A vertical HVPE growth apparatus

Abstract

A vertical HVPE growth device for growing single crystal gallium nitride, comprising a cavity tube, a gas source area, a single crystal growth tray and a heating system; the gas source area is composed of a plurality of gas conduits nested, and the heating system comprises three heating devices corresponding to three temperature zones, in the order from top to bottom of the vertical HVPE device, in turn, the first heating device corresponding to the first temperature zone 800-900 DEG C, the second heating device corresponding to the second temperature zone 1400-1600 DEG C, and the third heating device corresponding to the temperature zone 1000-1100 DEG C, wherein the second heating device is a radio frequency coil. The gas conduit is composed of three parts spliced, from top to bottom, a quartz part, an insulation part and an induction part. The application can effectively inhibit the premature reaction of the gas by improving the heating system of the vertical HVPE growth device and the gas conduit, setting three specific temperature zones and controlling the temperature of the second temperature zone by radio frequency heating, and at the same time can ensure the full mixing of NH3 gas and GaCl gas in the single crystal growth tray, which is conducive to the generation of high-quality single crystal gallium nitride.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor materials, and is used for growing semiconductor materials, in particular to a vertical HVPE growth device for producing single crystal gallium nitride. BACKGROUND

[0002] The 3rd generation semiconductor material is known as a new engine for optoelectronic and microelectronic industries. Among them, the III-V nitride material (also known as GaN-based material) based on GaN has attracted much attention in recent years. With the increasing market demand, the performance requirements for GaN devices are also increasing. Therefore, the internal defect density of GaN epitaxy grown on a traditional sapphire substrate is insufficient to meet the demand. Therefore, growing a gallium nitride epitaxial wafer on a single crystal GaN substrate has become a solution in recent years.

[0003] In the traditional method, the vertical HVPE (Hydrogen Vapor Phase Epitaxy) device is used to grow single crystal GaN, which is the mainstream solution. The traditional device generally uses a hot wall heating, and the internal quartz reaction chamber. The reaction gas (NH3 gas, GaCl gas, etc.) is transmitted through the gas conduit to produce single crystal gallium nitride on the single crystal growth tray, and the reaction formula is as follows:

[0004]

[0005] However, in the growth process, the reaction gas will also react in advance in the gas conduit before reaching the single crystal growth tray, causing the deposition of gallium nitride, blocking the gas conduit, and affecting the normal reaction. In order to avoid this problem, a vertical hydrothermal vapor phase epitaxial growth system (CN102465333B) is adopted in China invention patent, which adds an isolation gas path in the gas conduit to introduce inert gas to isolate NH3 gas and GaCl gas, so as to inhibit the premature reaction and prevent the parasitic deposition in the gas conduit. However, since the NH3 gas and GaCl gas are isolated, the NH3 and GaCl gas cannot be fully mixed, and cannot uniformly reach the single crystal growth tray, which affects the quality of the generated single crystal GaN.

[0006] Therefore, how to improve the performance of the vertical HVPE growth device and produce high-quality single crystal gallium nitride is still a problem to be solved. SUMMARY

[0007] The present application aims to solve the problems in the background art, improve the vertical HVPE growth device, and ensure the full mixing of NH3 gas and GaCl gas on the basis of avoiding the reaction and deposition of NH3 gas and GaCl gas in the gas conduit, and uniformly reach the single crystal growth tray, which is beneficial to the growth of high-quality single crystal gallium nitride.

[0008] The technical scheme of the present application is as follows:

[0009] A vertical HVPE growth device, comprising: a cavity tube, a gas source area, a single crystal growth tray and a heating system;

[0010] The cavity tube opening part is the upper part of the vertical HVPE device, and the single crystal growth tray is located in the lower part of the device. The gas source area is on the inner side of the cavity tube and is composed of a plurality of gas conduits nested together. Different gases are transported by different gas conduits, and the gas conduit contains a gallium boat to provide a gallium source for the reaction. The single crystal growth tray is used to carry the growth of single crystal gallium nitride. The heating system is arranged on the outer side of the cavity tube.

[0011] The heating system comprises three heating devices corresponding to three temperature zones. In order from top to bottom of the vertical HVPE device, they are a first heating device corresponding to a first temperature zone with a temperature of 800-900°C, a second heating device corresponding to a second temperature zone with a temperature of 1400-1600°C, and a third heating device corresponding to a temperature zone with a temperature of 1000-1100°C. The second heating device is a radio frequency coil. The gas conduit is composed of three parts spliced together from top to bottom: a quartz part, an insulation part and an induction part. The bottom end of the quartz part is at a horizontal height lower than or equal to the horizontal height of the bottom end of the gallium boat.

[0012] The second heating device has a top end height between the bottom surface of the gallium boat and the bottom end of the insulation part, and the bottom end of the second heating device is 10-20 mm higher than the bottom end of the induction part.

[0013] Preferably, the vertical length of the second heating device is 200-400 nm.

[0014] Preferably, the length of the induction part is 50-100 nm.

[0015] Preferably, the length of the insulation part is 30-60 nm.

[0016] Preferably, the length of the quartz part is 300-600 nm.

[0017] Preferably, the vertical length of the first heating device is 200-400 mm, and the vertical length of the third heating device is 400-600 mm.

[0018] Preferably, the material of the quartz part is quartz, the material of the insulation part is a high-temperature and corrosion-resistant material such as silicon carbide ceramic, alumina ceramic, and the material of the induction part is graphite coated with a coating material such as silicon carbide, high-purity boron nitride, tantalum carbide, tungsten carbide and other high-temperature and corrosion-resistant materials.

[0019] Preferably, the above-mentioned HVPE device further comprises a tail gas treatment device, which is arranged in the cavity tube close to the bottom of the device, for treating the tail gas.

[0020] The present application can effectively inhibit the premature reaction of NH3 gas and GaCl gas, avoid parasitic deposition at the gas conduit, and ensure the sufficient mixing of NH3 gas and GaCl gas at the single crystal growth tray, thereby facilitating the generation of high-quality single crystal gallium nitride. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a schematic diagram of a prior art vertical HVPE growth device.

[0022] Figure 2 Figure 2 is a top view of the gas conduit of the prior art vertical HVPE growth device.

[0023] Figure 3 Figure 3 is a schematic diagram of the gas flow ratio on the single crystal growth tray of the prior art vertical HVPE growth device.

[0024] Figure 4 Figure 4 is a schematic diagram of the vertical HVPE growth device of the present application.

[0025] Figure 5 Figure 5 is a top view of the gas conduit of the vertical HVPE growth device of the present application.

[0026] Figure 6 Figure 6 is a schematic diagram of the gas conduit structure of the vertical HVPE growth device of the present application.

[0027] Figure 7 Figure 7 is a schematic diagram of the gas flow ratio on the single crystal growth tray of the vertical HVPE growth device of the present application. EMBODIMENTS

[0028] The embodiments of the present application will be described in detail below with reference to the accompanying drawings and examples. Before introducing the present application, it should be understood that the present application can be realized in various different forms, and therefore the present application is not limited to the specific embodiments described below.

[0029] Figure 1 is a schematic diagram of a prior art vertical HVPE growth device. Figure 1 In order to avoid the premature reaction of NH3 and GaCl reaction gases, a nitrogen or argon gas is arranged to separate them, as shown in Figure 2. Figure 2A top view of the gas conduits in an existing vertical HVPE apparatus shows three layers of gas conduits. The innermost gas conduit carries GaCl (HCl) gas, NH3 is placed between the outermost gas conduits, and an intermediate gas conduit carries inert gases such as nitrogen to separate GaCl and NH3. However, this isolation design results in an excessive separation between NH3 and GaCl, hindering their thorough mixing and preventing them from uniformly reaching the single crystal growth apparatus. Figure 3 As shown, the distribution of the 5:3 gas ratio (the ratio of NH3 gas to GaCl gas) on the single crystal growth tray is a curve with a very deep bottom. The GaCl gas and NH3 gas are not uniform on the surface of the single crystal growth tray. The GaCl gas is concentrated in the middle of the single crystal growth tray, while the NH3 gas is concentrated on both sides. Therefore, it is impossible to obtain high-quality single crystal gallium nitride.

[0030] The problem solved by this invention is to prevent NH3 gas and GaCl gas from reacting prematurely, while also ensuring that both can reach the single crystal growth device uniformly.

[0031] like Figure 4 As shown, this embodiment discloses a vertical HVPE device, which includes a cavity tube, a gas source area, a single crystal growth tray, and a heating system.

[0032] The inside of the cavity tube is the reaction chamber, the outside is the heating system, and the opening of the cavity tube is above the device.

[0033] Specifically, according to function, the reaction chamber can be divided into two parts: a gas source area and a single crystal growth tray. The gas source area consists of multiple nested gas conduits. The gas conduits are introduced into the reaction chamber from the opening of the chamber tube. In this embodiment, the gas conduits are cylindrical structures, and different gases are transported by different gas conduits. Specifically, HCl gas and NH3 gas are transported by different gas conduits. Each conduit is also equipped with a carrier gas, which can be an inert gas such as nitrogen, hydrogen, or argon, to carry and transport the reaction gas. A gallium boat is set inside the gas conduit, which is connected to the gas conduit containing HCl gas, and is used to provide the gallium source for gallium nitride single crystals.

[0034] In this embodiment, as Figure 5 The diagram shows a top view of the gas conduit of this invention. The gas conduit has inner and outer layers. The inner layer introduces HCl gas, which reacts with the gallium boat to produce GaCl gas. The outer layer introduces NH3 gas, which is used to react with GaCl gas at the single crystal growth tray to produce single-crystal GaN. The specific reaction formula will be described below. Typically, to facilitate the transport of HCl and NH3, an inert gas such as N2 or H2 (not shown in the figure) is also transported in the gas conduit as a carrier gas. In this embodiment, the inner gas conduit introduces HCl and N2, while the outer gas conduit introduces NH3 and N2.

[0035] After the HCl gas reaches the gallium boat, the HCl gas reacts with the Ga source in a suitable temperature range to obtain GaCl gas for subsequent growth of single crystal gallium nitride, and the specific reaction formula is:

[0036]

[0037] The reaction is referred to as the first reaction.

[0038] In order to generate GaCl gas, the reaction temperature is set to be between 800°C and 900°C. Therefore, the first heating device temperature is set to be between 800°C and 900°C to ensure that the reaction is in the first temperature zone of 800°C to 900°C. In this embodiment, the first heating device is a resistance radiation furnace, and the vertical length is 200mm to 400mm, so that the first reaction can be fully carried out.

[0039] It should be noted that after the first reaction, the obtained GaCl gas is easy to react with NH3 in advance near the outlet of the gas conduit and deposit into GaN, and the reaction formula is:

[0040]

[0041] The reaction is referred to as the second reaction.

[0042] The deposited GaN is easy to block the gas conduit, affecting the transmission and circulation of the gas, and is not conducive to the subsequent generation of single crystal gallium nitride. Therefore, in this application, a second heating device is arranged in the corresponding area, and the temperature is controlled to be between 1400°C and 1600°C, that is, the second temperature zone. In this high temperature, the second reaction is effectively inhibited, and it is difficult to generate GaN parasitic deposition. Specifically, the application uses a radio frequency coil as the second heating device, because radio frequency heating can provide higher temperature, and radio frequency induction heating is fast, and there is no temperature transition, so that the temperature can be suddenly raised from the original first temperature zone to the predetermined second temperature zone, preventing the second reaction from generating parasitic deposition inside the gas conduit. Reference Figure 6 , preferably, in order to further prevent parasitic deposition from blocking the gas conduit, the height of the top end of the second heating device in this embodiment is set to be between the bottom surface of the gallium boat and the bottom end of the heat insulation part, and the bottom end of the second heating device is 10mm to 20mm higher than the bottom end of the induction part. Such design can ensure that the outlet part and the surrounding area of the gas conduit are in the second temperature zone, preventing the outlet of the gas conduit from being blocked. More preferably, the vertical length of the radio frequency coil in this embodiment is 200mm to 400mm, which can reasonably control the temperature gradient of the second temperature zone, and will not affect the overall length of the device.

[0043] Corresponding to the second heating device, the gas conduit in this application has a special structure, such as Figure 6The gas conduit structure of the present application is composed of three parts from top to bottom: a quartz part, an insulation part, and an induction part. The material of the quartz part is quartz, and the bottom end of the quartz part is at a horizontal level lower than or equal to the bottom end of the gallium boat. In this embodiment, the length of the quartz part is in the range of 300-600 mm, which can ensure the length of the first temperature zone and ensure the first reaction, without causing the overall device to be too high. The insulation part is connected below the quartz part, which is used to insulate the high temperature (1400-1600℃) of the second temperature zone, so as to avoid the softening of the quartz part due to high temperature. In this embodiment, the material of the insulation part is preferably alumina ceramic, and can also be other materials with high temperature resistance and corrosion resistance, such as silicon carbide ceramic. In this embodiment, the length of the insulation part is preferably 30-60 nm. If the length is too short, the insulation effect will be affected, and the quartz material will be damaged. If the length is too long, the height of the entire reaction chamber will be affected. The induction part is connected below the insulation part. In this embodiment, the length of the induction part is 50-100 nm. The induction part is used to couple with the radio frequency coil of the second heating device to generate an induced current, so as to heat the temperature to 1400-1600℃, and inhibit the parasitic deposition of GaN at the outlet of the gas conduit. If the length of the induction part is too short, the gas may diffuse to the low-temperature area such as the insulation part or the quartz part, causing deposition. If the length is too long, the overall length of the device reaction chamber will be increased, which will increase the energy consumption and is not conducive to maintenance and large-scale production. Preferably, the material of the induction part is graphite coated with a coating material. Graphite itself is conductive and can generate an induced current with the radio frequency coil to increase the temperature. However, graphite is prone to volatile impurities. Therefore, in this embodiment, a high-temperature and corrosion-resistant material is selected as a coating to cover the graphite. In this embodiment, the coating material is silicon carbide. In other embodiments, high-purity boron nitride, tantalum carbide, tungsten carbide, and other high-temperature and corrosion-resistant materials can also be selected.

[0044] Subsequently, the GaCl gas and the NH3 gas that have not been reacted in advance reach the single crystal growth tray uniformly. The single crystal growth tray is located in the third temperature zone. In this embodiment, the third heating device is an electric resistance furnace, and the vertical length thereof is 400-600 mm, which can ensure the uniformity and temperature gradient of the temperature.

[0045] The third temperature zone is 1000-1100℃, which can meet the temperature requirement of the reaction, and generate single crystal gallium nitride. The specific reaction formula is the same as the second reaction.

[0046]

[0047] After the reaction, GaN is deposited and grown on the single crystal growth tray, and high-quality single crystal gallium nitride is obtained.

[0048] The top view of the gas conduit of the existing vertical HVPE device Figure 2 and the top view of the gas conduit part of the vertical HVPE device in the present application Figure 5), it can be obviously seen that the vertical HVPE device provided by the application saves Figure 3 The isolation gas path (the gas conduit in which the N2 gas is located) is arranged, so that the GaCl gas and the NH3 gas can be fully mixed after leaving the gas conduit and reaching the single crystal growth device.

[0049] The inventors conducted comparative experiments on the uniformity of the GaCl gas and the NH3 gas on the surface of the single crystal growth tray, and the experimental data are shown in Figure 3 and Figure 7 .

[0050] Figure 3 The five-three ratio of the gas on the single crystal growth tray of the prior art vertical HVPE device.

[0051] Figure 7 The five-three ratio of the gas on the single crystal growth tray of the vertical HVPE device of the application.

[0052] Figure 3 The horizontal coordinate of and Figure 7 is the position of the single crystal growth tray, and the 0 point is the center of the single crystal growth tray, and the horizontal coordinate is the distance from other positions to the center. Figure 3 The vertical coordinate of and Figure 7 is the five-three ratio, which refers to the ratio of the N source and the Ga source on the single crystal growth tray, the higher the five-three ratio, the more the N source, the lower the five-three ratio, the more the Ga source, in the application, the N source is from the NH3, and the Ga source is from the GaCl gas obtained by the first reaction, therefore, the five-three ratio can be equivalent to the ratio of the NH3 gas and the GaCl gas above the single crystal growth tray. The same source gas and gas flow are provided for the two devices, in the experiment, the input flow of the HCl gas is 200 SCCM, and the input flow of the NH3 gas is 5000 SCCM.

[0053] Figure 3 It is shown that, on the single crystal growth device of the prior art vertical HVPE device, the five-three ratio changes greatly with the change of the position, the ratio on both sides is high, the ratio of the NH3 gas is high, the ratio in the middle is low, the ratio of the GaCl gas is high, which reflects that the two are not mixed uniformly.

[0054] Figure 7 It is shown that, on the single crystal growth device of the vertical HVPE device of the application, the five-three ratio only has a slight fluctuation with the change of the position, compared with Figure 3 the prior art device, the device of the application can ensure that the GaCl gas and the NH3 are mixed uniformly, so that the growth of the single crystal GaN with higher quality is realized.

[0055] In summary, the application can effectively inhibit the premature reaction of NH3 gas and GaCl gas, avoid parasitic deposition at the gas guide pipe, and ensure the sufficient mixing of NH3 gas and GaCl gas at the single crystal growth tray by improving the heating system and the gas guide pipe of the vertical HVPE growth device, setting three temperature zones with specific temperatures, and controlling the temperature of the second temperature zone by radio frequency heating, which is conducive to generating high-quality single crystal gallium nitride.

Claims

1. A vertical HVPE growth apparatus, characterized in that, This includes the cavity tube, gas source area, single crystal growth tray, and heating system; The opening of the cavity tube is the upper part of the vertical HVPE device, the single crystal growth tray is located at the lower part of the device, the gas source area is inside the cavity tube and is composed of multiple nested gas conduits. Different gases are delivered by different gas conduits. The gas conduits contain a gallium boat to provide the gallium source for the reaction. The single crystal growth tray is used to support the growth of single crystal gallium nitride. The heating system is located outside the cavity tube. Its features include a heating system comprising three heating devices corresponding to three temperature zones. In the vertical HVPE device, from top to bottom, the devices are: the first heating device, corresponding to a first temperature zone of 800℃ to 900℃; the second heating device, corresponding to a second temperature zone of 1400℃ to 1600℃; and the third heating device, corresponding to a temperature zone of 1000℃ to 1100℃. The second heating device is a radio frequency coil. The gas conduit is composed of three parts: a quartz section, a heat insulation section, and a sensing section, from top to bottom. The bottom of the quartz section is at a horizontal height lower than or equal to the bottom of the gallium boat.

2. The vertical HVPE growth apparatus according to claim 1, characterized in that: The height of the top of the second heating device is between the bottom surface of the gallium boat and the bottom of the heat insulation part, and the bottom of the second heating device extends 10mm to 20mm beyond the bottom of the sensing part.

3. A vertical HVPE growth apparatus according to claim 2, characterized in that: The vertical length of the second heating device ranges from 200mm to 400mm.

4. A vertical HVPE growth apparatus according to claim 3, characterized in that: The length of the sensing element is 50mm to 100mm.

5. A vertical HVPE growth apparatus according to claim 3, characterized in that: The length of the heat insulation part is 30mm to 60mm.

6. A vertical HVPE growth apparatus according to claim 3, characterized in that: The length of the quartz portion is 300 mm to 600 mm.

7. A vertical HVPE growth apparatus according to claim 3, characterized in that: The vertical length of the first heating device is 200mm to 400mm, and the vertical length of the third heating device is 400mm to 600mm.

8. A vertical HVPE growth apparatus according to claim 1, characterized in that... The quartz part of the gas conduit is made of quartz, the heat insulation part is made of silicon carbide ceramic, alumina ceramic or other high temperature and corrosion resistant materials, and the sensing part is made of graphite coated with a coating material, which is silicon carbide, high-purity boron nitride, tantalum carbide, tungsten carbide or other high temperature and corrosion resistant materials.

9. A vertical HVPE growth apparatus according to claim 1, characterized in that... It also includes an exhaust gas treatment device, located in a cavity tube near the bottom of the device, for treating exhaust gases.

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