An epitaxial structure of a GaN-based HEMT device and its growth method

Abstract

This invention belongs to the field of semiconductor device technology, specifically relating to an epitaxial structure for a GaN-based HEMT device. The structure includes a silicon substrate and, sequentially, an AlN layer, an AlGaN dislocation recombination control layer, a high-resistivity GaN epitaxial layer, a GaN channel layer, an AlGaN barrier layer, and a GaN cap layer grown from the surface of the silicon substrate. The AlGaN dislocation recombination control layer comprises sequentially stacked AlxGa1-xN single-crystal layers, AllyGa1-yN single-crystal layers, AlzGa1-zN single-crystal layers, and AlvGa1-vN single-crystal layers. The optimized AlGaN dislocation recombination control layer includes an epitaxial functional layer with Ga vacancies. By introducing a large number of Ga vacancies during epitaxial growth, dislocations are bent and annihilated, thereby improving crystal quality, reducing dislocations, and enhancing the leakage current characteristics and breakdown voltage of the GaN-based HEMT device.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, specifically relating to an epitaxial structure of a GaN-based HEMT device and its growth method. Background Technology

[0002] The substrates required for the growth of GaN-based epitaxial structures include sapphire, silicon, and silicon carbide. Since silicon substrates are inexpensive and the fabrication process is mature, growing GaN-based HEMT devices on large-size silicon substrates has a significant cost advantage and is also easier to mass-produce.

[0003] Due to the 20.4% lattice mismatch and 56% thermal mismatch between the Si substrate and GaN material, the GaN epitaxial layer exhibits significant tensile stress after growth, making crystal quality difficult to control. Furthermore, the large thermal mismatch between the Si substrate and GaN material leads to a violent chemical reaction between ammonia and Si at high temperatures, generating amorphous SiNx (silicon nitride). SiNx severely impacts the crystal quality of subsequent GaN growth. Therefore, current processes involve growing an AlN buffer layer and an AlGaN layer as a transition layer after Si substrate nitriding and pre-pass Al treatment.

[0004] Traditional AlGaN buffer layers are mostly gradient and superlattice structures, which cannot effectively release stress and reduce dislocations. Therefore, existing technologies still need improvement and development. Summary of the Invention

[0005] The purpose of this invention is to provide an epitaxial structure and growth method for GaN-based HEMT devices, overcoming the shortcomings of existing technologies. The optimized AlGaN dislocation recombination control layer includes an epitaxial functional layer with Ga vacancies. By introducing a large number of Ga vacancies during epitaxial growth, dislocations are bent and annihilated, thereby improving crystal quality, reducing dislocations, and improving the leakage current characteristics and breakdown voltage of GaN-based HEMT devices.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] An epitaxial structure of a GaN-based HEMT device and its growth method thereon, comprising a silicon substrate and an AlN layer, an AlGaN dislocation recombination control layer, a high-resistivity GaN epitaxial layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer grown sequentially from the surface of the silicon substrate.

[0008] The AlGaN dislocation composite control layer comprises sequentially stacked AlxGa1-xN single crystal layers, AlyGa1-yN single crystal layers, AlzGa1-zN single crystal layers, and AlvGa1-vN single crystal layers.

[0009] Furthermore, the AlxGa1-xN single crystal layer is a Buck layer with an Al composition of 0.55-0.85 and a thickness of 50-200 nm; the AllyGa1-yN single crystal layer is a Ga vacancy introduction layer and a dislocation control layer with a growth thickness of 50-200 nm, wherein the Al composition y is a constant value with an Al composition of 0.65-0.95; the AlzGa1-zN single crystal layer is a Buck layer with an Al composition of 0.45-0.75 and a thickness of 50-200 nm; the AlvGa1-vN single crystal layer is a gradient layer with an Al composition that gradually changes from 0.45-0.75 to 0.02-0.15 and a thickness of 10-200 nm.

[0010] This invention also protects a method for growing the epitaxial structure of a GaN-based HEMT device, comprising the following steps:

[0011] Step 1: Place a silicon substrate into the growth chamber of the material growth equipment. The growth atmosphere is pure hydrogen or nitrogen. Control the temperature at 1000-1150℃, the reaction chamber pressure at 50-200 torr, and introduce NH3 at a flow rate of 2-10 slm to grow an AlN layer with a thickness of 50-500 nm on its surface.

[0012] Step 2: Control the temperature, reaction chamber pressure, and ammonia gas injection rate to grow an AlGaN dislocation composite control layer with a thickness of 160-800 nm on the surface of the AlN layer.

[0013] Step 3: Control the temperature to 1000-1050℃, the reaction chamber pressure to 50-200 torr, and introduce NH3 at a flow rate of 5-30 slm, with a carbon doping concentration of 2E18-2E19 atoms / cm³. 3 A high-resistivity GaN epitaxial layer with a thickness of 1.5-3.5 μm was grown on the surface of the AlGaN dislocation composite control layer.

[0014] Step 4: Control the temperature at 1000-1100℃, the reaction chamber pressure at 100-300 torr, and introduce NH3 at a flow rate of 50-80 slm to grow and prepare a GaN channel layer with a thickness of 100-500 nm on the surface of the high-resistivity GaN epitaxial layer.

[0015] Step 5: Maintain the temperature at 1050-1150℃, the reaction chamber pressure at 50-200 torr, and introduce NH3 at a flow rate of 20-50 slm. The AL component is 0.15-0.4. Grow an AlGaN barrier layer with a thickness of 10-30 nm on the surface of the GaN channel layer.

[0016] Step 6: Control the temperature at 1000-1050℃, maintain the pressure in the reaction chamber at 50-200 torr, and introduce NH3 at a flow rate of 20-50 slm and TMGa at a flow rate of 10-20 sccm to grow and prepare a GaN cap layer with a thickness of 2-5 nm on the surface of the AlGaN barrier layer.

[0017] Step 7: Lower the temperature to room temperature to end the growth process and remove the crystal.

[0018] Furthermore, the growth conditions of the AlxGa1-xN single crystal layer are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

[0019] Furthermore, the growth conditions of the AlyGa1-yN single crystal layer are high temperature, low growth rate and high V / III ratio, with the temperature greater than 1050°C, the growth rate of 0.01-1.0 Å / s and the V / III ratio between 1000-30000.

[0020] Furthermore, the growth conditions of the AlzGa1-zN single crystal layer are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

[0021] Furthermore, the growth conditions of the AlvGa1-vN single crystal layer are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention discloses an epitaxial structure and growth method for a GaN-based HEMT device. By incorporating an optimized AlGaN dislocation recombination control layer containing an epitaxial functional layer with Ga vacancies, and by introducing a large number of Ga vacancies during epitaxial growth, dislocations are bent and annihilated, thereby improving crystal quality, reducing dislocations, and enhancing the leakage current characteristics and breakdown voltage of the GaN-based HEMT device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of GaN crystal material.

[0025] In the figure: 1. Silicon substrate; 2. AlN layer; 3. AlGaN dislocation recombination control layer; 4. High-resistivity GaN epitaxial layer; 5. GaN channel layer; 6. AlGaN barrier layer; 7. GaN cap layer. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] like Figure 1 As shown, this embodiment discloses an epitaxial structure of a GaN-based HEMT device, including a silicon substrate 1 and an AlN layer 2, an AlGaN dislocation recombination control layer 3, a high-resistivity GaN epitaxial layer 4, a GaN channel layer 5, an AlGaN barrier layer 6, and a GaN cap layer 7 sequentially grown from the surface of the silicon substrate 1.

[0029] The AlGaN dislocation control layer 3 comprises sequentially stacked AlxGa1-xN single crystal layers, AlyGa1-yN single crystal layers, AlzGa1-zN single crystal layers, and AlvGa1-vN single crystal layers. The AlxGa1-xN single crystal layer is a Buck layer with an Al composition of 0.55-0.85 and a thickness of 50 nm. Its growth conditions are a temperature of 950-1200 °C, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm. The AlyGa1-yN single crystal layer is a Ga vacancy introduction layer and a dislocation control layer. Its growth conditions are high temperature, low growth rate, and high V / III ratio, with a temperature greater than 1050 °C and a growth rate of 0.01-1.0 Å / s. The growth ratio is between 1000-30000, with a growth thickness of 50 nm. The Al composition y is a constant value, and the Al composition is between 0.65-0.95. The AlzGa1-zN single crystal layer is a Buck layer with an Al composition of 0.45-0.75 and a thickness of 50 nm. The growth conditions are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm. The AlvGa1-vN single crystal layer is a graded layer with an Al composition that gradually changes from 0.45-0.75 to 0.02-0.15 and a thickness of 10 nm. The growth conditions are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

[0030] The specific growth steps are as follows:

[0031] Step 1: Place a silicon substrate 1 into the growth chamber of the material growth equipment. The growth atmosphere is pure hydrogen or nitrogen atmosphere. Control the temperature to 1000-1150℃, the reaction chamber pressure to 50-200 torr, and introduce NH3 with a flow rate of 2-10 slm. Grow an AlN layer 2 with a thickness of 50nm on its surface.

[0032] Step 2: Controlling the temperature, reaction chamber pressure, and ammonia gas injection rate, an AlGaN dislocation composite control layer 3 with a thickness of 160 nm is grown on the surface of AlN layer 2.

[0033] Step 3: Control the temperature to 1000-1050℃, the reaction chamber pressure to 50-200 torr, and introduce NH3 at a flow rate of 5-30 slm. The carbon doping concentration is 2E18-2E19 atoms / cm3. Grow a high-resistivity GaN epitaxial layer 4 with a thickness of 1.5 μm on the surface of the AlGaN dislocation composite control layer 3.

[0034] Step 4: Control the temperature at 1000-1100℃, the reaction chamber pressure at 100-300 torr, and introduce NH3 at a flow rate of 50-80 slm to grow and prepare a GaN channel layer 5 with a thickness of 100 nm on the surface of the high-resistivity GaN epitaxial layer 4.

[0035] Step 5: Maintain the temperature at 1050-1150℃, the reaction chamber pressure at 50-200 torr, and introduce NH3 at a flow rate of 20-50 slm. The AL component is 0.15-0.4. Grow an AlGaN barrier layer 6 with a thickness of 10 nm on the surface of the GaN channel layer 5.

[0036] Step 6: Control the temperature at 1000-1050℃, maintain the pressure in the reaction chamber at 50-200 torr, and introduce NH3 at a flow rate of 20-50 slm and TMGa at a flow rate of 10-20 sccm to grow and prepare a GaN cap layer 7 with a thickness of 2nm on the surface of AlGaN barrier layer 6.

[0037] Step 7: Lower the temperature to room temperature to end the growth process and remove the crystal.

[0038] Example 2

[0039] The epitaxial growth method disclosed in this embodiment is basically the same as that in Embodiment 1, except that an AlN layer 2 with a thickness of 500 nm is grown on the surface of the silicon substrate 1.

[0040] Example 3

[0041] The epitaxial growth method disclosed in this embodiment is basically the same as that in Embodiment 1, except that: an AlGaN dislocation composite control layer 3 with a thickness of 800 nm is grown on the surface of AlN layer 2; wherein, the thickness of AlxGa1-xN single crystal layer is 200 nm, the thickness of AllyGa1-yN single crystal layer is 200 nm, the thickness of AlzGa1-zN single crystal layer is 200 nm and the thickness of AlvGa1-vN single crystal layer is 200 nm.

[0042] Example 4

[0043] The epitaxial growth method disclosed in this embodiment is basically the same as that in Embodiment 1, except that a high-resistivity GaN epitaxial layer 4 with a thickness of 3.5 μm is grown on the surface of the AlGaN dislocation composite control layer 3.

[0044] Example 5

[0045] The epitaxial growth method disclosed in this embodiment is basically the same as that in Embodiment 1, except that a GaN channel layer 5 with a thickness of 500 nm is grown on the surface of the high-resistivity GaN epitaxial layer 4.

[0046] Example 6

[0047] The epitaxial growth method disclosed in this embodiment is basically the same as that in Embodiment 1, except that an AlGaN barrier layer 6 with a thickness of 30 nm is grown on the surface of the GaN channel layer 5.

[0048] Example 7

[0049] The epitaxial growth method disclosed in this embodiment is basically the same as that in Embodiment 1, except that a GaN cap layer 7 with a thickness of 5 nm is grown on the surface of the AlGaN barrier layer 6.

[0050] In summary, this invention improves crystal quality, reduces dislocations, and enhances the leakage current characteristics and breakdown voltage of GaN-based HEMT devices by incorporating an optimized AlGaN dislocation recombination control layer 3 containing an epitaxial functional layer with Ga vacancies and introducing a large number of Ga vacancies during epitaxial growth.

[0051] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An epitaxial structure for a GaN-based HEMT device, characterized in that: It includes a silicon substrate and an AlN layer, an AlGaN dislocation recombination control layer, a high-resistivity GaN epitaxial layer, a GaN channel layer, an AlGaN barrier layer, and a GaN cap layer grown sequentially from the surface of the silicon substrate. The AlGaN dislocation recombination control layer comprises sequentially stacked Al... x Ga 1-x N single crystal layer, Al y Ga 1-y N single crystal layer, Al z Ga 1- z N single crystal layer and Al v Ga 1-v N single crystal layer; The Al x Ga 1-x The N single crystal layer is a bulk layer with an Al composition of 0.55-0.85 and a thickness of 50-200 nm; the Al... y Ga 1-y The N single crystal layer is a Ga vacancy introduction layer and a dislocation control layer, with a growth thickness of 50-200 nm. The Al composition γ is a constant value, and the Al content is 0.65-0.

95. z Ga 1-z The N single crystal layer is a bulk layer with an Al composition of 0.45-0.75 and a thickness of 50-200 nm; the Al... v Ga 1-v The N single crystal layer is a graded layer with an Al composition that gradually changes from 0.45-0.75 to 0.02-0.15, and its thickness is 10-200 nm.

2. A method for growing an epitaxial structure of a GaN-based HEMT device according to claim 1, characterized in that: Includes the following steps: Step 1: Place a silicon substrate into the growth chamber of the material growth equipment. The growth atmosphere is pure hydrogen or nitrogen. Control the temperature at 1000-1150℃, the reaction chamber pressure at 50-200 torr, and introduce NH3 at a flow rate of 2-10 slm to grow an AlN layer with a thickness of 50-500 nm on its surface. Step 2: Control the temperature, reaction chamber pressure, and ammonia gas injection rate to grow an AlGaN dislocation composite control layer with a thickness of 160-800 nm on the surface of the AlN layer. Step 3: Control the temperature to 1000-1050℃, the reaction chamber pressure to 50-200 torr, and introduce NH3 at a flow rate of 5-30 slm, with a carbon doping concentration of 2E18-2E19 atoms / cm³. 3 A high-resistivity GaN epitaxial layer with a thickness of 1.5-3.5 μm was grown on the surface of the AlGaN dislocation composite control layer. Step 4: Control the temperature at 1000-1100℃, the reaction chamber pressure at 100-300 torr, and introduce NH3 at a flow rate of 50-80 slm to grow and prepare a GaN channel layer with a thickness of 100-500 nm on the surface of the high-resistivity GaN epitaxial layer. Step 5: Maintain the temperature at 1050-1150℃, the reaction chamber pressure at 50-200 torr, and introduce NH3 at a flow rate of 20-50 slm to grow and prepare an AlGaN barrier layer with a thickness of 10-30 nm and an Al composition of 0.15-0.4 on the surface of the GaN channel layer. Step 6: Control the temperature at 1000-1050℃, maintain the pressure in the reaction chamber at 50-200 torr, and introduce NH3 at a flow rate of 20-50 slm and TMGa at a flow rate of 10-20 sccm to grow and prepare a GaN cap layer with a thickness of 2-5 nm on the surface of the AlGaN barrier layer. Step 7: Lower the temperature to room temperature to end the growth process and remove the crystal.

3. The epitaxial structure growth method for a GaN-based HEMT device according to claim 2, characterized in that: The Al x Ga 1-x The growth conditions for the N single crystal layer are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

4. The epitaxial structure growth method for a GaN-based HEMT device according to claim 2, characterized in that: The Al y Ga 1-y The growth conditions for N single crystal layers are high temperature, low growth rate and high V / III ratio. The temperature is greater than 1050℃, the growth rate is 0.01-1.0 Å / s and the V / III ratio is between 1000-30000.

5. The epitaxial structure growth method for a GaN-based HEMT device according to claim 2, characterized in that: The Al z Ga 1-z The growth conditions for the N single crystal layer are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

6. The epitaxial structure growth method for a GaN-based HEMT device according to claim 2, characterized in that: The Al v Ga 1-v The growth conditions for the N single crystal layer are a temperature of 950-1200℃, a reaction chamber pressure of 50-200 torr, and an NH3 flow rate of 0.04-10 slm.

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