Gallium nitride single crystal growth method and equipment based on HVPE

Abstract

The invention provides a method and equipment for growing a gallium nitride single crystal based on HVPE (High Vapor Phase Extraction). The growth method comprises the following steps: introducing hydrogen chloride gas into a gallium boat to generate a reactant; the chlorogallium compounds in the reactants comprise a gallium chloride precursor and other chlorogallium compounds; carrying out zone control on the temperature of the gallium boat, and adjusting the partial pressure of the hydrogen chloride gas in real time so as to eliminate metal gallium steam and maintain the ratio of other chlorogallium compounds to the gallium chloride precursor to be 0.15 or below; and introducing ammonia gas and a chlorogallium compound into the second reaction cavity, and reacting to generate the gallium nitride single crystal. The method provided by the invention focuses on the reaction process of the liquid metal gallium and the hydrogen chloride, basically eliminates the evaporation of the metal gallium and inhibits the formation of a high-valence chlorogallium compound by executing temperature adjustment and dynamic adjustment of partial pressure of the hydrogen chloride, greatly reduces the proportion of parasitic reaction in the growth of the gallium nitride single crystal, and improves the yield of the gallium nitride single crystal. And the utilization rate of gallium and the quality of the gallium nitride single crystal obtained by growth are obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material preparation technology, specifically relating to a method and equipment for growing gallium nitride single crystals based on HVPE. Background Technology

[0002] Hydride vapor phase epitaxy (HVPE) is a technique for epitaxial growth of semiconductor materials by reacting group III metal chlorides with group V hydrides on a high-temperature substrate surface. This technique utilizes a normal-pressure hot-wall reactor, with GaCl and NH3 as the main reaction sources, achieving growth rates of tens to hundreds of micrometers per hour. It is widely used to prepare group III nitride thin films such as GaN and AlN.

[0003] A gallium boat is a device component specifically designed for the growth of semiconductor materials. Especially in the HVPE process, it is typically used as a reaction vessel to hold metallic gallium to react with gases (such as hydrogen chloride) to generate a gallium-containing gas source, which is then used to grow gallium nitride wafers.

[0004] Parasitic reactions refer to side reactions that occur outside the desired reaction, typically leading to problems such as abnormal product purity and poor product morphology. While parasitic reactions have been noted in the field of gallium nitride (GaN) preparation via high-volume glass (HVPE), the focus has been primarily on controlling the growth conditions of HVPE or introducing inhibitors, with little attention paid to parasitic reactions originating from the gallium boat. Summary of the Invention

[0005] The main objective of this invention is to provide a method and apparatus for growing gallium nitride single crystals based on HVPE, so as to overcome the shortcomings of the prior art.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, a method for growing gallium nitride single crystals based on HVPE is provided, applied to an HVPE device. The HVPE device includes a first reaction chamber and a second reaction chamber connected to each other. A gallium boat is disposed in the first reaction chamber, and liquid gallium is stored in the gallium boat. The growth method includes: Hydrogen chloride gas is introduced into the gallium boat to react with the liquid gallium to generate reactants. The reactants include gallium chloride compounds and H2, and the gallium chloride compounds include gallium chloride precursors and other gallium chloride compounds. During the introduction of hydrogen chloride gas, the temperature of the gallium boat is controlled in zones, and the partial pressure of the hydrogen chloride gas in the reactants is adjusted in real time to eliminate metallic gallium vapor in the gallium chloride compounds introduced into the second reaction chamber and maintain the molar ratio (of the other gallium chloride compounds to the gallium chloride precursor) below 0.15. Ammonia gas and the gallium chloride compound are introduced into the second reaction chamber so that the gallium chloride precursor in the gallium chloride compound reacts with the ammonia gas to generate gallium nitride single crystal.

[0007] Secondly, the present invention also provides an HVPE apparatus for implementing the above-described method for growing gallium nitride single crystals based on HVPE, comprising: A first reaction chamber is provided inside the first reaction chamber, and a gallium boat is stored inside the gallium boat; The second reaction chamber is connected to the first reaction chamber; A temperature control device is used to regulate the temperature of the gallium boat.

[0008] Compared with the prior art, the beneficial effects of the present invention include at least the following: The HVPE gallium nitride single crystal growth method provided by this invention focuses on the reaction process of liquid gallium metal and hydrogen chloride. By performing temperature adjustment and dynamic adjustment of hydrogen chloride partial pressure, the evaporation of metallic gallium is basically eliminated and the formation of high-valence gallium chloride compounds is suppressed. This ensures that the gallium chloride compounds provided do not contain gallium vapor and high-valence gallium chloride compounds, which significantly reduces the proportion of parasitic reactions in HVPE gallium nitride single crystal growth, and significantly improves gallium utilization and the quality of the grown gallium nitride single crystals.

[0009] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the overall process of the growth method provided in a typical embodiment of the present invention; Figure 2 This is a curve showing the change of Ga vapor pressure with temperature according to a typical embodiment of the present invention; Figure 3 This is a simulation diagram showing the correlation between various components in the reactants and temperature, provided in a typical embodiment of the present invention. Figure 4 This is a simulation diagram showing the correlation between the various components in the reactants and the partial pressure of hydrogen chloride gas, provided in a typical embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of a gallium boat provided in a typical embodiment of the present invention; Figure 6 This is a simulated image of temperature distribution in a gallium boat provided in a typical embodiment of the present invention; Figure 7 This is an optical photograph of the growth product before optimization, provided by a typical embodiment of the present invention. Figure 8 This is an optical photograph of the optimized growth product provided by a typical embodiment of the present invention. Detailed Implementation

[0012] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate the technical solution, its implementation process, and its principles.

[0013] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0014] like Figure 1 As shown, this embodiment of the invention first provides a method for growing gallium nitride single crystals based on HVPE, applied to an HVPE device. The HVPE device includes a first reaction chamber and a second reaction chamber connected to each other. A gallium boat is disposed within the first reaction chamber, and liquid gallium is stored within the gallium boat. Figure 1 As shown, the method for growing gallium nitride single crystals based on HVPE includes the following steps: S1: Hydrogen chloride gas is introduced into the gallium boat to react with liquid gallium to generate reactants; wherein, the reactants include gallium chloride compounds and H2, and the gallium chloride compounds include gallium chloride precursors and other gallium chloride compounds; during the introduction of hydrogen chloride gas, the temperature of the gallium boat is controlled in sections, and the partial pressure of hydrogen chloride gas in the reactants is adjusted in real time to eliminate metallic gallium vapor in the gallium chloride compounds introduced into the second reaction chamber and maintain the ratio of other gallium chloride compounds to gallium chloride precursors in the gallium chloride compounds below 0.15.

[0015] S2: Ammonia and gallium chloride compound are introduced into the second reaction chamber so that the gallium chloride precursor in the gallium chloride compound reacts with ammonia to generate gallium nitride single crystal.

[0016] In some embodiments, other gallium chloride compounds include GaCl2 and / or GaCl3, wherein the GaCl2 / GaCl ratio and the GaCl3 / GaCl ratio are both below 0.15.

[0017] Unlike existing technologies that focus on reducing parasitic reactions in the second reaction chamber used for HVPE growth, the technical solution proposed in this invention focuses on the impact of the gallium chloride compound supply process on parasitic reactions.

[0018] Within the gallium boat of the HVPE device, a small amount of liquid Ga may evaporate into the gas phase. According to the thermodynamic phase equilibrium theory, in a single-component system, vapor pressure and temperature follow the Clausius-Clapeyron equation: In the formula, p, T, ΔH m R and R represent pressure, temperature, molar latent heat of vaporization, and gas constant, respectively.

[0019] Furthermore, according to the formula for the change of vapor pressure in a single-component system with external pressure, namely the Gibbs equation: In the formula, , , , These represent vapor pressure, external pressure, gas molar volume, and liquid molar volume, respectively. Because >> Therefore, changes in external pressure have little effect on vapor pressure, and the influence of external pressure can be ignored when calculating Ga vapor pressure.

[0020] According to the thermodynamics handbook, the boiling point of Ga is T. m =2478K, latent heat of vaporization =258.722 kJ·mol, substituting into equation (1-1), we can obtain the following relationship for the vapor pressure of Ga at any temperature: In the formula, p0 is the standard atmospheric pressure.

[0021] Figure 2 The calculated relationship between Ga vapor pressure and temperature is shown. According to the calculation, at T=1000K, the Ga vapor pressure is 1.00×10⁻⁶. -4 Pa; at T=1250K, Ga vapor has a pressure of 0.40 Pa, from Figure 2The curves show that the Ga vapor pressure is very small below 1200K; when the temperature exceeds 1200K, the Ga vapor pressure increases rapidly. When T=1300K, the Ga vapor pressure is 1.15Pa. The partial pressure of GaCl at the Ga source inlet in common HVPE equipment is usually around 400Pa. At this time, according to the principle of gas partial pressure, the mass fraction of metallic Ga vapor in the gaseous Ga source is calculated to be 0.19% of GaCl. Therefore, the influence of gaseous metallic Ga cannot be ignored in the gas-phase chemical reaction of HVPE. If metallic Ga exists in the form of vapor, it is easy to enter the second reaction chamber with the source gas and undergo parasitic reactions to form polycrystalline GaN. For example, metallic Ga reacts with NH3 to form polycrystalline gallium nitride. The occurrence of parasitic reactions is extremely detrimental to the growth of GaN single crystal controlled in the growth region. Therefore, it is necessary to control the reaction temperature at the gallium boat to control the partial pressure of metallic gallium, thereby controlling the evaporation of gallium and controlling the parasitic reactions in the first reaction chamber.

[0022] The parasitic reaction chemical mechanism associated with metallic Ga vapor is as follows: 1. Ga(g) + NH3(g) → GaN (poly, meaning polycrystalline) + 3 / 2H2(g) (ΔG < 0 at, T > 800 K) 2.3Ga(g)+2NH3(g)→2GaN(poly)+GaH3(g)+3 / 2H2(g) The desired reaction pathway is: GaCl(g) + NH3(g) → GaN (single crystal) + HCl(g) The parasitic reaction pathway is: Ga(g) + NH3(g) → GaN(poly) + 3 / 2H2(g) Based on thermodynamic calculations, the formula for calculating the reaction free energy in the range of 1073-1273 K is as follows: ΔG_Ga_NH3 = -85.3 + 0.012 T kJ / mol ΔG_GaCl_NH3=-120.5+0.015TkJ / mol Therefore, the Ga(g) + NH3 reaction is thermodynamically feasible at the HVPE operating temperature. Although the activation energy is low, the reaction is kinetically prone to the phenomenon of gaseous Ga atoms providing additional nucleation sites, thereby promoting polycrystalline formation. This mechanism was also verified during actual growth. Compositional analysis of the GaN polycrystalline deposits on the quartz wall of the second reaction chamber showed the presence of metallic Ga residue, and GaN particles formed in the low-temperature region upstream of the second reaction chamber. Abnormal fluctuations in the growth rate were correlated with fluctuations in the gallium boat temperature. Accordingly, the optimal temperature range for the gallium boat is 1050-1150 K, and the forbidden temperature is >1200 K.

[0023] In addition, the parasitic reactions caused by high-valent gallium chloride in the first reaction chamber must also be considered. The parasitic reaction mechanism related to high-valent gallium chloride compounds is shown below.

[0024] The desired reaction pathway is: 2Ga(l) + 2HCl(g) → 2GaCl(g) + H2(g) Parasitic reaction 1: 2Ga(l) + 4HCl(g) → 2GaCl2(g) + 2H2(g) Parasitic reaction 2: 2Ga(l) + 6HCl(g) → 2GaCl3(g) + 3H2(g) GaCl2(g) + 2NH3(g) → GaN(poly) + 2HCl(g) + [byproducts] GaCl3(g)+NH3(g)→GaN(poly)+3HCl(g) GaCl3(g)+3NH3(g)→GaN(poly)+3NH4Cl(s) Therefore, temperature has a selective effect on the reaction pathway. In the low-temperature region (<1000K), GaCl3 formation is dominant; in the medium-temperature region (1000-1150K), GaCl2 formation increases; and in the high-temperature region (>1150K), GaCl is the optimal product. Thus, GaCl exhibits the highest selectivity in the 1100-1200K temperature range. Considering the optimal temperature range for Ga evaporation (1050-1150K), the temperature for GaCl formation needs to be precisely controlled within 1100-1150K to maximize gallium source utilization, reduce parasitic reactions, and improve the growth quality of GaN single crystals.

[0025] In addition to temperature, the inventors discovered that the partial pressure of hydrogen chloride gas is also a major factor affecting parasitic reactions. By synergistically controlling the temperature of the gallium boat and the partial pressure of HCl, the ratios of GaCl2 / GaCl and GaCl3 / GaCl can be controlled below 0.15, thereby suppressing parasitic reactions caused by high-valence gallium chloride. The specific principle is as follows.

[0026] The formation reactions of gallium chloride compounds in various valence states, which are related to the partial pressure of HCl, are divided into: In the formula, P represents the Gibbs free energy change of the reaction at standard pressure 1 atm, where R is the universal gas constant and T is the corresponding reaction temperature; xThis represents the partial pressure of substance x. For example, if x is H2, its partial pressure is... .

[0027] K1-K3 represent the chemical reaction equilibrium constants, calculated using formula (2-4). K1-K3 collectively determine which (or which types) of gallium chloride compounds (GaCl, GaCl2, GaCl3) will be formed in the gallium boat when Ga reacts with HCl, and their relative yields. Specifically, K1 measures the strength of the tendency to form the target product GaCl at a specific temperature. A larger K1 value means that the partial pressure of GaCl is higher relative to the partial pressures of HCl and H2 at chemical equilibrium, indicating a more "complete" reaction to form GaCl. K2 measures the tendency to form the byproduct GaCl2. At high temperatures, GaCl2 is usually not the final stable product, but rather GaCl undergoes a disproportionation reaction (2GaCl2 → GaCl2). GaCl2+Ga) intermediates or related products; K3 is used to measure the tendency to generate the byproduct GaCl3. The larger the K3 value, the easier it is to generate highly reactive GaCl3 at equilibrium.

[0028] The partial pressure of HCl refers to the partial pressure of HCl gas in the reactants (H2, GaCl, GaCl2, GaCl3). Because the partial pressure of HCl can be artificially controlled (by adjusting the flow rate, increasing or decreasing the amount of HCl introduced into the gallium boat), the main purpose is to balance the partial pressures of GaCl2 and GaCl3 by adjusting the partial pressure of HCl, so that the partial pressures of these two undesirable substances (GaCl2 and GaCl3) are in a direction unfavorable to the reaction, thereby inhibiting the occurrence of subsequent parasitic reactions.

[0029] Using data fitting software such as MATLAB, equations can be established for numerical iterative calculations. This allows for the simulation of how the proportions of each component change with temperature or the partial pressure of hydrogen chloride gas. The specific process is as follows: List all independent equations, if we want to solve P H2 P GaCl3 P GaCl2 P GaCl P HCl The partial pressure requires a system of five equations: in, This represents the total amount of chlorine atoms input. In the gallium boat, these chlorine atoms are all provided by the initial input HCl gas. This indicates the amount of unreacted HCl gas at chemical equilibrium. This indicates the amount of CaCl gas present when chemical equilibrium is reached. This indicates the amount of CaCl2 gas at chemical equilibrium. This indicates the amount of CaCl3 gas at chemical equilibrium.

[0030] By constructing the above equations and using MATLAB for numerical iteration, the relationship between the partial pressure of each substance and temperature can be solved, such as... Figure 3 As shown; and the relationship between the partial pressures of the remaining components and the partial pressure of HCl, as shown. Figure 4 As shown.

[0031] Therefore, the technical solution proposed in this invention controls the ratios of GaCl2 / GaCl and GaCl3 / GaCl below 0.15 by synergistically controlling the gallium boat temperature and HCl partial pressure, and eliminates the influence of metallic Ga vapor, thereby suppressing various parasitic reactions caused by high-valent gallium chloride compounds and metallic gallium.

[0032] In actual growth processes, the proportion of reactants generated may fluctuate over time. To achieve dynamic control during the growth process, in some implementation schemes, the above-mentioned growth method specifically includes the following steps: monitoring the GaCl2 / GaCl ratio and the GaCl3 / GaCl ratio; adjusting process parameters based on the currently detected GaCl2 / GaCl ratio and GaCl3 / GaCl ratio; wherein, the process parameters include the flow rate of hydrogen chloride gas and the temperature of the gallium boat.

[0033] Furthermore, the aforementioned dynamic adjustment process specifically includes: determining whether the GaCl2 / GaCl ratio or the GaCl3 / GaCl ratio exceeds 0.15; if so, adjusting the flow rate of hydrogen chloride gas to reduce the partial pressure of hydrogen chloride gas in the reactants by a first set ratio and / or increasing the temperature of the gallium boat by a second set ratio.

[0034] The above technical solution adjusts the HCl flow rate according to a set step size (i.e., the first set ratio) and adjusts the temperature in the three regions of the gallium boat synchronously according to set step sizes (i.e., the second set ratio), thereby achieving regional and proportional parameter control.

[0035] As a typical example, the concentration ratio of GaCl, GaCl2, and GaCl3 in the reactants can be monitored in real time by online mass spectrometry, and the process parameters can be dynamically adjusted based on the monitoring results. The process parameters can be adjusted based on preset correlation curves or databases. It is preferable to adjust the partial pressure and temperature in a coordinated manner, and the temperature adjustment must not exceed the limit range shown above to avoid the generation of metallic Ga vapor (Ga vapor pressure <0.1 Pa means that metallic Ga vapor has been basically eliminated. At this vapor pressure, a small amount of metallic Ga vapor will not have an observable negative impact on the growth quality).

[0036] The main purpose of the aforementioned partial pressure regulation is to balance the partial pressures of GaCl2 and GaCl3 by adjusting the partial pressure of HCl, thereby directing the related reactions of these two undesirable substances (GaCl2 and GaCl3) in a direction unfavorable to the reaction process, and thus inhibiting the occurrence of parasitic reactions in subsequent processes (in accordance with thermodynamic principles, this is...). When ≥0, the reaction is not conducive to proceeding, and This relates to K; the relevant calculation method can be found above.

[0037] More specifically, in some embodiments, the gallium boat includes an injection region, a core region, and a transition preheating region. The injection region has an injection channel for hydrogen chloride gas. The core region is located below the injection region and coaxial with the injection channel. The transition preheating region surrounds the core region. The maximum temperature limit of the gallium boat is 1200K, and the temperature of the injection region is lower than the temperatures of the transition preheating region and the core region.

[0038] For details on the gallium boat structure, please refer to [link / reference]. Figure 5 As shown, the quartz injection channel is arranged from top to bottom to form an injection area 1, which is used to purge gas onto the gallium liquid surface 4. The core area 2 and the transition preheating area 3, which store liquid gallium, are located below the injection channel. The core area 2 is the location directly purged by the injection channel and its vicinity, while the transition preheating area 3 is the area surrounding the core area. In addition, multiple gas outlet pipes 8 are arranged from bottom to top in the core area 2 and the transition preheating area 3 to collect the gallium chloride compound formed by the reaction and output it from top to bottom to the outside of the gallium boat.

[0039] In some implementations, preferred embodiments of the present invention also provide a more specific temperature zone control strategy, namely: the temperature range of the injection zone is 1050-1070K, the temperature range of the core zone is 1120±10K, and the temperature range of the transition preheating zone is 1070-1120K.

[0040] As a typical example, a zoned temperature optimization control strategy can be adopted, with each zone using an independent heating and regulation system. The temperature of the gallium boat core zone is 1120±10K to promote GaCl formation; the temperature of the transition preheating zone is 1070-1120K to suppress GaCl3 formation; and the temperature of the HCl injection zone is 1050-1070K to control the reaction initiation temperature, thereby achieving target temperature control throughout the entire reaction process.

[0041] To facilitate achieving the aforementioned temperature target, in some implementations, the gallium boat is made of quartz material; wherein the thermal performance coefficients of the quartz material located near the injection region, core region, and transition preheating region are different.

[0042] Regarding the specific material, in some implementation schemes, the thermal performance coefficient includes thermal conductivity and radiation absorption coefficient; the quartz material includes, but is not limited to, two or more of porous quartz, black quartz, and translucent quartz.

[0043] For example, the injection zone is made of milky white quartz, the core zone is made of high-purity quartz, and the injection zone is made of porous quartz.

[0044] In the above embodiments, the injection zone is made of milky white quartz. In this material, a large number of submicron-sized bubbles strongly scatter light across all wavelengths, resulting in an opaque white appearance. It has good temperature uniformity and low infrared transmittance (less than 10%), which is used to make the temperature of the injection zone significantly lower than that of the other two zones. The core zone is made of high-purity quartz, which is high-purity amorphous SiO2 with low intrinsic absorption. It is an excellent infrared light-transmitting material with high infrared transmittance (greater than 85%), resulting in good internal heating and providing sufficient thermal energy for the core zone. The transition preheating zone is made of porous quartz. Its high porosity leads to extremely strong light scattering, making it macroscopically opaque and white. Its high porosity and excellent thermal insulation properties are used for edge insulation. The three zones have different thermophysical parameters, which can achieve different functional values ​​and work together to achieve the effect of temperature zone control.

[0045] Furthermore, in some implementation schemes, to achieve more precise temperature control, independent temperature compensators are installed in the injection zone, core zone, and transition preheating zone, such as... Figure 5 The temperature compensators A group 5 and temperature compensators B group 6 described herein, and not limited to the positions and numbers shown in the figure, include jet cooling components and heating components.

[0046] As a typical example of the above-described implementation method, in order to meet the control requirements of different temperature ranges, the gallium boat used in this invention employs different types of quartz in different functional areas, such as porous quartz, black quartz, and different translucent quartz, whose thermal performance parameters, such as thermal conductivity and radiation absorption coefficient, are different. Combined with the application of temperature compensation regulators near the injection area and the transition preheating area (activating the cooling condition mechanism when the temperature exceeds the range value, spraying cooling carrier gas to lower the temperature, and activating an independent heating device to heat the local area when the temperature is below the range value), and the preliminary temperature field simulation, the temperature of each area is controlled within the target range, achieving precise zonal control and meeting the requirements of different reaction states in the above-described different temperature zones.

[0047] See also Figure 5 As shown, a constant temperature zone 7 is usually surrounded by the gallium boat. Under normal circumstances, the temperature of the constant temperature zone is controlled at around 850℃ (1123K). However, by adopting the above structure, combined with different quartz materials and temperature zone control in different parts, it is possible to achieve three-zone differential temperature regulation on the basis of the commonly used constant temperature zone.

[0048] like Figure 6 As shown, this invention presents a simulated thermal field design in a specific application scenario. By combining different materials, different regions are required to reach different temperatures.

[0049] Furthermore, in the preferred embodiments of the present invention, based on the above-mentioned condition control, the generation of high-valence gallium chloride compounds is suppressed by carrier gas control. That is, in some embodiments, the growth method specifically includes the following steps: mixing the reactants with the carrier gas and then conveying them to the second reaction chamber; wherein the carrier gas is an H2-N2 mixed carrier gas, and the volume ratio of H2 is maintained at 80-90%.

[0050] As a typical example, a mixed H2-N2 carrier gas can be used in the gallium boat region to transport the generated reactants, with the H2 ratio maintained at 80-90% to promote GaCl generation and inhibit GaCl3 generation during transport. Before entering the second reaction chamber for HVPE growth, N2 / Ar or other gases are added to adjust the concentration, thereby significantly reducing parasitic deposition while ensuring the growth atmosphere.

[0051] Furthermore, a preferred embodiment of the present invention may also introduce a reaction order control strategy: maintaining an optimized ratio of HCl / Ga surface contact to further improve Ga utilization and suppress the formation of undesirable components.

[0052] This invention also provides an HVPE apparatus for implementing the gallium nitride single crystal growth method based on HVPE provided in any of the above embodiments, comprising: a first reaction chamber, a second reaction chamber, and a temperature control device.

[0053] A gallium boat containing liquid gallium is placed inside the first reaction chamber; the second reaction chamber is connected to the first reaction chamber; a temperature control device is used to regulate the temperature of the gallium boat.

[0054] In some implementations, the gallium boat includes an injection region, a core region, and a transition preheating region. The injection region has an injection channel for hydrogen chloride gas. The core region is located below the injection region and coaxial with the injection channel. The transition preheating region surrounds the core region. The core region and the transition preheating region are used to store liquid gallium.

[0055] In some implementations, the temperature control device includes independent temperature compensators corresponding to the injection zone, core zone, and transition preheating zone, respectively, and the temperature compensators include jet cooling components and heating components.

[0056] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0057] Example 1 This embodiment illustrates the HVPE gallium nitride single crystal growth method described above, specifically using a gallium boat structure as follows: Figure 5 As shown, the gallium boat is formed by a tubular channel made of milky white quartz extending from top to bottom, forming an injection zone 1. The inside of this channel is used to purge a mixture of carrier gas and HCl gas onto the gallium liquid surface 4. Directly below the injection zone 1 is the core zone 2, which is made of high-purity quartz. Surrounding the core zone 2 is the transition preheating zone 3, which is made of porous quartz. Multiple gas outlet pipes 8 also run through the bottom and top of the core zone 2 and the transition preheating zone 3. The injection zone 1, the core zone 2, and the transition preheating zone 3 are surrounded by a constant temperature zone 7 to provide heat energy. Each zone is equipped with an independent temperature control unit, which is shown as temperature control unit group A 5 and temperature control unit group B 6 in the figure. The temperature can be reduced by purging with cooling gas or locally heated by electric heating. The gas produced by the reaction is output through the gas outlet pipes 8.

[0058] The temperature of the gallium boat's injection region 1 was set to 1050 K, the core region 2 to 1110 K, and the transition preheating region 3 to 1070 K. HCl was introduced, and component monitoring and control were performed using online mass spectrometry. The monitoring parameters are as follows: (1) Ga + (m / z = 69): Gas phase Ga atoms.

[0059] (2) GaCl + (m / z = 104): Target precursor.

[0060] (3) GaCl2 + (m / z = 139): Parasitic reaction indicator.

[0061] (4) GaCl3 + (m / z = 174): Indicator of severe parasitic reaction.

[0062] In the above formula, m / z represents the "mass-to-charge ratio," where m represents the mass of the ion (or particle), usually expressed in atomic mass units (u or Da), and z represents the charge number of the ion (usually an integer, such as +1, +2, or -1). m / z describes the behavior of a charged particle in electric and magnetic fields and serves as the "identity card" for mass spectrometers to identify and distinguish different chemical substances. In online mass spectrometry monitoring, gaseous molecules (such as GaCl) are bombarded and ionized by electrons, losing one electron to form a positively charged ion (such as GaCl). + This ion can be separated and detected by a mass spectrometer based on its m / z value.

[0063] The temperature range of the gallium boat core area 2, transition preheating area 3, and injection area 1 is adjusted in real time to be within a reasonable range, and the HCl injection amount is adjusted in a coordinated manner to ensure that the parasitic reaction of the HVPE equipment is precisely suppressed. When the GaCl2 / GaCl ratio or GaCl3 / GaCl ratio exceeds the warning value, the partial pressure of hydrogen chloride gas in the reactants is reduced and the temperature of injection area 1, core area 2, and transition preheating area 3 is increased (but not exceeding the upper limit of the range shown above).

[0064] This embodiment summarizes the control strategies for online mass spectrometry detection as follows.

[0065] The overall core control objective is: to achieve m / z = 104 (GaCl) + The signal is strongest at m / z = 139 (GaCl2). + ) and m / z = 174 (GaCl3) + The signal control is relatively weak; this indicates that the main reaction proceeds efficiently, while the parasitic reaction is suppressed.

[0066] Regulation logic: ①When m / z = 69(Ga + If the signal is too strong, it indicates that excessive gallium has evaporated. Attempts should be made to appropriately lower the gallium boat temperature (especially in injection region 1 and core region 2), or increase the flow rate of the carrier gas (such as H2) to dilute and remove the gaseous Ga.

[0067] ② When m / z = 139 (GaCl2) + ) or m / z = 174 (GaCl3) + An excessively strong signal indicates a severe parasitic reaction (disproportionation reaction). This usually means: 1. Inappropriate temperature: There may be local low temperature zones (such as poor temperature gradient from transition preheating zone 3 to core zone 2), which may cause GaCl to decompose during transportation. The temperature gradient should be checked and optimized to ensure that the temperature of GaCl remains high (>1000K) from generation to transportation path, and to avoid entering the medium temperature disproportionation window (approximately 700-900K).

[0068] The advantages of temperature zoning design can be leveraged through temperature control: the designed temperature gradient (1050K → 1070K → 1110K) is a crucial condition, designed to initiate GaCl generation in injection zone 1 (around 1050K) while suppressing high-temperature Ga evaporation; the preheating zone (around 1070K) further promotes GaCl generation and prevents GaCl gas from disproportionating due to the intermediate and low temperatures before entering the higher-temperature core zone 2; core zone 2 (around 1110K) ensures that the GaCl generation reaction reaches the optimal kinetic rate and thermodynamically suppresses the generation of GaCl3 (at high temperatures, K1 is much greater than K3).

[0069] 2. Excessive residence time: The gas stays in the first reaction chamber for too long, giving the disproportionation reaction enough time to proceed. It is advisable to appropriately increase the total gas flow rate to shorten the residence time.

[0070] 3. Excessive HCl partial pressure: According to the equilibrium reaction equation mentioned above, an excessively high HCl partial pressure may thermodynamically favor the formation of GaCl3. You can try fine-tuning and reducing the input partial pressure of HCl, observe the signal changes, and find the optimal equilibrium point.

[0071] In summary, m / z is the "probe" for online mass spectrometry monitoring. By tracking these four key signals in real time, the reaction state can be intuitively assessed, and the adjustment of the two core process parameters, temperature and gas flow rate (HCl / H2), can be guided in reverse to achieve the optimization goal of maximizing GaCl yield and minimizing parasitic reactions.

[0072] Figure 7 and Figure 8 Images of samples obtained before and after optimization using the technical method provided in this embodiment are shown respectively. It can be clearly seen that the technical solution provided in this embodiment suppresses the formation of polycrystalline material and significantly improves the quality of the grown product.

[0073] In addition, experimental data show that after the above optimization: the raw material utilization rate increased by 35%, the cleaning cycle of HVPE equipment was extended by 4 times, the product yield increased by 28%, and the polycrystalline gallium nitride particles on the sample surface were significantly reduced.

[0074] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for growing gallium nitride single crystals based on HVPE, applied to an HVPE device, the HVPE device comprising a first reaction chamber and a second reaction chamber interconnected, wherein a gallium boat is disposed in the first reaction chamber, and liquid gallium is stored in the gallium boat, characterized in that, The growth method includes: Hydrogen chloride gas is introduced into the gallium boat to react with the liquid gallium to generate reactants. The reactants include gallium chloride compounds and H2, and the gallium chloride compounds include gallium chloride precursors and other gallium chloride compounds. During the introduction of hydrogen chloride gas, the temperature of the gallium boat is controlled in zones, and the partial pressure of the hydrogen chloride gas in the reactants is adjusted in real time to eliminate metallic gallium vapor in the gallium chloride compounds introduced into the second reaction chamber and maintain the ratio of the other gallium chloride compounds to the gallium chloride precursor in the gallium chloride compounds below 0.

15. Ammonia gas and the gallium chloride compound are introduced into the second reaction chamber so that the gallium chloride precursor in the gallium chloride compound reacts with the ammonia gas to generate gallium nitride single crystal.

2. The method for growing gallium nitride single crystals based on HVPE according to claim 1, characterized in that, The other gallium chloride compounds include GaCl2 and GaCl3, wherein the GaCl2 / GaCl ratio and the GaCl3 / GaCl ratio are both below 0.

15.

3. The method for growing gallium nitride single crystals based on HVPE according to claim 2, characterized in that, Specifically, it includes: Monitor the GaCl2 / GaCl ratio and the GaCl3 / GaCl ratio; Based on the currently detected GaCl2 / GaCl ratio and GaCl3 / GaCl ratio, the process parameters are adjusted; wherein, the process parameters include the flow rate of the hydrogen chloride gas and the temperature of the gallium boat.

4. The method for growing gallium nitride single crystals based on HVPE according to claim 3, characterized in that, Specifically, it includes: Determine whether the GaCl2 / GaCl ratio or the GaCl3 / GaCl ratio exceeds 0.15; If so, the flow rate of the hydrogen chloride gas is adjusted so that the partial pressure of the hydrogen chloride gas in the reactants is reduced by a first predetermined ratio and / or the temperature of the gallium boat is increased by a second predetermined ratio.

5. The method for growing gallium nitride single crystals based on HVPE according to claim 4, characterized in that, The gallium boat includes an injection region, a core region, and a transition preheating region. The injection region has an injection channel for the hydrogen chloride gas. The core region is located below the injection region and is coaxial with the injection channel. The transition preheating region surrounds the core region. The maximum temperature limit for the gallium boat is 1200K, and the temperature of the injection region is lower than that of the transition preheating region and the core region.

6. The method for growing gallium nitride single crystals based on HVPE according to claim 5, characterized in that, The temperature of the gallium boat is controlled in zones, including: The temperature of the injection zone is controlled at 1050-1070K, the temperature of the core zone is controlled at 1110-1130K, and the temperature of the transition preheating zone is controlled at 1070-1120K.

7. The method for growing gallium nitride single crystals based on HVPE according to claim 5, characterized in that, The injection zone, the core zone, and the transition preheating zone are each equipped with an independent temperature compensator, which includes a jet cooling assembly and a heating assembly. And / or, the gallium boat is made of quartz material, and the thermal performance coefficients of the quartz material in the injection region, the core region, and the transition preheating region are different.

8. The method for growing gallium nitride single crystals based on HVPE according to claim 1, characterized in that, Specifically, it includes: The hydrogen chloride gas is delivered to the first reaction chamber using a carrier gas; The generated gallium chloride compound is transported to the second reaction chamber using the carrier gas; The carrier gas includes H2 and N2, with the volume fraction of H2 maintained at 80-90%.

9. An HVPE apparatus for implementing the gallium nitride single crystal growth method based on HVPE according to any one of claims 1-8, characterized in that, include: A first reaction chamber is provided inside the first reaction chamber, and a gallium boat is stored inside the gallium boat; The second reaction chamber is connected to the first reaction chamber; A temperature control device is used to regulate the temperature of the gallium boat.

10. The HVPE equipment according to claim 9, characterized in that, The gallium boat includes an injection region, a core region, and a transition preheating region. The injection region has an injection channel for hydrogen chloride gas. The core region is located below the injection region and is coaxial with the injection channel. The transition preheating region surrounds the core region. The core region and the transition preheating region are used to store liquid gallium. The temperature control device includes independent temperature compensators corresponding to the injection zone, core zone, and transition preheating zone, respectively. The temperature compensator includes a jet cooling assembly and a heating assembly.

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