Gallium nitride semiconductor device and preparation method and application thereof

Abstract

The invention discloses a gallium nitride semiconductor device and a preparation method and application thereof. The method comprises the following steps: growing and forming a nucleating layer on a silicon substrate; growing and forming a first two-dimensional GaN layer on the nucleating layer; growing and forming a three-dimensional dislocation annihilation transition layer on the first two-dimensional GaN layer; growing and forming a second two-dimensional GaN layer on the three-dimensional dislocation annihilation transition layer; growing and forming a barrier layer on the second two-dimensional GaN layer; the three-dimensional dislocation annihilation transition layer comprises a mixed island structure formed by at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN and three-dimensional GaN. Accordingly, the invention further provides a gallium nitride semiconductor device, at least one three-dimensional dislocation annihilation transition layer is inserted into the GaN layer, the dislocation density in the GaN epitaxial layer can be effectively reduced, the crystal quality of Si-based GaN is improved, and then the application of the Si-based GaN is effectively expanded.

Description

Technical Field

[0001] The present invention relates to the field of nitride semiconductors, and in particular to silicon-based gallium nitride semiconductor devices applied to semiconductor devices in the radio frequency field. Background Art

[0002] As a typical representative of the third generation of semiconductors, GaN has attracted extensive research due to its large bandgap, high electron mobility, and high electron saturation rate. The gallium nitride high electron mobility transistor (GaN HEMT) utilizes the strong piezoelectric polarization effect of the AlGaN / GaN heterojunction to form a high-mobility, high-density two-dimensional electron gas (2DEG) at the interface, thereby realizing the processing and transmission capabilities of high-frequency signals under high-power conditions. At present, it has gradually been widely used in optoelectronics and power electronic devices. However, due to the high difficulty and high cost of GaN homogeneous substrates, GaN has always been grown on heterogeneous substrates, such as sapphire substrates, SiC substrates and Si substrates. Compared with sapphire and SiC substrates, Si substrates are considered to be the most promising choice for large-scale growth and mass production of GaN due to their low cost, easy integration and large size. However, due to the large lattice mismatch (16.9%) and thermal mismatch (115%) between GaN and Si, GaN on Si often has severe cracks and dislocation density, which once limited the industrial application of Si-based GaN.

[0003] The Si substrate has a large lattice mismatch with GaN. GaN grown on the Si substrate usually has a large dislocation density, that is, the crystal quality is poor. Due to the large thermal mismatch between the Si substrate and GaN, the existing technology usually needs to grow ~200 AlN and a thicker buffer layer to adjust its warping, thereby controlling crack formation. Inserting a thicker buffer layer causes the epitaxial layer to increase unnecessary thickness, resulting in high thermal resistance.

[0004] Currently, epitaxial growth of GaN on Si is achieved by MOCVD, and AlN and Al(Ga)N / (Al)GaN buffer layers are usually used to solve the above problems, that is, compressive stress is introduced in GaN growth to offset the tensile stress in the cooling process, and dislocation movement and annihilation are promoted by the introduction of heterogeneous interfaces to improve crystal quality, such as the application of AlN insertion layers and SiN insertion layers. However, the application of AlN and SiN will affect the stress state of the epitaxial layer and cause cracks in the epitaxial layer; Al(Ga)N / (Al)GaN buffer increases unnecessary epitaxial layer thickness and increases the thermal resistance of RF devices, greatly limiting its application. In addition, the growth of SiN will also affect the surface state of the epitaxial film layer and there is a risk of Si non-active doping. Therefore, more effective buffer structure optimization is urgently needed to obtain high-quality Si-based GaN. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a gallium nitride semiconductor device to realize a method for preparing the device and related applications.

[0006] In order to achieve the above object, in a specific embodiment of the present invention, a method for preparing a gallium nitride semiconductor device is provided, comprising the following steps:

[0007] A nucleation layer is grown on a silicon substrate; a first two-dimensional GaN layer is grown on the nucleation layer; a three-dimensional dislocation annihilation transition layer is grown on the first two-dimensional GaN layer that is not intentionally doped; a second two-dimensional GaN layer is grown on the three-dimensional dislocation annihilation transition layer; a barrier layer is grown on the second two-dimensional GaN layer; the three-dimensional dislocation annihilation transition layer comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a mixed island structure. In some specific embodiments, the first two-dimensional GaN layer is an unintentionally doped GaN layer.

[0008] The first two-dimensional GaN layer is grown on the nucleation layer, specifically, in an atmosphere of hydrogen as a carrier gas, with trimethylgallium at a first flow rate and ammonia at a fifth flow rate as reactants for a third growth time.

[0009] Furthermore, a three-dimensional dislocation annihilation transition layer is grown on the first two-dimensional GaN layer, and the growth time is a fourth time, specifically: in an atmosphere of hydrogen as a carrier gas, the second flow rate of trimethylgallium and the sixth flow rate of ammonia are used as the reactant to grow for a first preset time; in an atmosphere of hydrogen as a carrier gas, the second preset time is used for trimethylaluminum and the seventh flow rate of ammonia; in an atmosphere of hydrogen as a carrier gas, the third flow rate of trimethylgallium and the eighth flow rate of ammonia are used as the reactant to grow for a third preset time.

[0010] The second two-dimensional GaN layer is grown on the three-dimensional dislocation annihilation transition layer, specifically, in an atmosphere of hydrogen as a carrier gas, with a fourth flow rate of trimethyl gallium and a ninth flow rate of ammonia as reactants for a fifth time. In some specific embodiments, the second two-dimensional GaN layer is an unintentionally doped GaN layer.

[0011] Furthermore, in the above method, the first flow rate and the fourth flow rate are both greater than the second flow rate; the first flow rate and the fourth flow rate are both greater than the third flow rate; the fifth flow rate, the sixth flow rate, the eighth flow rate, and the ninth flow rate are all greater than the seventh flow rate; the cavity pressure when forming the first two-dimensional GaN layer and the second two-dimensional GaN layer is less than the cavity pressure when forming the three-dimensional dislocation annihilation transition layer; the third time and the fifth time are both greater than the fourth time; the first preset time is 60 to 300 s; the second preset time is 200 to 300 s; the third preset time is 60 to 300 s;.

[0012] Furthermore, in the above method, the step of forming the nucleation layer specifically includes: forming a first AlN layer on a silicon substrate; cyclically growing a preset number of Al sublayers and AlN sublayers on the first AlN layer to form an alternatingly stacked structural layer;

[0013] In other embodiments, the preparation method of the gallium nitride semiconductor device also includes forming a second AlN layer on the silicon substrate before forming the first AlN layer; forming the first AlN layer on the second AlN layer; the second AlN layer growth condition is formed at a second temperature, in the atmosphere of trimethylaluminum and ammonia as reactants, and hydrogen as a carrier gas; the first AlN layer growth condition is formed at a first temperature, in the atmosphere of trimethylaluminum and ammonia as reactants, and hydrogen as a carrier gas; wherein the second temperature is less than the first temperature; the second temperature range is 800 to 1000°C; the first temperature range is 1000 to 1260°C; growing an Al sublayer and an AlN sublayer for a period of time, specifically as follows: turning off the ammonia, and maintaining the Al sublayer for a first time in the atmosphere of trimethylaluminum as a reactant and hydrogen as a carrier gas; introducing trimethylaluminum and ammonia as reactants, and maintaining the AlN sublayer for a second time in the atmosphere of hydrogen as a carrier gas; the first time is 5 to 20s; the second time is 5 to 40s.

[0014] Accordingly, the present invention provides a gallium nitride semiconductor device, comprising a silicon substrate, and a nucleation layer, a GaN layer with at least one three-dimensional dislocation annihilation transition layer inserted, and an epitaxial layer of a barrier layer stacked in sequence; the three-dimensional dislocation annihilation transition layer comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a mixed island structure.

[0015] Furthermore, in the above-mentioned gallium nitride semiconductor device, the GaN layer inserted with at least one three-dimensional dislocation annihilation transition layer includes a first two-dimensional GaN layer, a three-dimensional dislocation annihilation transition layer formed on the first two-dimensional GaN layer, and a second two-dimensional GaN layer formed on the three-dimensional dislocation annihilation transition layer. In some embodiments, there is one three-dimensional dislocation annihilation transition layer in the GaN layer, and in other embodiments, there are two three-dimensional dislocation annihilation transition layers in the GaN layer. In other embodiments not shown, the number of three-dimensional dislocation annihilation transition layers can be greater.

[0016] Furthermore, in the above-mentioned gallium nitride semiconductor device, the longitudinal dimension of the hybrid island structure ranges from 5 to 50 nm; the lateral dimension of the hybrid island structure ranges from 5 to 50 nm; the thickness of the first two-dimensional GaN layer (31) is 50 to 100 nm; and the distance between the barrier layer and the nearest three-dimensional dislocation annihilation transition layer is 100 to 300 nm.

[0017] In the above-mentioned gallium nitride semiconductor device, the nucleation layer is an AlN layer or a first AlN layer stacked in sequence, a structural layer composed of Al sublayers and AlN sublayers alternately stacked, and the alternately stacked structural layer contains a preset periodic number of Al sublayers and AlN sublayers.

[0018] Furthermore, in the above-mentioned gallium nitride semiconductor device, the thickness of the alternating stacked structural layer ranges from 50 to 300 nm; the alternating stacked structural layer includes n groups of Al sublayers and AlN sublayers; wherein n is a positive integer, 5≤n≤200; if the number of groups of Al sublayers and AlN sublayers in the alternating stacked structural layer is too small, the overall thickness is too thin, which is not conducive to control, and cannot provide a good wetting layer for GaN growth, which is not conducive to warping control and deteriorates the quality of GaN crystals; if the number of groups is too large, the overall thickness of the alternating stacked structural layer is too thick, which will also affect the warping control of the GaN layer and cause cracks in the GaN epitaxial layer. Furthermore, in a more optimal solution of the embodiment of the present invention, 15≤n≤35. When the thickness of the alternately stacked structural layers is less than 50nm, the stress regulation effect on the epitaxial layer cannot meet the requirements, and the stress relief effect during the cooling process is not good; because GaN materials are grown on the alternately stacked structural layers, the thickness and quality of the alternately stacked structural layers affect the stress of the GaN film grown thereon. When the thickness of the alternately stacked structural layers is greater than 300nm, it will also affect the stress in the GaN epitaxial layer, thereby affecting the control of warping, which may cause cracks in the epitaxial wafer.

[0019] The thickness of the Al sublayer is a first thickness d1; the thickness of the AlN sublayer is a second thickness d2, the first thickness d1 ranges from 0.3 to 2 nm, and the second thickness d2 ranges from 1 to 6 nm. The Al sublayer is controlled to grow by shutting off the ammonia NH3. If the Al sublayer is too thin, on the one hand, the control accuracy of the thickness of the Al sublayer is tested, which will affect the overall structure of the alternating stacked structural layers, and make it difficult to achieve consistency in the epitaxial batches, thereby affecting the stability of epitaxy and device performance. On the other hand, when the thickness d1 of the Al sublayer is less than 0.3 nm, the Al sublayer is too thin, making it difficult to play a stress relief role in the cooling stage after the growth is completed; if the Al layer is too thick, it will affect the growth quality of the AlN sublayer, resulting in poor quality of the AlN crystal, affecting the quality of the entire alternating stacked structural layer, and then causing poor quality of the GaN crystal. Therefore, when the thickness d1 of the Al sublayer is greater than 2 nm, it is difficult to achieve high-quality n groups of Al sublayers and AlN sublayers to form an alternating stacked structural layer. When the thickness d2 of the AlN sublayer is less than 1 nm, it is difficult to obtain stably grown high-quality AlN. When the thickness d2 of the AlN sublayer is greater than 6 nm, the effect of the Al sublayer will be significantly weakened, and the stress in the subsequent GaN growth will be affected, which is not conducive to stress control.

[0020] Further, in a more preferred embodiment of the present invention, the thickness range of the alternately stacked structural layers is 100-150 nm. When the thickness range of the alternately stacked structural layers is 100-200 nm, it is more preferable. At this time, the warping of the GaN epitaxial layer is better controlled, and high-quality AlN is beneficial to the growth of GaN. The dislocation density in the GaN epitaxial layer is lower, and the threading dislocations are less, so that the leakage current of the device is smaller and the breakdown voltage is higher.

[0021] Further, in the above gallium nitride semiconductor device, 0.05×d2 < d1 < 0.3×d2. When the thickness d1 of the Al sub-layer is less than 0.05×d2, the Al sub-layer is too thin, making it difficult to play the role of stress relaxation in the cooling stage after growth is completed; when the thickness d1 of the Al sub-layer is greater than 0.3×d2, it will affect the growth quality of the AlN sub-layer, resulting in poor crystal quality of AlN, affecting the quality of the entire alternately stacked structural layer, and further resulting in poor crystal quality of GaN, and it is difficult to obtain a high-quality alternately stacked structural layer.

[0022] In other embodiments, a second AlN layer is provided between the first AlN layer and the silicon substrate. The second AlN layer grown by the low-temperature growth method can be used as a seed layer or a nucleation layer, which is beneficial to the nucleation and growth of the first AlN layer, improves the crystal quality of AlN therein. The first AlN layer is grown at a high temperature, and the atomic mobility of Al is higher, closer to the 2D growth mode than the second AlN layer, and has better crystal quality and a smoother surface.

[0023] Correspondingly, the present invention also provides a radio frequency amplifier, including the above-mentioned gallium nitride semiconductor device.

[0024] Correspondingly, the present invention also provides a communication device, including the above-mentioned radio frequency amplifier.

[0025] Based on MOCVD growth, the present invention optimizes the growth method of the bottom AlN, grows a structure layer similar to an alternate stack, and based on this AlN structure, grows a GaN layer with at least one three-dimensional dislocation annihilation transition layer inserted therein. The alternately stacked structural layer of the present invention not only provides a high-quality nucleation layer for the growth of GaN, but also meets the stress regulation requirements. Moreover, this alternately stacked structural layer can effectively relieve the stress and deformation received by the epitaxial layer due to thermal mismatch during the cooling process, and can further obtain a buffer-free and crack-free GaN epitaxial film layer, from which a GaN device with low thermal resistance can be prepared. On the other hand, the GaN layer is inserted with a three-dimensional dislocation annihilation transition layer, which can effectively reduce the dislocation density in the GaN epitaxial layer, improve the crystal quality of Si-based GaN, and can effectively expand the application of Si-based GaN. Description of the Drawings

[0026] Figure 1is a schematic diagram of a gallium nitride semiconductor device according to a first embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of a gallium nitride semiconductor device according to a second embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of a gallium nitride semiconductor device according to a third embodiment of the present invention;

[0029] Figure 4 Schematic diagram of a gallium nitride semiconductor device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0031] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. The drawings in the specification of the present invention are only for illustration, and it should be understood that the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0032] Embodiment 1

[0033] A gallium nitride semiconductor device, such as Figure 1 As shown, it includes a substrate 10, an epitaxial layer arranged on the substrate 10, a source S and a drain D arranged on the epitaxial layer, and a gate G, the source S and the drain D are arranged opposite to each other, and the substrate 10 is a silicon substrate.

[0034] The epitaxial layer comprises a nucleation layer 1, a GaN layer 3 with at least one three-dimensional dislocation annihilation transition layer inserted therein, and an epitaxial layer of a barrier layer 4 stacked in sequence on a substrate 10; the three-dimensional dislocation annihilation transition layer 32 comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a mixed island structure. In this embodiment, the number of three-dimensional dislocation annihilation transition layers is 1. The GaN layer 3 with at least one three-dimensional dislocation annihilation transition layer inserted therein comprises a first two-dimensional GaN layer 31, a three-dimensional dislocation annihilation transition layer 32 formed on the first two-dimensional GaN layer 31, and a second two-dimensional GaN layer 33 formed on the three-dimensional dislocation annihilation transition layer 32. The thickness of the first two-dimensional GaN layer 31 is 50 to 100 nm; the distance between the barrier layer 4 and the three-dimensional dislocation annihilation transition layer 32 is 100 to 300 nm. The longitudinal dimension of the hybrid island structure ranges from 5 to 50 nm; the lateral dimension of the hybrid island structure ranges from 5 to 50 nm; the longitudinal dimension is along the growth direction of the epitaxial layer, and the lateral dimension is perpendicular to the growth direction of the epitaxial layer.

[0035] In the embodiment of the present invention, the nucleation layer is an AlN layer, and the thickness of the AlN layer ranges from 50 to 150 nm. A first two-dimensional GaN layer 31 is grown on the AlN layer. Due to the lattice matching problem between the AlN material and the GaN material, defects are formed in the first two-dimensional GaN layer 31. The dislocation density of the first two-dimensional GaN layer 31 is relatively high. The GaN layer forming a three-dimensional dislocation annihilation transition layer on the first two-dimensional GaN layer 31 can bend the dislocations of the first two-dimensional GaN layer 31, and at the same time, a second two-dimensional GaN layer 33 is formed on the three-dimensional dislocation annihilation transition layer. The dislocations are rapidly reduced from the first two-dimensional GaN layer 31 to the second two-dimensional GaN layer 33, which can effectively reduce the dislocation density in the GaN epitaxial layer and improve the crystal quality of Si-based GaN.

[0036] Accordingly, an embodiment of the present invention further provides a method for manufacturing a gallium nitride semiconductor device, which adopts MOCVD growth and includes the following steps:

[0037] (1) growing a nucleation layer on a silicon substrate;

[0038] The first two-dimensional GaN layer is grown on the nucleation layer, specifically: trimethylgallium TMGa at a first flow rate and ammonia at a fifth flow rate are used as reactants, and hydrogen is used as a carrier gas atmosphere to form and maintain for a third time to grow the 2DGaN layer; in some specific embodiments, the first two-dimensional GaN layer is an unintentionally doped layer;

[0039] (2) growing a three-dimensional dislocation annihilation transition layer on the first two-dimensional GaN layer; the growth time is a fourth time, specifically: using trimethylgallium (TMGa) at a second flow rate and ammonia at a sixth flow rate as reactants, growing for a first preset time in an atmosphere of hydrogen as a carrier gas to form 3D GaN; turning off trimethylgallium (TMGa), using trimethylaluminum (TMAl) and ammonia at a seventh flow rate as reactants, growing for a second preset time in an atmosphere of hydrogen as a carrier gas to form 3D Al-containing nitride islands, wherein the flow rate of trimethylaluminum (TMAl) is adjusted to 30 to 100 sccm;

[0040] Turn off trimethylaluminum TMAl, use trimethylgallium TMGa at a third flow rate and ammonia NH3 at an eighth flow rate as reactants, and grow for a third preset time in an atmosphere of hydrogen as a carrier gas to form a 3D hybrid island structure; the three-dimensional dislocation annihilation transition layer includes at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a hybrid island structure;

[0041] (3) growing a second two-dimensional GaN layer on the three-dimensional dislocation annihilation transition layer, specifically: growing an unintentionally doped second two-dimensional GaN layer on the three-dimensional dislocation annihilation transition layer, specifically: forming 2D GaN in an atmosphere of hydrogen as a carrier gas with a fourth flow rate of trimethyl gallium TMGa and a ninth flow rate of ammonia NH3 as reactants, and a growth time of a fifth time; in some specific embodiments, the second two-dimensional GaN layer is an unintentionally doped layer;

[0042] (4) growing a barrier layer on the second two-dimensional GaN layer;

[0043] (5) Forming source, drain and gate.

[0044] Specifically, the first flow rate and the fourth flow rate are both greater than the second flow rate; the first flow rate and the fourth flow rate are both greater than the third flow rate; the second flow rate of trimethyl gallium TMGa is controlled to form a 3D GaN island on the 2DGaN (second two-dimensional GaN layer);

[0045] The fifth flow rate, the sixth flow rate, the eighth flow rate, and the ninth flow rate are all greater than the seventh flow rate.

[0046] In some specific embodiments, the first flow rate is 150-400 sccm, the second flow rate is 10-80 sccm, the third flow rate is 10-80 sccm, and the fourth flow rate is 150-400 sccm; the fifth flow rate is 10000-40000 sccm, the sixth flow rate is 10000-40000 sccm, the seventh flow rate is 800-3000 sccm, the eighth flow rate is 10000-40000 sccm, and the ninth flow rate is 10000-40000 sccm.

[0047] The cavity pressure when forming the first two-dimensional GaN layer is 70-300 mbar, the cavity pressure when forming the second two-dimensional GaN layer is 70-300 mbar; the cavity pressure when forming the three-dimensional dislocation annihilation transition layer is 200-500 mbar;

[0048] Controlling the seventh flow rate of ammonia NH3 (lower than the sixth flow rate of ammonia NH3) at a cavity pressure of 200-500 mbar is conducive to the formation of 3D islands containing Al elements that continue to grow on the 3D GaN islands. The 3D islands of Al elements can improve the stability of the initial 3D GaN and stabilize its 3D morphology, making it easier to obtain large 3D GaN island structures in subsequent growth.

[0049] Controlling the third flow rate of trimethyl gallium TMGa and the eighth flow rate of ammonia NH3, wherein the third flow rate is less than the first flow rate and the eighth flow rate is greater than the seventh flow rate, is conducive to forming a three-dimensional material containing at least two of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN on the 3D island containing the Al element to form a mixed island structure. At the same time, the eighth flow rate and the ninth flow rate are similar or the same, which is conducive to the formation of a second two-dimensional gallium nitride layer when the mixed island structure is transformed from three-dimensional to two-dimensional.

[0050] During the growth process, if trimethylgallium (TMGa) is turned off, some TMGa may still remain in the reaction chamber, and a small amount of Ga element may be doped into the subsequently grown 3D islands. During the growth process, if trimethylaluminum (TMAl) is turned off, some TMAl may still remain in the reaction chamber, and a small amount of Al element may be doped into the subsequently grown 3D islands.

[0051] Preferably, the third time and the fifth time are both greater than the fourth time; the cavity pressure when forming the first two-dimensional GaN layer and the second two-dimensional GaN layer is less than the cavity pressure when forming the three-dimensional dislocation annihilation transition layer. The fourth time is 300 to 1200s. The first preset time for growing 3D GaN is 60 to 300s; the second preset time for growing 3D Al-containing nitride islands is 60 to 300s; the third preset time is 200 to 300s. The method of the present invention forms a three-dimensional dislocation annihilation transition layer by setting the flow rate of trimethylgallium TMGa, trimethylgallium TMAl, and ammonia NH3 and the cavity pressure. The three-dimensional dislocation annihilation transition layer contains at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a mixed island structure. The longitudinal size of the hybrid island structure ranges from 5 to 50 nm; the lateral size of the hybrid island structure ranges from 5 to 50 nm; due to the existence of the hybrid island structure of the three-dimensional dislocation annihilation transition layer, the dislocations transferred from the first two-dimensional GaN layer 31 to the second two-dimensional GaN layer 33 decrease rapidly, which can effectively reduce the dislocation density in the GaN epitaxial layer and improve the crystal quality of Si-based GaN.

[0052] Embodiment 2

[0053] The difference from the embodiment is that the nucleation layer 1 of the embodiment 1 is an AlN layer. In the gallium nitride semiconductor device of this embodiment, there is still a structural layer 2 composed of an alternate stack of Al sublayers and AlN sublayers between the nucleation layer 1 and the GaN layer 3 inserted with at least one three-dimensional dislocation annihilation transition layer, as shown in the attached figure. Figure 2 shown.

[0054] A gallium nitride semiconductor device, such as Figure 2 As shown, it includes a substrate 10, an epitaxial layer arranged on the substrate 10, a source S and a drain D arranged on the epitaxial layer, and a gate G, the source S and the drain D are arranged opposite to each other, and the substrate 10 is a silicon substrate.

[0055] The epitaxial layer comprises a first AlN layer 1 sequentially stacked on a substrate 10, a structural layer 2 comprising a preset number of periodic Al sublayers and AlN sublayers alternately stacked, a GaN layer 33 inserted with at least one three-dimensional dislocation annihilation transition layer, and a barrier layer 4, wherein the thickness D4 of the barrier layer 4 is 2 to 30 nm; the barrier layer 4 is made of AlGaN material or AlGaInN material. The thickness D1 of the first AlN layer 1 is 10 to 60 nm; the thickness D2 of the alternately stacked structural layer 2 is 50 to 300 nm;

[0056] The structural layer 2 is composed of an alternating stack of Al sub-layers and AlN sub-layers. The alternating stacked structural layer 2 consists of n groups of Al sub-layers and AlN sub-layers, where n is a positive integer and 5 ≤ n ≤ 200. The thickness of the Al sub-layer is the first thickness d1, and the thickness of the AlN sub-layer is the second thickness d2, where 0.05×d2 < d1 < 0.3×d2. When the thickness d1 of the Al sub-layer is less than 0.05×d2, the Al sub-layer is too thin, making it difficult to play a stress relief role during the cooling stage after growth completion. When the thickness d1 of the Al sub-layer is greater than 0.3×d2, it will affect the growth quality of the AlN sub-layer, resulting in poor AlN crystal quality, affecting the quality of the entire alternating stacked structural layer 2, and further causing poor GaN crystal quality, making it difficult to obtain a high-quality nitride epitaxial structure.

[0057] The value range of the first thickness d1 is 0.3 - 2 nm, and the value range of the second thickness d2 is 1 - 6 nm.

[0058] The growth of the Al sub-layer is controlled by shutting off ammonia NH3. When the Al sub-layer is too thin, on the one hand, the control accuracy of the thickness of the Al sub-layer is tested, which will affect the overall structure of the alternating stacked structural layer 2 and make it difficult to achieve consistency in epitaxial batches, thus affecting the stability of epitaxial and device performance. On the other hand, when the thickness d1 of the Al sub-layer is less than 0.3 nm, the Al sub-layer is too thin, making it difficult to play a stress relief role during the cooling stage after growth completion. If the Al layer is too thick, it will affect the growth quality of the AlN sub-layer, resulting in poor AlN crystal quality, affecting the quality of the entire alternating stacked structural layer 2, and further causing poor GaN crystal quality. Therefore, when the thickness d1 of the Al sub-layer is greater than 2 nm, it is difficult to form a high-quality alternating stacked structural layer composed of n groups of Al sub-layers and AlN sub-layers. When the thickness d2 of the AlN sub-layer is less than 1 nm, it is difficult to obtain high-quality AlN with stable growth. When the thickness d2 of the AlN sub-layer is greater than 6 nm, the role of the Al sub-layer will be significantly weakened, and it will affect the stress in subsequent GaN growth, which is not conducive to stress control.

[0059] The thickness D2 of the alternating stacked structural layer 2 ranges from 50 to 300 nm. When the thickness of the alternating stacked structural layer is less than 50 nm, the stress regulation effect on the epitaxial layer cannot meet the requirements, and the stress relief effect during the cooling process is not good; because GaN material is grown on the alternating stacked structural layer, the thickness and quality of the alternating stacked structural layer affect the stress of the GaN film grown thereon. When the thickness of the alternating stacked structural layer is greater than 300 nm, it will also affect the stress in the GaN epitaxial layer, thereby affecting the control of warping, so that the epitaxial wafer may crack. Further, in a more optimal solution of the embodiment of the present invention, the thickness range of the alternating stacked structural layer is 100 to 150 nm. When the thickness range of the alternating stacked structural layer is 100 to 150 nm, it is better. At this time, the warping control of the GaN epitaxial layer is better, and the high-quality AlN is conducive to the growth of GaN, the dislocation density in the GaN epitaxial layer is low, and there are fewer penetration dislocations, so that the device leakage is smaller and the withstand voltage is higher.

[0060] In a specific embodiment, the alternately stacked structure layer 2 includes n groups of Al sublayers and AlN sublayers, a first Al sublayer 211, a first AlN sublayer 212, a second Al sublayer 221, a second AlN sublayer 222, ... an nth Al sublayer 2n1, an nth AlN sublayer 2n2; the thickness of the first Al sublayer 211 is d 211 , the thickness of the first AlN sublayer 212 is d 212 , the thickness of the second Al sublayer 211 is d 221 , the thickness of the first AlN sublayer 212 is d 222 , the thickness of the nth Al sublayer 2n1 is d 2n1 , the thickness of the nth AlN sublayer 2n2 is d 2n2 In this embodiment, d 211 =d 221 =…=d 2n1 ;d 212 =d 222 =…=d 2n2 , d 211 <d 212 , d 221 <d 222 , d 2n1 <d 2n2 .

[0061] The alternatingly stacked structural layers in the gallium nitride semiconductor device of the present invention include n groups of Al sublayers and AlN sublayers; wherein n is a positive integer, 5≤n≤200. If the number of groups of Al sublayers and AlN sublayers in the alternatingly stacked structural layers is too small, the overall thickness is too thin, which is not conducive to control, and cannot provide a good wetting layer for GaN growth, which is not conducive to warping control and deteriorates the quality of GaN crystals; if the number of groups is too large, the overall thickness of the alternatingly stacked structural layers 2 is too thin, which will also affect the warping control of the GaN layer and cause cracks in the GaN epitaxial layer. Furthermore, in a more optimal solution of the embodiment of the present invention, 15≤n≤35.

[0062] In other optional embodiments of the present invention, the thickness of the i-th Al sublayer may be equal to or different from the thickness of other Al sublayers; the thickness of the j-th AlN sublayer may be equal to or different from the thickness of other AlN sublayers, wherein i and j are both positive integers, i≤n, j≤n. The thickness of any Al sublayer is less than the thickness of the adjacent AlN sublayer, and the thickness of any AlN sublayer is greater than the thickness of the adjacent Al sublayer. The thickness of the i-th Al sublayer is less than the thickness of the j-th AlN sublayer.

[0063] A method for preparing a gallium nitride semiconductor device comprises the following steps:

[0064] Step S1, forming a first AlN layer on a silicon substrate;

[0065] The first AlN layer is grown under the conditions of 1000-1260°C with trimethylgallium TMAl and ammonia NH3 as reactants and hydrogen as carrier gas.

[0066] Step S2, cyclically growing a preset number of Al sublayers and AlN sublayers on the first AlN layer to form an alternately stacked structural layer;

[0067] In step S2, an Al sublayer and an AlN sublayer of one cycle are grown, specifically as follows: ammonia NH3 is turned off, and the Al sublayer is formed for a first time in a trimethylgallium TMAl atmosphere; trimethylgallium TMAl and ammonia NH3 are introduced as reactants, and an AlN sublayer is formed for a second time in an atmosphere of hydrogen as a carrier gas; the first time is less than the second time, wherein the first time is 5 to 20 seconds; and the second time is 5 to 40 seconds.

[0068] Step S3, growing a GaN layer 3 on the alternately stacked structural layers and inserting at least one three-dimensional dislocation annihilation transition layer;

[0069] Step S4, forming a barrier layer 4 by growing the GaN layer 3 into which at least one three-dimensional dislocation annihilation transition layer is inserted.

[0070] The growth method of forming the GaN layer 3 with at least one three-dimensional dislocation annihilation transition layer inserted therein is the same as that in the first embodiment, and the embodiment of the present invention will not be described in detail herein.

[0071] The present invention lists several specific embodiments in which the alternately stacked structural layer 2 includes n groups of Al sublayers and AlN sublayers, as shown in the following table:

[0072]

[0073] Embodiment 3

[0074] Different from the second embodiment, the epitaxial layer of the gallium nitride semiconductor device of this embodiment further includes a second AlN layer 11, and the second AlN layer is arranged between the first AlN layer 1 and the substrate 10. Figure 3 As shown. The growth temperature of the second AlN layer 11 is lower than the growth temperature of the first AlN layer 1. The second AlN layer grown at low temperature can be used as a seed layer or a nucleation layer, which is beneficial to the nucleation and growth of the first AlN layer and improves the crystal quality of AlN. The first AlN layer grows at high temperature, and the atomic mobility of Al is higher. Compared with the second AlN layer, it is closer to the 2D growth mode, and has better crystal quality and a smoother surface.

[0075] The embodiment of the present invention discloses a method for preparing a gallium nitride semiconductor device, which is different from the first embodiment in that, in step S1, it also includes forming a second AlN layer on a silicon substrate before forming the first AlN layer; forming the first AlN layer on the second AlN layer; the second AlN layer is grown under the conditions of being formed at a first temperature in an atmosphere of trimethylgallium TMAl and ammonia NH3 as reactants and hydrogen as a carrier gas, and the first AlN layer is grown under the conditions of being formed at a second temperature in an atmosphere of trimethylgallium TMAl and ammonia; wherein the first temperature is less than the second temperature; the first temperature range is 800-1000°C; and the second temperature range is 1000-1260°C.

[0076] The detailed steps of a method for preparing a gallium nitride semiconductor device in this embodiment are as follows:

[0077] Step 1: Raise the temperature of the MOCVD chamber to 1000-1300°C, introduce 90-180L of hydrogen for 3-10 minutes to remove impurities on the surface of the Si substrate;

[0078] Step 2: The temperature of the MOCVD chamber is 600-900°C, trimethylaluminum TMAl is introduced as an aluminum source, and Al is pre-coated on the surface of the Si substrate;

[0079] Step 3: The MOCVD chamber is heated to 800-1000°C, trimethylaluminum TMAl and ammonia NH3 are introduced, the trimethylaluminum TMAl flow rate is 100-300 sccm, and the ammonia NH3 flow rate is 2000-5000 sccm, and the first AlN layer (called low-temperature AlN layer, denoted as LT-AlN) is grown with a thickness of 10-60 nm;

[0080] Step 4: Keep trimethylaluminum TMAl and ammonia NH3 open, raise the temperature of the MOCVD chamber to 1000-1260°C, and grow the second AlN layer (called high-temperature AlN layer, denoted as HT-AlN) with a thickness of 10-60nm;

[0081] Step 5: The temperature of the MOCVD chamber remains unchanged, the flow rate of trimethylaluminum TMAl is 300-600sccm, the flow rate of ammonia NH3 is 600-2000sccm, trimethylaluminum TMAl and ammonia NH3 are turned on at the same time, and the ammonia NH3 is turned off after 5-30s, and trimethylaluminum TMAl is introduced alone for 5-15s; trimethylaluminum TMAl and ammonia NH3 are turned on at the same time, and the ammonia NH3 is turned off after 5-30s, and trimethylaluminum TMAl is introduced alone for 5-15s, thereby cyclically switching the growth of ammonia NH3, and forming an alternating stacked structural layer according to a preset number of cycles composed of Al sublayers and AlN sublayers; the thickness range of the alternating stacked structural layer is 50-200nm, and a more optimal solution is that the thickness of the alternating stacked structural layer is 100-150nm.

[0082] Step 6: forming the GaN layer 3 inserted with at least one three-dimensional dislocation annihilation transition layer on the alternately stacked structural layers;

[0083] Step seven: forming a barrier layer 4 on the GaN layer 3 into which at least one three-dimensional dislocation annihilation transition layer is inserted.

[0084] Step 8: Form a source S, a drain D and a gate G on the epitaxial layer respectively.

[0085] Embodiment 4

[0086] The difference from the first embodiment is that the epitaxial layer of the gallium nitride semiconductor device of this embodiment includes two three-dimensional dislocation annihilation transition layers, that is, the GaN layer is inserted into the two three-dimensional dislocation annihilation transition layers, as shown in the attached Figure 4 As shown, it includes a substrate 10, an epitaxial layer arranged on the substrate 10, a source S and a drain D arranged on the epitaxial layer, and a gate G, the source S and the drain D are arranged opposite to each other, and the substrate 10 is a silicon substrate.

[0087] The epitaxial layer comprises a nucleation layer 1, a GaN layer 3 with at least one three-dimensional dislocation annihilation transition layer inserted therein, and an epitaxial layer of a barrier layer 4, which are sequentially stacked on a substrate 10; the GaN layer 3 with at least one three-dimensional dislocation annihilation transition layer inserted therein comprises a first two-dimensional GaN layer 31, a first three-dimensional dislocation annihilation transition layer 321, a second two-dimensional GaN layer 331, a second three-dimensional dislocation annihilation transition layer 322, and a third two-dimensional GaN layer 332, which are sequentially arranged;

[0088] The first three-dimensional dislocation annihilation transition layer 321 includes three-dimensional materials of at least two of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a mixed island structure.

[0089] The second three-dimensional dislocation annihilation transition layer 322 comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a mixed island structure. The distance between the barrier layer 4 and the second three-dimensional dislocation annihilation transition layer 322 is 100-300nm. The thickness of the second two-dimensional GaN layer 331 is 50-100nm; the thickness of the third two-dimensional GaN layer 332 is 100-300nm. The distance between the barrier layer 4 and the nearest three-dimensional dislocation annihilation transition layer is 100-300nm.

[0090] The formation method of the first three-dimensional dislocation annihilation transition layer 321 and the second three-dimensional dislocation annihilation transition layer 322 in the gallium nitride semiconductor device manufacturing method of this embodiment is the same as the formation method of the three-dimensional dislocation annihilation transition layer in the first embodiment, which will not be repeated here.

[0091] During the preparation process of the gallium nitride semiconductor device of this embodiment, due to the existence of the mixed island structure of the first three-dimensional dislocation annihilation transition layer, the dislocations transferred from the first two-dimensional GaN layer 31 to the second two-dimensional GaN layer 331 decrease rapidly. Due to the existence of the mixed island structure of the second three-dimensional dislocation annihilation transition layer, the dislocations transferred from the second two-dimensional GaN layer 331 to the third two-dimensional GaN layer 332 further attenuate, which can effectively reduce the dislocation density in the GaN epitaxial layer and improve the crystal quality of Si-based GaN.

[0092] Embodiment 5

[0093] Different from other embodiments, the epitaxial layer of the gallium nitride semiconductor device of this embodiment further includes a cap layer, which is made of gallium nitride material. It should be noted that the cap layer can also be provided on the basis of the epitaxial layer of embodiments one to three, and the specific detailed scheme of the embodiment of the present invention is not repeated here. The GaN cap layer can protect the AlGaN barrier layer from oxidation and prevent the device performance from being degraded, and can also reduce surface traps and improve the device performance.

[0094] Embodiment 5

[0095] Different from other embodiments, the epitaxial layer of this embodiment also includes an insertion layer arranged between the barrier layer 4 and the GaN layer 3 inserted with at least one three-dimensional dislocation annihilation transition layer, and in this embodiment, the insertion layer is made of aluminum nitride material. The AlN insertion layer can enhance the polarization effect of the AlGaN / GaN HEMT device, increase the concentration of the two-dimensional electron gas 2DEG, and improve the device performance. It should be noted that an insertion layer can also be provided on the basis of the epitaxial layer of embodiments one to three, and the insertion layer can also be made of other materials in addition to aluminum nitride material. The specific detailed scheme of the embodiment of the present invention will not be repeated here.

[0096] Embodiment 6

[0097] An embodiment of the present invention provides a radio frequency amplifier, including a gallium nitride semiconductor device. The gallium nitride semiconductor device is the gallium nitride semiconductor device described in embodiments 1 to 5. The radio frequency amplifier of the present invention uses a silicon substrate, has low cost, is conducive to mass production, and further promotes the industrial application of Si-based gallium nitride in the radio frequency field.

[0098] Embodiment 7

[0099] An embodiment of the present invention provides a communication device, including a radio frequency amplifier. The radio frequency amplifier is the radio frequency amplifier in the sixth embodiment.

[0100] It should be noted that the structural layer 2 of the present invention is composed of a preset number of Al sublayers and AlN sublayers alternately stacked, wherein the Al sublayer can be a pure aluminum layer or an unintentionally doped aluminum layer. During the growth process of the Al sublayer, some ammonia NH3 may still remain in the reaction chamber, and a small amount of N element may be doped into the Al sublayer. In TEM analysis, there is a significant difference in the light and dark contrast between the Al sublayer and the AlN sublayer, and the structural difference between the two sublayers can be distinguished, but it may be difficult to distinguish their clear interface. In SIMS analysis, the Al sublayer and the AlN sublayer have different secondary ion outputs of Al, and the analysis will obtain a difference in Al concentration, so they can also be distinguished by SIMS.

[0101] It should be noted that the three-dimensional dislocation annihilation transition layer in the present invention comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN to form a hybrid island structure. The longitudinal dimension of the hybrid island structure ranges from 5 to 50 nm; the lateral dimension of the hybrid island structure ranges from 5 to 50 nm; the longitudinal dimension is along the growth direction of the epitaxial layer, and the lateral dimension is perpendicular to the growth direction of the epitaxial layer. The lateral dimension of the hybrid island structure can also be understood as the dimension of the hybrid island structure from a top view. A single hybrid island may be composed of one of three-dimensional AlN, three-dimensional AlGaN, and three-dimensional GaN, or may be a mixture of the three-dimensional AlN, for example, a single hybrid island is a single hybrid island composed of three-dimensional AlN and three-dimensional AlGaN.

[0102] Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a gallium nitride semiconductor device, characterized in that: The following steps are involved: Growing a nucleation layer on a silicon substrate; Growing a first two-dimensional GaN layer on the nucleation layer; A three-dimensional dislocation annihilation transition layer is grown on the first two-dimensional GaN layer; Growing a second two-dimensional GaN layer on the three-dimensional dislocation annihilation transition layer; growing a barrier layer on the second two-dimensional GaN layer; The three-dimensional dislocation annihilation transition layer comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN and three-dimensional GaN to form a mixed island structure.

2. The method for preparing a gallium nitride semiconductor device according to claim 1, characterized in that: Growing a first two-dimensional GaN layer on the nucleation layer, wherein the first two-dimensional GaN layer is an unintentionally doped GaN layer; specifically, growing the layer for a third time in an atmosphere of hydrogen as a carrier gas with trimethylgallium at a first flow rate and ammonia at a fifth flow rate as reactants; A three-dimensional dislocation annihilation transition layer is grown on the first two-dimensional GaN layer, and the growth time is a fourth time, specifically: in an atmosphere of hydrogen as a carrier gas, trimethylgallium at a second flow rate and ammonia at a sixth flow rate are used as reactants to grow for a first preset time; in an atmosphere of hydrogen as a carrier gas, trimethylaluminum and ammonia at a seventh flow rate are used as reactants to grow for a second preset time; in an atmosphere of hydrogen as a carrier gas, trimethylgallium at a third flow rate and ammonia at an eighth flow rate are used as reactants to grow for a third preset time; A second two-dimensional GaN layer is grown on the three-dimensional dislocation annihilation transition layer, wherein the second two-dimensional GaN layer is an unintentionally doped GaN layer; specifically, in an atmosphere of hydrogen as a carrier gas, trimethylgallium at a fourth flow rate and ammonia at a ninth flow rate are used as reactants for a fifth growth time.

3. The method for preparing a gallium nitride semiconductor device according to claim 2, characterized in that: The first flow rate and the fourth flow rate are both greater than the second flow rate; the first flow rate and the fourth flow rate are both greater than the third flow rate; The fifth flow rate, the sixth flow rate, the eighth flow rate, and the ninth flow rate are all greater than the seventh flow rate; The cavity pressures when forming the first two-dimensional GaN layer and the second two-dimensional GaN layer are both lower than the cavity pressure when forming the three-dimensional dislocation annihilation transition layer; The third time and the fifth time are both greater than the fourth time; the first preset time is 60 to 300 seconds; the second preset time is 200 to 300 seconds; and the third preset time is 60 to 300 seconds.

4. The method for preparing a gallium nitride semiconductor device according to claim 1, characterized in that: The steps of forming the nucleation layer specifically include: forming a first AlN layer on a silicon substrate; cyclically growing a preset number of Al sublayers and AlN sublayers on the first AlN layer to form an alternately stacked structural layer.

5. The method for preparing a gallium nitride semiconductor device according to claim 4, characterized in that: The method also includes forming a second AlN layer on a silicon substrate before forming the first AlN layer; forming the first AlN layer on the second AlN layer; the second AlN layer is grown under the conditions of trimethyl gallium TMAl and ammonia as reactants and hydrogen as a carrier gas at a second temperature; the first AlN layer is grown under the conditions of trimethyl aluminum and ammonia as reactants and hydrogen as a carrier gas at a first temperature; wherein the second temperature is lower than the first temperature; the second temperature range is 800-1000°C; the first temperature range is 1000-1260°C; The Al sublayer and the AlN sublayer are grown for one cycle as follows: the ammonia is turned off, and the Al sublayer is formed for a first time in an atmosphere of trimethylaluminum as a reactant and hydrogen as a carrier gas; trimethylaluminum and ammonia are introduced as reactants, and the AlN sublayer is formed for a second time in an atmosphere of hydrogen as a carrier gas; the first time is 5 to 20 seconds; the second time is 5 to 40 seconds.

6. A gallium nitride semiconductor device, characterized in that: It includes a silicon substrate, and a nucleation layer, a GaN layer inserted with at least one three-dimensional dislocation annihilation transition layer, and an epitaxial layer of a barrier layer stacked in sequence; The three-dimensional dislocation annihilation transition layer comprises at least two three-dimensional materials of three-dimensional AlN, three-dimensional AlGaN and three-dimensional GaN to form a mixed island structure.

7. The gallium nitride semiconductor device according to claim 6, characterized in that: The GaN layer inserted with at least one three-dimensional dislocation annihilation transition layer includes a first two-dimensional GaN layer, a three-dimensional dislocation annihilation transition layer formed on the first two-dimensional GaN layer, and a second two-dimensional GaN layer formed on the three-dimensional dislocation annihilation transition layer.

8. The gallium nitride semiconductor device according to claim 7, characterized in that: The longitudinal dimension of the hybrid island structure is in the range of 5 to 50 nm; the lateral dimension of the hybrid island structure is in the range of 5 to 50 nm; The thickness of the first two-dimensional GaN layer is 50 to 100 nm; The distance between the barrier layer and the nearest three-dimensional dislocation annihilation transition layer is 100-300 nm.

9. The gallium nitride semiconductor device according to claim 6, characterized in that: The nucleation layer is an AlN layer or a first AlN layer stacked in sequence, a structural layer composed of Al sublayers and AlN sublayers alternately stacked, and the alternately stacked structural layer contains a preset number of Al sublayers and AlN sublayers in a periodic manner.

10. The gallium nitride semiconductor device according to claim 9, characterized in that: The thickness of the alternately stacked structural layers ranges from 50 to 300 nm; the alternately stacked structural layers include n groups of Al sublayers and AlN sublayers; wherein n is a positive integer, 5≤n≤200; the thickness of the Al sublayer is a first thickness d1; the thickness of the AlN sublayer is a second thickness d2, the value range of the first thickness d1 is 0.3 to 2 nm, and the value range of the second thickness d2 is 1 to 6 nm.

11. The gallium nitride semiconductor device according to claim 10, characterized in that: in, 0.05×d2 <d1<0.3×d2。 12. The gallium nitride semiconductor device according to claim 9, characterized in that: A second AlN layer is disposed between the first AlN layer and the silicon substrate.

13. A radio frequency amplifier, characterized in that: It comprises the gallium nitride semiconductor device according to any one of claims 1 to 12.

14. A communication device, characterized in that: Comprising the radio frequency amplifier as claimed in claim 13.

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