattice constants of nucleation layer 20 and buffer layer 30 are the same. However, in order to achieve lattice matching between nucleation layer 20 and buffer layer 30, and to enable nucleation layer 20 and buffer layer 30 to perform different functions of their respective layers, the band gap between nucleation layer 20 and buffer layer 30 needs to be adjusted so that the band gap of nucleation layer 20 is smaller than that of buffer layer 30. This allows buffer layer 30 to have better and higher conductivity than nucleation layer 20.
[0027] The nucleation layer 20 has the same bandgap as the aluminum gallium nitride (AGaN) barrier layer 50, and its lattice constant is greater than that of the AGaN barrier layer 50. The nucleation layer 20 has a higher bandgap than the gallium nitride (GaN) channel layer 40, and its lattice constant is the same as that of the GaN channel layer 40. The buffer layer 30 has a higher bandgap than the GaN channel layer 40. By defining the materials of the buffer layer 30 and the nucleation layer 20, the variation between the lattice constant and bandgap of each layer grown on the estimated substrate can be made as follows: Figure 2As shown, the corresponding material composition of the nucleation layer 20 and the buffer layer 30 can be set by changing the lattice constant gradient, thereby making the stress in the nucleation layer 20 and the buffer layer 30 adjustable, reducing the problem caused by lattice mismatch, and the buffer layer 30 can act as a barrier layer to prevent defects (such as dislocations, microcracks, etc.) from the silicon substrate layer 10 from propagating to the upper structure.
[0028] [Second Embodiment]
[0029] In this embodiment, the epitaxial wafer structure is basically similar to the epitaxial wafer structure provided in the first embodiment above, except that: the nucleation layer 20 is not doped with indium, the lattice constant of the nucleation layer 20 is smaller than the lattice constant of the buffer layer 30, and the buffer layer 30 includes a first buffer layer 31 and a second buffer layer.
[0030] Specifically, such as Figure 3 and Figure 4 As shown, the band gap of the nucleation layer 20 is higher than that of the buffer layer 30, and the lattice constant of the nucleation layer 20 is lower than that of the buffer layer 30; the lattice constant of the nucleation layer 20 is greater than that of the aluminum gallium nitride barrier layer 50. In this embodiment, the nucleation layer 20 is not doped with indium, while the buffer layer is doped with indium, so the lattice constants and band gaps of the nucleation layer 20 and the buffer layer 30 are different.
[0031] Furthermore, the buffer layer 30 includes a first buffer layer 31 and a second buffer layer 32 arranged sequentially from the silicon substrate layer 10 toward the aluminum gallium nitride barrier layer 50. The first buffer layer 31 is an indium aluminum nitride (InAlN) layer, and the second buffer layer 32 is an indium aluminum gallium nitride (InAlGaN) layer. The band gap of the first buffer layer 31 is higher than that of the second buffer layer 32, and the lattice constant of the first buffer layer 31 is the same as that of the second buffer layer 32.
[0032] Furthermore, such as Figure 4As shown, the bandgap of the first buffer layer 31 is the same as that of the aluminum gallium nitride barrier layer 50, and the lattice constant of the first buffer layer 31 is greater than that of the aluminum gallium nitride barrier layer 50. The bandgap of the first buffer layer 31 is higher than that of the gallium nitride channel layer 40, and the lattice constant of the first buffer layer 31 is the same as that of the gallium nitride channel layer 40. The bandgap of the second buffer layer 32 is higher than that of the gallium nitride channel layer 40. By limiting the changes in lattice constant and bandgap among the first buffer layer 31, the second buffer layer 32, the gallium nitride channel layer 40, and the aluminum gallium nitride barrier layer 50, the epitaxial wafer structure 1 can use the gradient change of lattice constant to adjust the specific composition and structure of the buffer layer 30, thereby further improving the quality of the epitaxial wafer structure 1 and reducing the loss of the silicon substrate layer 10.
[0033] [Third Embodiment]
[0034] In this embodiment, the epitaxial wafer structure is basically similar to the epitaxial wafer structure provided in the first embodiment above, except that the lattice constant of the nucleation layer 20 is smaller than the lattice constant of the buffer layer 30, and the buffer layer 30 includes a first buffer layer 31 and a second buffer layer.
[0035] Specifically, such as Figures 5-6 As shown, the nucleation layer 20 includes an indium-doped aluminum nitride layer. The band gap of the nucleation layer 20 is higher than that of the buffer layer 30, and the lattice constant of the nucleation layer 20 is lower than that of the buffer layer 30. In this embodiment, both the nucleation layer 20 and the buffer layer 30 are doped with indium. The nucleation layer 20 is an indium aluminum nitride (InAlN) layer, while the buffer layer 30 does not contain aluminum. Therefore, the lattice constant of the nucleation layer 20 is lower than that of the buffer layer 30. Figure 6 As shown,
[0036] Furthermore, the buffer layer 30 includes a first buffer layer 31 and a second buffer layer 32 arranged sequentially from the silicon substrate layer 10 toward the aluminum gallium nitride barrier layer 50. The first buffer layer 31 is an indium nitride (InN) layer, and the second buffer layer 32 is an indium gallium nitride (InGaN) layer. The band gap of the first buffer layer 31 is lower than that of the second buffer layer 32, and the lattice constant of the first buffer layer 31 is greater than that of the second buffer layer 32.
[0037] The bandgap of the nucleation layer 20 is the same as that of the aluminum gallium nitride (AGaN) barrier layer 50, and the lattice constant of the nucleation layer 20 is greater than that of the AGaN barrier layer 50. The bandgap of the gallium nitride (GaN) channel layer 40 is higher than that of the second buffer layer 32, and the bandgap lattice constant of the GaN channel layer 40 is the same as that of the nucleation layer 20. By limiting the changes in lattice constant and bandgap among the first buffer layer 31, the second buffer layer 32, the GaN channel layer 40, and the AGaN barrier layer 50, the epitaxial wafer structure 1 can use a gradient change in lattice constant to adjust the specific composition and structure of the buffer layer 30, thereby further improving the quality of the epitaxial wafer structure 1 and reducing the loss of the silicon substrate layer 10.
[0038] [Fourth Embodiment]
[0039] like Figures 7-8 As shown, this application provides a method for preparing an epitaxial wafer structure, which may include, for example:
[0040] S101. An epitaxial nucleation layer is grown on a silicon substrate; wherein the nucleation layer includes an aluminum nitride layer;
[0041] S102. A buffer layer is epitaxially grown on the nucleation layer at a first preset temperature; the buffer layer is an indium-doped aluminum gallium nitride layer, and the first preset temperature is 700-850 degrees Celsius.
[0042] S103. A gallium nitride channel layer is grown on the buffer layer;
[0043] S104. An aluminum gallium nitride barrier layer is grown on the gallium nitride channel layer.
[0044] In step S101, the growth of the nucleation layer, buffer layer, channel layer, and barrier layer on the silicon substrate 10 can be performed in a metal-organic chemical vapor deposition (MOCVD) apparatus. Trimethylaluminum (TMAl), trimethylgallium (TMGa), trimethylindium (TMIn), and ammonia (NH3) are used as the aluminum (Al) source, gallium (Ga) source, indium (In) source, and nitrogen (N) source, respectively, and hydrogen (H2), nitrogen (N2), or a mixture of both are used as the carrier gas. Of course, in other embodiments, metal-organic chemical vapor deposition or molecular beam epitaxy can also be used for preparation, and the specific method is not limited here.
[0045] In existing technologies, while an aluminum nitride nucleation layer is also present on the epitaxial wafer structure, the buffer layer used to adjust the stress of the nucleation layer is an aluminum gallium nitride buffer layer. The growth temperature of this nucleation layer and buffer layer exceeds 1000 degrees Celsius. This growth temperature causes losses in the silicon substrate, which in turn affects the epitaxial wafer structure, leading to transmission difficulties during high-frequency signal transmission and ultimately reducing the device's quality. In order to reduce or minimize substrate loss, this application incorporates indium doping into the aluminum gallium nitride layer included in the buffer layer 30. This allows the buffer layer 30 to grow and achieve lattice matching. More importantly, the growth temperature of the indium-doped aluminum gallium nitride layer is also lower. Compared to the prior art, the temperature required to grow the nucleation layer 20 and the buffer layer 30 on the silicon substrate 10 is lower. The temperature of 700-850 degrees Celsius, compared to the previous temperature of over 1000 degrees Celsius, can further reduce the loss of the silicon substrate 10. Therefore, by doping the buffer layer 30 of the epitaxial wafer structure 1 with indium, this application can reduce the occurrence of loss in the silicon substrate 10 of the epitaxial wafer structure 1, thereby improving the quality and performance of the epitaxial wafer structure 1 and reducing the generation of defects.
[0046] Furthermore, such as Figure 8 As shown, the nucleation layer includes an indium-doped aluminum nitride layer, specifically an InAlN layer, and step S101 may specifically include:
[0047] S1011. The nucleation layer is epitaxially grown on a silicon substrate at a second preset temperature; wherein the second preset temperature is 700-850 degrees Celsius.
[0048] In existing technologies, aluminum nitride nucleation layers are also present on the epitaxial wafer structure. However, the buffer layer used to adjust the stress of the nucleation layer is an aluminum gallium nitride buffer layer. The growth temperature of this nucleation layer and buffer layer is greater than 1000 degrees Celsius. This growth temperature causes losses in the silicon substrate, which in turn affects the epitaxial wafer structure, leading to transmission problems during high-frequency signal transmission and a reduction in device quality. To reduce these substrate losses, this application dops indium into the aluminum nitride layer of the nucleation layer 20. This results in a lower growth temperature for the nucleation layer 20 compared to existing technologies. The temperature of 700-850 degrees Celsius, compared to the previous temperatures exceeding 1000 degrees Celsius, further reduces the losses in the silicon substrate layer 10.
[0049] Furthermore, it is understood that the foregoing embodiments are merely illustrative examples of the present invention. Provided that the technical features do not conflict, the structure is not contradictory, and the purpose of the invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used.
[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. An epitaxial wafer structure (1), characterized in that, include: Silicon-based substrate (10); A nucleation layer (20) is disposed on the silicon substrate layer (10), and the nucleation layer (20) includes an aluminum nitride layer; A buffer layer (30) is disposed on the nucleation layer (20), and the buffer layer (30) includes an indium-doped aluminum gallium nitride layer; A gallium nitride channel layer (40) is disposed on the buffer layer (30); and An aluminum gallium nitride barrier layer (50) is disposed above the gallium nitride channel layer (40).
2. The epitaxial wafer structure (1) according to claim 1, characterized in that, The nucleation layer (20) includes an aluminum nitride layer doped with indium, the band gap of the nucleation layer (20) is higher than that of the buffer layer (30), and the lattice constant of the nucleation layer (20) is the same as that of the buffer layer (30).
3. The epitaxial wafer structure (1) according to claim 2, characterized in that, The band gap of the nucleation layer (20) is the same as that of the aluminum gallium nitride barrier layer (50), and the lattice constant of the nucleation layer (20) is greater than that of the aluminum gallium nitride barrier layer (50); the band gap of the nucleation layer (20) is higher than that of the gallium nitride channel layer (40), and the lattice constant is the same as that of the gallium nitride channel layer (40); the band gap of the buffer layer (30) is higher than that of the gallium nitride channel layer (40).
4. The epitaxial wafer structure (1) according to claim 1, characterized in that, The band gap of the nucleation layer (20) is higher than that of the buffer layer (30), and the lattice constant of the nucleation layer (20) is lower than that of the buffer layer (30); the lattice constant of the nucleation layer (20) is greater than that of the aluminum gallium nitride barrier layer (50).
5. The epitaxial wafer structure (1) according to claim 4, characterized in that, The buffer layer (30) includes a first buffer layer (31) and a second buffer layer (32) arranged sequentially from the silicon substrate layer (10) toward the aluminum gallium nitride barrier layer (50). The first buffer layer (31) is an indium aluminum nitride layer, and the second buffer layer (32) is an indium aluminum gallium nitride layer. The band gap of the first buffer layer (31) is higher than that of the second buffer layer (32), and the lattice constant of the first buffer layer (31) is the same as that of the second buffer layer (32).
6. The epitaxial wafer structure (1) according to claim 5, characterized in that, The band gap of the first buffer layer (31) is the same as that of the aluminum gallium nitride barrier layer (50), and the lattice constant of the first buffer layer (31) is greater than that of the aluminum gallium nitride barrier layer (50). The band gap of the first buffer layer (31) is higher than that of the gallium nitride channel layer (40), and the lattice constant of the first buffer layer (31) is the same as that of the gallium nitride channel layer (40). The band gap of the second buffer layer (32) is higher than that of the gallium nitride channel layer (40).
7. The epitaxial wafer structure (1) according to claim 1, characterized in that, The nucleation layer (20) includes an aluminum nitride layer doped with indium, the band gap of the nucleation layer (20) is higher than that of the buffer layer (30), and the lattice constant of the nucleation layer (20) is lower than that of the buffer layer (30).
8. The epitaxial wafer structure (1) according to claim 7, characterized in that, The buffer layer (30) includes a first buffer layer (31) and a second buffer layer (32) arranged sequentially from the silicon substrate layer (10) toward the aluminum gallium nitride barrier layer (50). The first buffer layer (31) is an indium nitride layer, and the second buffer layer (32) is an indium gallium nitride layer. The band gap of the first buffer layer (31) is lower than that of the second buffer layer (32), and the lattice constant of the first buffer layer (31) is greater than that of the second buffer layer (32).
9. The epitaxial wafer structure (1) according to claim 8, characterized in that, The band gap of the nucleation layer (20) is the same as that of the aluminum gallium nitride barrier layer (50), and the lattice constant of the nucleation layer (20) is greater than that of the aluminum gallium nitride barrier layer (50). The band gap of the gallium nitride channel layer (40) is higher than that of the second buffer layer (32), and the band gap lattice constant of the gallium nitride channel layer (40) is the same as that of the nucleation layer (20).
10. A method for preparing an epitaxial wafer structure, characterized in that, include: A nucleation layer is epitaxially grown on a silicon substrate; wherein the nucleation layer includes an aluminum nitride layer; A buffer layer is epitaxially grown on the nucleation layer at a first preset temperature; the buffer layer is an indium-doped aluminum gallium nitride layer, and the first preset temperature is 700-850 degrees Celsius. A gallium nitride channel layer is grown on the buffer layer; An aluminum gallium nitride barrier layer is grown on a gallium nitride channel layer.
11. The method for preparing the epitaxial wafer structure according to claim 10, characterized in that, The nucleation layer includes an indium-doped aluminum nitride layer, and the epitaxial growth of the nucleation layer on the silicon substrate specifically includes: The nucleation layer is epitaxially grown on a silicon substrate at a second preset temperature, wherein the second preset temperature is 700-850 degrees Celsius.