Large-size, low-stress nitride epitaxial materials and their preparation methods

Abstract

This invention discloses a large-size, low-stress nitride epitaxial material and its preparation method. The preparation method includes depositing a first three-dimensional columnar structure on a C-plane sapphire substrate using physical vapor deposition; placing the C-plane sapphire substrate in an MOCVD reaction chamber and using MOCVD to generate an aluminum nitride epitaxial structure on the first three-dimensional columnar structure; depositing a second three-dimensional columnar structure on the aluminum nitride epitaxial structure using physical vapor deposition; and placing the C-plane sapphire substrate in an MOCVD reaction chamber and using MOCVD to generate an epitaxial functional layer on the second three-dimensional columnar structure. The thickness of the epitaxial structure of this invention is much smaller than that of traditional epitaxial materials, which greatly saves the preparation time and cost of the epitaxial structure. Furthermore, due to the small thickness of the epitaxial structure, there is no need to design a stress relief layer and a high-voltage control layer, further reducing the preparation steps and costs.

Description

Technical Field

[0001] This invention relates to the field of gallium nitride material preparation technology, and more particularly to large-size, low-stress nitride epitaxial materials and their preparation methods. Background Technology

[0002] With the development of industrial technology, high-power, high-current-density, and high-conversion-efficiency devices are increasingly meeting the social requirements of future green development. Third-generation semiconductor gallium nitride materials and devices, with their advantages of high power density and strong field strength, are gaining increasing market favor.

[0003] Currently, gallium nitride (GaN) materials and devices are mainly used for epitaxy and fabrication on heteroepitaxial substrates. However, the main problems faced by heteroepitaxial epitaxy are the resulting high epitaxial stress and the curvature caused by thermal mismatch with the substrate, which can easily lead to bending and cracking of GaN materials and devices. For large-sized GaN materials and devices ranging from 6 to 8 inches, the curvature is even more critical.

[0004] The three main substrate materials used for fabricating gallium nitride materials and devices on large-size substrates are silicon substrates, sapphire substrates, and silicon carbide substrates.

[0005] The existing epitaxial material technology route mainly involves the following process:

[0006] First, an aluminum nitride buffer layer is grown using MOCVD technology as a nucleation site, followed by the growth of a thicker stress-modulated layer (such as graded aluminum gallium nitride, gallium nitride / aluminum nitride superlattice, etc.). To improve the material's voltage withstand capability, carbon and iron doping are also performed to form a doped voltage withstand layer. Then, the structure of the gallium nitride channel layer, aluminum gallium nitride barrier layer, and gallium nitride cap layer is grown to obtain the epitaxial material structure.

[0007] The common feature of the above epitaxial structures is that the internal stress of the epitaxial layer is relatively large. It is necessary to balance the thermal mismatch caused by the substrate in order to prevent the gallium nitride material and device from cracking. Therefore, it is necessary to grow epitaxial materials larger than 3 micrometers to reduce the occurrence of cracking.

[0008] The existing epitaxial material technology route has a more prominent problem of stress control in 6 to 8-inch substrates. The internal stress of large-size epitaxial materials can easily cause chip cracking in the back-end chip fabrication, which brings many challenges to product yield and seriously restricts the development of gallium nitride materials and devices. Summary of the Invention

[0009] The purpose of this invention is to provide large-size, low-stress nitride epitaxial materials and their preparation methods. The thickness of the epitaxial structure is much smaller than that of traditional epitaxial materials, which greatly saves the preparation time and cost of the epitaxial structure. Furthermore, due to the small thickness of the epitaxial structure, there is no need to design a stress relief layer and a high-pressure control layer, which further reduces the preparation process and cost.

[0010] To achieve the above objectives, this invention discloses a method for preparing large-size, low-stress nitride epitaxial materials, comprising the following steps:

[0011] S1. A first three-dimensional columnar structure is deposited on a C-plane sapphire substrate using physical vapor deposition.

[0012] S2. Place the C-plane sapphire substrate in the MOCVD reaction chamber and use the MOCVD process to generate an aluminum nitride epitaxial structure on the first three-dimensional columnar structure.

[0013] S3. A second three-dimensional columnar structure is deposited on an aluminum nitride epitaxial structure using physical vapor deposition.

[0014] S4. Place the C-plane sapphire substrate in the MOCVD reaction chamber and use the MOCVD process to generate an epitaxial functional layer on the second three-dimensional columnar structure.

[0015] Compared with existing technologies, this invention sequentially generates a first three-dimensional columnar structure, an aluminum nitride epitaxial structure, a second three-dimensional columnar structure, and an epitaxial functional layer on a C-plane sapphire substrate. By adding the first and second three-dimensional columnar structures, it is suitable for effectively reducing the thickness of the aluminum nitride epitaxial structure and the epitaxial functional layer, thereby reducing the thickness of the finished material. Furthermore, since the thickness of the epitaxial structure is much smaller than that of traditional epitaxial materials, it greatly saves the preparation time and cost of the epitaxial structure. Moreover, due to the small thickness of the epitaxial structure, there is no need to design a stress relief layer and a high-voltage control layer, further reducing the preparation process and cost.

[0016] Preferably, step S1 specifically includes:

[0017] S11. Place the C-side sapphire substrate inside the physical vapor deposition reaction chamber;

[0018] S12. Evacuate the physical vapor deposition reaction chamber to a vacuum level of 5*10. -5 Pa;

[0019] S13. Argon and nitrogen are introduced into the physical vapor deposition reaction chamber, wherein the flow ratio of argon to nitrogen is 8:1, and the vacuum degree of the physical vapor deposition reaction chamber is controlled at 1 Pa.

[0020] S13. Preheat the C-side sapphire substrate and aluminum target to 200°C;

[0021] S14. DC sputtering is performed on the C-plane sapphire substrate, wherein the sputtering power is 300W, the sputtering rate is 0.1nm / s, and the sputtering time is 100.00s, so as to deposit a first three-dimensional columnar structure on the C-plane sapphire substrate.

[0022] Preferably, step S2 specifically includes:

[0023] S21. Place the C-plane sapphire substrate inside the MOCVD reaction chamber;

[0024] S22. Set the temperature of the MOCVD reaction chamber to 1100℃ and the gas pressure to 50mbar.

[0025] S23. Using hydrogen as a carrier gas, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylaluminum to ammonia is 5:3:500, so as to generate an aluminum nitride epitaxial structure on the first three-dimensional columnar structure.

[0026] S24. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the aluminum nitride epitaxial structure to 0.2 nm / s and the growth time to 50.00 s.

[0027] Preferably, step S3 specifically includes:

[0028] S31. Place the C-plane sapphire substrate inside the physical vapor deposition reaction chamber;

[0029] S32. Evacuate the physical vapor deposition reaction chamber to a vacuum level of 5*10. -5 Pa;

[0030] S33. Argon and nitrogen are introduced into the physical vapor deposition reaction chamber, wherein the flow ratio of argon to nitrogen is 8:1, and the vacuum degree of the physical vapor deposition reaction chamber is controlled at 1 Pa.

[0031] S34. Preheat the C-side sapphire substrate and aluminum target to 200°C;

[0032] S35. DC sputtering is performed on the C-plane sapphire substrate, wherein the sputtering power is 300W, the sputtering rate is 0.1nm / s, and the sputtering time is 100.00s, to deposit a second three-dimensional columnar structure on the aluminum nitride epitaxial structure.

[0033] Preferably, step S4 specifically includes:

[0034] S411. Place the C-plane sapphire substrate inside the MOCVD reaction chamber;

[0035] S412. Set the temperature of the MOCVD reaction chamber to 1080℃ and the gas pressure to 100mbar.

[0036] S413. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium to ammonia is 5:3:1500, in order to generate a gallium nitride channel layer on the second three-dimensional columnar structure.

[0037] S414. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the gallium nitride channel layer to 0.6 nm / s and the growth time to 375.00 s.

[0038] S415. Using hydrogen as a carrier gas, trimethylgallium, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium, trimethylaluminum and ammonia is 800, so as to generate an aluminum gallium nitride barrier layer on the gallium nitride channel layer.

[0039] S416. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the aluminum gallium nitride barrier layer to 0.4 nm / s and the growth time to 62.50 s.

[0040] S417. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber to generate a gallium nitride cap layer on the aluminum gallium nitride barrier layer.

[0041] S418. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the gallium nitride cap layer to 0.5 nm / s and the growth time to 4.00 s.

[0042] Specifically, the aluminum composition of the aluminum gallium nitride barrier layer is 25%.

[0043] Preferably, step S4 specifically includes:

[0044] S421. Place the C-plane sapphire substrate inside the MOCVD reaction chamber;

[0045] S422. Set the temperature of the MOCVD reaction chamber to 1110℃ and the gas pressure to 70mbar.

[0046] S423. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium to ammonia is 5:3:1500, in order to generate a gallium nitride channel layer on the second three-dimensional columnar structure.

[0047] S424. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the gallium nitride channel layer to 0.6 nm / s and the growth time to 333.33 s.

[0048] S425. Using hydrogen as a carrier gas, trimethylgallium, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium, trimethylaluminum and ammonia is 5:3:600, so as to generate an aluminum gallium nitride barrier layer on the gallium nitride channel layer.

[0049] S426. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the aluminum gallium nitride barrier layer to 0.3 nm / s and the growth time to 66.67 s.

[0050] S427. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber to generate a gallium nitride cap layer on the aluminum gallium nitride barrier layer.

[0051] S428. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the gallium nitride cap layer to 0.5 nm / s and the growth time to 3.00 s.

[0052] Specifically, the aluminum composition of the aluminum gallium nitride barrier layer is 30%.

[0053] Preferably, the size of the C-side sapphire substrate is 6 to 8 inches.

[0054] Accordingly, the present invention also discloses a large-size, low-stress nitride epitaxial material, which is prepared by the large-size, low-stress nitride epitaxial material preparation method described above. The large-size, low-stress nitride epitaxial material includes a C-plane sapphire substrate and a first three-dimensional columnar structure, an aluminum nitride epitaxial structure, a second three-dimensional columnar structure, and an epitaxial functional layer sequentially epitaxially formed on the C-plane sapphire substrate. The epitaxial functional layer consists of a gallium nitride channel layer, an aluminum gallium nitride barrier layer, and a gallium nitride cap layer sequentially epitaxially formed on the second three-dimensional columnar structure. Attached Figure Description

[0055] Figure 1 This is a flowchart of the method for preparing large-size, low-stress nitride epitaxial materials according to the present invention;

[0056] Figure 2 This is a schematic diagram of the structure of the large-size, low-stress nitride epitaxial material of the present invention;

[0057] Figure 3 This is a schematic diagram of the first three-dimensional columnar structure or the second three-dimensional columnar structure of the present invention;

[0058] Figure 4 This is a topographic diagram of the epitaxial functional layer of the present invention;

[0059] Figure 5 This is a test image showing the curvature test of the epitaxial structure of the large-size, low-stress nitride epitaxial material prepared by the method of the present invention. Detailed Implementation

[0060] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0061] Please see Figures 1-5 As shown, the method for preparing large-size, low-stress nitride epitaxial materials in this embodiment is used to prepare large-size, low-stress nitride epitaxial materials. The large-size, low-stress nitride epitaxial materials include a C-plane sapphire substrate 1 and a first three-dimensional columnar structure 2, an aluminum nitride epitaxial structure 3, a second three-dimensional columnar structure 4, and an epitaxial functional layer 5 sequentially epitaxially formed on the C-plane sapphire substrate 1. The epitaxial functional layer 5 consists of a gallium nitride channel layer 51, an aluminum gallium nitride barrier layer 52, and a gallium nitride cap layer 53 sequentially epitaxially formed on the second three-dimensional columnar structure 4. The aluminum nitride epitaxial structure 3 and the epitaxial functional layer 5 are the epitaxial structures of the large-size, low-stress nitride epitaxial materials.

[0062] It is understandable that the epitaxial structure is grown on a three-dimensional columnar structure, which is suitable for making the thickness of the epitaxial structure thinner, thereby reducing the thickness of the finished material. Since the thickness of the epitaxial structure is much smaller than that of traditional epitaxial materials, it greatly saves the preparation time and cost of the epitaxial structure. Furthermore, due to the small thickness of the epitaxial structure, there is no need to design stress relief layers and high-pressure control layers, further reducing the preparation process and cost.

[0063] The method for preparing this large-size, low-stress nitride epitaxial material includes the following steps:

[0064] S1. A first three-dimensional columnar structure 2 is deposited on a C-plane sapphire substrate 1 using physical vapor deposition.

[0065] S2. Place the C-plane sapphire substrate 1 in the MOCVD reaction chamber and use the MOCVD process to generate an aluminum nitride epitaxial structure 3 on the first three-dimensional columnar structure 2.

[0066] S3. A second three-dimensional columnar structure 4 is deposited on the aluminum nitride epitaxial structure 3 using physical vapor deposition.

[0067] S4. Place the C-plane sapphire substrate 1 in the MOCVD reaction chamber and use the MOCVD process to generate an epitaxial functional layer 5 on the second three-dimensional columnar structure 4.

[0068] The first three-dimensional columnar structure 2, the aluminum nitride epitaxial structure 3, and the second three-dimensional columnar structure 4 together constitute the three-dimensional epitaxial structure.

[0069] It is understandable that the size of commercially available large-size nitride epitaxial materials is mainly 6 to 8 inches, correspondingly requiring a 6 to 8-inch C-plane sapphire substrate 1 for fabrication. This embodiment uses a 6-inch nitride epitaxial material as an example, in which case the C-plane sapphire substrate 1 is 6 inches. Of course, for nitride epitaxial materials with sizes of 6 to 8 inches, the C-plane sapphire substrate 1 used is also 6 to 8 inches. Furthermore, the method for preparing large-size, low-stress nitride epitaxial materials provided in this embodiment is also applicable to other sizes of nitride epitaxial materials (such as nitride epitaxial materials smaller than 6 inches and nitride epitaxial materials larger than 8 inches).

[0070] Preferably, step S1 specifically includes:

[0071] S11. Place the C-plane sapphire substrate 1 inside the physical vapor deposition reaction chamber.

[0072] S12. Evacuate the physical vapor deposition reaction chamber to a vacuum level of 5*10. -5 Pa.

[0073] S13. Argon and nitrogen are introduced into the physical vapor deposition reaction chamber, wherein the flow ratio of argon to nitrogen is 8:1, and the vacuum degree of the physical vapor deposition reaction chamber is controlled at 1 Pa.

[0074] S13. Preheat the C-side sapphire substrate 1 and the aluminum target to 200°C.

[0075] S14. DC sputtering is performed on the C-plane sapphire substrate 1, wherein the sputtering power is 300W, the sputtering rate is 0.1nm / s, and the sputtering time is 100.00s, so as to deposit a first three-dimensional columnar structure 2 on the C-plane sapphire substrate 1. The thickness of the first three-dimensional columnar structure 2 obtained at this time is 10nm, which is actually an aluminum nitride three-dimensional epitaxial layer.

[0076] Preferably, step S2 specifically includes:

[0077] S21. Place the C-plane sapphire substrate 1 into the MOCVD reaction chamber;

[0078] S22. Set the temperature of the MOCVD reaction chamber to 1100℃ and the gas pressure to 50mbar.

[0079] S23. Using hydrogen as a carrier gas, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylaluminum to ammonia is 500, so as to generate an aluminum nitride epitaxial structure 3 on the first three-dimensional columnar structure 2.

[0080] S24. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of aluminum nitride epitaxial structure 3 to 0.2 nm / s and the growth time to 50.00 s. At this time, the thickness of aluminum nitride epitaxial structure 3 is 10 nm.

[0081] Preferably, step S3 specifically includes:

[0082] S31. Place the C-plane sapphire substrate 1 inside the physical vapor deposition reaction chamber;

[0083] S32. Evacuate the physical vapor deposition reaction chamber to a vacuum level of 5*10. -5 Pa;

[0084] S33. Argon and nitrogen are introduced into the physical vapor deposition reaction chamber, wherein the flow ratio of argon to nitrogen is 8:1, and the vacuum degree of the physical vapor deposition reaction chamber is controlled at 1 Pa.

[0085] S34. Preheat the C-side sapphire substrate 1 and the aluminum target to 200°C;

[0086] S35. DC sputtering is performed on the C-plane sapphire substrate 1, wherein the sputtering power is 300W, the sputtering rate is 0.1nm / s, and the sputtering time is 100.00s, to deposit a second three-dimensional columnar structure 4 on the aluminum nitride epitaxial structure 3. The thickness of the second three-dimensional columnar structure 4 obtained at this time is 10nm, which is actually an aluminum nitride three-dimensional epitaxial layer. Figure 3 The three-dimensional columnar morphology of the aluminum nitride three-dimensional epitaxial layer is shown.

[0087] Preferably, step S4 specifically includes:

[0088] S411. Place the C-plane sapphire substrate 1 into the MOCVD reaction chamber;

[0089] S412. Set the temperature of the MOCVD reaction chamber to 1080℃ and the gas pressure to 100mbar.

[0090] S413. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium to ammonia is 5:3:1500, so as to generate a gallium nitride channel layer 51 on the second three-dimensional columnar structure 4. The thickness of the gallium nitride channel layer 51 obtained at this time is 150nm.

[0091] S414. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of gallium nitride channel layer 51 to 0.6 nm / s and the growth time to 375.00 s.

[0092] S415. Using hydrogen as a carrier gas, trimethylgallium, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium, trimethylaluminum and ammonia is 800, so as to generate an aluminum gallium nitride barrier layer 52 on the gallium nitride channel layer 51.

[0093] S416. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the aluminum gallium nitride barrier layer 52 to 0.4 nm / s and the growth time to 62.50 s. At this time, the thickness of the aluminum gallium nitride barrier layer 52 is 25 nm.

[0094] S417. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber to generate a gallium nitride cap layer 53 on the aluminum gallium nitride barrier layer 52.

[0095] S418. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of gallium nitride cap layer 53 to 0.5 nm / s and the growth time to 4.00 s. At this time, the thickness of gallium nitride cap layer 53 is 2 nm.

[0096] Specifically, the aluminum composition of the aluminum gallium nitride barrier layer 52 is 25%.

[0097] Through the above steps, an epitaxial functional layer 5 with a total thickness of 177 nm is obtained. Combined with the thicknesses of the second three-dimensional columnar structure 4, the aluminum nitride epitaxial structure 3, and the first three-dimensional columnar structure 2, an epitaxial material with a total thickness of 207 nm is obtained. This epitaxial material is approximately one-twentieth the thickness of conventional epitaxial materials, and its epitaxial surface morphology is as follows: Figure 4 As shown, from Figure 4 As can be seen, the large-size, low-stress nitride epitaxial material prepared in this embodiment achieves a relatively smooth epitaxial surface.

[0098] Figure 5 Test data for epitaxial curvature testing of this large-size, low-stress nitride epitaxial material are shown. Figure 5 It can be seen that the TTV, WARP, and other epitaxial materials that have been grown are all in the range of a few micrometers, which is comparable to the value of a commercial 6-inch sapphire substrate. Therefore, a state of no epitaxial stress has been basically achieved.

[0099] To adapt this embodiment to radio frequency material applications, the parameters of step S4 in this embodiment can be adjusted so that the actually generated epitaxial functional layer 5 is a radio frequency channel layer. In this case, step S4 specifically includes:

[0100] S421. Place the C-plane sapphire substrate 1 into the MOCVD reaction chamber;

[0101] S422. Set the temperature of the MOCVD reaction chamber to 1110℃ and the gas pressure to 70mbar.

[0102] S423. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium to ammonia is 5:3:1500, so as to generate a gallium nitride channel layer 51 on the second three-dimensional columnar structure 4.

[0103] S424. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of gallium nitride channel layer 51 to 0.6 nm / s and the growth time to 333.33 s. At this time, the thickness of gallium nitride channel layer 51 is 200 nm.

[0104] S425. Using hydrogen as a carrier gas, trimethylgallium, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium, trimethylaluminum and ammonia is 5:3:600, so as to generate an aluminum gallium nitride barrier layer 52 on the gallium nitride channel layer 51.

[0105] S426. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of the aluminum gallium nitride barrier layer 52 to 0.3 nm / s and the growth time to 66.67 s. At this time, the thickness of the aluminum gallium nitride barrier layer 52 is 20 nm.

[0106] S427. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber to generate a gallium nitride cap layer 53 on the aluminum gallium nitride barrier layer 52.

[0107] S428. Control the hydrogen carrier gas rate and carrier gas time to control the growth rate of gallium nitride cap layer 53 to 0.5 nm / s and the growth time to 3.00 s. At this time, the thickness of gallium nitride cap layer 53 is 1.5 nm.

[0108] Specifically, the aluminum composition of the aluminum gallium nitride barrier layer 52 is 30%.

[0109] Preferably, the size of the C-side sapphire substrate 1 is 6 to 8 inches.

[0110] Understandably, this invention addresses the issues of high internal stress and excessive curvature in epitaxial layers by combining a three-dimensional structural layer with an epitaxial functional layer 5. This invention directly fabricates the epitaxial functional layer 5 on a three-dimensional structure, eliminating the need for the stress-regulating layer and doped voltage-resistant layer found in traditional epitaxial structures. Because these layers are unnecessary, the overall epitaxial material thickness is significantly thinner, less than 500 nm, effectively achieving high device performance with a single thin-layer structure. Furthermore, the relatively thin epitaxial material structure, much smaller than traditional structures (which refer to epitaxial material structures larger than 3 micrometers), results in lower epitaxial stress, leading to a smaller curvature and higher yield in epitaxial chip fabrication.

[0111] For other types of large-size materials, under the condition that the thickness of the aluminum nitride three-dimensional epitaxial layer is between 5-15nm and the thickness of the aluminum nitride epitaxial structure 3 is between 2-5nm, or the total thickness of the periodic structure design of the aluminum nitride three-dimensional epitaxial layer, aluminum nitride epitaxial structure 3, and aluminum nitride three-dimensional epitaxial layer does not exceed 100nm and the total thickness of the epitaxial functional layer 5 does not exceed 500nm, it is possible to achieve epitaxial materials with larger size and thinner total thickness.

[0112] Combination Figures 1-5 The present invention sequentially forms a first three-dimensional columnar structure 2, an aluminum nitride epitaxial structure 3, a second three-dimensional columnar structure 4, and an epitaxial functional layer 5 on a C-plane sapphire substrate 1. By adding the first three-dimensional columnar structure 2 and the second three-dimensional columnar structure 4, the thickness of the aluminum nitride epitaxial structure 3 and the epitaxial functional layer 5 can be effectively reduced, thereby reducing the thickness of the finished material. Since the thickness of the epitaxial structure is much smaller than that of traditional epitaxial materials, the preparation time and cost of the epitaxial structure are greatly saved. Furthermore, due to the small thickness of the epitaxial structure, there is no need to design a stress relief layer and a high-voltage control layer, further reducing the preparation process and cost.

[0113] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing large-size, low-stress nitride epitaxial materials, characterized in that, Includes the following steps: A first three-dimensional columnar structure was deposited on a C-plane sapphire substrate using physical vapor deposition. A C-plane sapphire substrate was placed in the MOCVD reaction chamber, and an aluminum nitride epitaxial structure was generated on the first three-dimensional columnar structure using the MOCVD process. A second three-dimensional columnar structure was deposited on an aluminum nitride epitaxial structure using physical vapor deposition. A C-plane sapphire substrate is placed in an MOCVD reaction chamber, and an epitaxial functional layer is generated on the second three-dimensional columnar structure using the MOCVD process. The deposition of the first three-dimensional columnar structure on a C-plane sapphire substrate using physical vapor deposition specifically includes: The C-side sapphire substrate is placed inside the physical vapor deposition reaction chamber; The vacuum level in the physical vapor deposition reaction chamber was evacuated to 5*10. -5 Pa; Argon and nitrogen are introduced into the physical vapor deposition reaction chamber, with a flow rate ratio of 8:1 for argon and nitrogen, and the vacuum level of the physical vapor deposition reaction chamber is controlled at 1 Pa. Preheat the C-side sapphire substrate and aluminum target to 200°C; DC sputtering was performed on the C-plane sapphire substrate, wherein the sputtering power was 300W, the sputtering rate was 0.1nm / s, and the sputtering time was 100.00s, in order to deposit a first three-dimensional columnar structure on the C-plane sapphire substrate. The deposition of a second three-dimensional columnar structure on an aluminum nitride epitaxial structure using physical vapor deposition specifically includes: The C-side sapphire substrate is placed inside the physical vapor deposition reaction chamber; The vacuum level in the physical vapor deposition reaction chamber was evacuated to 5*10. -5 Pa; Argon and nitrogen are introduced into the physical vapor deposition reaction chamber, with a flow rate ratio of 8:1 for argon and nitrogen, and the vacuum level of the physical vapor deposition reaction chamber is controlled at 1 Pa. Preheat the C-side sapphire substrate and aluminum target to 200°C; DC sputtering was performed on the C-plane sapphire substrate, with a sputtering power of 300W, a sputtering rate of 0.1nm / s, and a sputtering time of 100.00s, to deposit a second three-dimensional columnar structure on the aluminum nitride epitaxial structure.

2. The method for preparing large-size, low-stress nitride epitaxial materials as described in claim 1, characterized in that, The step of placing the C-plane sapphire substrate within the MOCVD reaction chamber and using the MOCVD process to generate an aluminum nitride epitaxial structure on the first three-dimensional columnar structure specifically includes: The C-plane sapphire substrate is placed inside the MOCVD reaction chamber; Set the temperature of the MOCVD reaction chamber to 1100℃ and the gas pressure to 50mbar. Using hydrogen as a carrier gas, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylaluminum to ammonia is 5:3:500, in order to generate an aluminum nitride epitaxial structure on the first three-dimensional columnar structure. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the aluminum nitride epitaxial structure to 0.2 nm / s and the growth time to 50.00 s.

3. The method for preparing large-size, low-stress nitride epitaxial materials as described in claim 1, characterized in that, The epitaxial functional layer comprises a gallium nitride channel layer, an aluminum gallium nitride barrier layer, and a gallium nitride cap layer sequentially epitaxially formed on the second three-dimensional columnar structure. The step of placing the C-plane sapphire substrate within the MOCVD reaction chamber and using MOCVD technology to form the epitaxial functional layer on the second three-dimensional columnar structure specifically includes: The C-plane sapphire substrate is placed inside the MOCVD reaction chamber; Set the temperature of the MOCVD reaction chamber to 1080℃ and the gas pressure to 100mbar. Using hydrogen as the carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium to ammonia is 5:3:1500, in order to generate a gallium nitride channel layer on the second three-dimensional columnar structure. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the gallium nitride channel layer to 0.6 nm / s and the growth time to 375.00 s. Using hydrogen as the carrier gas, trimethylgallium, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium, trimethylaluminum and ammonia is 800, in order to generate an aluminum gallium nitride barrier layer on the gallium nitride channel layer. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the aluminum gallium nitride barrier layer to 0.4 nm / s and the growth time to 62.50 s. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber to generate a gallium nitride cap layer on the aluminum gallium nitride barrier layer. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the gallium nitride cap layer to 0.5 nm / s and the growth time to 4.00 s.

4. The method for preparing large-size, low-stress nitride epitaxial materials as described in claim 3, characterized in that, The aluminum composition of the aluminum gallium nitride barrier layer is 25%.

5. The method for preparing large-size, low-stress nitride epitaxial materials as described in claim 1, characterized in that, The epitaxial functional layer comprises a gallium nitride channel layer, an aluminum gallium nitride barrier layer, and a gallium nitride cap layer sequentially arranged. The process of placing the C-plane sapphire substrate within the MOCVD reaction chamber and using MOCVD technology to generate the epitaxial functional layer on the second three-dimensional columnar structure specifically includes: The C-plane sapphire substrate is placed inside the MOCVD reaction chamber; Set the temperature of the MOCVD reaction chamber to 1110℃ and the gas pressure to 70mbar. Using hydrogen as the carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium to ammonia is 5:3:1500, in order to generate a gallium nitride channel layer on the second three-dimensional columnar structure. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the gallium nitride channel layer to 0.6 nm / s and the growth time to 333.33 s. Using hydrogen as the carrier gas, trimethylgallium, trimethylaluminum and ammonia are introduced into the MOCVD reaction chamber, wherein the ratio of trimethylgallium, trimethylaluminum and ammonia is 5:3:600, in order to generate an aluminum gallium nitride barrier layer on the gallium nitride channel layer. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the aluminum gallium nitride barrier layer to 0.3 nm / s and the growth time to 66.67 s. Using hydrogen as a carrier gas, trimethylgallium and ammonia are introduced into the MOCVD reaction chamber to generate a gallium nitride cap layer on the aluminum gallium nitride barrier layer. The hydrogen carrier gas rate and carrier gas time were controlled to control the growth rate of the gallium nitride cap layer to 0.5 nm / s and the growth time to 3.00 s.

6. The method for preparing large-size, low-stress nitride epitaxial materials as described in claim 5, characterized in that, The aluminum composition of the aluminum gallium nitride barrier layer is 30%.

7. The method for preparing large-size, low-stress nitride epitaxial materials as described in claim 1, characterized in that, The C-side sapphire substrate is 6 to 8 inches in size.

8. A large-size, low-stress nitride epitaxial material, characterized in that, The large-size, low-stress nitride epitaxial material is prepared by any one of the methods described in claims 1-7. The large-size, low-stress nitride epitaxial material includes a C-plane sapphire substrate and a first three-dimensional columnar structure, an aluminum nitride epitaxial structure, a second three-dimensional columnar structure, and an epitaxial functional layer sequentially epitaxially formed on the C-plane sapphire substrate. The epitaxial functional layer consists of a gallium nitride channel layer, an aluminum gallium nitride barrier layer, and a gallium nitride cap layer sequentially epitaxially formed on the second three-dimensional columnar structure.

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