A boron nitride crucible and impurity release real-time monitoring method

Abstract

This invention provides a boron nitride crucible and a method for real-time monitoring of impurity release, relating to the field of boron nitride crucible technology. The boron nitride crucible of this invention includes a crucible substrate, the inner surface of which is covered with a barrier layer. An impurity trap region is formed inside the crucible substrate by doping with an impurity-capturing material. This impurity trap region is used to capture impurities diffusing from the crucible substrate. The boron nitride crucible of this invention aims to solve the problem of continuous release of inherent trace impurities during long-term use of boron nitride crucibles in molecular beam epitaxy (MBE) processes, leading to a decrease in epitaxial film purity and affecting device performance and yield. It can effectively suppress impurity diffusion, thereby improving crucible purity and epitaxial film quality.

Description

Technical Field

[0001] This invention relates to the field of boron nitride crucible technology, and more specifically, to a boron nitride crucible and a method for real-time monitoring of impurity release. Background Technology

[0002] Molecular beam epitaxy (MBE) is a high-precision epitaxial growth method commonly used to prepare high-purity III-V group semiconductor epitaxial materials, such as GaAs, InP, and GaN. To achieve a stable supply of high-purity molecular beams, boron nitride (PBN) crucibles are widely used in MBE systems as containers for low vapor pressure metal source materials such as Ga and In. PBN crucibles possess high melting points, chemical inertness, and good thermal stability, thus exhibiting excellent physical and chemical properties under high-temperature and vacuum conditions.

[0003] However, although PBN crucibles are certified as high-purity at the time of manufacture, they are not absolutely flawless. After multiple batches of prolonged high-temperature operations and repeated thermal cycling (cooling to standby temperature after each growth cycle and reheating to high temperature before the next growth cycle), trace impurities inherent in the crucible material, such as extremely low levels of silicon oxide, become active. These inherent trace impurities (such as silicon oxide compounds) gradually migrate to the crucible surface and volatilize into the vacuum chamber at high temperatures. These impurities may directly enter the molecular beam and dope into the epitaxial film, leading to a decrease in the purity and electronic / optical properties of the epitaxial layer. Especially in the fabrication of high-quality optoelectronic devices (such as lasers, detectors, and power devices), the introduction of trace impurities can significantly affect device performance and yield.

[0004] Therefore, how to effectively suppress the release of silicon-oxygen impurities during the long-term use of PBN crucibles, extend the crucible's service life, and ensure the purity of the epitaxial film is a key issue that urgently needs to be addressed in the current MBE process.

[0005] Existing technical solutions to the problem of impurity release from PBN crucibles mainly focus on high-temperature pretreatment methods. This involves heating the crucible at high temperatures before its first use to allow internal impurities to volatilize, thus reducing contamination during the formal growth process. However, this method is limited to the crucible surface or even the shallow surface layer, and may adsorb some gas molecules (such as water vapor and oxygen). It is ineffective against the inherent trace impurities in the PBN material and cannot prevent the continuous migration of new impurities from within the PBN matrix during long-term use. Furthermore, prolonged high-temperature treatment itself may accelerate the structural deterioration of the crucible.

[0006] There is currently no effective technical solution to the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a boron nitride crucible and a real-time monitoring method for impurity release, aiming to solve the problem that during long-term use of boron nitride crucibles in molecular beam epitaxy, the inherent trace impurities inside the crucible are continuously released, leading to a decrease in the purity of the epitaxial film and affecting device performance and yield. This invention can effectively suppress impurity diffusion, thereby improving crucible purity and epitaxial film quality.

[0008] In a first aspect, the present invention provides a boron nitride crucible, comprising a crucible substrate, wherein the inner surface of the crucible substrate is covered with a barrier layer, and an impurity trap region is formed inside the crucible substrate by doping with an impurity trapping material, the impurity trap region being used to trap impurities diffused from the crucible substrate.

[0009] The boron nitride crucible provided by this invention has a barrier layer on the inner surface of the crucible, which effectively inhibits the diffusion of impurities from the crucible substrate to the outside. At the same time, an impurity trap region is formed inside the crucible substrate, which can capture the diffused impurities, thereby significantly reducing the release of impurities to the epitaxial film. This solves the problem of continuous release of impurities from the crucible leading to film contamination in the prior art and extends the service life of the crucible.

[0010] Furthermore, the barrier layer is made of yttrium oxide.

[0011] Furthermore, the barrier layer is a yttrium oxide film with a thickness of 1 to 5 nanometers formed by atomic layer deposition technology. The yttrium oxide film densely and uniformly covers the inner surface of the crucible substrate without pinholes.

[0012] Furthermore, the impurity capturing material includes titanium nitride particles or zirconium carbide particles with a particle size in the micrometer range.

[0013] Furthermore, the impurity trap regions are non-uniformly distributed inside the crucible substrate, and the impurity trap regions are concentrated in the low-temperature zone of the thermal field of the crucible substrate; the low-temperature zone of the thermal field is the impurity diffusion target region determined according to the temperature gradient of the crucible substrate under working conditions.

[0014] Furthermore, the low-temperature zone of the thermal field includes the bottom region of the crucible substrate or the outlet region of the crucible substrate.

[0015] Secondly, the present invention provides a real-time monitoring method for impurity release from the boron nitride crucible described above, applied to a vacuum chamber integrated with a residual gas analyzer, wherein the residual gas analyzer is positioned directly opposite or adjacent to the outlet of the boron nitride crucible, and includes the following steps:

[0016] During the initial use of a new crucible, the residual gas analyzer is controlled to record the impurity ion flow intensity at the standard operating temperature as a reference value.

[0017] In subsequent use, the residual gas analyzer monitors the current ion current intensity in real time and calculates the ratio of the current ion current intensity to the reference value.

[0018] When the ratio continuously exceeds a preset threshold, a graded warning is issued based on the magnitude of the ratio.

[0019] Furthermore, it also includes the following steps:

[0020] Store data on impurity release during multiple use cycles of the boron nitride crucible;

[0021] A dynamic model of impurity release is established by fitting the impurity release data.

[0022] Based on the impurity release kinetic model, the saturation point or remaining usable lifetime of the impurity trapping capability of the boron nitride crucible is predicted.

[0023] Furthermore, the impurity release kinetic model is expressed as follows:

[0024] ;

[0025] in, The ion current intensity after the nth thermal cycle of the boron nitride crucible. The preset reference ion current intensity, This represents the total increment of the ion current intensity relative to the reference ion current intensity when impurity release reaches saturation. The number of hot and cold cycles of the boron nitride crucible. This is the preset time constant.

[0026] Furthermore, the impurity release kinetic model is expressed as follows:

[0027] ;

[0028] in, The ion current intensity after the nth thermal cycle of the boron nitride crucible. The preset reference ion current intensity, The preset average growth rate, The number of hot and cold cycles performed on the boron nitride crucible.

[0029] As can be seen from the above, the boron nitride crucible provided by this invention effectively suppresses the outward diffusion of impurities from inside the crucible by covering the inner surface of the crucible substrate with a barrier layer. Simultaneously, an impurity trap region is formed inside the crucible substrate by doping with an impurity-capturing material. This region can actively capture impurities diffusing from the crucible substrate. This dual protection mechanism blocks the release of impurities from both the source and the diffusion path, effectively solving the technical problem in the prior art where inherent trace impurities in PBN crucibles continuously migrate outward and contaminate the epitaxial film during long-term use. Compared to existing methods that rely solely on high-temperature pretreatment, the technical solution of this application can more thoroughly and persistently suppress impurity release, significantly extending the service life of the crucible and ensuring the high purity of the epitaxial film, thereby improving the performance and yield of optoelectronic devices.

[0030] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0031] Figure 1 The main flowchart of the real-time monitoring method for impurity release provided in the embodiments of the present invention is shown.

[0032] Figure 2 Additional flowchart for the real-time monitoring method for impurity release provided in embodiments of the present invention. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Also, in the description of this invention, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0040] In molecular beam epitaxy (MBE), after repeated thermal cycles, the silicon-oxygen impurities inherent in the boron nitride crucible are activated at high temperatures. These impurities migrate to the crucible surface via diffusion and then volatilize into the molecular beam within the vacuum chamber. This impurity diffusion is thermodynamically driven, leading to impurity doping into the epitaxial growth layer, causing a decrease in film purity and consequently affecting the electronic and optical properties of the epitaxial layer. Furthermore, this problem is particularly prominent in the fabrication of high-quality optoelectronic devices, resulting in device performance degradation and reduced manufacturing yield.

[0041] For example, in the epitaxial growth of gallium arsenide lasers, after repeated thermal cycling, silicon-oxygen impurity signals are detected on the surface of the boron nitride crucible. These impurities enter the growth region with the arsenic source molecular beam and dope into the epitaxial layer. Specifically, impurity doping leads to abnormal leakage current characteristics and decreased threshold voltage stability of the device, forcing the growth process to be interrupted and the crucible to be replaced, affecting production continuity and device consistency.

[0042] If the problem of impurity diffusion inside the boron nitride crucible is not solved, the purity of the epitaxial film cannot be maintained, and the performance of optoelectronic devices based on this film will continue to degrade. This results in a shortened crucible lifespan, increased process costs, and limitations on the reliability of molecular beam epitaxy in the manufacture of high-end semiconductor devices.

[0043] In response, the present invention provides a boron nitride crucible, including a crucible substrate, the inner surface of which is covered with a barrier layer, and an impurity trap region is formed inside the crucible substrate by doping with an impurity trapping material, the impurity trap region being used to trap impurities diffused from the crucible substrate.

[0044] For ease of understanding, the following explains some key terms in this embodiment:

[0045] Boron nitride crucible: A container made of boron nitride, typically used in high-temperature, vacuum environments to hold high-purity metal source materials, such as gallium (Ga) and indium (In) in molecular beam epitaxy (MBE) systems. Its characteristics include a high melting point, chemical inertness, and good thermal stability.

[0046] Crucible substrate: refers to the main structure of the boron nitride crucible, which is made of boron nitride material and is the core part that supports the source material and provides structural support.

[0047] Barrier layer: A thin film covering the inner surface of the crucible substrate. Its main function is to form a physical barrier to inhibit the diffusion and volatilization of impurities inside the crucible substrate.

[0048] Impurity trapping materials: Specific materials doped into the crucible matrix that have a strong chemical affinity for impurities (such as silicon-oxygen impurities) that may exist in the crucible matrix. These materials can react with and fix the impurities, thereby preventing further migration and release of the impurities.

[0049] Impurity trapping regions: These refer to areas within the crucible substrate doped with impurity trapping materials. These regions are designed to actively trap impurities diffusing from the crucible substrate, fixing them inside the crucible and preventing them from entering the vacuum chamber and contaminating the epitaxial film.

[0050] This application discloses a boron nitride crucible designed to address the problem of contamination of the epitaxial thin film caused by the diffusion of internal impurities during long-term use of conventional boron nitride crucibles. The boron nitride crucible includes a crucible substrate with an inner surface covered by a barrier layer. An impurity trap region is formed inside the crucible substrate by doping with an impurity trapping material, which traps impurities that diffuse from the crucible substrate.

[0051] Specifically, the crucible substrate is the core component of a boron nitride crucible, and its main function is to serve as a container to hold the source material. This crucible substrate can be formed using conventional boron nitride crucible manufacturing processes, such as high-temperature sintering of boron nitride powder. In practical applications, the size and shape of the crucible substrate can be customized according to the specific molecular beam epitaxy system and source material requirements.

[0052] A barrier layer can be applied to the inner surface of the crucible substrate. This barrier layer acts as a physical barrier, effectively inhibiting the migration and volatilization of impurities from inside the crucible substrate into the crucible's interior space. The barrier layer can be formed in various ways, such as through chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD). As one implementation method, the barrier layer can be composed of oxide materials, such as alumina, zirconium oxide, or hafnium oxide. These oxide materials typically possess good chemical stability and density, effectively hindering the diffusion of impurities.

[0053] Furthermore, impurity trapping regions can be formed within the crucible matrix by doping with impurity-trapping materials. The selection of these materials is crucial; they need to possess a strong chemical affinity for any impurities that may be present in the crucible matrix, such as silicon-oxygen impurities. For example, impurity-trapping materials can include titanium nitride particles, zirconium carbide particles, or yttrium oxide particles. These materials can chemically react with silicon-oxygen impurities at high temperatures to form stable compounds, thereby immobilizing the impurities within the crucible matrix. The doping method can involve mixing the impurity-trapping material powder with boron nitride raw material powder during the crucible matrix forming process, followed by sintering the mixed powder. In this way, the impurity-trapping material can be uniformly distributed within the crucible matrix, forming an effective impurity trapping region.

[0054] The following example will provide a more detailed explanation of the above technical solution:

[0055] In a molecular beam epitaxy (MBE) system, a boron nitride crucible is required to hold high-purity gallium (Ga) source material to prepare high-quality semiconductor thin films. However, after prolonged high-temperature use and repeated thermal cycling, the inherent trace amounts of silicon-oxygen impurities within the conventional boron nitride crucible gradually diffuse to the crucible surface and volatilize, contaminating the vacuum chamber and the epitaxial film, leading to a decline in film performance.

[0056] To address this issue, this application proposes a boron nitride crucible that employs a dual mechanism to resolve the aforementioned impurity diffusion problem. First, during the manufacturing process of the boron nitride crucible, after the crucible substrate is formed, an atomic layer deposition (ALD) technique is used to form a yttrium oxide (Y₂O₃) film with a thickness of approximately 1 to 5 nanometers on its inner surface. This dense and uniform yttrium oxide film densely and uniformly covers the inner wall of the crucible, acting as the first physical barrier to effectively prevent the migration of silicon-oxygen impurities from the PBN substrate into the crucible's interior space. Specifically, the crucible is placed in an ALD chamber, and under the alternating introduction of yttrium source precursor and oxidant gas, a yttrium oxide passivation layer is deposited on the crucible surface.

[0057] Secondly, during the manufacturing of the PBN crucible, a focus is placed on pre-doping micron-sized titanium nitride (TiN) particles into the lower sidewall and the area around the outlet pipe (i.e., the relatively low-temperature zone in the thermal field). These TiN particles are then ball-milled with the PBN raw material powder at high speed to achieve uniform mixing. The mixed powder is then sintered at high temperature using a conventional PBN crucible sintering process. Ultimately, the TiN particles are uniformly fixed within the PBN crucible's body structure, with a particularly high doping density in the lower sidewall and the area around the outlet pipe, thus forming impurity trap regions. These TiN particles have a strong chemical affinity for silicon and oxygen. When silicon-oxygen impurities (such as SiO2) inside the PBN diffuse into these TiN regions at high temperatures, they immediately react chemically with the TiN and become firmly fixed in the crucible, forming stable compounds that can no longer volatilize.

[0058] Through the aforementioned dual mechanism—the barrier layer on the inner surface and the impurity trapping region inside—this boron nitride crucible can effectively capture and immobilize impurities diffusing from the interior of the crucible substrate. The barrier layer forms a physical barrier on the inner surface of the crucible, preventing impurities from escaping directly from the surface. Simultaneously, the internal impurity trapping region sets chemical capture points in the impurity diffusion path, actively capturing deep-seated impurities and preventing them from further migrating to the surface. This synergistic effect ensures that impurities are effectively immobilized inside the crucible, significantly reducing the release of impurities into the vacuum chamber, thereby guaranteeing the purity of the epitaxial film and extending the crucible's service life.

[0059] The boron nitride crucible proposed in this application achieves dual suppression of impurity diffusion by covering the inner surface of the crucible substrate with a barrier layer and forming an impurity trap region by doping the inside of the crucible substrate with an impurity trapping material. Compared with the existing technology that relies solely on high-temperature pretreatment, the solution of this application can more effectively prevent the continuous outward migration of inherent trace impurities in PBN materials. The barrier layer, as a physical barrier, directly reduces the possibility of impurities escaping from the surface; while the internal impurity trap region fixes the diffusing impurities at the source through a chemical trapping mechanism. This strategy, combining physical barrier and chemical trapping, significantly improves the ability of the boron nitride crucible to suppress impurity release during long-term use, thereby ensuring the high purity of molecular beam epitaxy films and solving the long-standing film contamination problem in the prior art.

[0060] In some embodiments, the barrier layer is made of yttrium oxide.

[0061] Yttrium oxide (Y₂O₃) is a ceramic material with a high melting point, excellent chemical stability, and low vapor pressure. It maintains its structural integrity under high-temperature vacuum conditions and is not easily chemically reacted with impurities in the crucible substrate or the cavity environment. As a barrier layer material, yttrium oxide can effectively prevent the diffusion of impurities. Besides atomic layer deposition (ALD), yttrium oxide barrier layers can also be formed using other physical vapor deposition (PVD) methods, such as magnetron sputtering or electron beam evaporation, or chemical vapor deposition (CVD). These methods can all form a dense and uniform yttrium oxide film on the inner surface of the crucible to effectively block impurities.

[0062] This solution utilizes yttrium oxide (YO) as the material for the barrier layer, fully leveraging its inherent high chemical stability, excellent thermal stability, and low impurity content. Under the high-temperature vacuum operating environment of a molecular beam epitaxy (MBE) system, YO forms a dense, uniform, and well-adhesive thin film that tightly covers the inner surface of the crucible substrate. This YO barrier layer acts as a robust physical and chemical barrier, effectively inhibiting the diffusion and volatilization of trace impurities (especially silicon-oxygen impurities) from within the crucible substrate. Because YO is not easily decomposed or reacts with impurities to generate volatile products, it maintains its barrier properties over a long period, ensuring the purity of the molecular beam and extending the crucible's lifespan. This material selection significantly enhances the functionality of the barrier layer, enabling it to more reliably prevent impurity contamination, thus solving the problem of poor barrier performance caused by inappropriate material selection in existing technologies.

[0063] The above technical solution utilizes yttrium oxide as the barrier layer material. Its inherent high chemical and thermal stability allows the barrier layer to form a dense, uniform, and pinhole-free coating under high-temperature vacuum conditions, significantly enhancing the ability to suppress the outward diffusion of impurities (such as silicon-oxygen impurities) from within the crucible substrate. This effectively avoids the risk of impurity leakage, ensuring the purity of the source material during molecular beam epitaxy, thereby improving the quality of the epitaxial film and device performance. This solution not only solves the problem of poor barrier effect caused by inappropriate selection of barrier layer materials in existing technologies, but also extends the service life of the boron nitride crucible and reduces production costs by providing a more reliable and durable impurity barrier.

[0064] In some embodiments, the barrier layer is a yttrium oxide film with a thickness of 1 to 5 nanometers formed by atomic layer deposition technology. The yttrium oxide film densely and uniformly covers the inner surface of the crucible substrate without pinholes.

[0065] Specifically, the barrier layer refers to a functional thin film disposed on the inner surface of the crucible substrate, whose main function is to physically or chemically prevent impurities inside the crucible substrate from diffusing outward. Atomic layer deposition (ALD) is an advanced thin film deposition method characterized by the alternating introduction of precursor gases and the use of self-limiting surface reactions to grow thin films layer by layer, thereby achieving atomic-level precise control over the film thickness and uniformity. This technology ensures that the formed film has excellent density and conformal properties. The yttrium oxide thin film, made of yttrium oxide, is a ceramic material with high chemical stability and good barrier properties, especially effective against silicon-oxygen impurities. The thickness of the film is limited to the range of 1 nanometer to 5 nanometers. This thickness ensures both the continuity and effective barrier capability of the film while avoiding the increased cost or negative impact on the thermal performance of the crucible that might result from excessive thickness. The dense, uniform, and pinhole-free yttrium oxide film indicates a compact internal structure without voids or defects, a smooth and consistent surface, and the absence of any microscopic penetrating pores, which is crucial for ensuring the barrier effect. The inner surface of the crucible substrate refers to the barrier layer being directly attached to the interface between the crucible substrate and the material it contains, thereby providing protection at the starting point of impurity diffusion.

[0066] This application addresses the problem of pinholes or uneven coverage in existing barrier layers by defining the barrier layer as a yttrium oxide film with a thickness of 1 to 5 nanometers formed using atomic layer deposition (ALD). The film is required to densely, uniformly, and without pinholes cover the inner surface of the crucible substrate. In a boron nitride crucible, the inner surface of the crucible substrate is covered with a barrier layer, and impurity trapping regions are formed inside the crucible substrate by doping with impurity-capturing materials. Based on this, ALD enables atomic-level precise control of the yttrium oxide film, ensuring a highly uniform, dense, and pinhole-free coverage across the entire inner surface of the crucible substrate. This high-quality yttrium oxide film acts as the first line of defense, reliably preventing the migration of silicon-oxygen impurities from inside the crucible substrate. Even if trace amounts of impurities penetrate the barrier layer, the impurity trapping regions inside the crucible substrate can further capture these impurities, forming a dual protection mechanism. This synergistic effect significantly improves the overall purity of the crucible and extends its service life.

[0067] In one specific implementation, after the boron nitride crucible substrate is fabricated, it can be placed in an atomic layer deposition chamber. Within the chamber, yttrium source precursors (e.g., tris(N,N'-diisopropylacetamyl)yttrium(III) or tris(2,2,6,6-tetramethyl-3,5-heptadecyl)yttrium(III)) and oxidizing gases (e.g., water vapor or ozone) are introduced alternately under precise control. Each time a precursor is introduced, a self-limiting surface chemical reaction occurs, forming a monolayer adsorption. Unreacted precursors and byproducts are then removed by purging with an inert gas. This deposition cycle is repeated until a yttrium oxide film with a thickness of approximately 1 to 5 nanometers is formed on the inner surface of the crucible substrate. This layer-by-layer growth method ensures that the yttrium oxide film exhibits extremely high density, uniformity, and pinhole-free characteristics, thereby completely sealing the inner wall of the crucible at the microscopic level and effectively blocking impurity diffusion paths.

[0068] Through the above technical solution, this application can significantly improve the integrity and reliability of the barrier layer, effectively avoiding the risk of impurity leakage caused by pinholes or uneven coverage in the barrier layer. This allows silicon-oxygen impurities diffusing from the crucible substrate to be more effectively suppressed, thereby ensuring the purity of the source material during molecular beam epitaxy growth, and ultimately guaranteeing the quality of the epitaxial film and device performance. This high-quality barrier layer, combined with the impurity trapping region inside the crucible, forms a strong barrier against impurity release, greatly extending the service life of the boron nitride crucible and reducing production costs.

[0069] In some embodiments, the impurity trapping material includes titanium nitride particles or zirconium carbide particles with a particle size in the micrometer range.

[0070] The impurity capturing material is a substance used to adsorb or chemically react and fix impurities. Besides titanium nitride particles and zirconium carbide particles, the impurity capturing material can also be other ceramic materials with high affinity for silicon-oxygen impurities and stability at high temperatures, such as silicon nitride particles or silicon carbide particles. These materials typically have a porous structure or high specific surface area to enhance their capturing ability. The particle size is in the micrometer range, meaning the particle size of the impurity capturing material is on the order of micrometers, for example, between 1 micrometer and 999 micrometers. This particle size range ensures that the particles can be uniformly dispersed within the crucible matrix, avoiding both uncontrollable distribution due to excessively small particle size and impact on the structural integrity or sintering performance of the crucible due to excessively large particle size. For example, the particle size can be controlled between 1 micrometer and 50 micrometers, or between 50 micrometers and 200 micrometers. The titanium nitride particles are a ceramic material with a high melting point, high hardness, and excellent chemical stability. They have a strong chemical affinity for silicon and oxygen, and can chemically react with silicon-oxygen impurities at high temperatures, converting them into stable compounds, thereby effectively fixing the impurities. The zirconium carbide particles are also a ceramic material with extremely high melting point, high hardness, and good chemical inertness. They also exhibit good capture ability for silicon-oxygen impurities, fixing diffused impurities inside the crucible matrix through chemical adsorption or reaction mechanisms.

[0071] This application optimizes the impurity trapping capability of the impurity trapping region by specifically defining the type and particle size of the impurity trapping material, thereby solving the problem caused by unclear material selection. During the manufacturing process of the boron nitride crucible, micron-sized titanium nitride particles or zirconium carbide particles are incorporated into the crucible matrix as impurity trapping materials, forming an impurity trapping region. After the crucible matrix is ​​sintered, these micron-sized particles are uniformly and stably distributed within the crucible body structure. When the crucible is operating at high temperatures, the inherent silicon-oxygen impurities within the crucible matrix begin to diffuse outwards. Once these impurities diffuse into the region doped with the impurity trapping material, they will chemically react with or be adsorbed by the titanium nitride or zirconium carbide particles. For example, titanium nitride particles can react with silicon-oxygen impurities (such as SiO2) to generate more stable compounds (such as TiO and SiN), thereby firmly fixing silicon and oxygen atoms inside the crucible and preventing them from further migrating to the crucible surface and volatilizing into the vacuum chamber. This mechanism ensures that impurities are effectively intercepted and trapped along the diffusion path, significantly reducing the risk of impurity release.

[0072] Combining the overall structure of the boron nitride crucible described above, the inner surface of the crucible substrate is covered with a barrier layer, and an impurity trap region is formed inside the crucible substrate by doping with an impurity-capturing material. This impurity trap region is used to capture impurities diffusing from the crucible substrate. The barrier layer forms the first line of defense on the inner surface of the crucible, physically inhibiting the outward diffusion of impurities. Based on this, this solution further incorporates a chemical capture mechanism inside the crucible substrate. When a small amount of impurities penetrates the barrier layer or diffuses from the deeper layers of the crucible substrate, the impurity-capturing material can actively react with these impurities, permanently fixing them. This dual protection mechanism, combining physical barrier and chemical capture, greatly enhances the crucible's ability to suppress impurity release, ensuring the purity of the epitaxial growth environment. In particular, by selecting an impurity-capturing material with a suitable particle size and high chemical activity, the impurity trap region can function effectively for a long time, extending the crucible's lifespan and ensuring the purity of the epitaxial film.

[0073] The above technical solution clarifies the specific type and particle size of the impurity capture material, thus solving the problems of insufficient impurity capture efficiency and material compatibility. Micron-sized titanium nitride or zirconium carbide particles, due to their moderate size, ensure uniform dispersion and stable fixation within the crucible matrix, avoiding structural defects or decreased capture efficiency that might result from excessively large or small particles. Simultaneously, these materials exhibit high chemical stability and strong affinity for silicon-oxygen impurities, effectively adsorbing and fixing diffused impurities at high temperatures, significantly improving the impurity capture effect. This not only extends the service life of the boron nitride crucible but also ensures the purity of the vacuum chamber during epitaxial growth, ultimately guaranteeing the quality of the epitaxial film and device performance.

[0074] In some embodiments, the impurity trap regions are non-uniformly distributed inside the crucible substrate, and the impurity trap regions are concentrated in the low-temperature zone of the thermal field of the crucible substrate; the low-temperature zone of the thermal field is the impurity diffusion target region determined according to the temperature gradient of the crucible substrate under working conditions.

[0075] Specifically, the impurity trap regions are non-uniformly distributed within the crucible substrate, meaning that the distribution of the impurity trapping material within the crucible substrate is not uniform but strategically configured according to specific needs. For example, the impurity trapping material can be concentrated in a specific area of ​​the crucible substrate, or its doping density can vary in different areas. This non-uniform distribution aims to optimize impurity trapping efficiency, avoid resource waste in areas where impurity diffusion is inactive, and enhance trapping capabilities in critical areas. The impurity trap regions are concentrated in the low-temperature zone of the thermal field of the crucible substrate, meaning that the impurity trapping material is mainly configured in areas of the crucible substrate with relatively low temperatures during operation. For example, this can be achieved by pre-doping the impurity trapping material into the lower part or the colder end of the sidewall of the crucible. This concentrated distribution utilizes the physical property of impurities migrating to the low-temperature zone under a temperature gradient, ensuring that impurities are effectively intercepted before reaching the crucible outlet. The low-temperature zone of the thermal field is the impurity diffusion target area determined based on the temperature gradient of the crucible substrate during operation, indicating that the determination of this low-temperature zone is not arbitrary but based on a scientific analysis of the temperature distribution and impurity diffusion behavior under actual crucible operating conditions. This can be accurately identified through numerical simulations (such as finite element analysis) or actual measurements (such as using thermocouple arrays), thereby ensuring that the arrangement of impurity traps is highly matched with the actual migration path of impurities, maximizing capture efficiency.

[0076] This application's solution improves impurity suppression by optimizing the distribution strategy of the impurity trap regions, thus addressing the low capture efficiency that can result from uniform distribution. During operation, a temperature gradient exists within the boron nitride crucible, moving from a high-temperature region to a low-temperature region. This gradient drives highly volatile silicon-oxygen impurity molecules to diffuse towards the low-temperature region. By non-uniformly distributing the impurity trap regions within the low-temperature zone of the crucible substrate's thermal field, this solution precisely intercepts these migrating impurities. When impurity molecules diffuse into these pre-defined low-temperature trap regions, they are effectively captured and fixed by the impurity trapping material, preventing further diffusion to the crucible surface and volatilization into the vacuum chamber. This targeted arrangement matches the impurity trapping mechanism with the thermodynamic behavior of impurity diffusion, significantly improving the efficiency and reliability of impurity capture. Compared to solutions with uniformly distributed impurity trap regions, this solution more effectively prevents impurities from escaping to certain areas, ensuring the crucible's continuous suppression of impurity release during long-term use and maintaining the high purity of the epitaxial film.

[0077] Through the above technical solution, this application effectively solves the problem of low capture efficiency in uniformly distributed impurity trap regions. By non-uniformly distributing the impurity trap regions within the low-temperature zone of the crucible substrate's thermal field, and determining the impurity diffusion target region based on the temperature gradient of the crucible substrate under operating conditions, this solution can capture impurities diffusing from the crucible substrate more accurately and efficiently. This significantly improves the impurity capture efficiency, reduces the possibility of impurity escape, thereby extending the service life of the boron nitride crucible, ensuring the purity of the epitaxial film, and avoiding the adverse effects of impurities on the epitaxial layer performance and yield.

[0078] In some embodiments, the low-temperature zone of the thermal field includes the bottom region of the crucible substrate or the outlet region of the crucible substrate.

[0079] The low-temperature zone of the thermal field refers to the relatively low-temperature area inside the boron nitride crucible during operation. These areas are typically where impurities easily migrate and accumulate under the influence of temperature gradients. For example, in a molecular beam epitaxy (MBE) system, the crucible operates at high temperatures, and natural temperature gradients form in different parts, with some areas having significantly lower temperatures than others. The bottom region of the crucible substrate refers to the bottom portion of the boron nitride crucible substrate that carries the source material. During crucible operation, due to heat transfer and dissipation conditions, the temperature in this region may be lower than other core heating areas inside the crucible, thus forming a relatively low-temperature zone. The outlet region of the crucible substrate refers to the area near the channel or opening where the source material vapor escapes from the boron nitride crucible substrate. This region is typically the interface between the crucible and the external vacuum environment, or its temperature may be relatively low due to the cooling effect of vapor flow, forming a critical area where impurities easily condense or escape.

[0080] This solution addresses the problem of unclear location of the low-temperature zone in the thermal field by clearly defining the specific distribution of the impurity trapping regions. During operation, a natural thermal gradient forms within the boron nitride crucible. Typically, the area at the bottom center of the crucible, containing the molten source material, has the highest temperature, while the bottom and outlet areas of the crucible substrate are relatively cooler. This temperature gradient drives volatile impurities (such as silicon-oxygen impurities) within the crucible substrate to diffuse from the high-temperature zone to the low-temperature zone. By precisely positioning the impurity trapping regions in the bottom or outlet areas where these impurities easily diffuse and accumulate, it ensures that impurities are effectively captured before reaching the crucible surface or escaping the crucible. This precise positioning allows the impurity trapping material to function at maximum efficiency, significantly improving the efficiency and reliability of impurity capture.

[0081] The above technical solution clarifies the precise distribution of the impurity trap regions within the crucible substrate, specifically their concentration at the bottom or outlet. This precise positioning allows the impurity trapping material to more effectively intercept and capture impurities diffusing from the high-temperature zone to the low-temperature zone during crucible operation, particularly those impurities about to escape from the crucible outlet. Given the high degree of matching between the distribution of the impurity trap regions and the low-temperature zone of the thermal field during crucible operation, the impurity capture efficiency is significantly improved, thereby further reducing impurity doping into the epitaxial film, ensuring the purity of the epitaxial film, and extending the service life of the boron nitride crucible.

[0082] Reference Appendix Figure 1 This invention provides a real-time monitoring method for impurity release from a boron nitride crucible based on the above embodiments. The method is applied to a vacuum chamber integrated with an enhanced residual gas analyzer. The enhanced residual gas analyzer is positioned directly opposite or adjacent to the outlet of the boron nitride crucible and is configured to have detection sensitivity for mass numbers 44 and 61. The method includes the following steps:

[0083] In the initial stage of using a new crucible, the enhanced residual gas analyzer is controlled to automatically learn and record the impurity ion current intensity at the standard operating temperature as a reference value. (Although the ordinary residual gas analyzer (RGA) equipped in the existing MBE can be used as a means of detecting chamber impurities, its detection sensitivity or recognition ability may be insufficient, causing trace impurities that may be released from the crucible to go undetected in the early stages until they accumulate to a level sufficient to affect film growth; while the enhanced residual gas analyzer of this application uses a high-sensitivity quadrupole mass spectrometer, whose detection channel has been optimized to accurately identify and quantify ion fragment signals with mass numbers around 44 (SiO) and 61 (SiOH), and provides the signal intensity of impurity release in real time through a dedicated vacuum interface).

[0084] In subsequent use, the current ion current intensity is monitored in real time by an enhanced residual gas analyzer, and the ratio of the current ion current intensity to the reference value is calculated.

[0085] When the ratio continuously exceeds the preset threshold, a graded warning is issued according to the size of the ratio. Specifically, when the ratio continuously exceeds the first-level threshold (e.g., 1.5) of the preset threshold, a primary warning is issued; when the ratio continuously exceeds the second-level threshold (e.g., 3) of the preset threshold, a critical alarm is issued and the interlock with the epitaxial growth program is triggered.

[0086] The real-time impurity release monitoring method of this application strategically positions a highly sensitive enhanced residual gas analyzer at the outlet of the boron nitride crucible, focusing it on detecting impurity ions of specific mass numbers (such as SiO and SiOH), thereby accurately capturing even minute impurity release signals. The method first establishes a reliable impurity ion flow intensity baseline during the initial use of a new crucible, representing the background impurity release level under optimal conditions. Subsequently, during routine use of the crucible, the system continuously monitors the current impurity ion flow intensity in real time and compares it with the preset baseline value, calculating the ratio. This real-time comparison mechanism can sensitively reflect any subtle changes in the impurity release level. When the ratio consistently exceeds a preset grading threshold, the system issues different levels of warnings or alarms based on the degree of exceedance, until it triggers an interlock with the epitaxial growth process, thus intervening in time before impurity contamination reaches a critical point. This monitoring method effectively complements the aforementioned structural improvements to boron nitride crucibles (e.g., crucibles including barrier layers and impurity trapping regions). Although boron nitride crucibles significantly suppress the diffusion and release of internal impurities through barrier layers (such as dense and uniform yttrium oxide films) and impurity trapping regions (such as doped titanium nitride particles), prolonged high-temperature operation and repeated thermal cycling can still cause a small number of impurities to break through these barriers or gradually saturate the trapping regions. This monitoring method targets these "slipped fish" or "saturation critical points" for real-time monitoring. The high sensitivity of the enhanced residual gas analyzer enables it to detect early trace impurity signals that are difficult to detect with conventional equipment. These signals may indicate that the impurity suppression capability inside the crucible is weakening. In this way, the system can provide early warnings even before the structural protection measures of the crucible have completely failed, allowing operators to take preventive measures before the epitaxial film is significantly contaminated, such as adjusting process parameters, performing maintenance, or replacing the crucible. This strategy, which combines active suppression with real-time monitoring, greatly improves the purity assurance of epitaxial growth and effectively extends the actual usable life of the crucible, ensuring the stable preparation of high-purity epitaxial films.

[0087] Through the above technical solution, this application provides a method for real-time, high-sensitivity monitoring of impurity release from boron nitride crucibles. This method effectively solves the problem in existing technologies where early trace signals of impurity release are difficult to identify, avoiding the predicament of impurities accumulating to the point of affecting film growth before being detected. By configuring an enhanced residual gas analyzer at the crucible outlet and specifically detecting impurity ions of a certain mass number, this method can accurately capture even trace amounts of silicon-oxygen impurities released. Establishing benchmark values ​​and comparing them in real time allows any anomalies in impurity release to be quantified and detected promptly. A graded early warning mechanism ensures the timeliness and targeting of risk response, providing operators with sufficient decision-making time from initial warnings to severe alarms and program interlocks, enabling intervention measures to be taken before the epitaxial film is significantly contaminated. This not only ensures the purity of the epitaxial film and device performance, but also, combined with the impurity suppression structure of the boron nitride crucible itself (such as barrier layers and impurity trap regions), forms a more complete impurity control system, significantly extending the effective service life of the crucible and improving the stability and yield of the MBE process.

[0088] In some embodiments, reference is made to the appendix. Figure 2 The real-time monitoring method for impurity release also includes the following steps:

[0089] Store data on impurity release from boron nitride crucibles during multiple use cycles;

[0090] A dynamic model of impurity release was established by fitting impurity release data.

[0091] The system predicts the saturation time or remaining usable lifetime of the boron nitride crucible's impurity trapping capacity based on an impurity release kinetic model. (The system extrapolates the ion current intensity after several future cycles based on model parameters to predict the remaining capacity of the impurity trapping region and the remaining usable lifetime of the crucible. For example, when the fitting results show...) At that time, it can be determined that in After one cycle, the impurity trap area will be saturated or the crucible will reach the end of its service life. (This is a preset ion current intensity threshold).

[0092] Specifically, storing impurity release data from the boron nitride crucible during multiple use cycles aims to accumulate historical data, providing a foundation for subsequent analysis and prediction. By recording impurity release at different stages of crucible use, a comprehensive dataset reflecting the trend of crucible performance changes over time can be constructed. For example, ion current intensity data monitored in real time by an enhanced residual gas analyzer, along with corresponding metadata such as the number of hot and cold cycles and cumulative heating time, can be stored in non-volatile memory connected to the control system, such as a solid-state drive or database server. Alternatively, data can be periodically uploaded to a cloud storage service or local server to create a traceable and analyzable historical database of crucible performance.

[0093] By fitting the impurity release data to establish an impurity release kinetic model, this step aims to extract regularities from stored historical impurity release data and build a mathematical model that can describe the changes in impurity release behavior over time or in usage cycles. This model forms the basis for predicting the future performance of the crucible. For example, statistical regression analysis methods, such as least squares, can be used to fit the historical data to determine the model parameters. Linear models, multinomial models, or exponential models can be explored. Furthermore, machine learning algorithms, such as support vector regression or neural networks, can be used to learn from complex data patterns and construct a nonlinear kinetic model to more accurately capture the complex behavior of impurity release.

[0094] The impurity release kinetic model is used to predict the saturation point or remaining usable lifespan of the boron nitride crucible's impurity trapping capacity. This step utilizes the established kinetic model to extrapolate future impurity release trends, thereby predicting when the crucible's impurity trapping capacity will reach saturation or estimating the crucible's remaining usable lifespan. This helps users plan crucible replacement and maintenance in advance. For example, the model can be extrapolated to several future thermal cycles to calculate the ion current intensity after these cycles. When the predicted ion current intensity reaches or exceeds a preset threshold (e.g., a multiple compared to a new crucible's baseline value), it can be determined as the saturation point or the end of the lifespan. Furthermore, the theoretical saturation capacity of the impurity trapping material can be calculated using the model, and combined with the current impurity release rate, the time or number of cycles required to reach saturation can be estimated, thus determining the remaining usable lifespan.

[0095] This application's solution combines real-time monitoring with long-term data analysis to achieve a comprehensive understanding of the impurity release behavior of boron nitride crucibles. Building upon the immediate early warning provided by the aforementioned real-time impurity release monitoring method, this solution systematically stores impurity release data from boron nitride crucibles across multiple usage cycles, constructing a fundamental dataset reflecting the long-term evolution trend of crucible performance. Subsequently, using this accumulated data, a kinetic model of impurity release is established through fitting techniques, revealing the intrinsic laws governing impurity release changes over time or usage cycles. Finally, based on this kinetic model, the system can extrapolate future impurity release trends, accurately determining when the impurity capture capacity of the boron nitride crucible reaches saturation or estimating its remaining usable lifespan. This shift from real-time monitoring to predictive maintenance allows users to move from passively responding to excessive impurity release to proactively planning crucible maintenance and replacement, effectively avoiding production interruptions and epitaxial film contamination risks caused by sudden crucible failure.

[0096] Through the above technical solution, this application further solves the problem of the inability to predict the long-term use status of boron nitride crucibles in traditional methods, based on real-time monitoring of impurity release. By systematically storing impurity release data of boron nitride crucibles in multiple use cycles, a solid data foundation is provided for subsequent analysis, overcoming the limitation of lacking long-term data support. Based on this, a kinetic model reflecting the impurity release pattern is successfully established by fitting these historical data, enabling the system to learn and master the behavior patterns of impurity release from complex historical data. Furthermore, based on the established impurity release kinetic model, the system can accurately predict when the impurity capture capacity of the boron nitride crucible will reach saturation, as well as its remaining usable lifespan. This allows users to shift from passively responding to excessive impurity release to proactively planning crucible maintenance and replacement, thereby avoiding production interruptions and epitaxial film contamination risks caused by sudden crucible failure. Compared with solutions that only provide real-time warnings, this solution, by introducing predictive capabilities, significantly improves the stability and controllability of molecular beam epitaxy processes, ensures the continuous high purity of epitaxial films, and optimizes crucible utilization efficiency and cost management. This forward-looking management approach effectively ensures the yield and performance of high-quality optoelectronic devices.

[0097] In some embodiments, the impurity release kinetic model is expressed as:

[0098] ;

[0099] in, The ion current intensity after the nth thermal cycle of the boron nitride crucible. The preset reference ion current intensity, This represents the total increment of the ion current intensity relative to the reference ion current intensity when impurity release reaches saturation. This refers to the number of hot and cold cycles of the boron nitride crucible. This is the preset time constant.

[0100] Through the above technical solution, this application provides a more accurate and reliable impurity release kinetic model. This exponential function model effectively captures the nonlinear and asymptotic saturation characteristics of impurity release during the use of boron nitride crucibles, overcoming the problem of inaccurate predictions caused by oversimplification in existing technologies. Therefore, fitting impurity release data based on this model can significantly improve the prediction accuracy of the saturation time point or remaining usable lifetime of the boron nitride crucible's impurity trapping capacity. This allows users to predict the crucible's contamination risk earlier and more accurately, thereby avoiding a decrease in epitaxial film purity due to accidental impurity release and ensuring the fabrication of high-quality optoelectronic devices. Simultaneously, accurate lifetime prediction also helps optimize crucible replacement cycles, reducing unnecessary downtime and material waste, and improving production efficiency and economic benefits.

[0101] In some embodiments, the impurity release kinetic model is expressed as:

[0102] ;

[0103] in, The ion current intensity after the nth thermal cycle of the boron nitride crucible. The preset reference ion current intensity, The preset average growth rate (which describes the average rate at which the intensity of the ion current released by the impurities increases linearly with the number of cycles). This represents the number of hot and cold cycles performed on the boron nitride crucible.

[0104] Through the above technical solution, this application provides a simplified impurity release kinetic model, effectively solving the problem that existing models may be too complex and difficult to fit quickly, resulting in low prediction efficiency. This linear model, with its concise mathematical form, significantly reduces the complexity of model building and parameter fitting, making the construction and application of the impurity release kinetic model more efficient and easier to implement. Specifically, by adopting a linear growth model, the system can quickly extract key parameters from historical data. and This model simplifies the process by avoiding the solution and iterative calculation of complex nonlinear equations, significantly reducing prediction time and improving real-time performance. Furthermore, the intuitiveness of the linear model makes it easier for operators to understand impurity release trends and crucible lifespan status, facilitating decision-making. Combined with the aforementioned real-time impurity release monitoring method, this linear model can quickly update and adjust prediction results based on real-time acquired ion current intensity data, providing timely and reliable assessments of the impurity trapping capacity saturation point or remaining usable lifespan of the boron nitride crucible. This allows users to more accurately plan crucible replacement cycles, avoiding accidental film contamination caused by crucible impurity release saturation, thus ensuring the purity of epitaxial films and device production yield, while optimizing production costs and efficiency.

[0105] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0106] The use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refers to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0107] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A boron nitride crucible, comprising a crucible base, characterized in that, The inner surface of the crucible substrate is covered with a barrier layer, and an impurity trap region is formed inside the crucible substrate by doping with an impurity trapping material. The impurity trap region is used to trap impurities that diffuse out of the crucible substrate. The impurity trap regions are non-uniformly distributed inside the crucible substrate, and the impurity trap regions are concentrated in the low-temperature zone of the thermal field of the crucible substrate; the low-temperature zone of the thermal field is the impurity diffusion target region determined according to the temperature gradient of the crucible substrate under working conditions.

2. The boron nitride crucible according to claim 1, characterized in that, The barrier layer is made of yttrium oxide.

3. The boron nitride crucible according to claim 2, characterized in that, The barrier layer is a yttrium oxide film with a thickness of 1 to 5 nanometers formed by atomic layer deposition technology. The yttrium oxide film covers the inner surface of the crucible substrate in a dense, uniform and pinhole-free manner.

4. The boron nitride crucible according to claim 1, characterized in that, The impurity capturing material includes titanium nitride particles or zirconium carbide particles with a particle size in the micrometer range.

5. The boron nitride crucible according to claim 1, characterized in that, The low-temperature zone of the thermal field includes the bottom region of the crucible base or the outlet region of the crucible base.

6. A method for real-time monitoring of impurity release from a boron nitride crucible as described in any one of claims 1-5, applied to a vacuum chamber integrated with a residual gas analyzer, wherein the residual gas analyzer is positioned directly opposite or adjacent to the outlet of the boron nitride crucible, characterized in that... Includes the following steps: During the initial use of a new crucible, the residual gas analyzer is controlled to record the impurity ion flow intensity at the standard operating temperature as a reference value. In subsequent use, the residual gas analyzer monitors the current ion current intensity in real time and calculates the ratio of the current ion current intensity to the reference value. When the ratio continuously exceeds a preset threshold, a graded warning is issued based on the magnitude of the ratio.

7. The method for real-time monitoring of impurity release according to claim 6, characterized in that, It also includes the following steps: Store data on impurity release during multiple use cycles of the boron nitride crucible; A dynamic model of impurity release is established by fitting the impurity release data. Based on the impurity release kinetic model, the saturation point or remaining usable lifetime of the impurity trapping capability of the boron nitride crucible is predicted.

8. The method for real-time monitoring of impurity release according to claim 7, characterized in that, The impurity release kinetic model is expressed as follows: ； in, The ion current intensity after the nth thermal cycle of the boron nitride crucible. The preset reference ion current intensity, This represents the total increment of the ion current intensity relative to the reference ion current intensity when impurity release reaches saturation. The number of hot and cold cycles of the boron nitride crucible. This is the preset time constant.

9. The method for real-time monitoring of impurity release according to claim 7, characterized in that, The impurity release kinetic model is expressed as follows: ； in, The ion current intensity after the nth thermal cycle of the boron nitride crucible. The preset reference ion current intensity, The preset average growth rate, The number of hot and cold cycles performed on the boron nitride crucible.

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