A method for preparing an aluminum source crucible and the aluminum source crucible itself.

Abstract

This invention belongs to the field of crucible preparation technology, and relates to a method for preparing an aluminum source crucible and the aluminum source crucible itself. The preparation method includes preparing an aluminum nitride crucible using a powder molding method; immersing the aluminum nitride crucible in an acidic solution, cleaning it with an alkaline solution, and ultrasonically cleaning it with an organic solution; wrapping the cleaned aluminum nitride crucible and then baking it at a low temperature; and degassing the baked aluminum nitride crucible at a high temperature under vacuum conditions to obtain the prepared aluminum source crucible. The aluminum source crucible prepared by this method solves the problems of unstable aluminum beam flow caused by high-temperature aluminum solution wetting in the crucible, aluminum liquid solidification causing crucible baffle adhesion, and aluminum melt sliding into the crucible causing temperature changes and evaporation rate fluctuations in the aluminum liquid. At the same time, the aluminum source crucible has good chemical stability, avoiding the release of water vapor and volatilization of organic impurities during molecular beam epitaxy, which would affect the quality of the epitaxial material.

Description

Technical Field

[0001] This invention relates to the field of crucible preparation technology, and in particular to a method for preparing an aluminum source crucible and the aluminum source crucible itself. Background Technology

[0002] Molecular beam epitaxy (MBE) is an advanced technique for growing single-crystal thin films. In MBE, different high-purity materials are placed in specific crucible furnaces. These furnaces are electrically heated and cooled by circulating water, allowing for precise temperature control of the furnace bottom and opening. Within an ultra-high vacuum chamber at high temperatures, multiple ultra-high-purity single-element sources are thermally evaporated or pyrolyzed to form atomic or molecular beams. These different types of gaseous beams are simultaneously sprayed onto a substrate with a specific lattice at a designed ratio. The gaseous beams then form corresponding crystalline thin films on this substrate. As the spraying time progresses, the crystalline film expands and accumulates, increasing its thickness and area. The thickness is typically controlled by adjusting the spraying time and beam magnitude. The type of crystal grown is adjusted by changing the spraying sequence and ratio of different materials, thus allowing the growth of different material types. The advantages of this technique are: low substrate temperature, slow film growth rate, easily and precisely controlled beam intensity, and rapid adjustment of film composition and doping concentration based on changes in the high-purity single-element sources.

[0003] Molecular beam epitaxy (MBE) is a kinetic process that does not require consideration of intermediate chemical reactions and is unaffected by mass transport, allowing it to grow thin films that are difficult to grow using conventional thermal equilibrium methods. MBE technology plays a crucial role in materials science and device engineering due to its precise control over film growth and quality. Initially used primarily for scientific research, the semiconductor epitaxial materials produced by this technology have found widespread application in recent years thanks to its development. Its highly precise growth control and ability to grow a variety of materials have led to its widespread use in semiconductor device manufacturing, optoelectronic devices, and quantum devices. As technology continues to evolve to meet the specific needs of different materials and devices, it is expected to find applications in even more fields. With the development of focal plane array detectors, the requirements for the consistency of performance among various surface array units are becoming increasingly stringent, thus placing higher demands on the uniformity of the evaporated raw material beam.

[0004] Due to the complexity and high difficulty of molecular beam epitaxy (MBE) technology, the cost of equipment and raw materials remains high, resulting in high added value for the products. Therefore, improving product yield is of paramount importance in MBE production. As one of the core components of MBE technology, the evaporation crucible typically uses pyrolytic boron nitride (PBN) crucible material. PBN is highly pure, has excellent airtightness, high temperature resistance, and does not wet or react with most molten metals and semiconductors at high temperatures. It also exhibits good thermal conductivity, a low coefficient of thermal expansion, high electrical resistance, and excellent infrared transmission properties, making it the preferred crucible material for the purification of high-purity materials. However, boron nitride crucibles exhibit a significant wetting phenomenon on aluminum metal materials: during MBE growth, the high-temperature liquefied aluminum rises upwards from the lower part of the tilted crucible. As heat is lost through radiation at the furnace opening and the temperature decreases, aluminum accumulates at the crucible opening. This phenomenon causes uneven heating of the crucible and, due to the uneven distribution of molten aluminum in the crucible and at the furnace opening, instability in the molecular beam, affecting product quality. Furthermore, the aluminum accumulated at the furnace opening can thicken, and in severe cases, cause shutter adhesion, affecting the normal opening and closing of the shutter, resulting in deviations in opening time, significantly reducing product yield and epitaxial material quality. Additionally, the aluminum accumulated at the crucible opening can cause molten aluminum to slide into the crucible due to temperature fluctuations at the furnace opening, causing significant changes in the temperature of the molten aluminum inside the crucible, excessive fluctuations in the evaporation rate, deviations in material composition from the design, affecting product quality, and even causing material scrap.

[0005] In summary, existing crucibles for molecular beam epitaxy have a significant wetting problem with liquid aluminum under high-temperature vacuum working conditions, which in turn affects the quality of molecular beam epitaxy products. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the crucible used in molecular beam epitaxy has obvious wetting problem with liquid aluminum under high temperature and vacuum working environment, which affects the quality of molecular beam epitaxy products.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for preparing an aluminum source crucible, comprising:

[0008] Aluminum nitride crucibles were prepared using a powder molding method;

[0009] The aluminum nitride crucible was immersed in an acidic solution, cleaned with an alkaline solution, and ultrasonically cleaned with an organic solution.

[0010] After cleaning, the aluminum nitride crucible is wrapped and then baked at a low temperature.

[0011] The aluminum nitride crucible, after being baked at low temperature, was degassed at high temperature under vacuum to obtain the prepared aluminum source crucible.

[0012] In this application, an aluminum nitride crucible is prepared using a powder molding method. This avoids the problem of high-temperature liquefied aluminum rising from the bottom to the top of the crucible, which leads to instability in the aluminum beam during the entire production process, solidification of the molten aluminum at the crucible mouth causing adhesion of the crucible baffle, and molten aluminum accumulating at the crucible mouth sliding into the crucible, causing changes in the temperature of the molten aluminum and fluctuations in the evaporation rate. At the same time, by cleaning, low-temperature baking, and high-temperature degassing of the aluminum nitride crucible, most of the water vapor, low-melting-point volatile substances, and gaseous deposits on the surface and inside of the crucible prepared by the powder molding method are removed. This ensures that the crucible does not release other substances during the growth of MBE materials, and the purity of the evaporated aluminum element is determined solely by the aluminum source inside the crucible. This strictly prevents other elements from participating in the material growth, changes the designed composition and structure, and effectively solves the problem of aluminum nitride crucibles releasing water vapor or other gases and volatile dopants during use, thus affecting product yield.

[0013] Preferably, the aluminum nitride crucible is immersed in an acidic solution, including:

[0014] Immerse the aluminum nitride crucible in an acidic solution for 5-10 minutes;

[0015] Rinse the soaked aluminum nitride crucible with deionized water for 3-5 minutes.

[0016] In this application, residual metal on the surface of the aluminum nitride crucible is removed by acid immersion, and then the acidic solution residue on the aluminum nitride crucible is rinsed with deionized water. By controlling the immersion time and rinsing time, the cleaning effect can be ensured, while reducing waste and environmental pollution caused by the volatilization of reagents during the cleaning process.

[0017] Preferably, the aluminum nitride crucible is cleaned using an alkaline solution, including:

[0018] Immerse the aluminum nitride crucible in a 5%~10% sodium hydroxide solution for 5~10 minutes;

[0019] Rinse the soaked aluminum nitride crucible with deionized water for 3-5 minutes.

[0020] In this application, an alkaline solution is used to remove organic matter from the surface of the aluminum nitride crucible and neutralize the residual acidic solution, and then deionized water is used to remove the residual alkaline solution.

[0021] Preferably, the aluminum nitride crucible is ultrasonically cleaned using an organic solution, including:

[0022] The aluminum nitride crucible is ultrasonically cleaned for 5-15 minutes using a first organic solution, which is acetone, diethyl ether, or carbon tetrachloride.

[0023] The aluminum nitride crucible is ultrasonically cleaned for 5-15 minutes using a second organic solution, which is isopropanol, ethanol, or methanol.

[0024] Rinse the ultrasonically cleaned aluminum nitride crucible with deionized water for 5-10 minutes.

[0025] In this application, a first organic solution is first used to remove salts and high molecular weight organic matter from the surface of the aluminum nitride crucible, then a second organic solution is used to dissolve example compounds and polar organic matter to further remove organic reagents from the surface of the aluminum nitride crucible, and finally deionized water is used to rinse the surface of the aluminum nitride crucible to remove the residual first and second organic solutions.

[0026] Preferably, after ultrasonic cleaning of the aluminum nitride crucible with an organic solution, the process further includes:

[0027] The aluminum nitride crucible was ultrasonically cleaned for 15 minutes using anhydrous ethanol.

[0028] The aluminum nitride crucible, after ultrasonic cleaning, was cleaned and dried using a nitrogen gun.

[0029] In this application, ultrasonic cleaning with anhydrous ethanol followed by drying of the surface moisture with a nitrogen gun can accelerate the removal of liquid residue from the surface of the aluminum nitride crucible.

[0030] Preferably, the low-temperature baking temperature is 200°C; the low-temperature baking time is 4 hours.

[0031] After low-temperature baking, the aluminum nitride crucible is cooled along with the temperature of the low-temperature baking device.

[0032] In this application, water molecules remaining on the surface of the aluminum nitride crucible can be further removed by low-temperature baking and furnace cooling.

[0033] Preferably, the aluminum nitride crucible after low-temperature baking is subjected to high-temperature degassing under vacuum conditions, including:

[0034] The aluminum nitride crucible, after being baked at low temperature, is placed in an ultra-high vacuum furnace, and the temperature of the ultra-high vacuum furnace is controlled to reach and be maintained at 1100℃~1300℃ within 5~10 minutes.

[0035] Real-time monitoring of the pressure inside the ultra-high vacuum furnace; when the pressure is lower than... At that time, a quadrupole mass spectrometer was used to obtain the gas composition inside the ultra-high vacuum furnace;

[0036] When the ultra-high vacuum furnace is inside , , The peak values ​​are all lower than At that time, the temperature of the ultra-high vacuum furnace is controlled to decrease at a rate of 5℃ / min to 6℃ / min.

[0037] In this application, the aluminum nitride crucible is degassed at high temperature to remove gaseous components, volatile substances, and gaseous deposits from its surface. When controlling the heating and cooling rates of the ultra-high vacuum furnace, it is necessary to shorten the temperature change process while avoiding excessive thermal stress caused by rapid temperature changes, which could lead to cracking of the aluminum nitride crucible. When the source furnace is at a high temperature of 1200℃, the equipment vacuum is lower than... And the highest , , Peak value below This indicates that the baked aluminum nitride crucible meets the growth requirements; otherwise, continue baking at high temperature.

[0038] Preferably, after obtaining the prepared aluminum source crucible, the process further includes:

[0039] The aluminum solution is placed in the prepared aluminum source crucible, and the aluminum source crucible is placed in an ultra-high vacuum furnace;

[0040] The ultra-high vacuum furnace is heated at a rate of less than or equal to 10℃ / min, so that the temperature inside the ultra-high vacuum furnace reaches and is maintained at 1150℃.

[0041] When the temperature inside the ultra-high vacuum furnace remains at 1150°C for at least one hour, the power to the ultra-high vacuum furnace is cut off to reduce the temperature to below 100°C.

[0042] Remove the aluminum source crucible and obtain the wetting angle of the aluminum solution. If the wetting angle of the aluminum solution is less than 90°, clean the aluminum source crucible again, bake it at low temperature and degas it at high temperature until the wetting angle of the aluminum solution is greater than or equal to 90°, and obtain the processed aluminum source crucible.

[0043] In this application, wettability studies are conducted to determine whether the aluminum source crucible can solve the problem of aluminum solution wetting and rising from the bottom of the crucible, thereby determining whether the aluminum source crucible needs to be reprocessed.

[0044] Preferably, the aluminum nitride crucible is prepared using a powder forming method, comprising:

[0045] Alumina and carbon are mixed in a predetermined ratio and then introduced... and The mixed gas was reduced by C at a temperature of 1450℃~1750℃. Aluminum nitride powder was obtained;

[0046] Aluminum nitride crucibles are prepared by adding a sintering agent to aluminum nitride powder, pre-pressing it, and sintering it at a temperature of 1600℃~1800℃.

[0047] The present invention also provides an aluminum source crucible, which is prepared by the above-described method for preparing an aluminum source crucible.

[0048] The method for preparing the aluminum source crucible provided in this application employs a powder molding method to prepare the aluminum nitride crucible. The aluminum nitride crucible is immersed in an acidic solution, cleaned with an alkaline solution, and ultrasonically cleaned with an organic solution. After cleaning, the aluminum nitride crucible is wrapped and then baked at low temperature. The baked crucible is then degassed at high temperature under vacuum to obtain the prepared aluminum source crucible. Using aluminum nitride as the aluminum source crucible for MBE growth, the powder molding method, which uses micron-sized aluminum nitride powder, results in numerous pores within the crucible. Water vapor and other gases present inside these pores can be released during molecular beam epitaxy (MBE), causing beam instability and leading to material growth defects, thus affecting product yield. Furthermore, the sintering agents and other materials used in powder molding result in insufficient purity of the aluminum nitride crucible, which can volatilize during use. Various components can form dopants within the epitaxial material, affecting product performance. This application addresses these issues by cleaning, low-temperature baking, and high-temperature degassing of the aluminum nitride crucible. This resolves the problems of unstable aluminum beams caused by the upward movement of liquefied aluminum from the bottom of the crucible during MBE growth, as well as the problems of aluminum solution solidifying at the crucible opening, leading to crucible baffle adhesion and evaporation rate fluctuations caused by temperature changes in the aluminum solution after aluminum slides off the furnace opening. Simultaneously, it removes a large portion of water vapor, low-melting-point volatile substances, and gaseous deposits from the crucible surface and interior, ensuring that the crucible does not release other substances during MBE material growth. The purity of the evaporated aluminum is determined solely by the aluminum source within the crucible, preventing other elements from incorporating into the material growth process. This alters the design composition and structure, effectively solving the problem of water vapor or other gases and volatile dopants released by the aluminum nitride crucible during use, thus affecting product yield. Attached Figure Description

[0049] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0050] Figure 1 A flowchart illustrating the preparation method of the aluminum source crucible provided in this application;

[0051] Figure 2 A flowchart illustrating another method for preparing an aluminum source crucible provided in this application;

[0052] Figure 3 A schematic diagram of the aluminum nitride crucible provided in this application;

[0053] Figure 4 A schematic diagram of gas composition analysis using a four-stage mass spectrometer provided in this application;

[0054] Figure 5This diagram illustrates the wetting effect of the aluminum nitride crucible and aluminum source crucible on the aluminum solution provided in the embodiments of this application; wherein, Figure 5 (a) in the diagram is a schematic diagram of the wetting effect of the aluminum nitride crucible on the aluminum solution. Figure 5 (b) in the figure is a schematic diagram of the wetting effect of the aluminum source crucible on the aluminum solution. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0056] Boron nitride crucibles exhibit a significant wetting phenomenon on aluminum metal materials: during MBE growth, the high-temperature liquefied aluminum rises upwards from the lower part of the tilted crucible. As heat is lost through radiation at the furnace opening and the temperature decreases, the aluminum accumulates at the crucible opening. This phenomenon causes uneven heating of the crucible and, due to the uneven distribution of molten aluminum in the crucible and at the furnace opening, instability in the molecular beam, affecting product quality. Furthermore, the aluminum accumulated at the furnace opening can thicken, potentially causing shutter sticking in severe cases, affecting normal shutter opening and closing, resulting in deviations in opening time, significantly reducing product yield and epitaxial material quality. Additionally, due to temperature fluctuations at the furnace opening, molten aluminum accumulated at the crucible opening can slide back into the crucible. Significant temperature fluctuations in the molten aluminum within the crucible, excessively fluctuating evaporation rates, and deviations in material composition from design parameters all contribute to product quality issues and can even lead to material scrap. While crucibles made with aluminum nitride can mitigate the aluminum molten aluminum wetting problem to some extent, this application reveals that aluminum nitride crucibles contain internal pores. Water vapor and other gases within these pores are released during molecular beam epitaxy, causing beam instability and resulting in material growth defects that negatively impact product yield. Furthermore, the sintering agents and other materials used in powder molding result in insufficient purity in the aluminum nitride crucible, leading to the volatilization of various components during use. These volatilize into dopants within the epitaxial material, further affecting product performance.

[0057] Please see Figure 1 , Figure 1 The diagram shown is a flowchart of the preparation method of the aluminum source crucible provided in this application. The method specifically includes:

[0058] S1: Aluminum nitride crucibles were prepared using a powder molding method.

[0059] S2: The aluminum nitride crucible is immersed in an acidic solution, cleaned with an alkaline solution, and ultrasonically cleaned with an organic solution.

[0060] S3: Wrap the cleaned aluminum nitride crucible and bake it at a low temperature.

[0061] Specifically, the wrapped aluminum nitride crucible is placed in a vacuum oven for low-temperature baking.

[0062] S4: The aluminum nitride crucible after low-temperature baking is degassed at high temperature under vacuum to obtain the prepared aluminum source crucible.

[0063] First, this application uses aluminum nitride as the aluminum source crucible for MBE growth. Similar to boron nitride, aluminum nitride is a material with high thermal conductivity, electrical insulation, and good dielectric properties, with a resistivity as high as... It has high light transmittance in the visible and infrared bands and stable chemical properties; in addition, aluminum nitride can be stable up to 1500℃ in a vacuum, hardly reacts with concentrated inorganic acids, has a larger coefficient of thermal expansion than boron nitride, has a higher bending strength than boron nitride (280~350MPa), a Mohs hardness of 8, and strong resistance to molten metal corrosion, making it an ideal crucible material for aluminum or aluminum alloys.

[0064] There are various methods for preparing aluminum nitride crucibles, ranging from traditional direct nitriding and carbothermal reduction methods for powder manufacturing to advanced methods such as chemical vapor deposition and plasma methods for preparing thin films and single crystals. However, due to the special shape of the crucible, current methods for growing thin film materials cannot produce aluminum nitride crucibles with a certain three-dimensional depth. Furthermore, the coating uniformity of deposition growth methods also has problems. Therefore, this application adopts a powder forming method to prepare aluminum nitride crucibles, which solves the problems of high-temperature liquefied aluminum rising from the bottom to the top of the crucible, causing instability of the aluminum beam throughout the production process, aluminum solidification causing crucible baffle adhesion, and aluminum molten at the crucible mouth sliding into the crucible, causing changes in aluminum liquid temperature and fluctuations in evaporation rate.

[0065] Furthermore, since the powder forming method uses micron-sized aluminum nitride powder to prepare aluminum nitride crucibles, the crucibles contain numerous pores after forming. Water vapor and other gases present inside these pores are released during the molecular beam epitaxy (MBE) process, causing beam instability and resulting in material growth defects, thus affecting product yield. Simultaneously, the sintering agents and other materials used in powder forming lead to insufficient purity of the aluminum nitride crucibles, which volatilize various components during use, forming dopants within the epitaxial material and affecting product performance. Therefore, this application removes most of the water vapor, low-melting-point volatile substances, and gaseous deposits from the surface and interior of the aluminum nitride crucible through cleaning, low-temperature baking, and high-temperature degassing. This ensures that the crucible does not release other substances during MBE material growth, and the purity of the evaporated aluminum is determined solely by the aluminum source within the crucible, preventing other elements from incorporating into the material growth. This alters the designed composition and structure, effectively solving the problem of water vapor or other gases and volatilized dopants released by the aluminum nitride crucible during use, thus affecting product yield.

[0066] Specifically, based on the above embodiments, this application also provides another method for preparing an aluminum source crucible to further explain and illustrate the above-described method for preparing an aluminum source crucible, such as... Figure 2 As shown, it specifically includes:

[0067] S100: Alumina and carbon are mixed in a preset ratio and then introduced... and The mixed gas was reduced by C at a temperature of 1450℃~1750℃. Aluminum nitride powder was obtained.

[0068] Specifically, the aluminum nitride powder has a particle size of approximately 1μm to 5μm, exhibiting stable performance and fine particle size.

[0069] S101: An aluminum nitride crucible is prepared by adding a sintering agent to aluminum nitride powder, pre-pressing it, and sintering it at a temperature of 1600℃~1800℃. Figure 3 As shown.

[0070] Because aluminum nitride ceramics have a small diffusion coefficient, they are difficult to sinter. In order to reduce the sintering temperature of aluminum nitride crucibles, Y2O3-CaF2 binary sintering agent is added to the aluminum nitride powder for pre-pressing in this embodiment.

[0071] Because the powder-formed and sintered aluminum nitride crucible is composed of micron-sized particles with high hardness, it contains many pores. Water vapor and other gases in the air within these pores are released during high-temperature use, causing beam instability or excessive beam fluctuations, leading to defects in material growth during molecular beam epitaxy. Furthermore, the purity of the aluminum nitride powder used to prepare the crucible is insufficient, and the addition of sintering agents and binders further reduces the purity of the aluminum nitride crucible. These materials also volatilize various components during high-temperature use, forming dopant-like elements in the epitaxial material and affecting product performance. Therefore, this application employs a series of post-processing techniques on the prepared aluminum nitride crucible.

[0072] S102: Immerse the aluminum nitride crucible in an acidic solution for 5-10 minutes.

[0073] S103: Rinse the soaked aluminum nitride crucible with deionized water for 3-5 minutes.

[0074] Specifically, steps S102 and S103 remove residual metal from the surface of the aluminum nitride crucible by acid immersion, and then rinse the acidic solution residue on the aluminum nitride crucible with deionized water. By controlling the immersion time and rinsing time, the cleaning effect can be ensured, while reducing waste and environmental pollution caused by the volatilization of reagents during the cleaning process.

[0075] S104: Immerse the aluminum nitride crucible in a 5%~10% sodium hydroxide solution for 5~10 minutes.

[0076] S105: Rinse the soaked aluminum nitride crucible with deionized water for 3-5 minutes.

[0077] Furthermore, in steps S104 and S105, an alkaline solution is used to remove organic matter from the surface of the aluminum nitride crucible and neutralize the residual acidic solution, and then deionized water is used to remove the residual alkaline solution.

[0078] S106: Ultrasonically clean the aluminum nitride crucible for 5-15 minutes using a first organic solution; wherein, the first organic solution is acetone, diethyl ether or carbon tetrachloride.

[0079] As a preferred choice, acetone is selected as the first organic solvent because diethyl ether is flammable and carbon tetrachloride is highly toxic, posing safety hazards during use.

[0080] S107: Ultrasonically clean the aluminum nitride crucible for 5-15 minutes using a second organic solution; wherein the second organic solution is isopropanol, ethanol or methanol.

[0081] Preferably, isopropanol is selected as the second organic solution because isopropanol has a stronger solubility for lipophilic substances.

[0082] S108: Rinse the ultrasonically cleaned aluminum nitride crucible with deionized water for 5-10 minutes.

[0083] Specifically, in steps S106 to S108, a first organic solution is used to remove salts and high-molecular-weight organic matter from the surface of the aluminum nitride crucible, and a second organic solution is used to dissolve the example compound and polar organic matter to further remove organic reagents from the surface of the aluminum nitride crucible. Finally, deionized water is used to rinse the surface of the aluminum nitride crucible to remove any remaining first and second organic solutions.

[0084] S109: Ultrasonic cleaning of the ultrasonically cleaned aluminum nitride crucible is performed for 15 minutes using anhydrous ethanol.

[0085] S110: Use a nitrogen gun to clean and dry the ultrasonically cleaned aluminum nitride crucible.

[0086] Furthermore, in order to accelerate the removal of liquid residue from the surface of the aluminum nitride crucible, it can be ultrasonically cleaned with anhydrous ethanol first, and then dried with a nitrogen gun.

[0087] S111: After wrapping the aluminum nitride crucible with high-vacuum aluminum foil, place it in a vacuum oven and bake at a low temperature of 200℃ for 4 hours. Cool it with the oven to further remove residual water molecules on the surface of the aluminum nitride crucible.

[0088] S112: Place the aluminum nitride crucible, which has been baked at low temperature, into an ultra-high vacuum furnace, and control the temperature of the ultra-high vacuum furnace to reach and maintain 1100℃~1300℃ within 5~10 minutes.

[0089] S113: Real-time monitoring of the pressure inside the ultra-high vacuum furnace; when the pressure is lower than... At that time, a quadrupole mass spectrometer was used to obtain the gas composition inside the ultra-high vacuum furnace.

[0090] like Figure 4 The diagram shows a schematic of gas composition analysis using a four-stage mass spectrometer provided in this application. As can be seen from the diagram, the preceding processing steps have removed most of the water vapor, low-melting-point volatile substances, and gaseous contaminants (hydrogen, oxygen, nitrogen, carbon dioxide, and organic matter) from the surface and interior of the aluminum nitride crucible.

[0091] S114: When the ultra-high vacuum furnace is inside , , The peak values ​​are all lower than At that time, the temperature of the ultra-high vacuum furnace is controlled to decrease at a rate of 5℃ / min to 6℃ / min.

[0092] Specifically, when controlling the heating and cooling rates of the ultra-high vacuum furnace, it is necessary to shorten the temperature change process while avoiding excessive thermal stress caused by rapid temperature changes, which could lead to cracking of the aluminum nitride crucible. When the source furnace is at a high temperature of 1200℃, the equipment vacuum is lower than... And the highest , , Peak value below This indicates that the baked aluminum nitride crucible meets the growth requirements; otherwise, continue baking at high temperature.

[0093] S115: Place the aluminum solution into the prepared aluminum source crucible and then place the aluminum source crucible into an ultra-high vacuum furnace.

[0094] S116: Control the ultra-high vacuum furnace to heat up at a rate of less than or equal to 10℃ / min, so that the temperature inside the ultra-high vacuum furnace reaches and is maintained at 1150℃.

[0095] S117: When the temperature inside the ultra-high vacuum furnace remains at 1150°C for at least one hour, the power to the ultra-high vacuum furnace shall be cut off to reduce the temperature to below 100°C.

[0096] S118: Remove the aluminum source crucible and obtain the wetting angle of the aluminum solution. If the wetting angle of the aluminum solution is less than 90°, clean the aluminum source crucible again, bake it at low temperature and degas it at high temperature until the wetting angle of the aluminum solution is greater than or equal to 90°, and obtain the processed aluminum source crucible.

[0097] After post-processing the aluminum nitride crucible to obtain the aluminum source crucible, this application uses wettability studies to determine whether the aluminum source crucible can solve the problem of aluminum solution wetting and rising from the bottom of the crucible, and then performs post-processing on the aluminum source crucible again.

[0098] like Figure 5 The diagram shows the wetting effect of the aluminum nitride crucible (before post-treatment) and the aluminum source crucible (after post-treatment) on the aluminum solution provided in the embodiments of this application; wherein, Figure 5 (a) in the diagram is a schematic diagram of the wetting effect of the aluminum nitride crucible on the aluminum solution. Figure 5 (b) shows a schematic diagram of the wetting effect of the aluminum source crucible on the aluminum solution. Before post-processing, the wetting angle of the aluminum solution in the aluminum nitride crucible was less than 40°, and there was a significant upward climbing phenomenon along the aluminum nitride crucible wall. However, in the aluminum source crucible prepared in this application, the wetting angle of the aluminum solution was greater than or equal to 90°, indicating that the aluminum solution did not wet the crucible. This comparison demonstrates the effectiveness of the method. Figure 5 As can be seen from (a) and (b) in this application, the aluminum source crucible prepared by the method provided in this application effectively solves the problem of aluminum solution wetting, and the chemical properties of the crucible are very stable. It does not release water vapor or other gases during the MBE process, nor does it volatilize doping elements. It solves the problems of high-temperature liquefied aluminum rising from the bottom to the top in the crucible, causing the aluminum beam to be unstable throughout the production process, aluminum liquid solidification causing crucible baffle adhesion, and aluminum molten at the crucible mouth sliding into the crucible, causing changes in aluminum liquid temperature and fluctuations in evaporation rate. It also solves the problem of aluminum source crucible releasing gases and doping elements during the MBE process, thus affecting product yield.

[0099] Based on the above-mentioned method for preparing aluminum source crucibles, this application also provides an aluminum source crucible that replaces the existing HBN crucible. This aluminum source crucible is used to solve the problem of high-temperature liquefied aluminum wetting in the HBN crucible during MBE growth, ensuring that the beam flow is precisely controllable during the evaporation process, the aluminum component content strictly meets the design, and the product performance meets the requirements and the quality is stable, thereby achieving a significant improvement in yield and increased production efficiency.

[0100] The technical solution of this application will be described in more detail below with reference to the embodiments and comparative examples. However, it should be understood that the following embodiments and comparative examples are only for explaining and illustrating the technical solution and do not limit the scope of this application.

[0101] Embodiment 1 of this application provides a method for preparing an aluminum source crucible, which specifically includes the following steps:

[0102] S1: Aluminum nitride crucibles were prepared using a powder molding method.

[0103] S2: Immerse the aluminum nitride crucible in an acidic solution for 5 minutes, clean it with sodium hydroxide for 5 minutes, ultrasonically clean it with acetone (the first organic solution) for 5 minutes, and ultrasonically clean it with isopropanol (the second organic solution) for 5 minutes.

[0104] S3: Wrap the cleaned aluminum nitride crucible and bake it in a vacuum oven at 200℃ for 4 hours.

[0105] S4: Place the low-temperature baked aluminum nitride crucible into the ultra-high vacuum furnace, and control the temperature of the ultra-high vacuum furnace to reach and maintain 1100℃ within 5 minutes; monitor the pressure inside the ultra-high vacuum furnace in real time, and when the pressure is lower than... At that time, a quadrupole mass spectrometer was used to obtain the gas composition inside the ultra-high vacuum furnace; when the gas composition inside the ultra-high vacuum furnace was... , , The peak values ​​are all lower than At that time, the temperature of the ultra-high vacuum furnace was controlled to decrease at a rate of 5℃ / minute to obtain the prepared aluminum source crucible.

[0106] Embodiment 2 of this application provides a method for preparing an aluminum source crucible, which specifically includes the following steps:

[0107] S1: Aluminum nitride crucibles were prepared using a powder molding method.

[0108] S2: Immerse the aluminum nitride crucible in an acidic solution for 7 minutes, clean it with sodium hydroxide for 7 minutes, ultrasonically clean it with acetone (the first organic solution) for 10 minutes, and ultrasonically clean it with isopropanol (the second organic solution) for 10 minutes.

[0109] S3: Wrap the cleaned aluminum nitride crucible and bake it in a vacuum oven at 200℃ for 4 hours.

[0110] S4: Place the low-temperature baked aluminum nitride crucible into the ultra-high vacuum furnace, and control the temperature of the ultra-high vacuum furnace to reach and maintain 1200℃ within 7 minutes; monitor the pressure inside the ultra-high vacuum furnace in real time, and when the pressure is lower than... At that time, a quadrupole mass spectrometer was used to obtain the gas composition inside the ultra-high vacuum furnace; when the gas composition inside the ultra-high vacuum furnace was... , , The peak values ​​are all lower than At that time, the temperature of the ultra-high vacuum furnace was controlled to decrease at a rate of 5.5℃ / min to obtain the prepared aluminum source crucible.

[0111] Embodiment 3 of this application provides a method for preparing an aluminum source crucible, which specifically includes the following steps:

[0112] S1: Aluminum nitride crucibles were prepared using a powder molding method.

[0113] S2: Immerse the aluminum nitride crucible in an acidic solution for 10 minutes, clean the aluminum nitride crucible with sodium hydroxide for 10 minutes, ultrasonically clean the aluminum nitride crucible with acetone (the first organic solution) for 15 minutes, and ultrasonically clean the aluminum nitride crucible with isopropanol (the second organic solution) for 15 minutes.

[0114] S3: Wrap the cleaned aluminum nitride crucible and bake it in a vacuum oven at 200℃ for 4 hours.

[0115] S4: Place the low-temperature baked aluminum nitride crucible into the ultra-high vacuum furnace, and control the temperature of the ultra-high vacuum furnace to reach and maintain 1300℃ within 10 minutes; monitor the pressure inside the ultra-high vacuum furnace in real time, and when the pressure is lower than... At that time, a quadrupole mass spectrometer was used to obtain the gas composition inside the ultra-high vacuum furnace; when the gas composition inside the ultra-high vacuum furnace was... , , The peak values ​​are all lower than At that time, the temperature of the ultra-high vacuum furnace was controlled to decrease at a rate of 6℃ / min to obtain the prepared aluminum source crucible.

[0116] This application provides a comparative example of a method for preparing an aluminum source crucible, which specifically includes the following steps:

[0117] S1: Configure aluminum nitride powder.

[0118] S2: Prepare the slurry.

[0119] S3: Embryo body forming.

[0120] S4: De-glue.

[0121] S5: Oxidation.

[0122] S6: Sintering of the embryo.

[0123] S7: Finished product after polishing.

[0124] The performance of the aluminum source crucibles prepared using the methods provided in the above embodiments and comparative examples was tested, and the performance test results are shown in Table 1 below:

[0125] Table 1

[0126] Aluminum solution wetting angle Chemical stability Example 1 110° No Al atomic groups were detected by mass spectrometry. Example 2 103° No Al atomic groups were detected by mass spectrometry. Example 3 112° No Al atomic groups were detected by mass spectrometry. Comparative Example 70° Mass spectrometry results showed the presence of Al atomic groups.

[0127] Specifically, the wetting angle refers to the angle between the liquid-solid interface and the liquid-gas interface at the junction of the aluminum solution and the surface of the aluminum nitride crucible. The method for detecting the aluminum solution wetting angle is as follows: After placing the aluminum block into the aluminum nitride crucible, heat it to a preset temperature and hold it for a period of time. Then, slowly cool it down and allow it to solidify naturally into a solid aluminum block. Remove the aluminum block, and adhere the bottom surface in contact with the aluminum nitride crucible to a glass plate with paraffin wax. After the paraffin wax solidifies, place the side of the block on the stage of an optical microscope. Adjust the microscope's focus and light source to clearly image the aluminum-aluminum nitride contact interface. Take a side view image of the contact section using the microscope's built-in camera or an external high-definition camera. Perform noise reduction and other preprocessing on the captured images. Manually outline or automatically identify the solidification profile of the liquid-gas interface of the solid aluminum block (i.e., the liquid-gas interface in the liquid state) and the liquid-solid contact line between the aluminum block and the crucible wall using software. Using the inner wall surface of the aluminum nitride crucible as a baseline (liquid-solid interface), determine the liquid-gas interface along the tangent direction of the aluminum block's solidification profile. At the gas interface, the software will automatically calculate the angle between the two interfaces at the contact line, which is the wetting angle.

[0128] The measurement procedure for the chemical stability of aluminum nitride crucibles is as follows: The aluminum nitride crucible is heated to 1100℃~1300℃ in a high-temperature vacuum furnace and then held at that temperature. The gaseous products volatilized at high temperature are introduced into the mass spectrometer inlet for detection. Based on the detection results of the mass spectrometer, the characteristic peak intensity of aluminum atom groups is observed to determine whether aluminum atom groups are present.

[0129] As can be seen from the table, when the aluminum solution is placed into the aluminum source crucible (Examples 1 to 3) prepared by the preparation method provided in this application, the wetting angle is greater than 90°, which solves the problem of wetting of high-temperature aluminum solution. Moreover, the prepared aluminum source crucible has stable chemical properties and will not react chemically with the aluminum solution, which solves the problem of impurities in the crucible volatilizing during high-temperature MBE and thus affecting the quality of epitaxial material.

[0130] Compared with the preparation method provided in this application, the prior art (comparative example) does not perform post-treatment on the aluminum nitride crucible prepared by the powder forming method. Although its aluminum solution wetting angle is greater than that of the boron nitride crucible (40°), it still has wetting problems compared with the aluminum source crucible prepared in this application. At the same time, the performance of the untreated crucible is unstable, which leads to the release of gas and doping elements during use. That is, the purity of the evaporated aluminum element is affected by the crucible material, not just by the aluminum source in the crucible. This changes the designed composition and structure, thus affecting the product yield.

[0131] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an aluminum source crucible, characterized by, include: Aluminum nitride crucibles were prepared using a powder molding method; The aluminum nitride crucible was immersed in an acidic solution, cleaned with an alkaline solution, and ultrasonically cleaned with an organic solution. After cleaning, the aluminum nitride crucible is wrapped and then baked at a low temperature. The aluminum nitride crucible, after being baked at low temperature, was degassed at high temperature under vacuum to obtain the prepared aluminum source crucible.

2. The method of claim 1, wherein the aluminum source crucible is prepared by the steps of: The aluminum nitride crucible is immersed in an acidic solution, including: ​ Immerse the aluminum nitride crucible in an acidic solution for 5-10 minutes; Rinse the soaked aluminum nitride crucible with deionized water for 3-5 minutes.

3. The method of claim 1, wherein the aluminum source crucible is prepared by the steps of: The aluminum nitride crucible is cleaned using an alkaline solution, including: ​ Immerse the aluminum nitride crucible in a 5%~10% sodium hydroxide solution for 5~10 minutes; Rinse the soaked aluminum nitride crucible with deionized water for 3-5 minutes.

4. The method of claim 1, wherein the aluminum source crucible is prepared by the steps of: preparing a mixture of aluminum and a fluxing agent; and heating the mixture to a temperature of 700 to 800°C for 1 to 3 hours. The aluminum nitride crucible was ultrasonically cleaned using an organic solvent, including: The aluminum nitride crucible is ultrasonically cleaned for 5-15 minutes using a first organic solution, which is acetone, diethyl ether, or carbon tetrachloride. The aluminum nitride crucible is ultrasonically cleaned for 5-15 minutes using a second organic solution, which is isopropanol, ethanol, or methanol. Rinse the ultrasonically cleaned aluminum nitride crucible with deionized water for 5-10 minutes.

5. The method for preparing the aluminum source crucible according to claim 1, characterized in that, After ultrasonic cleaning of the aluminum nitride crucible with an organic solvent, the process also includes: The aluminum nitride crucible was ultrasonically cleaned for 15 minutes using anhydrous ethanol. The aluminum nitride crucible, after ultrasonic cleaning, was cleaned and dried using a nitrogen gun.

6. The method for preparing the aluminum source crucible according to claim 1, characterized in that, The low-temperature baking temperature is 200℃; the low-temperature baking time is 4 hours. After low-temperature baking, the aluminum nitride crucible is cooled along with the temperature of the low-temperature baking device.

7. The method for preparing the aluminum source crucible according to claim 1, characterized in that, The aluminum nitride crucible, after low-temperature baking, is subjected to high-temperature degassing under vacuum conditions, including: The aluminum nitride crucible, after being baked at low temperature, is placed in an ultra-high vacuum furnace, and the temperature of the ultra-high vacuum furnace is controlled to reach and be maintained at 1100℃~1300℃ within 5~10 minutes. Real-time monitoring of the pressure in the ultra-high vacuum furnace, when the pressure is lower than the gas composition in the ultra-high vacuum furnace is obtained using a quadrupole mass spectrometer; When the ultra-high vacuum furnace is inside , , The peak values ​​are all lower than At that time, the temperature of the ultra-high vacuum furnace is controlled to decrease at a rate of 5℃ / min to 6℃ / min.

8. The method for preparing the aluminum source crucible according to claim 1, characterized in that, After obtaining the prepared aluminum source crucible, the following steps are also included: The aluminum solution is placed in the prepared aluminum source crucible, and the aluminum source crucible is placed in an ultra-high vacuum furnace; The ultra-high vacuum furnace is heated at a rate of less than or equal to 10℃ / min, so that the temperature inside the ultra-high vacuum furnace reaches and is maintained at 1150℃. When the temperature inside the ultra-high vacuum furnace remains at 1150°C for at least one hour, the power to the ultra-high vacuum furnace is cut off to reduce the temperature to below 100°C. Remove the aluminum source crucible and obtain the wetting angle of the aluminum solution. If the wetting angle of the aluminum solution is less than 90°, clean the aluminum source crucible again, bake it at low temperature and degas it at high temperature until the wetting angle of the aluminum solution is greater than or equal to 90°, and obtain the processed aluminum source crucible.

9. The method for preparing the aluminum source crucible according to claim 1, characterized in that, Aluminum nitride crucibles are prepared using a powder molding method, including: Alumina and carbon are mixed in a predetermined ratio and then introduced... and The mixed gas was reduced by C at a temperature of 1450℃~1750℃. Aluminum nitride powder was obtained; Aluminum nitride crucibles are prepared by adding a sintering agent to aluminum nitride powder, pre-pressing it, and sintering it at a temperature of 1600℃~1800℃.

10. An aluminum source crucible, characterized in that, The aluminum source crucible is prepared using the method described in any one of claims 1 to 9.

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