A method for producing high-purity gallium antimonide / indium antimonide compound semiconductor crystals by a zone melting method

Abstract

The application discloses a method for preparing high-purity gallium antimonide / indium antimonide compound semiconductor crystals by a reaction zone melting method. The method combines a chemical reaction with a zone melting method, directly prepares high-purity gallium antimonide or indium antimonide crystals from low-purity elemental raw materials through a crystal lattice rearrangement spontaneous impurity removal effect. After lower-purity (such as 4N-grade) refined antimony and refined gallium or refined indium are mixed as raw materials and filled in a longitudinally placed reaction pipeline, local zone heating melting is sequentially performed from top to bottom, so that the elements are melted and a chemical reaction is generated to form gallium antimonide or indium antimonide. Since the crystal lattice rearrangement effect occurs when the compound is generated, impurity segregation and high-efficiency self-removal are realized in the subsequent condensation and crystal growth process, and high-purity (up to 6N-grade or higher) compound crystals are directly obtained.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material preparation technology, specifically relating to a method for preparing high-purity gallium antimonide (GaSb) or indium antimonide (InSb) crystals directly from low-purity elemental raw materials by combining chemical reactions with zone melting and utilizing the spontaneous impurity removal effect of lattice rearrangement. Background Technology

[0002] Gallium antimonide (GaS) and indium antimonide (IIS) are important III-V compound semiconductor materials with wide applications in infrared detection, optoelectronic devices, and high-frequency electronic devices. Since trace impurities can significantly affect the electrical and optical performance of these devices, extremely high-purity single-crystal materials are required, typically reaching 6N (99.9999%) or even 7N (99.99999%) levels. Currently, the mainstream process in the industry involves deeply purifying elemental antimony, gallium, or indium separately before chemically growing them into high-purity GaS or IIS crystals. The core route uses industrial-grade antimony, gallium, or indium as initial raw materials, employing multiple energy-intensive purification processes such as vacuum distillation, zone melting, and electron beam melting to purify the crude elements to 7N-level ultra-high purity. The 7N-level ultra-high purity elements are then stoichiometrically proportioned and fed into a crystal growth furnace for high-temperature chemical combination and melt growth to prepare high-purity GaS or IIS single crystals. However, existing processes suffer from several bottlenecks that severely restrict production efficiency: First, stable impurities are difficult to remove, limiting the purification limit. Purifying crude elemental substances to 4N grade refined elements is relatively easy, but further purification from 4N to 7N grade and above becomes significantly more difficult. This is because impurities in refined antimony, gallium, indium, and other refined elements have formed relatively stable solid solution structures in the crystal lattice. These difficult-to-remove impurity atoms have high compatibility and stable bonding with the matrix elemental lattice. Conventional purification methods struggle to remove stable, solid-solid impurities, thus requiring multiple purification steps. This leads to the second bottleneck: extremely high energy consumption and a lengthy process. Traditional processes require multiple repeated zone melting and high-vacuum, high-temperature distillation to upgrade elemental purity from 4N to 7N, with each batch purification process taking tens of hours and consuming extremely high energy. Therefore, there is an urgent need to develop a new preparation method with low energy consumption, a shorter process, and self-cleaning capabilities for impurities. Summary of the Invention

[0003] This invention aims to overcome the problems of long process flow and high cost in traditional methods that first purify the elemental substance and then combine it to grow crystals. It provides a reaction zone melting method and apparatus that combines the combination reaction with zone melting. Based on the spontaneous impurity removal effect caused by the deviation of the impurity distribution coefficient after lattice rearrangement, solid solution impurities are removed at the same time as the combination reaction, so as to obtain ultra-high purity gallium antimonide / indium antimonide crystals.

[0004] To achieve the above objectives, the present invention adopts the following short-process solution, which eliminates the need for elemental purification of raw materials throughout the entire process. The specific steps are as follows: 1. Raw material pretreatment: Select refined antimony, refined gallium, or refined indium as initial materials. Crush the initial materials into uniformly sized particles, then ultrasonically clean them with anhydrous ethanol and vacuum dry them. The purity of refined antimony, refined gallium, and refined indium is 2N (99.9%)–4N (99.99%) grade pure elemental. Prepare the mixture according to the stoichiometric ratio of gallium antimonide and indium antimonide, with an excess of antimony of 0.5% to 2%, and weigh it for later use. Based on the volatility characteristics of elements, an appropriate excess of antimony is added to compensate for the volatilization of antimony during the high-temperature reaction process, ensuring accurate product proportions.

[0005] 2. Chemical reaction and impurity purification: Design a reaction zone smelting furnace with longitudinally placed furnace pipes, each covered by a vertically movable heating jacket, as shown in the attached diagram. Figure 1 As shown, elemental antimony, gallium, or indium are thoroughly mixed and loaded into the pipes of the melting furnace in the reaction zone, then compacted. A layer of inert compound is then spread evenly on top of the material. The pipes are then evacuated to a vacuum of 5-15 Pa, and high-purity argon gas is introduced from bottom to top to maintain this vacuum. Subsequently, the heating jacket is heated and slowly moved from top to bottom, allowing the antimony and gallium / indium in the heating zone to fully melt and undergo a chemical reaction. During the reaction, the original elemental lattice is reconstructed, and the original stable impurities are spontaneously removed. As the heating jacket moves, the gallium antimonide or indium antimonide formed by the molten reaction begins to condense and crystallize from top to bottom. At this time, lighter impurities segregate to the surface of the melt, while heavier impurities condense by gravity at the solid-liquid interface. As the heating jacket moves to the bottom, the synthesis and initial spontaneous purification of impurities are completed. Finally, the condensed gallium antimonide or indium antimonide crystals are removed from the pipes, and the surface and head and tail portions of the material are cut off to obtain primary coarse crystals.

[0006] 3. Deep Purification Through Multiple Cyclic Melting Processes: The obtained primary coarse crystals are crushed again, filled into a pipeline, and compacted. A layer of inert compound is then spread on top of the material. The pipeline is then evacuated to 5-15 Pa, and high-purity argon gas is introduced from bottom to top to maintain this vacuum. The heating jacket is then heated and slowly moved from top to bottom. As the jacket reaches the bottom, impurities are purified again. Finally, the condensed material is removed from the pipeline, and the surface impurity-rich layer is removed. After repeating the melting and purification process several times, surface impurities are removed to obtain ultra-high purity gallium antimonide / indium antimonide crystals with a purity ≥6N. Each crystal growth process involves ordered lattice rearrangement, continuously removing residual trace impurities and gradually increasing the material purity to 6N and above, resulting in high-purity gallium antimonide / indium antimonide polycrystalline material. This high-purity polycrystalline material is used as raw material for growing gallium antimonide / indium antimonide single crystal rods using the liquid-sealed Czochralski method or the Bridgman method.

[0007] Preferably, in step 1, the initial material is crushed into uniform particles of 10-60 mesh size.

[0008] Preferably, the compaction density in steps 2 and 3 is 3~5.3 g / cm³. 3 between.

[0009] Preferably, in steps 2 and 3, the heating mantle is heated to a temperature between 500 and 700°C for the preparation of indium antimonide and between 700 and 850°C for the preparation of gallium antimonide.

[0010] Preferably, the inert compound in steps 2 and 3 includes one or more of sodium chloride, potassium chloride, magnesium chloride, and boron oxide, and the thickness of the inert compound layer is 1 to 10 mm.

[0011] Preferably, in steps 2 and 3, the heating jacket moves slowly from top to bottom, with the moving speed controlled between 0.1 and 5 mm / min.

[0012] Preferably, the primary coarse grains in step 3 are crushed into 40-60 mesh particles.

[0013] Preferably, the repeated melting and purification process in step 3 is repeated 2-5 times, and the moving speed of the heating jacket is faster than that in step 2 during the repeated melting and purification process.

[0014] The core mechanism of this invention lies in the following: when elements with different crystal structures (such as trigonal antimony and orthorhombic gallium, or tetragonal indium) react to form gallium antimonide or indium antimonide with a cubic zincblende structure, atoms need to rearrange and enter new lattice sites. During this lattice rearrangement process, impurities originally present in the metallic element have an effective partition coefficient of less than 1 in the gallium antimonide or indium antimonide lattice (i.e., the solubility of impurities in the gallium antimonide or indium antimonide solid phase is much less than their solubility in the metallic element), or are in a thermodynamically unstable state in the gallium antimonide or indium antimonide lattice structure. Therefore, during slow combination, melting, and cooling crystallization, impurities are expelled to the liquid phase or grain boundaries, thus spontaneously excluding them from the interior of the gallium antimonide or indium antimonide compound crystal. Combined with directional solidification, the segregation behavior of impurities at the solid-liquid interface can be further utilized to directly obtain high-purity gallium antimonide / indium antimonide crystals.

[0015] This invention skips the elemental purification step and directly uses low-purity (e.g., 4N grade) refined antimony and refined gallium or refined indium as raw materials. It utilizes the lattice rearrangement effect during the chemical reaction of the two to synthesize gallium antimonide or indium antimonide. Combined with the subsequent high-temperature melting and directional solidification / crystal growth process, it achieves efficient self-removal of impurities and directly obtains high-purity (up to 6N grade or higher) compound polycrystalline materials. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a smelting furnace in the reaction zone; Figure 2Electron microscope images of the surface of the gallium antimonide crystal grown in Example 1; Figure 3 Example 1: X-ray energy dispersive spectroscopy scan of the antimony distribution in gallium antimonide crystal; Figure 4 Example 1: X-ray energy dispersive spectroscopy scan of gallium distribution in gallium antimonide crystal. Detailed Implementation

[0017] Example 1: Short-process preparation of high-purity gallium antimonide This embodiment uses the short-process technology of the present invention to prepare high-purity gallium antimonide, and the specific steps are as follows: 1. Raw material preparation: 4N grade antimony and 4N grade gallium were selected as raw materials. Tests showed that the main impurity in antimony was arsenic, and the main impurity in gallium was zinc. The particles of both elements were crushed into 10-12 mesh particles, ultrasonically cleaned with anhydrous ethanol for 15 minutes, and vacuum dried (80℃, 2 hours). According to the stoichiometric ratio of gallium antimonide, antimony element was added in excess by 1% and accurately weighed for later use.

[0018] 2. Loading and chemical reaction: After thoroughly mixing the raw materials, fill the pipe from bottom to top, and compact it inside the pipe to 3g / cm³. 3 A 2 mm thick layer of sodium chloride was then spread on top of the material. The pipe was then evacuated to 10 Pa, and high-purity argon gas was introduced from bottom to top to maintain this vacuum. The heating mantle was then heated to 750 °C at a rate of 8 °C / min and moved downwards at a speed of 1 mm / min, allowing antimony and gallium to fully combine in the area it passed through, forming gallium antimonide. As the heating mantle moved downwards, the combined gallium antimonide in the upper part began to condense and crystallize. At this point, the elemental lattice was completely reconstructed, and impurities originally dissolved in the antimony and gallium spontaneously repelled and segregated to the solid-liquid interface of the melt. As the heating mantle moved to the bottom, the synthesis and initial spontaneous purification of impurities were completed. Finally, the condensed gallium antimonide crystal was removed from the pipe, and the surface and the beginning and end portions of the material were removed to obtain primary coarse crystals.

[0019] 3. Circulating smelting and purification: The obtained primary coarse crystals are crushed again and filled into the pipeline from bottom to top, and compacted to 3g / cm³ within the pipeline. 3 A 2 mm thick layer of sodium chloride was then spread on top of the material. The pipe was then evacuated to 10 Pa, and high-purity argon gas was introduced from bottom to top to maintain this vacuum. The heating mantle was then heated to 800 °C at a rate of 8 °C / min and moved downwards at a speed of 2 mm / min. As the heating mantle reached the bottom, impurities were purified again. Finally, the condensed material was removed from the pipe, and the surface impurity enrichment layer was removed. This process was repeated twice to remove the surface impurities and obtain ultra-high purity gallium antimonide polycrystalline material with a purity >6N.

[0020] Testing revealed that the molar ratio of antimony to gallium in the gallium antimonide material prepared in this embodiment was 49:51, and the antimony and gallium elements were uniformly distributed (e.g., Figure 2-4 As shown in the figure, it contains no steady-state residual impurities that are difficult to remove with traditional processes, and the material has excellent uniformity. Compared with traditional processes, the overall process is shortened by 40%, and the overall energy consumption is reduced by more than 35%.

[0021] Example 2: Preparation of high-purity indium antimonide This embodiment uses the short-process technology of the present invention to prepare high-purity indium antimonide, and the specific steps are as follows: 1. Raw material preparation: 4N grade antimony and 4N grade indium were selected as raw materials. Tests showed that the main impurity in antimony was arsenic, and the main impurity in indium was tin. The two elements were crushed into particles of about 20 mesh, ultrasonically cleaned with anhydrous ethanol for 15 minutes, and vacuum dried (80℃, 2 hours). Antimony was accurately weighed according to the stoichiometric ratio of indium antimonide, with an excess of 1.5%.

[0022] 2. Loading and chemical reaction: After thoroughly mixing the raw materials, fill the pipe from bottom to top, and compact it inside the pipe to 4 g / cm³. 3 A 3 mm thick layer of potassium chloride was then spread on top of the material. The pipe was then evacuated to 10 Pa, and high-purity argon gas was introduced from bottom to top to maintain this vacuum. The heating mantle was then heated to 525 °C at a rate of 8 °C / min and moved downwards at a speed of 0.5 mm / min, allowing antimony and indium to fully combine in the area it passed through, forming indium antimonide. As the heating mantle moved downwards, the combined indium antimonide in the upper part began to condense and crystallize. At this point, the elemental lattice was completely reconstructed, and impurities originally dissolved in the antimony and indium spontaneously repelled and segregated to the solid-liquid interface of the melt. As the heating mantle moved to the bottom, the synthesis and initial spontaneous purification of impurities were completed. Finally, the condensed indium antimonide crystals were removed from the pipe, and the surface and the beginning and end portions of the material were removed to obtain primary coarse crystals.

[0023] 3. Circulating smelting and purification: The obtained primary coarse crystals are crushed again and filled into the pipeline from bottom to top, and compacted to 4 g / cm³ within the pipeline. 3 A 3 mm thick layer of potassium chloride was then spread on top of the material. The pipe was then evacuated to 10 Pa, and high-purity argon gas was introduced from bottom to top to maintain this vacuum. The heating mantle was then heated to 600 °C at a rate of 8 °C / min and moved downwards at a speed of 1 mm / min. As the heating mantle reached the bottom, impurities were purified again. Finally, the condensed material was removed from the pipe, and the surface impurity enrichment layer was removed. This process was repeated twice to remove the surface impurities and obtain ultra-high purity indium antimonide polycrystalline material with a purity >6N.

[0024] Testing revealed that the indium antimonide material prepared in this embodiment had a total content of less than 0.1 ppm for both metallic and non-metallic impurities, and exhibited excellent material uniformity.

Claims

1. A method for preparing high-purity gallium antimonide / indium antimonide compound semiconductor crystals by reactive zone melting, characterized in that, include: Step 1, Raw material pretreatment: Select refined antimony, refined gallium, or refined indium as the initial material, crush the initial material into uniform particles, then ultrasonically clean it with anhydrous ethanol, and vacuum dry it. The purity of refined antimony, refined gallium, and refined indium is 2N~4N grade refined elemental. According to the stoichiometric ratio of gallium antimonide and indium antimonide, with an excess of antimony of 0.5%~2%, weigh it for later use. Step 2, Chemical Reaction and Impurity Purification: A reaction zone melting furnace is designed with longitudinally placed pipes, all wrapped with a vertically movable heating jacket. Antimony, gallium, or indium are thoroughly mixed and loaded into the pipes of the reaction zone melting furnace and compacted. A layer of inert compound is then spread on top of the material. The pipes are then evacuated to 5-15 Pa, and high-purity argon is introduced from bottom to top to maintain this vacuum. The heating jacket is then heated and slowly moved from top to bottom, allowing the antimony and gallium / indium in the heating zone to fully melt and undergo a chemical reaction. As the heating jacket moves to the bottom, the synthesis and initial spontaneous purification of impurities are completed. Finally, the condensed gallium antimonide or indium antimonide crystals are removed from the pipes, and the surface and head / tail portions of the material are removed to obtain primary coarse crystals. Step 3, multiple cycles of deep refining: The obtained primary coarse crystals are crushed again, filled into the pipeline and compacted. Then, an inert compound is spread on the top layer of the material. The pipeline is then evacuated to 5-15 Pa and high-purity argon is introduced from bottom to top to maintain this vacuum. The heating jacket is then heated and slowly moved from top to bottom. As the heating jacket moves to the bottom, the impurities are purified again. Finally, the condensed material is taken out of the pipeline and the surface impurity enrichment layer is removed. After repeating the refining process several times, the surface impurities are removed to obtain ultra-high purity gallium antimonide / indium antimonide crystals with a purity ≥6N.

2. The method as described in claim 1, characterized in that, In step 1, the initial material is crushed into uniform particles of 10-60 mesh size.

3. The method as described in claim 1, characterized in that, In steps 2 and 3, the compaction density is between 3 and 5.3 g / cm³. 3 between.

4. The method as described in claim 1, characterized in that, In steps 2 and 3, the heating mantle is heated. For the preparation of indium antimonide, the temperature is controlled between 500 and 700°C; for the preparation of gallium antimonide, the temperature is controlled between 700 and 850°C.

5. The method as described in claim 1, characterized in that, The inert compounds mentioned in steps 2 and 3 include one or more of sodium chloride, potassium chloride, magnesium chloride, and boron oxide, and the thickness of the inert compound layer is 1 to 10 mm.

6. The method as described in claim 1, characterized in that, In steps 2 and 3, the heating jacket moves slowly from top to bottom, with the moving speed controlled between 0.1 and 5 mm / min.

7. The method as described in claim 1, characterized in that, In step 3, the primary coarse grains are crushed into 40-60 mesh particles.

8. The method as described in claim 1, characterized in that, The repeated melting and purification process in step 3 is repeated 2-5 times, and the moving speed of the heating jacket is faster than that in step 2 during the repeated melting and purification process.

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