A method for preparing high-purity gallium oxide from high-purity metallic gallium

Abstract

The application discloses a method for preparing high-purity gallium oxide from high-purity metal gallium, and belongs to the technical field of wide-bandgap semiconductor materials. The method uses 5N-7N electronic-grade high-purity gallium as raw material, and sequentially completes raw material pretreatment, segmented low-temperature mild oxidation of high-purity oxygen, deep purification of water phase, vacuum low-temperature dehydration, and segmented high-temperature crystallization calcination in a high-purity oxygen atmosphere in a hundred-grade super-clean environment. No strong acid or strong base is introduced in the whole process, there is no chloride ion or nitrate ion residue, and problems such as crucible impurity dissolution, powder agglomeration and generation of impurity phases are effectively avoided. Finally, 6N-7N high-purity gallium oxide is prepared, the total content of metal impurities is lower than 0.5ppm, the crystal phase is single, and the dispersibility is excellent, so that the high-purity gallium oxide can be directly applied to high-end fields such as single-crystal semiconductor substrates, power device epitaxy and deep ultraviolet optoelectronic devices, the process flow is short, the impurity controllability is strong, and the method is suitable for industrial stable mass production.

Description

Technical Field

[0001] This invention aims to provide a method for preparing ultra-high purity gallium oxide from high-purity metallic gallium, solving the problems of excessive impurities, impure crystal phase, powder agglomeration, and serious secondary pollution in traditional processes, and stably producing semiconductor-grade high-purity Ga2O3. Background Technology

[0002] Gallium oxide (GaO), as a novel ultrawide bandgap semiconductor material, exhibits high breakdown field strength, high temperature resistance, and high voltage resistance, making it widely used in high-voltage power devices, ultraviolet detection, and new energy power electronics. High-purity GaO is a core precursor material for growing GaO single-crystal substrates and thin-film epitaxy. Semiconductor-grade products require a purity of 6N or higher, with extremely low levels of heavy metals and anionic impurities.

[0003] Existing preparation processes mostly employ a crude gallium acid dissolution, chemical precipitation, and high-temperature calcination route, which is cumbersome and prone to leaving harmful anions such as nitrate and chloride ions. Direct high-temperature oxidation of metallic gallium involves a violent reaction, easily leading to incomplete oxidation, grain agglomeration, and a high amount of impurities. Furthermore, the high temperature easily causes crucible impurities to precipitate, making it difficult to stably obtain ultra-high purity gallium oxide, which cannot meet the requirements of high-end semiconductor devices. Therefore, there is an urgent need for a short-process, low-pollution, high-purity, and easily scalable high-purity gallium oxide preparation process. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing ultra-high purity gallium oxide from high-purity metallic gallium. This method aims to solve the technical problems of anion residue, impurity contamination, powder agglomeration, impure crystal phase, and substandard product purity in traditional preparation processes, thereby achieving stable, efficient, and large-scale preparation of 6N-7N high-purity Ga2O3.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution, which specifically includes the following steps.

[0006] 1. High-purity gallium pretreatment.

[0007] High-purity metallic gallium of electronic grade with a purity of 5N to 7N was selected and placed in a Class 100 clean bench. It was first ultrasonically degreased with electronic-grade anhydrous ethanol to remove surface oil and adsorbed impurities. Then, it was repeatedly rinsed with ultrapure water with a resistivity ≥18.2 MΩ·cm until neutral. Subsequently, it was placed in a vacuum drying oven and dried for 30 to 60 minutes at a temperature of 40 to 50℃ and a vacuum degree of -0.08 to -0.09 MPa to remove surface moisture, thus obtaining clean pretreated high-purity gallium.

[0008] 2. Low-temperature controlled oxidation.

[0009] The pretreated high-purity gallium was placed in a high-purity quartz boat and transferred to a sealed atmosphere tube furnace. Ultra-high purity oxygen with a purity ≥99.9999% was introduced into the furnace, and after the air in the furnace was purged, the oxygen flow rate was controlled at 60-120 mL / min to maintain a slight positive pressure in the furnace. The temperature was programmed to rise to 300-380℃ at a slow rate of 1-3℃ / min and oxidized at a constant temperature for 6-10 hours to ensure that the high-purity gallium was uniformly oxidized and completely converted into gallium hydroxyl oxide precursor.

[0010] 3. Aqueous phase purification and washing.

[0011] The gallium hydroxy oxide precursor was taken out and dispersed in ultrapure water to form a suspension. It was then aged at low speed at room temperature for 2-4 hours to completely convert trace amounts of unreacted elemental gallium. Subsequently, it was separated by high-speed centrifugation at 8000-10000 r / min. The supernatant was discarded, and the precipitate was repeatedly washed with ultrapure water until the conductivity of the washing solution was ≤0.06 μS / cm to thoroughly remove soluble impurity ions.

[0012] 4. Vacuum drying and dehydration.

[0013] The washed precipitate was transferred to a vacuum drying oven and dried at 80-90°C for 5-7 hours to fully remove free water and water of crystallization from the precursor, resulting in a loose, clump-free dried precursor powder.

[0014] 5. Crystallization in a high-temperature atmosphere.

[0015] The dried precursor powder was placed into a 99.999% ultra-high purity corundum crucible and then placed in an atmosphere tube furnace for segmented calcination under a high-purity oxygen atmosphere: in the first stage, the temperature was increased to 600℃ at a rate of 2-4℃ / min and held for 2 hours to remove residual hydroxyl groups from the precursor; in the second stage, the temperature was further increased to 920-980℃ and held for 4-6 hours to completely crystallize the precursor into monoclinic β-Ga2O3; after calcination, the furnace was cooled to room temperature to obtain the ultra-high purity gallium oxide product.

[0016] Beneficial effects:

[0017] The source uses high-purity gallium with extremely low impurity levels, and the product purity can reach 6N to 7N, meeting the standards for high-end semiconductor applications.

[0018] The entire process does not use strong acids or alkalis, and there are no harmful anions such as chlorine or nitrate residues, so it will not affect the electrical performance of the device.

[0019] Low-temperature slow oxidation combined with orderly high-temperature crystallization results in powders with uniform particle size, good dispersibility, no agglomeration, and pure crystalline phase.

[0020] The sealed atmosphere and Class 100 cleanroom environment eliminate secondary contamination from air and crucible, ensuring high batch stability.

[0021] The process is simple, energy consumption is low, no complex equipment is required, and it is easy to carry out continuous industrial production. Attached Figure Description

[0022] Figure 1 This invention relates to a method for preparing ultra-high purity gallium oxide from high-purity metallic gallium. Detailed Implementation

[0023] Example 1: 1. Select 6N high-purity metallic gallium, and in a Class 100 clean bench, ultrasonically degrease with electronic-grade anhydrous ethanol for 15 min, rinse 5 times with ultrapure water, and vacuum dry at 45℃ for 45 min.

[0024] 2. Place the vessel in a high-purity quartz boat, introduce 99.9999% high-purity oxygen at a flow rate of 80 mL / min, raise the temperature to 350℃ at a rate of 2℃ / min, and maintain the temperature for oxidation for 8 hours.

[0025] 3. Disperse the precursor in ultrapure water, age at room temperature for 3 hours, and wash 4 times by centrifugation at 9000 r / min until the conductivity of the washing solution is 0.05 μS / cm.

[0026] 4. Vacuum dry at 85℃ for 6 hours.

[0027] 5. Under a high-purity oxygen atmosphere, heat to 600℃ at a rate of 3℃ / min and hold for 2 hours, then continue heating to 950℃ and hold for 5 hours, followed by furnace cooling.

[0028] Example 2: 1. Select 7N high-purity metallic gallium, ultrasonically degrease with anhydrous ethanol for 20 min, rinse with ultrapure water 6 times, and vacuum dry at 50℃ for 40 min.

[0029] 2. Oxygen flow rate 100 mL / min, temperature increased to 360℃ at 3℃ / min, constant temperature oxidation for 7 h.

[0030] 3. Centrifuge at 10000 r / min and wash until conductivity is 0.04 μS / cm.

[0031] 4. Vacuum dry at 90℃ for 5.5 hours.

[0032] 5. Heat to 960℃ and hold for 4.5 hours, then cool with the furnace.

Claims

1. A method for preparing high-purity gallium oxide from high-purity metallic gallium, characterized in that, Includes the following steps: (1) High-purity gallium pretreatment: Select 5N to 7N high-purity metallic gallium, use electronic grade anhydrous ethanol for ultrasonic degreasing in a Class 100 clean environment, then rinse repeatedly with ultrapure water with resistivity ≥18.2MΩ·cm, and then vacuum dry at 40 to 50℃ to remove surface oil, moisture and adsorbed impurities. (2) Low-temperature controllable oxidation: Pretreated high-purity gallium is placed in a high-purity quartz boat and placed in an atmosphere tube furnace. Ultra-high purity oxygen with a purity ≥99.9999% is introduced at a flow rate of 60-120 mL / min. The temperature is increased to 300-380℃ at a rate of 1-3℃ / min and oxidized at a constant temperature for 6-10 h to obtain gallium hydroxy oxide precursor. (3) Aqueous purification and washing: The oxidized precursor was dispersed in ultrapure water and aged at room temperature with low-speed stirring for 2-4 hours. It was then separated by high-speed centrifugation and washed with ultrapure water multiple times until the conductivity of the washing solution was ≤0.06μS / cm. (4) Vacuum drying and dehydration: After washing, the precursor is vacuum dried at 80-90℃ for 5-7 hours to fully remove free water and water of crystallization; (5) High-temperature atmosphere crystallization: The dried precursor is placed in an ultra-high purity corundum crucible and calcined under a high-purity oxygen atmosphere by programmed heating. First, the temperature is raised to 600℃ and held for 2 hours, then raised to 920-980℃ and held for 4-6 hours. After cooling in the furnace, high-purity Ga2O3 powder is obtained.

2. The method for preparing high-purity gallium oxide from high-purity metallic gallium according to claim 1, characterized in that, The entire preparation process is carried out in a closed environment under Class 100 cleanroom conditions to isolate it from dust and impurities in the air.

3. The method for preparing high-purity gallium oxide from high-purity metallic gallium according to claim 1, characterized in that, The high-purity oxygen used for oxidation and calcination has a purity of no less than 99.9999%, and a slight positive pressure is maintained inside the furnace throughout the process.

4. The method for preparing high-purity gallium oxide from high-purity metallic gallium according to claim 1, characterized in that, The high-purity gallium oxide obtained was ≥99.9999%, and the individual impurities of Fe, Cu, Zn, and Si were all <0.1ppm.

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