Environment-friendly method for vapor phase growth of III-group nitride crystal

Abstract

The invention relates to an environment-friendly method for vapor phase growth of a group III nitride crystal, and belongs to the field of semiconductor materials. Alloy formed by fluxing agent metal and Al / Ga is used as a source material, argon is used as carrying gas, and nitrogen is used as a nitrogen source. And growing AlN and GaN crystals at a medium temperature (1400-1800 DEG C) by adopting a vapor phase transmission method. According to the invention, controllable nitride crystal growth is realized. The gas-phase metal source and the nitrogen source are isolated and controllably transmitted in a mode that the inert gas carries the metal source, and the defects of a traditional gas-phase metal source direct nitriding method are overcome. In addition, the technological process is simple, no pollution gas is discharged, and the environment-friendly requirement of the current society is met.

Description

Technical Field

[0001] The invention relates to an environmentally friendly method for growing III-group nitride crystals in vapor phase, belonging to the field of semiconductor materials. Background Art

[0002] The third generation of semiconductor materials represented by gallium nitride (GaN), silicon carbide (SiC), aluminum nitride (AlN), etc. are becoming a new strategic high ground for the global semiconductor industry due to their excellent properties such as wide band gap, high breakdown electric field, high thermal conductivity, high electron saturation rate and strong radiation resistance. In particular, group III nitride semiconductors, such as GaN and AlN, are very suitable for manufacturing high-temperature, high-frequency, and high-power microelectronic devices.

[0003] The remarkable achievements of nitride semiconductors in the fields of optoelectronics and microelectronics are inseparable from the improvement of crystal quality. Therefore, it is of great significance to prepare large-sized, high-quality AlN and GaN crystals. At present, the methods for preparing nitride semiconductor crystals include physical vapor transport (PVT), metal organic chemical vapor deposition (MOCVD), and hydride vapor phase epitaxy (HVPE). Among them, PVT is recognized as the most promising method for preparing large-sized AlN materials, and HVPE is the most effective method for preparing GaN.

[0004] However, when preparing GaN by HVPE, the HCl gas used is corrosive to the equipment, and ammonia as a nitrogen source will pollute the environment. The PVT method for growing AlN needs to be carried out at high temperatures (around 2200°C), and currently only tungsten or tantalum carbide crucibles have been proven to withstand such harsh growth conditions. These factors lead to the method requiring expensive costs and high energy consumption.

[0005] As for the direct nitridation method using nitrogen as the nitrogen source, the process is simple and no polluting gas is generated. However, during the nitridation process, the reaction between the metal source and nitrogen will generate a nitride shell on the surface of the metal melt, which hinders further nitridation. In addition, the temperature gradient of the crucible is difficult to control accurately, which directly affects the gas phase transmission rate. These reasons make it difficult to grow crystals in a continuous, stable and high-quality manner. Summary of the invention

[0006] In view of the above technical deficiencies, the purpose of the present invention is to provide an environmentally friendly method for vapor phase growth of group III nitride crystals, which realizes a continuous and stable supply of a vapor source in a special growth device, and achieves the purpose of growing high-quality nitride crystals on heterogeneous or homogeneous substrates without pollution.

[0007] The present invention can be implemented by the following technical solutions:

[0008] An environmentally friendly method for vapor phase growth of group III nitride crystals, specifically comprising the following steps:

[0009] (1) placing a seed crystal on a specially made seed crystal rod, and then fixing them together at the outlet end of a specially made tubular resistance heating furnace, and then placing a crucible boat containing alloy raw materials in an argon gas channel, close to the inlet end of the tubular furnace inlet channel; the alloy is an aluminum-X alloy or a gallium-Y alloy; wherein X is selected from copper, calcium, titanium or iron, and Y is selected from aluminum, sodium, calcium, lithium or barium; and X and Y are flux metals or functional additives;

[0010] (2) Open the argon channel, inject high-purity argon gas into the channel where the raw materials are located, and gradually increase the temperature until the alloy is melted. Then open another channel, start to introduce nitrogen and maintain it for 10 minutes.

[0011] (3) Continue to raise the temperature to the growth temperature and keep it constant for 1-10 hours to allow nitrogen and metal vapor to fully react at the substrate. Then cool it down to the lowest temperature that can be detected by the temperature meter in the furnace chamber.

[0012] (4) Continue to cool down to room temperature, and extract the grown seed crystals after cooling.

[0013] Furthermore, in step (1), the growth device used is a specially made tubular resistance heating furnace with two gas inlet channels, and the gases passing through the two channels are high-purity nitrogen and argon respectively.

[0014] Furthermore, in step (1), the crucible boat used is made of graphite, corundum, tantalum carbide or graphite with tantalum carbide coating. The seed crystal rod is made of graphite, one end of which can be fixed with the seed crystal by a special mechanical fixing device and placed inside the furnace chamber together.

[0015] Furthermore, in step (2), after the seed crystal is fixed, the argon gas channel is opened and its flow rate is set to 0.1-1 L / min.

[0016] Furthermore, in step (2), the heating rate is 4°C / min.

[0017] Furthermore, in step (2), when the temperature rises to 1200° C., the nitrogen channel is opened and its flow rate is set to 0.1-1 L / min.

[0018] Compared with the prior art, the present invention provides an environmentally friendly method for vapor-phase growth of III-nitride crystals, which can be used to grow nitride crystals using large-sized commercial substrate materials such as SiC without polluting gas emissions. Compared with the existing preparation methods, it solves the problem of scarcity of large-sized nitride homogeneous substrates and provides a basis for the large-scale commercial production of III-nitride semiconductors. In addition, the present invention grows at moderate temperatures and has the function of protecting seed crystals and the graphite devices used, making device processing easier while reducing costs. This technological innovation is of great significance to the development of the semiconductor industry and related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the dual-channel tubular furnace growth system of the present invention;

[0020] In the figure, 1-argon channel, 2-nitrogen channel, 3-graphite crucible boat, 4-gas nozzle and reaction chamber, 5-seed crystal substrate, 6-hollow seed crystal rod, 7-insulation cotton, 8-exhaust outlet DETAILED DESCRIPTION

[0021] The following embodiments are all in Figure 1 The double-channel tubular furnace growth system shown is implemented, and the device includes 1-argon channel, 2-nitrogen channel, 3-graphite crucible boat, 4-gas nozzle and reaction chamber, 5-seed crystal substrate, 6-hollow seed crystal rod, 7-insulation cotton, and 8-exhaust gas outlet. The present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but the scope of protection of this patent is not limited to the following embodiments.

[0022] Embodiment 1

[0023] (1) SiC seed crystals are placed on a special seed crystal rod, and then fixed together at the outlet end of a special tubular resistance heating furnace. Metal Al and flux metal Cu are evenly mixed in a molar ratio of 60:40 and placed in a crucible boat, which is then placed in an argon gas channel, close to the inlet end of the tubular furnace gas inlet channel.

[0024] (2) Open the argon channel and inject high-purity argon gas into the channel where the raw materials are located at a gas flow rate of 0.1L / min. Then, increase the temperature to 1500℃ at a heating rate of 5℃ / min and keep it for 5h to melt the metal and form an alloy. Then open another channel and pass nitrogen at a flow rate of 0.2L / min and keep it for 10 minutes.

[0025] (3) Continue to raise the temperature to the growth temperature and maintain the constant temperature for 1-10 hours to allow nitrogen and metal vapor to fully react at the substrate. Then cool down to the lowest temperature that can be detected by the temperature meter in the furnace chamber.

[0026] (4) Turn off the heating switch and let the temperature drop naturally to room temperature. After cooling, take out the crucible boat and extract the grown seed crystal.

[0027] Embodiment 2

[0028] (1) Place the SiC seed crystal on a special seed crystal rod, and then fix them together at the outlet end of a special tubular resistance heating furnace. Mix metal Ga and flux metal A1 at a molar ratio of 70:30 and place them in a crucible boat. Place it in the argon channel, close to the inlet end of the tubular furnace inlet channel.

[0029] (2) Open the argon channel and inject high-purity argon gas into the channel where the raw materials are located at a gas flow rate of 0.1L / min. Then, increase the temperature to 1500℃ at a heating rate of 5℃ / min and keep it for 5h to melt the metal and form an alloy. Then open another channel and pass nitrogen at a flow rate of 0.2L / min and keep it for 10 minutes.

[0030] (3) Continue to raise the temperature to the growth temperature and maintain the constant temperature for 1-10 hours to allow nitrogen and metal vapor to fully react at the substrate. Then cool down to the lowest temperature that can be detected by the temperature meter in the furnace chamber.

[0031] (4) Turn off the heating switch and let the temperature drop naturally to room temperature. After cooling, take out the crucible boat and extract the grown seed crystal.

[0032] The description of the above embodiments is intended to enable those skilled in the art to understand and implement the invention. Those skilled in the art can adjust these embodiments and apply the disclosed basic principles to other situations without having to perform innovative work. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications based on the disclosure of the present invention should fall within the scope of protection of the present invention.

Claims

1. An environmentally friendly method for vapor phase growth of group III nitride crystals, characterized in that: Nitride is grown using a vapor transport method using the following steps: Step 1: placing a seed crystal on a special seed crystal rod, and then fixing them together at the outlet end of a special tubular resistance heating furnace, and then placing a crucible boat containing alloy raw materials in an argon gas channel, close to the inlet end of the tubular furnace inlet channel; the alloy raw materials are aluminum-X alloy or gallium-Y alloy; wherein X is selected from copper, calcium, titanium or iron, and Y is selected from aluminum, sodium, calcium, lithium or barium; X and Y are flux metals or functional additives; Step 2: Open the argon channel, inject high-purity argon gas into the channel where the raw materials are located, and gradually increase the temperature until the alloy is melted. Then open another channel, start to introduce nitrogen and keep it for 10 minutes. Step 3: Continue to raise the temperature to the growth temperature and keep it constant for 1-10 hours to promote the nitrogen and metal vapor to fully react at the substrate, and then cool it down to the lowest temperature that can be detected by the temperature meter in the furnace chamber. Step 4: Continue to cool down to room temperature, and take out the grown seed crystal after cooling.

2. The method according to claim 1, characterized in that: In step 1, the growth device used is a specially made double-inlet channel tubular resistance heating furnace, and the gases passing through the two channels are high-purity nitrogen and argon respectively.

3. The method according to claim 1, characterized in that: In step 1, the crucible boat is made of graphite, corundum, tantalum carbide or graphite with tantalum carbide coating. The seed crystal rod is made of graphite, one end of which can fix the seed crystal through a special mechanical fixing device and placed inside the furnace chamber together.

4. The method according to claim 1, characterized in that: In step 1, a crucible containing alloy raw materials is placed in the argon gas channel, close to the inlet end of the gas inlet channel.

5. The method according to claim 1 or 4, characterized in that: In step 2, after the seed crystal is fixed, the argon channel is opened and its flow rate is set to 0.1-1 L / min.

6. The method according to claim 1 or 5, characterized in that: In step 2, the heating rate is 4°C / min.

7. The method according to claim 6, characterized in that: In step 2, when the temperature rises to 1200° C., the nitrogen channel is opened and its flow rate is set to 0.1-1 L / min.

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