Epitaxial structure of silicon-based gallium nitride HEMT device and preparation method thereof

Abstract

The invention discloses an epitaxial structure of a silicon-based gallium nitride HEMT device and a preparation method of the epitaxial structure, the epitaxial structure comprises a Si substrate, an AlN nucleation layer, an AlGaN transition layer, a stress control layer, a high-resistance GaN layer, an unintentionally doped GaN layer, an AlGaN barrier layer and a cap layer from bottom to top, the stress control layer comprises a repetitive periodic structure n which is stacked in sequence, n is a natural number greater than 0, and n is an integer greater than 0. The material of the repetitive periodic structure n is (AlN / AlxnIn1-xnN / AlynGa1-ynN) pn, pn is the number of repetitive cycles, and pn is greater than or equal to 2 and less than or equal to 70, 99% lt; xn is smaller than 100%, yn is larger than 0 and smaller than 100%, and the single-cycle thickness of the repetitive periodic structure n ranges from 70 nm to 280 nm. By growing a repetitive periodic structure (AlN / AlxnIn1-xnN / AlynGa1-ynN) pn on the stress control layer, the thickness of a single cycle is large, the number of cycles of the repetitive structure is greatly reduced, the controllable stress and warping range is large, the room temperature stress and warping of the epitaxial wafer are accurately adjusted through the periodic thickness of the repetitive structure in the large warping range, and the yield of the epitaxial wafer is improved. And the adjusted thickness parameter and the warping change form a better regular correlation.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an epitaxial structure of a silicon-based gallium nitride HEMT device and a preparation method thereof. Background Art

[0002] Silicon-based gallium nitride (GaN-on-Si) power devices are widely used in the semiconductor field, especially in situations where high efficiency and high frequency are required. In the fields of electric vehicles, wireless charging, solar inverters and switching power supplies, the efficient conversion capability and high-frequency operation capability of silicon-based gallium nitride power devices have greatly improved the power density and energy efficiency of the system. For example, in the power transmission and management system of electric vehicles, silicon-based gallium nitride devices can effectively reduce energy loss and improve endurance. At the same time, in consumer electronics, they are also widely used to improve wireless charging efficiency and miniaturization of equipment.

[0003] Conventional silicon-based gallium nitride power epitaxial materials are grown on silicon substrates, but due to the large thermal mismatch and lattice mismatch between the epitaxial material and the substrate, a complex stress control layer needs to be introduced into the epitaxial structure to control the stress during epitaxial growth, so that the warping and stress of the epitaxial wafer after epitaxial growth are small at room temperature, reducing the tensile stress and cracks in the epitaxial material. Conventional stress control layers include one or more groups of gallium nitride superlattices. The AlN / AlGaN superlattice, which is widely used at present, usually has a thin period thickness of 5nm to 60nm. The optimal growth conditions of the AlN and AlGaN materials in the superlattice are different due to the different material combinations. Therefore, in order to achieve the designed total epitaxial thickness, during the epitaxial growth process, the epitaxial machine needs to frequently switch the epitaxial growth conditions so as to use the optimal conditions to grow the AlN layer and AlGaN layer in the superlattice respectively. The switching of epitaxial conditions may involve parameters such as temperature, pressure, and gas flow rates. The change of these conditions greatly increases the time required for epitaxial growth, reduces the production capacity of the machine, and increases the wear and tear of machine components (such as pneumatic valves, heaters, etc.).

[0004] Another important issue with conventional AlN / AlGaN superlattice stress control layers involves the warpage control of epitaxial wafers. Changes in substrate thickness, epitaxial thickness, and even substrate suppliers will require adjustments to the epitaxial process so that the warpage of the final epitaxial wafer is controlled within a certain range. When using this AlN / AlGaN superlattice as a stress layer, the warpage control and adjustment of the epitaxial wafer is difficult and can only be changed within a small range, making it difficult to adapt to the demand for precise control of wafer warpage during mass growth. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide an epitaxial structure of a silicon-based gallium nitride HEMT device and a preparation method thereof, which can reduce the time-consuming and loss problems caused by frequent switching of epitaxial growth conditions by the epitaxial machine, and at the same time facilitate the warpage control of the epitaxial wafer.

[0006] To solve the above technical problems, the present invention provides an epitaxial structure of a silicon-based gallium nitride HEMT device, which includes, from bottom to top:

[0007] A Si substrate, an AlN nucleation layer, an AlGaN transition layer, a stress control layer, a high-resistance GaN layer, an unintentionally doped GaN layer, an AlGaN barrier layer, and a cap layer. Among them, the stress control layer includes:

[0008] A repetitive periodic structure n stacked in sequence, where n is a natural number greater than 0. The material of the repetitive periodic structure n is (AlN / Al xn In 1-xn N / Al yn Ga 1-yn N) pn , where pn is the number of repetition periods, 2 ≤ pn ≤ 70, 99% < xn < 100%, 0 < yn < 100%, and the thickness of a single period of the repetitive periodic structure n is 70 nm to 280 nm.

[0009] In a specific embodiment, the thickness of Al xn In 1-xn N in a single period is 0.1 nm to 1 nm.

[0010] In a specific embodiment, the thickness of AlN in a single period is 6 nm to 30 nm.

[0011] In a specific embodiment, the thickness of Al yn Ga 1-yn N in a single period is 50 nm to 250 nm.

[0012] In a specific embodiment, the stress control layer is undoped or doped with C or Fe elements.

[0013] Based on the same inventive concept, the present invention also provides a preparation method for an epitaxial structure of a silicon-based gallium nitride HEMT device, including:

[0014] Step S1: Provide a Si substrate;

[0015] Step S2: Grow an AlN nucleation layer on the Si substrate;

[0016] Step S3: Grow an AlGaN transition layer on the AlN nucleation layer;

[0017] Step S4: Grow a stress control layer on the AlGaN transition layer, including growing a repetitive periodic structure n stacked in sequence, where n is a natural number greater than 0, and the material of the repetitive periodic structure n is (AlN / Al xn In 1-xn N / Al yn Ga 1-yn N) pn , where pn is the number of repetition periods, 2 ≤ pn ≤ 70, 99% < xn < 100%, 0 < yn < 100%, and the single-period thickness of the repetitive periodic structure n is 70 nm to 280 nm;

[0018] Step S5: Grow a high-resistance GaN layer, an unintentionally doped GaN layer, and an AlGaN barrier layer in sequence on the stress control layer;

[0019] Step S6: Grow a cap layer on the AlGaN barrier layer.

[0020] Preferably, the growth temperature of the stress control layer is 950 °C to 1200 °C, in an H 2 or N 2 atmosphere, the growth pressure is 30 to 500 mbar, and the thickness is 400 nm to 5500 nm.

[0021] In a specific embodiment, the Si substrate is subjected to high-temperature annealing in an H 2 atmosphere in an MOCVD reaction chamber, the annealing temperature is 900 °C to 1200 °C, the annealing time is 1 to 10 min, the H 2 flow rate is 1 to 100 L, and the pressure in the reaction chamber is 30 to 800 mbar.

[0022] In a specific embodiment, after high-temperature annealing, an Al source is pre-passed for a time of 3 sec to 90 sec, and the flow rate of trimethylaluminum (TMA) is 0.5 to 100 μmol / min.

[0023] Based on the same inventive concept, the present invention also provides a silicon-based gallium nitride HEMT device.

[0024] Compared with the prior art, the present invention provides an epitaxial structure of a silicon-based gallium nitride HEMT device and a preparation method thereof, and its beneficial effects at least include:

[0025] 1. By growing a repetitive periodic structure (AlN / Al xn In 1-xn N / Al yn Ga 1-yn N) pnCompared with superlattice, the single-period thickness is larger (70nm-280nm), and the number of periods of the repeated structure is greatly reduced, which reduces the number of epitaxial growth switching times of the machine, greatly reduces the time required for condition changes when switching between different material growths, saves production time, increases machine capacity, and reduces the damage of machine components (such as pneumatic valves, heaters, etc.);

[0026] 2. When the structure of the present invention is used, the stress and warping range that can be controlled is relatively large. Within the relatively large warping range, the room temperature stress and warping of the epitaxial wafer can be accurately adjusted by the periodic thickness of the periodically repeated structure. The adjusted thickness parameters and the change in warping form a relatively good regular correlation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the accompanying drawings, each identical or nearly identical component shown in different drawings is represented by a similar reference numeral. For clarity, not every component in every drawing will be labeled. The drawings are not necessarily drawn to scale, but instead emphasis is placed on illustrating various aspects of the techniques and devices described herein.

[0028] Figure 1 A schematic diagram of the epitaxial structure of a silicon-based gallium nitride HEMT device of the present invention is shown;

[0029] Figure 2a A schematic diagram of the epitaxial structure of sample 1 in embodiment 1 of the present invention is shown;

[0030] Figure 2b A schematic diagram of the stress control layer structure of sample 2 in embodiment 1 of the present invention is shown;

[0031] Figure 2c A schematic diagram of the stress control layer structure of sample three in embodiment one of the present invention is shown;

[0032] Figure 3 shows an in-situ curvature diagram of Embodiment 1 of the present invention;

[0033] Figure 4a A schematic diagram of the epitaxial structure of sample 1 in embodiment 2 of the present invention is shown;

[0034] Figure 4b A schematic diagram of the stress control layer structure of sample 2 in embodiment 2 of the present invention is shown;

[0035] Figure 5 The in-situ curvature diagram of the second embodiment of the present invention is shown.

[0036] The reference numerals are described as follows:

[0037] 1-Si substrate, 2-AlN nucleation layer, 3-AlGaN transition layer, 4-stress control layer, 5-high resistance GaN layer, 6-unintentionally doped GaN layer, 7-AlGaN barrier layer, 8-cap layer. DETAILED DESCRIPTION

[0038] The epitaxial structure of the silicon-based gallium nitride HEMT device and the preparation method thereof proposed by the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0039] Figure 1 The schematic diagram of the epitaxial structure of a silicon-based gallium nitride HEMT device is shown, with a Si substrate 1 at the bottom, and AlN nucleation layer 2, AlGaN transition layer 3, stress control layer 4, high-resistance GaN layer 5, unintentionally doped GaN layer 6, AlGaN barrier layer 7, and cap layer 8 stacked in sequence from bottom to top.

[0040] The preparation method is as follows:

[0041] Si substrate 1 is placed in MOCVD reaction chamber 2 High temperature annealing is carried out in the atmosphere, the annealing temperature is 900℃~1200℃, the annealing time is 1min~10min, H 2 Flow rate 1L~100L, pressure in reaction chamber 30mbar~800mbar.

[0042] Pre-pass Al source for 3 sec to 90 sec, TMA flow rate is 0.5 μmol / min to 100 μmol / min;

[0043] Growing an AlN nucleation layer 2 with a thickness ranging from 5 nm to 300 nm;

[0044] Growing an AlGaN transition layer 3 with a thickness ranging from 0 nm to 500 nm;

[0045] Growth stress control layer 4, growth temperature 950 ℃ ~ 1200 ℃, H 2 or N 2atmosphere, growth pressure 30mbar~500mbar, thickness range 400nm~5500nm, preferably thickness range 1608nm~2695nm. The material of stress control layer 4 can be undoped, or doped with C (unintentional doping or external doping), Fe and other elements. The thickness range of single period structure is 70nm~280nm, preferably 71nm~268nm. The number of periods is 2~70, preferably 2~24; the thickness range of AlN is 6nm~30nm, preferably 11nm~17nm; Al xn In 1-xn N thickness range 0.1nm~1nm, 0<In component<1%; Al yn Ga 1-yn N thickness ranges from 50nm to 250nm, preferably from 64nm to 250nm;

[0046] Grow high-resistance GaN layer 5 at a growth temperature of 950°C to 1200°C. 2 or N 2 atmosphere, growth pressure 30mbar~500mbar, thickness range 0nm~3000nm, material can be doped with C (unintentional doping or external doping), Fe and other elements;

[0047] Growth of unintentionally doped GaN layer (UID GaN channel) 6, growth temperature 950℃~1200℃, H 2 or N 2 atmosphere, growth pressure 30mbar~500mbar, thickness range 10nm~1000nm;

[0048] Grow AlGaN barrier layer 7 at a growth temperature of 950°C to 1200°C. 2 or N 2 Atmosphere, growth pressure 30mbar~500mbar, thickness range 1nm~50nm, material is non-doped. Preferably, before growing the AlGaN barrier layer 7, an AlN layer with a thickness of 0.1nm~2.0nm is grown under the same growth conditions, which plays an important role in improving interface quality, relieving stress, optimizing the performance of the AlGaN barrier layer 7, improving thermal stability and regulating the growth mode;

[0049] A cap layer 8 is grown, and the material of the cap layer 8 can be an unintentionally doped GaN layer with a thickness of 0.5nm to 5nm; the cap layer 8 can also be a P-type doped GaN layer (P-type GaN cap) with a thickness of 1nm to 200nm, and the dopant is Mg or Zn or other P-type dopants; the cap layer 8 can also be an in-situ grown SiNx material with a thickness of 1nm to 100nm.

[0050] The stress during growth can be controlled by adjusting the thickness of AlN and / or AlGaN in the repetitive periodic structure, thereby achieving the purpose of controlling and adjusting the warpage of the epitaxial wafer at room temperature. In order to keep the total epitaxial thickness consistent, the corresponding number of adjustment cycles is required.

[0051] In addition, the stress during growth can be controlled by adjusting the average Al composition difference between different repetitive periodic structures, thereby achieving the purpose of controlling and adjusting the warpage of the epitaxial wafer at room temperature.

[0052] Figure 2a The schematic diagram of the structure of sample 1 in Example 1 of the present invention is shown, and the specific preparation method is as follows:

[0053] Si (111) substrate 1 is placed in a MOCVD reaction chamber. 2 The annealing temperature was 1100℃, the annealing time was 8min, and the 2 Flow rate 50L, pressure in reaction chamber 50mbar;

[0054] Pre-flow Al source for 10 sec, TMA flow rate 20 μmol / min;

[0055] Growing AlN nucleation layer 2 with a thickness of 50 nm;

[0056] Growth Al 0.50 Ga 0.5 N transition layer 3, thickness is 300nm;

[0057] Growth stress control layer 4, growth temperature 1190℃, H 2 atmosphere, growth pressure 75mbar, the layer includes two repetitive periodic structures, repetitive periodic structure 1 is (AlN: 13nm / Al 0.999 In 0.001 N:1nm / Al 0.30 Ga 0.70 N:82nm) x10 , the repetitive periodic structure 2 is (AlN:13nm / Al 0.999 In 0.001 N:1nm / Al 0.10 Ga 0.90 N:71nm) x20 ;

[0058] Grow high-resistance GaN layer 5 at a growth temperature of 1180°C, H 2 atmosphere, growth pressure 200 mbar, thickness 1500 nm;

[0059] The unintentionally doped GaN layer 6 was grown at a growth temperature of 1180°C and H 2atmosphere, growth pressure 300 mbar, thickness 300 nm;

[0060] Growth Al 0.23 Ga 0.77 N barrier layer 7, growth temperature 1190℃, H 2 atmosphere, growth pressure 75mbar, thickness 12nm, material is non-doped;

[0061] Grow P-type GaN cap layer 8 at 1190°C, H 2 atmosphere, growth pressure 75 mbar, dopant is Mg, thickness is 80 nm.

[0062] Figure 2b The schematic diagram of the stress control layer structure of the sample 2 in the first embodiment of the present invention is shown. The sample 2 is prepared by the same method as the sample 1. The repetitive periodic structure 1 of the stress control layer 4 of the sample 2 is (AlN: 13nm / Al 0.999 In 0.001 N:1nm / Al 0.30 Ga 0.70 N:75nm) x11 , the repetitive periodic structure 2 is (AlN:13nm / Al 0.999 In 0.001 N:1nm / Al 0.10 Ga 0.90 N:64nm) x22 .

[0063] Figure 2c The schematic diagram of the stress control layer structure of sample 3 in Example 1 of the present invention is shown. The stress control layer 4 of sample 3 is prepared in the same manner as sample 1. The repetitive periodic structure 1 is (AlN: 13nm / Al 0.999 In 0.001 N:1nm / Al 0.30 Ga 0.70 N: 66nm) x12 , the repetitive periodic structure 2 is (AlN:13nm / Al 0.999 In 0.001 N:1nm / Al 0.10 Ga 0.90 N:57nm) x24 .

[0064] From sample 1 to sample 2 and then to sample 3, the number of periods of the repetitive periodic structure gradually increases, and the period thickness gradually decreases. The total thickness of the three samples is between 4920nm+-20nm. This embodiment controls the stress during growth by adjusting the thickness of the AlGaN layer and the Al composition in the repetitive periodic structure. Figure 3As shown in the figure, the compressive stress between samples 1, 2, and 3 also gradually decreases as the periodic thickness decreases, which is manifested as the curvature during growth gradually becoming more concave, and the Warp at room temperature also gradually becoming concave. The Warp / Bow values ​​of the three samples change from 8.17 / 1.25 in sample 1 to 21.91 / -10.21 in sample 2 and 26.65 / -11.54 in sample 3. With the continuous change of each parameter, the curvature and Warp / Bow value of the sample also change continuously, with good controllability.

[0065] Under the condition that the total thickness of the stress control layer 4 is basically the same, unlike the traditional superlattice structure with a smaller single-layer thickness, the repetitive periodic structure used in this embodiment has a large single-period thickness and a smaller number of preparation cycles. The time required for the condition change caused by switching the growth of different materials is greatly reduced, and the damage of machine components is also reduced.

[0066] In addition to the obvious differences in the thickness and preparation conditions of the single period of the repetitive periodic structure and the conventional superlattice structure, the repetitive periodic structure of this embodiment is added with Al 0.999 In 0.001 N layer has a special role. First, Al 0.999 In 0.001 The introduction of N layer can act as a buffer layer to adjust stress. 0.999 In 0.001 The In component in the N layer is small, and it still has a lattice constant similar to that of AlN, but the incorporation of In can slightly change the lattice constant, which helps to reduce the lattice mismatch with the upper material AlGaN and reduce the compressive stress relaxation in the AlGaN layer caused by defects, thereby increasing the adjustment range of wafer warpage; secondly, Al 0.999 In 0.001 The growth of the N layer can improve the surface quality and facilitate the growth of the subsequent AlGaN layer. Its surface activation can reduce the defect density.

[0067] Figure 4a The schematic diagram of the structure of sample 1 in Example 2 of the present invention is shown, and the specific preparation method is as follows:

[0068] Si (111) substrate 1 is placed in a MOCVD reaction chamber. 2 The annealing temperature was 1100℃, the annealing time was 8min, and the 2 Flow rate 50L, pressure in reaction chamber 50mbar;

[0069] Pre-flow Al source for 10 sec, TMA flow rate 20 μmol / min;

[0070] Growing AlN nucleation layer 2 with a thickness of 50 nm;

[0071] Growth Al 0.50 Ga 0.5 N transition layer 3, thickness is 300nm;

[0072] Growth stress control layer 4, growth temperature 1190℃, H 2 atmosphere, growth pressure 75mbar, the layer includes two repetitive periodic structures, repetitive periodic structure 1 is (AlN: 11nm / Al 0.999 In 0.001 N:1nm / Al 0.30 Ga 0.70 N:167nm) x3 , the repetitive periodic structure 2 is (AlN:11nm / Al 0.999 In 0.001 N:1nm / Al 0.10 Ga 0.90 N:167nm) x6 ;

[0073] Grow high-resistance GaN layer 5 at a growth temperature of 1180°C, H 2 atmosphere, growth pressure 200 mbar, thickness 1500 nm;

[0074] The unintentionally doped GaN layer 6 was grown at a growth temperature of 1180°C and H 2 atmosphere, growth pressure 300 mbar, thickness 300 nm;

[0075] Growth Al 0.23 Ga 0.77 N barrier layer 7, growth temperature 1190℃, H 2 or N 2 atmosphere, growth pressure 75mbar, thickness 12nm, material is non-doped;

[0076] Growth temperature of P-type GaN cap layer 8 is 1190℃, H 2 atmosphere, growth pressure 75 mbar, dopant is Mg, thickness is 80 nm.

[0077] Figure 4b The schematic diagram of the stress control layer structure of the sample 2 in the second embodiment of the present invention is shown. The sample 2 is prepared by the same method as the sample 1. The repetitive periodic structure 1 of the stress control layer 4 of the sample 2 is (AlN: 17nm / Al 0.999 In 0.001 N:1nm / Al 0.30 Ga 0.70 N:250nm) x2 , the repetitive periodic structure 2 is (AlN:17nm / Al 0.999 In 0.001N:1nm / Al 0.10 Ga 0.90 N:250nm) x4 .

[0078] From sample 1 to sample 2, the number of periods of the repetitive periodic structure gradually decreases, and the period thickness gradually increases. The total thickness of the two samples is between 3850nm+-3nm. This embodiment controls the stress during growth by adjusting the thickness of the AlGaN layer and the difference in Al composition between different repetitive periodic structures. Figure 5 As shown in the figure, the compressive stress between samples 1 and 2 also gradually increases with the increase of periodic thickness, which is manifested as the curvature during growth gradually becoming more convex, and the Warp at room temperature also gradually becoming convex. The Warp / Bow values ​​of the two samples change from 10.58 / 5.21 for sample 1 to 79.19 / 38.67 for sample 2. With the change of various parameters, the curvature and Warp / Bow value of the sample also change continuously, with good controllability.

[0079] Under the condition that the total thickness of the stress control layer 4 is the same, unlike the traditional superlattice structure with a smaller single-layer thickness, the repetitive periodic structure used in this embodiment has a large single-period thickness and a smaller number of preparation cycles. The time required for the condition change caused by switching the growth of different materials is greatly reduced, and the damage of machine components is also reduced.

[0080] In addition to the obvious differences in the thickness and preparation conditions of the single period of the repetitive periodic structure and the conventional superlattice structure, the repetitive periodic structure of this embodiment is added with Al 0.999 In 0.001 N has a special role, first of all, Al 0.999 In 0.001 The introduction of N layer can act as a buffer layer to adjust stress. 0.999 In 0.001 The In component in N is small, and it still has a lattice constant similar to that of AlN, but the incorporation of In can slightly change the lattice constant, which helps to reduce the lattice mismatch with the upper material AlGaN and reduce the compressive stress relaxation in the AlGaN layer caused by defects, thereby increasing the adjustment range of wafer warpage; secondly, Al 0.999 In 0.001 The growth of the N layer can improve the surface quality and facilitate the growth of the subsequent AlGaN layer. Its surface activation can reduce the defect density.

[0081] Comparative Example 1

[0082] The difference from the second embodiment is that the AlInN layer is not used in the repetitive periodic structure. The repetitive periodic structure 1 of the stress control layer 4 of the first sample is (AlN: 11nm / Al 0.30 Ga 0.70N:167nm) x3 , the repetitive periodic structure 2 is (AlN:11nm / Al 0.10 Ga 0.90 N:167nm) x6 ; The repetitive periodic structure 1 of the stress control layer 4 of the sample 2 is (AlN: 17nm / Al 0.30 Ga 0.70 N:250nm) x2 , the repetitive periodic structure 2 is (AlN:17nm / Al 0.10 Ga 0.90 N:250nm) x4 .

[0083] sample Warp(μm) Bow(μm) Sample 1 11.66 6.02 Sample 2 60.35 27.78

[0084] From sample one to sample two, the number of periods of the repetitive periodic structure gradually decreases, and the period thickness gradually increases. The total thickness of the two samples is 3844nm. The compressive stress between samples one and two also gradually increases with the increase of the period thickness, which is manifested as the curvature during growth gradually becomes more convex, and the Warp at room temperature also gradually becomes convex. As shown in the table above, the Warp / Bow values ​​of the two samples change from 11.66 / 6.02 of sample one to 60.35 / 27.87 of sample two. It can be seen that the AlInN layer has a certain degree of influence on the Warp / Bow value, and the adjustable range becomes smaller. With the change of various parameters, the curvature and Warp / Bow value of the sample also change continuously, with relatively good controllability.

[0085] Comparative Example 2

[0086] The difference from Example 1 is that, with reference to Sample 2, Sample 2 and Sample 3 of Example 1, AlN / AlGaN superlattice stress control layer is used, and the superlattice structure 1 of the stress control layer of Sample 1 is (AlN: 3nm / Al 0.30 Ga 0.70 N:35nm) x25 , superlattice structure 2 is (AlN:3nm / Al 0.10 Ga 0.90 N:31nm) x50 ; Sample 2 stress control layer superlattice structure 1 is (AlN: 3nm / Al 0.30 Ga 0.70 N:32nm) x27 , superlattice structure 2 is (AlN:3nm / Al 0.10 Ga 0.90 N:29nm) x54； The three-stress control layer superlattice structure of the sample 1 is (AlN: 3nm / Al 0.30 Ga 0.70 N:29nm)x29 , superlattice structure 2 is (AlN:3nm / Al 0.10 Ga 0.90 N:27nm) x58 .

[0087] sample Warp(μm) Bow(μm) Sample 1 10 2 Sample 2 15 4 Sample 3 11 3

[0088] From sample 1 to sample 2 and then to sample 3, the number of periods of the repetitive periodic structure gradually increases, and the period thickness gradually decreases. The total thickness of the three samples is between 4900nm+-20nm. As shown in the table above, the Warp / Bow values ​​of samples 1, 2, and 3 are 10 / 2, 15 / 4, and 11 / 3. Different from Example 1, the Warp value increases from sample 1 to sample 2, and decreases from sample 2 to sample 3. The adjustable range of Wrap becomes smaller and there is no longer a change pattern of directional consistency.

[0089] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. An epitaxial structure of a silicon-based gallium nitride HEMT device, characterized in that: From bottom to top, it includes: Si substrate, AlN nucleation layer, AlGaN transition layer, stress control layer, high resistance GaN layer, unintentionally doped GaN layer, AlGaN barrier layer, cap layer, wherein the stress control layer comprises: The repetitive periodic structure n stacked in sequence, where n is a natural number greater than 0, and the material of the repetitive periodic structure n is (AlN / Al xn In 1-xn N / Al yn Ga 1-yn N) pn , where pn is the number of repetition periods, 2 ≤ pn ≤ 70, 99% < xn < 100%, 0 < yn < 100%, and the thickness of a single period of the repetitive periodic structure n is 70 nm to 280 nm.

2. The epitaxial structure according to claim 1, characterized in that: Al in a single cycle xn In 1-xn The thickness of N is 0.1nm to 1nm.

3. The epitaxial structure according to claim 1, characterized in that: The thickness of AlN in a single period is 6 nm to 30 nm.

4. The epitaxial structure according to claim 1, characterized in that: Al in a single cycle yn Ga 1-yn The thickness of N is 50nm to 250nm.

5. The epitaxial structure according to claim 1, characterized in that: The stress control layer is undoped or doped with C or Fe elements.

6. A method for preparing an epitaxial structure of a silicon-based gallium nitride HEMT device, characterized in that: include: Step S1: providing a Si substrate; Step S2: growing an AlN nucleation layer on the Si substrate; Step S3: growing an AlGaN transition layer on the AlN nucleation layer; Step S4: Growing a stress control layer on the AlGaN transition layer, including growing a repetitive periodic structure n stacked in sequence, where n is a natural number greater than 0, and the material of the repetitive periodic structure n is (AlN / Al xn In 1-xn N / Al yn Ga 1-yn N) pn , where pn is the number of repetition periods, 2 ≤ pn ≤ 70, 99% < xn < 100%, 0 < yn < 100%, and the single-period thickness of the repetitive periodic structure n is 70 nm to 280 nm; Step S5: sequentially growing a high-resistance GaN layer, an unintentionally doped GaN layer, and an AlGaN barrier layer on the stress control layer; Step S6: growing a cap layer on the AlGaN barrier layer.

7. The method for preparing an epitaxial structure according to claim 6, characterized in that: The stress control layer is grown at a temperature of 950° C. to 1200° C. in an H2 or N2 atmosphere, at a growth pressure of 30 mbar to 500 mbar, and has a thickness of 400 nm to 5500 nm.

8. The method for preparing an epitaxial structure according to claim 6, characterized in that: The Si substrate is subjected to high temperature annealing in a H2 atmosphere in a MOCVD reaction chamber, the annealing temperature is 900°C to 1200°C, the annealing time is 1min to 10min, the H2 flow rate is 1L to 100L, and the pressure in the reaction chamber is 30mbar to 800mbar.

9. The method for preparing an epitaxial structure according to claim 8, characterized in that: After high temperature annealing, the Al source is pre-passed for 3 sec to 90 sec, and the flow rate of TMA is 0.5 μmol / min to 100 μmol / min.

10. A silicon-based gallium nitride HEMT device, characterized in that: The invention comprises the epitaxial structure as claimed in any one of claims 1 to 5.

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