Method for growing high-quality III-group nitride material by using Si / SiC composite substrate

Abstract

The invention discloses a method for growing a high-quality III-group nitride material by using a Si / SiC composite substrate, and belongs to the technical field of semiconductors. Different from a traditional method for growing SiC on a Si substrate, the Si / SiC composite substrate is formed through bonding, and the problems of high interface state density, mismatch dislocation and the like caused by growing SiC on the Si substrate can be avoided. The porous silicon layer prepared on the Si substrate provides non-complete tight coupling bonding, so that the stress in the bonding process can be released, and the warping of the composite substrate can be reduced. And meanwhile, the introduced SiC layer is beneficial to improving thermal conductivity and buffering stress, and the crystal quality of epitaxial nitride is improved by utilizing the excellent characteristic of high quality of PVD-AlN deposited on single crystal alpha-Al2O3, so that a high-quality III-group nitride material is obtained. According to the method for growing the high-quality III-group nitride material by effectively controlling stress and reducing mismatch dislocation, the performance and reliability of the device are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a method for growing high-quality group III nitride materials using a Si / SiC composite substrate. Background Art

[0002] Group III nitride materials have many advantages such as large bandgap, high breakdown field strength, large electron saturation drift rate, high temperature resistance and radiation resistance, and have important applications in power electronics, radio frequency electronics and optoelectronic devices. Among them, Si-based group III nitride radio frequency power devices have low cost, large-size substrates and good CMOS circuit compatibility, and have obvious advantages in the field of radio frequency microwave applications. However, there is a large lattice mismatch and thermal mismatch between the Si substrate and the epitaxial material, which leads to a large number of dislocations in the epitaxial layer and introduces a lot of stress. The existence of these defects and stress will affect the quality of the prepared heterostructure, thereby reducing the performance and reliability of the prepared device.

[0003] One of the existing technical routes is to form a composite substrate by epitaxially growing SiC on Si to reduce the lattice mismatch between the substrate and the nitride material, thereby improving the crystal quality of the epitaxial layer. However, the interface state density of SiC grown on a Si substrate is high, and there is also a 20% lattice mismatch and an 8% thermal expansion mismatch between the Si substrate and the SiC film, which limits the improvement effect. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention aims to provide a method for growing high-quality group III nitride materials using a Si / SiC composite substrate. The present invention is achieved through the following technical solutions:

[0005] A method for growing high-quality group III nitride materials using a Si / SiC composite substrate comprises the following steps:

[0006] (1) Preparing a porous silicon layer on a Si substrate and performing a polishing process;

[0007] (2) performing ion implantation on one side of the SiC substrate to form a defect layer at a preset depth;

[0008] (3) bonding the ion implantation surface of the SiC substrate to the porous silicon surface of the Si substrate, and peeling off part of the SiC substrate along the defect layer formed in step (2) to obtain a Si / SiC composite substrate;

[0009] (4) performing high temperature annealing pretreatment on the Si / SiC composite substrate and growing a single crystal α-Al2O3 layer on its SiC surface;

[0010] (5) depositing AlN on the single crystal α-Al2O3 layer by physical vapor deposition (PVD), optionally introducing oxygen during the deposition process, and optionally annealing the sample at high temperature;

[0011] (6) Growing Group III nitride materials on the deposited PVD-AlN layer.

[0012] The method for preparing the porous silicon layer in the above step (1) is to etch the Si substrate by inductively coupled plasma (ICP), wherein the etching gas is a mixture of hydrogen (H2) and argon (Ar), wherein the flow rate of H2 is 10 to 1000 sccm, the flow rate of Ar is 10 to 1000 sccm, the etching temperature range is 100 to 1100°C, the etching pressure is 1 to 200 Pa, and the etching time is 1 min to 1 h. Then, the porous silicon layer is polished, first mechanically polished and then chemically mechanically polished.

[0013] The ion implantation method in step (2) is hydrogen ion implantation, the energy of hydrogen ion implantation is 100keV to 500keV, and the dose of hydrogen ion implantation is 1e16cm -2 ~1e17cm -2 The angle of hydrogen ion implantation is 5° to 45°, and a defect layer is formed at a preset depth. Preferably, the preset depth is 100 nm to 5 μm.

[0014] The bonding method of the above step (3) is direct bonding, and then a portion of the SiC substrate is peeled off by annealing in a vacuum environment or in a protective atmosphere formed by at least one gas in an inert gas. Preferably, a two-stage annealing method is adopted, first annealing at a first temperature and then annealing at a second temperature, wherein the first temperature is lower than the second temperature, the first temperature is 200°C to 500°C, the annealing time is 15min to 25min, the second temperature is 500°C to 1000°C, and the annealing time is 5min to 15min.

[0015] In the above step (4), the Si / SiC composite substrate is subjected to high temperature annealing pretreatment using a tube furnace, the annealing temperature is 100-1500°C, the atmosphere is H2, and the time is 1-20 minutes. Then, the method for growing the single crystal α-Al2O3 layer can be plasma enhanced chemical vapor deposition (PECVD), liquid phase epitaxy (LPE) or molecular beam epitaxy (MBE), the growth temperature is 500-2000°C, the reaction sources are O2 and trimethylaluminum, the carrier gas is Ar, and the thickness of the single crystal α-Al2O3 layer is 25-75nm.

[0016] In the above step (5), AlN is deposited on the front side of the sample by PVD. Specifically, the Al source used is an Al target, the N source is nitrogen (N2), the deposition temperature is room temperature to 1000°C, and the deposition thickness is 10nm to 1μm.

[0017] In the above step (5), oxygen gas may be introduced during the deposition process. The flow rate of oxygen gas introduced during the deposition process may be 0.1 sccm to 10 sccm. Oxygen gas may be introduced during the entire deposition process or during part of the deposition process.

[0018] In the above step (5), the sample may be subjected to high temperature annealing, and the annealing temperature may be 100°C to 2000°C.

[0019] In the above step (6), metal organic chemical vapor deposition (MOCVD) is used to grow group III nitride materials on the sample surface. Specifically, the group III nitride materials include AlN, GaN, InN and ternary and quaternary compounds thereof, as well as stacked structures of the above materials.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a method for growing high-quality III-nitride materials on a Si / SiC composite substrate. Compared with the conventional method of growing SiC on a Si substrate, the method of forming a Si / SiC composite substrate by bonding can avoid the problems of high interface state density, misfit dislocations, etc. caused by growing SiC on a Si substrate. The porous silicon layer provided by this method provides a non-completely tightly coupled bonding, which helps to release stress during the bonding process and reduce the warping of the composite substrate. At the same time, the introduction of the SiC layer is also beneficial to improving thermal conductivity and buffering stress, and the excellent characteristics of high quality PVD-AlN deposited on single crystal α-Al2O3 are used to improve the crystal quality of epitaxial nitrides and obtain high-quality III-nitride materials. This method of effectively controlling stress and reducing misfit dislocations to grow high-quality III-nitride materials improves the performance and reliability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of a method for preparing high-quality group III nitride materials grown on a Si / SiC composite substrate according to a first embodiment of the present invention.

[0023] Figure 2 It is a schematic flow chart of a method for preparing high-quality Group III nitride materials grown on a Si / SiC composite substrate according to Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

[0025] Embodiment 1

[0026] See also Figure 1 , Figure 1 1 is a schematic flow chart of a method for growing a high-quality GaN film on a Si / SiC composite substrate according to a first embodiment of the present invention. The method comprises the following steps 1-1 to 1-6:

[0027] Step 1-1, prepare a porous silicon layer on a Si substrate and perform polishing. Place the silicon substrate in the reaction chamber of an ICP etcher, introduce H2 and Ar, with a H2 flow rate of 100 sccm, an Ar flow rate of 600 sccm, an etching temperature of 600°C, a working pressure of 100 Pa, an etching time of 5 min, and a porous silicon layer with a thickness of 5 μm; then polish the Si substrate, first mechanical polishing and then chemical mechanical polishing.

[0028] Step 1-2: hydrogen ion implantation is performed on one side of the SiC substrate to form a defect layer at a preset depth. The energy of the hydrogen ion implantation is 110 keV, and the dose of the hydrogen ion implantation is 1e16 cm -2 The angle of hydrogen ion implantation is 10°, forming a defect layer at a depth of 600nm.

[0029] Step 1-3, a Si substrate and a SiC substrate are bonded by direct bonding to form a Si / SiC composite substrate, and a two-stage annealing method is adopted, first annealing at 300° C. for 20 minutes, and then annealing at 800° C. for 10 minutes, both in an argon atmosphere.

[0030] Step 1-4, use a tubular furnace to perform high-temperature annealing pretreatment on the Si / SiC composite substrate at a temperature of 1100°C, anneal for 6 minutes in a H2 atmosphere to remove pollutants and surface states on the surface of the Si / SiC composite substrate, and provide a good substrate for subsequent growth; then put the Si / SiC composite substrate into a PECVD reaction chamber, adjust the temperature to 700°C, introduce O2, and use Ar as a carrier gas to carry trimethylaluminum to the reaction chamber. The pressure in the reaction chamber is 200Pa, O2 reacts with trimethylaluminum, and the growth time is 8 minutes to grow a single crystal α-Al2O3 layer with a thickness of 30nm on the Si / SiC composite substrate.

[0031] Step 1-5, PVD-AlN is deposited on the sample surface. Specifically, the Al source used is an Al target, the N source is nitrogen, the deposition temperature is 650° C., and the deposition thickness is 200 nm.

[0032] Step 1-6, using MOCVD to grow AlN and GaN stacks. The Al source, Ga source, and N source are TMAl, TMGa, and ammonia, respectively. The pressure in the reaction chamber is 100 mbar, and 200 nm AlN and 3 μm GaN are grown.

[0033] Embodiment 2

[0034] See also Figure 2 , Figure 2 1 is a schematic flow chart of a method for growing a high-quality GaN film on a Si / SiC composite substrate according to a second embodiment of the present invention. The method comprises the following steps 2-1 to 2-6:

[0035] Step 2-1, place the silicon substrate in the reaction chamber of the ICP etcher, prepare a porous silicon layer on the silicon substrate, introduce H2 and Ar, the H2 flow rate is 100sccm, the Ar flow rate is 600sccm, the etching temperature is 600℃, the working pressure is 100Pa, the etching time is 5min, and the thickness of the formed porous silicon layer is 5μm; then polish the Si substrate, first mechanical polishing and then chemical mechanical polishing.

[0036] Step 2-2: hydrogen ion implantation is performed on one side of the SiC substrate to form a defect layer at a preset depth. The energy of the hydrogen ion implantation is 110 keV, and the dose of the hydrogen ion implantation is 1e16 cm -2 The angle of hydrogen ion implantation is 10°, forming a defect layer at a depth of 600nm.

[0037] Step 2-3, the Si substrate and the SiC substrate are bonded by direct bonding to form a Si / SiC composite substrate. A two-stage annealing method is used, first annealing at 300° C. for 20 minutes, and then annealing at 800° C. for 10 minutes, both in an argon atmosphere.

[0038] Step 2-4, using a tube furnace to perform high temperature annealing pretreatment on the Si / SiC composite substrate, the temperature is 1100°C, annealing for 6 minutes in a H2 atmosphere, removing pollutants and surface states on the surface of the Si / SiC composite substrate, and providing a good substrate for subsequent growth; then, the Si / SiC composite substrate is placed in an MBE reaction chamber, the temperature is adjusted to 1000°C, O2 is introduced, and trimethylaluminum is carried to the reaction chamber using Ar as a carrier gas, and the pressure in the reaction chamber is 10 -3 Pa, O2 react with trimethylaluminum, and the growth time is 6 minutes to grow a single crystal α-Al2O3 layer with a thickness of 30 nm on the Si / SiC composite substrate.

[0039] Step 2-5, PVD-AlN is deposited on the sample surface, and the sample is subjected to high temperature annealing. Specifically, the Al source used is an Al target, the N source is nitrogen, the deposition temperature is 650°C, and the deposition thickness is 200nm. Oxygen is introduced throughout the deposition process, and the oxygen flow rate is 1sccm. The temperature of high temperature annealing is 850°C, the time is 30min, and the atmosphere is nitrogen.

[0040] Step 2-6, using MOCVD to grow AlN and GaN stacks. Using TMAl, TMGa and ammonia as Al source, Ga source and N source respectively, the reaction chamber pressure is 100 mbar, and 200nm AlN and 3μm GaN are grown.

[0041] Through the above steps, a high-quality GaN film on a Si / SiC composite substrate is obtained. This growth method is based on bonding technology and has better stress control, crystal quality and higher thermal conductivity, which improves the performance and reliability of the device.

[0042] The embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only some embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for growing high-quality group III nitride materials using a Si / SiC composite substrate, comprising the following steps: 1) Preparing a porous silicon layer on a Si substrate and performing a polishing process; 2) performing ion implantation on one side of the SiC substrate to form a defect layer at a preset depth; 3) bonding the ion implantation surface of the SiC substrate to the porous silicon surface of the Si substrate, and peeling off part of the SiC substrate along the defect layer formed in step 2) to obtain a Si / SiC composite substrate; 4) performing high temperature annealing pretreatment on the Si / SiC composite substrate and growing a single crystal α-Al2O3 layer on its SiC surface; 5) Depositing AlN on the single crystal α-Al2O3 layer using physical vapor deposition; 6) Growing a Group III nitride material on the AlN layer.

2. The method according to claim 1, characterized in that Step 1) etching the Si substrate by inductively coupled plasma to form a porous silicon layer; the polishing process is first mechanical polishing and then chemical mechanical polishing.

3. The method according to claim 2, characterized in that Step 1) The etching gas used in the inductively coupled plasma etching is a mixture of hydrogen and argon, wherein the flow rate of hydrogen is 10-1000sccm, the flow rate of argon is 10-1000sccm, the etching temperature is 100-1100°C, the etching pressure is 1-200Pa, and the etching time is 1min-1h.

4. The method according to claim 1, characterized in that Step 2) Hydrogen ion implantation is used with an implantation energy of 100keV to 500keV and an implantation dose of 1e16 cm -2 ~1e17 cm -2 The injection angle is 5° to 45°, and a defect layer is formed at a preset depth of 100nm to 5μm.

5. The method according to claim 1, characterized in that Step 3) Direct bonding first, and then peeling by annealing in a vacuum environment or in an inert atmosphere.

6. The method according to claim 5, characterized in that Step 3) peeling is performed by two-stage annealing, first annealing at a first temperature of 200-500° C. for 15-25 minutes, and then annealing at a second temperature of 500-1000° C. for 5-15 minutes, wherein the first temperature is lower than the second temperature.

7. The method according to claim 1, characterized in that Step 4) Use a tubular furnace to perform high-temperature annealing pretreatment on the Si / SiC composite substrate, the annealing temperature is 100-1500°C, the atmosphere is H2, and the time is 1-20 minutes; then, PECVD, LPE or MBE is used to grow a single crystal α-Al2O3 layer, the growth temperature is 500-2000°C, the reaction sources are O2 and trimethylaluminum, the carrier gas is argon, and the thickness of the single crystal α-Al2O3 layer is 25-75nm.

8. The method according to claim 1, characterized in that Step 5) The Al source used for physical vapor deposition is an Al target, the N source is nitrogen, the deposition temperature is room temperature to 1000° C., and the deposition thickness is 10 nm to 1 μm.

9. The method according to claim 1, characterized in that Step 5) introducing oxygen gas during the whole or part of the deposition process, with an oxygen flow rate of 0.1 sccm to 10 sccm; and / or, performing high temperature annealing after deposition, with an annealing temperature of 100° C. to 2000° C.

10. The method according to claim 1, characterized in that Step 6) MOCVD is used to grow group III nitride materials, wherein the group III nitride materials include AlN, GaN, InN and ternary and quaternary compounds thereof, and a stacked structure of the above materials.

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