Chemical vapor deposition device and preparation method of high-purity metal antimony

Abstract

The invention relates to a chemical vapor deposition device and a preparation method of high-purity metal antimony, and belongs to the technical field of high-purity antimony preparation.A seal head and a reactor of the vapor deposition device are connected in a sealed mode to form a reaction chamber and are both made of stainless steel, a heater is arranged outside the reactor, and a crucible is arranged inside the reactor; a high-temperature-resistant and corrosion-resistant coating is arranged on the inner wall of the crucible, the device is high in strength, safe, reliable and easy to apply in a large scale, the simple substance antimony is prepared in a gas-solid deposition mode, solid antimony is obtained through CVD deposition, Cl residues in the product can be avoided, impurities can be controlled, and the purity can be improved; after deposition is finished, the crucible is heated to melt the antimony solid, an antimony melt is formed at the bottom of the crucible, and then the antimony melt is cooled and solidified to obtain solid blocky antimony, so that the problem of stripping of the solid antimony from the crucible is solved, the preparation process is simple, the production efficiency is high, and the obtained product has the characteristics of high purity and large size.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity antimony preparation, and in particular to a chemical vapor deposition device and a preparation method of high-purity metallic antimony. Background Art

[0002] High-purity metallic antimony can be used as a dopant for silicon single crystals and is also the main basic raw material for various antimonide semiconductors. The purity of high-purity antimony directly affects the performance of compound semiconductors.

[0003] Currently, the main methods for producing high-purity metallic antimony are physical and chemical methods. When producing high-purity metallic antimony by the physical method, metallic antimony is used as the raw material, and impurities are removed through processes such as vacuum distillation, zone melting or vertical single crystal pulling to obtain high-purity metallic antimony of 5-6N or even 7N. When producing high-purity metallic antimony by the chemical method, purified high-purity antimony trichloride is used as the raw material, and a chemical reaction is carried out with hydrogen in a specific reactor to produce antimony element and by-product gases such as hydrogen chloride. Theoretically, the purity of high-purity metallic antimony produced by the chemical method depends on the purity of the raw material and can reach 7N or even higher.

[0004] The physical method of producing high-purity antimony requires repeated cycles, and certain impurities, such as As, are difficult to remove. Compared to the physical method, the chemical method can produce antimony with higher purity. In particular, when the purity of the raw antimony trichloride reaches 8N or 9N, the purity of the antimony obtained after reaction with hydrogen can also approach 8N or above. However, the chemical reaction requires high temperatures, usually above 850°C or even around 1000°C, which places extremely high demands on the reaction equipment. Not only must the structural stability under high temperature conditions be met, but the precipitation of metal impurities in the equipment itself under the hydrogen chloride atmosphere must also be avoided, which would reduce the purity of the antimony product.

[0005] Currently, the reactor used in the CVD (chemical vapor deposition) method is made of quartz glass, as shown in CN105333733A. However, quartz glass has problems such as low strength, high brittleness, and easy softening at high temperatures. In addition, the reaction tube of quartz equipment is not easy to scale up, which is not conducive to industrial-scale production. At the same time, the antimony produced by the existing CVD method is a fine powder, such as the metallic antimony powder in patent CN116197406A, which easily absorbs impurities in the air, resulting in a decrease in product purity.

[0006] In addition, since the CVD reaction temperature (800-1000°C) is usually higher than the melting point of elemental antimony (630°C), the liquid metallic antimony formed during the preparation process will adsorb the antimony trichloride raw material and carry it out of the reactor, resulting in incomplete reaction and a high Cl element content in the antimony product, which reduces the purity of the elemental antimony.

[0007] Patent CN119657942A discloses a method for preparing antimony particles. During the reaction process, the CVD temperature is lower than the melting point of elemental antimony, allowing solid antimony to be deposited directly from the gas phase, thus avoiding the problem of chlorides in the raw materials not reacting completely and entering the product, thereby reducing its purity. However, this method has cumbersome processes and complex equipment, and can only synthesize granular antimony. The initial deposition area is small, the efficiency is low, and due to the limited airflow suspension force, large-sized antimony blocks cannot be formed. Summary of the Invention

[0008] In view of the defects of the prior art, the purpose of the present invention is to provide a chemical vapor deposition device and preparation method for high-purity metallic antimony, which can produce large-sized, high-purity metallic antimony elements with a purity that can stably reach above 7N, thereby solving the current problems of complicated high-purity antimony preparation process, impurity contamination and Cl residue in the product, insufficient purity, low production efficiency and insufficient device reliability.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is: A chemical vapor deposition device for high-purity metallic antimony comprises a reactor at the bottom and a head at the top, the head and reactor being made of stainless steel, the reactor being a cylindrical structure with an open top and a closed bottom, heaters being respectively provided at the bottom and peripheral side of the reactor, the heaters on the bottom and peripheral sides being capable of independent heating and temperature control, a crucible being placed in the reactor, the crucible being in close contact with the inner wall and bottom surface of the reactor, the height of the crucible being higher than the height of the heater on the peripheral side, the crucible being made of a high-temperature resistant material and the inner surface being provided with a smooth, dense, high-temperature resistant, and corrosion-resistant coating; an air inlet and an air outlet being provided on the head; the head being sealingly connected to the upper part of the reactor to form a reaction chamber.

[0010] Furthermore, the high temperature resistant and corrosion resistant coating is high purity isostatically pressed graphite or high purity silicon carbide.

[0011] Furthermore, the head is designed to be hemispherical, semi-elliptical or flat, and is provided with several air inlets and a single air outlet. The single air outlet is provided at the center of the head, and the several air inlets are arranged around the air outlet in concentric circles or equilateral shapes.

[0012] Furthermore, the air inlet is connected to an extension tube to the interior of the reactor, and the extension tube is more than 10 cm away from the bottom surface of the reactor.

[0013] Furthermore, the upper head and the lower reactor are connected via a detachable sealing flange.

[0014] The present invention also provides a method for preparing high-purity antimony metal using the above-mentioned chemical vapor deposition device for high-purity antimony metal, comprising the following steps: (1) Replace the atmosphere of the reactor with nitrogen and hydrogen in sequence for more than 30 minutes; (2) Turn on the heater for preheating and set the temperature of the outer side and bottom heater to 550-600℃; (3) The vaporized antimony trichloride and hydrogen are mixed in a specific ratio, and the mixed gas is sent into the reaction chamber through the air inlet. During the reaction, antimony and tail gas hydrogen chloride are formed, and the hydrogen chloride gas and the unreacted antimony trichloride are discharged through the air outlet; (4) Maintaining the heater temperature constant, continuously introducing the mixed gas, the antimony element continues to grow on the inner wall of the crucible; (5) After the antimony element growth thickness reaches the target thickness, stop introducing the mixed gas and introduce pure hydrogen for more than 30 minutes to completely replace the atmosphere in the reactor; (6) Under the condition of continuous introduction of hydrogen, the temperature of the heater is raised to above the melting point of antimony, so that the antimony element deposited on the inner wall of the crucible is completely melted, flows and gathers at the bottom of the crucible; (7) After the solid antimony element on the inner wall of the crucible is completely melted, stop heating and allow it to cool naturally to obtain a block of high-purity metallic antimony.

[0015] Furthermore, during the natural cooling process, when the reactor is cooled to below 100° C., the introduction of hydrogen is stopped, and nitrogen is introduced for more than 30 minutes, after which the upper cover is opened and the intact block of high-purity antimony is taken out.

[0016] Furthermore, in the mixed gas, the molar ratio of hydrogen to antimony trichloride is 5:1 to 30:1.

[0017] Furthermore, in step (6), during the heating and melting process of the solid antimony element, the temperature of the heater on the outer side is increased to 750-800°C, and the temperature of the heater on the bottom is increased to 700-750°C.

[0018] Furthermore, high-purity antimony material with a purity of 7.5N or above is prepared using 8N antimony trichloride as a raw material.

[0019] Beneficial effects: The reactor of the present invention is made of stainless steel, which has high strength, high toughness and high-temperature stability. The reaction chamber is large, which effectively improves the reliability of large-scale and industrial applications of the device, is conducive to large-scale application and stable production, and avoids the unsafe problems and difficulty in large-scale application of current quartz devices.

[0020] A crucible with a high-purity coating is provided in the reactor of the present invention, and the height of the crucible is greater than the height of the heating section. On the one hand, direct contact between the material and the high-temperature metal wall of the reactor is avoided, which is beneficial to controlling impurity contamination and improving the purity of the antimony product; on the other hand, the inner wall of the crucible is used as a deposition carrier, which can provide a larger initial deposition area, and a certain deposition area is always maintained during the process, effectively improving the deposition efficiency, and avoiding the problems of limited initial deposition area and low deposition efficiency caused by deposition on the particle surface.

[0021] The present invention adopts a gas-solid deposition method to prepare antimony element. Solid antimony is first obtained by CVD deposition. The antimony generated by the CVD reaction is deposited on the inner wall of the crucible in solid form, without forming an antimony melt and adsorbing antimony trichloride. This avoids residual Cl in the product, is beneficial for controlling impurities, and improves purity. The present invention avoids the problem that the current CVD temperature is higher than the melting point of antimony, causing antimony trichloride to dissolve in the antimony melt, resulting in incomplete reaction and residual Cl element, which reduces its purity.

[0022] The present invention first obtains solid antimony through CVD deposition, and after the deposition is completed, heats the crucible to melt the antimony solid, forming an antimony melt at the bottom of the crucible, and then cools and solidifies to obtain solid block antimony. On the one hand, the problem of separation of the deposited solid antimony from the crucible is solved, and on the other hand, large-sized high-purity antimony blocks can be directly obtained through this method. The prepared antimony has the characteristics of high purity and large size. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic structural diagram of a chemical vapor deposition apparatus according to the present invention; Figure 2 Schematic diagram of the distribution of the air inlet and outlet of the present invention Figure 1 ; Figure 3 Schematic diagram of the distribution of the air inlet and outlet of the present invention Figure 2 .

[0024] Reference numerals: 1 head, 2 reactor, 3 crucible, 4 heater, 5 gas inlet, 6 gas outlet, 7 extension tube. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The present invention provides a chemical vapor deposition device and preparation method for high-purity antimony, which can realize the preparation of large-scale, high-purity metallic antimony with a purity of more than 7N. It solves the current problems of complicated high-purity antimony preparation process, impurity contamination and Cl residue in the product, insufficient purity, low production efficiency and insufficient device reliability.

[0027] like Figure 1As shown, a chemical vapor deposition device for high-purity antimony metal includes a reactor 2 located at the lower part and a head 1 located at the upper part. The upper and lower parts constitute an internal reaction chamber. The head 1 and reactor 2 are both made of stainless steel and have the characteristics of high strength and high temperature resistance.

[0028] The reactor 2 is a cylindrical structure with an open upper end and a closed bottom end. The bottom surface of the reactor 2 is a flat surface or an arc surface. Heaters 4 are respectively arranged at the bottom and the outer side of the reactor 2. The heaters 4 at the bottom and the outer side can be heated and temperature-controlled independently, and the heaters 4 can make the wall temperature of the reactor 2 reach about 1000°C; a crucible 3 is placed in the reactor 2, and the crucible 3 is tightly fitted with the inner wall and bottom surface of the reactor 2. The height of the crucible 3 is greater than the height of the heater on the outer side, and the upper edge of the crucible 3 is higher than the upper edge of the heater 4 on the outer side by at least 10 cm, which can avoid direct contact between the material and the wall of the reactor 2 under high temperature conditions and reduce metal impurity contamination; the crucible 3 is made of high-temperature resistant material and the inner surface is provided with a smooth and dense high-purity isostatic graphite coating or high-purity silicon carbide coating, which can provide a larger initial deposition area and facilitate the stripping of solid antimony.

[0029] The head 1 is designed to be hemispherical, semi-elliptical or flat, and is connected to the upper end of the reactor 2 through a detachable sealing flange to form a reaction chamber. The head 1 is provided with an air inlet 5 and an air outlet 6; usually, there are multiple air inlets 5 and one air outlet 6, and the single air outlet 6 is set at the center of the head 1, and several air inlets 5 are arranged around the air outlet 6 in concentric circles or equilateral shapes.

[0030] Multiple air inlets 5 are evenly arranged around a single air outlet 6. When the number of air inlets 5 is small, such as 1-6 air inlets 5, they are arranged in a ring. When the number of air inlets 5 is large, such as 12 air inlets 5, they are arranged in two concentric circles, with 6 in the inner circle and 6 in the outer circle, or in a dodecagonal arrangement. Figure 2 、 Figure 3 The arrangement of the air inlet 5 is shown as 4 and 8 respectively. It should be noted that Figure 2-3 It is a schematic diagram of the structure viewed from above in a perspective state.

[0031] Furthermore, the air inlet 5 of the present invention is connected to an extension tube 7 , and the extension tube 7 extends into the interior of the reactor 2 . The extension tube 7 is more than 10 cm away from the bottom surface of the reactor 2 .

[0032] The present invention proposes a specific CVD (chemical vapor deposition) apparatus. When preparing high-purity antimony, antimony trichloride is used as a raw material. After heating and vaporizing, it is mixed with hydrogen in a certain ratio to form a mixed gas. The mixed gas is then fed into the vapor deposition apparatus to produce a high-purity antimony material in the form of a block (the size of which depends on the inner diameter of the crucible 3 in the reactor 2). The method for preparing high-purity antimony using the above-mentioned chemical vapor deposition apparatus is as follows: (1) Replace the atmosphere inside the reactor 2 with nitrogen and hydrogen in sequence for more than 30 minutes; (2) Set the temperature of the heater 4 on the outer side and bottom to 550-600°C to ensure that the temperature of the inner wall of the crucible 3 is lower than the melting point of antimony; (3) The vaporized antimony trichloride and hydrogen are mixed in a specific ratio (the molar ratio of hydrogen to antimony trichloride is between 5:1 and 30:1) and fed into the chamber of the reactor 2 through the air inlet 5. During the reaction, antimony and tail gas hydrogen chloride are formed, and the antimony element is deposited on the inner wall of the crucible 3. The hydrogen chloride gas and the unreacted antimony trichloride are discharged through the air outlet 6; (4) The temperature of the heater 4 is maintained constant, the mixed gas is continuously introduced, and the antimony element continues to grow on the inner wall of the crucible 3; (5) After the antimony element has grown to the target thickness, stop introducing the mixed gas and introduce pure hydrogen into the gas inlet 5 for more than 30 minutes to completely replace the atmosphere in the reactor 2 to ensure that the antimony trichloride in the reaction chamber is completely reacted and discharged; (6) While continuously introducing hydrogen, the temperature of the outer heater 4 is raised to 750-800°C and the temperature of the bottom heater 4 is raised to 700-750°C, so that the antimony element deposited on the inner wall of the crucible 3 is completely melted, flows, and gathers at the bottom of the crucible 3; (7) After the solid antimony element on the inner wall of crucible 3 is completely melted, stop heating and allow the mixture to cool naturally. Under the action of surface tension, the antimony melt solidifies and peels off from crucible 3, and a block of high-purity metallic antimony can be obtained. (8) After the reactor 2 is cooled to below 100°C, the hydrogen is stopped and nitrogen is introduced for more than 30 minutes. Then, the upper end cap 1 of the reactor 2 is opened and the intact high-purity antimony block is taken out.

[0033] The present invention adopts a gas-solid deposition method to prepare elemental antimony. During the reaction process, the temperature is set at 550-600° C., so that the antimony generated by the reaction is deposited on the inner wall of the crucible 3 in solid form, without forming an antimony melt and adsorbing antimony trichloride, thereby avoiding residual Cl in the product and reducing the purity. After the deposition process is completed, the heating temperature is increased, and the solid antimony deposited on the inner wall of the crucible 3 is heated and melted in a hydrogen atmosphere to form an antimony melt at the bottom of the crucible 3. Then, solid block antimony in the shape of the bottom of the crucible 3 is obtained through natural cooling. The obtained antimony has the characteristics of high purity and large size. After the preparation is completed, the high-purity block antimony can be directly obtained from the reactor 2. The process is simple and the operation is simple.

[0034] The reactor 2 and the head 1 of the present invention are both made of stainless steel, which is easy to seal, has high strength, is safe and reliable, and can be easily applied on a large scale, thereby facilitating the large-scale production of high-purity antimony and improving production efficiency.

[0035] By using the above chemical vapor deposition device, 8N antimony trichloride is used as raw material, mixed with hydrogen, and then fed into the reactor 2 to obtain a high-purity antimony material with a purity of 7.5N or above. GDMS detection shows that the content of each metal impurity is below the detection limit.

[0036] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A chemical vapor deposition device for high-purity antimony metal, comprising a reactor at the bottom and a head at the top, characterized in that: The head and reactor are both made of stainless steel. The reactor is a cylindrical structure with an open upper end and a closed bottom end. Heaters are respectively provided at the bottom and outer side of the reactor. The heaters on the bottom and outer sides can be heated and temperature-controlled independently. A crucible is placed in the reactor. The crucible fits tightly against the inner wall and bottom surface of the reactor. The height of the crucible is higher than the height of the heater on the outer side. The crucible is made of high-temperature resistant material and the inner surface is provided with a smooth and dense high-temperature resistant and corrosion-resistant coating; an air inlet and an air outlet are provided on the head; the head is sealed and connected to the upper part of the reactor to form a reaction chamber.

2. The chemical vapor deposition device for high-purity antimony metal according to claim 1, characterized in that: The high temperature resistant and corrosion resistant coating is high purity isostatically pressed graphite or high purity silicon carbide.

3. The chemical vapor deposition device for high-purity antimony metal according to claim 1, characterized in that: The head is designed to be hemispherical, semi-elliptical or flat, and is provided with several air inlets and a single air outlet. The single air outlet is arranged at the center of the head, and the several air inlets are arranged around the air outlet in concentric circles or equilateral shapes.

4. The chemical vapor deposition device for high-purity antimony metal according to claim 3, characterized in that: The air inlet is connected to an extension tube to the interior of the reactor, and the extension tube is more than 10 cm away from the bottom surface of the reactor.

5. The chemical vapor deposition device for high-purity antimony metal according to claim 1, characterized in that: The upper head and the lower reactor are connected via a detachable sealing flange.

6. A method for preparing high-purity antimony metal using the chemical vapor deposition device for high-purity antimony metal according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Replace the atmosphere of the reactor with nitrogen and hydrogen in sequence for more than 30 minutes; (2) Turn on the heater for preheating and set the temperature of the outer side and bottom heater to 550-600℃; (3) The vaporized antimony trichloride and hydrogen are mixed in a specific ratio, and the mixed gas is sent into the reaction chamber through the air inlet. During the reaction, antimony and tail gas hydrogen chloride are formed, and the hydrogen chloride gas and the unreacted antimony trichloride are discharged through the air outlet; (4) Maintaining the heater temperature constant, continuously introducing the mixed gas, the antimony element continues to grow on the inner wall of the crucible; (5) After the antimony element growth thickness reaches the target thickness, stop introducing the mixed gas and introduce pure hydrogen for more than 30 minutes to completely replace the atmosphere in the reactor; (6) Under the condition of continuous introduction of hydrogen, the temperature of the heater is raised to above the melting point of antimony, so that the antimony element deposited on the inner wall of the crucible is completely melted, flows and gathers at the bottom of the crucible; (7) After the solid antimony element on the inner wall of the crucible is completely melted, stop heating and allow it to cool naturally to obtain a block of high-purity metallic antimony.

7. The method for preparing high-purity metallic antimony according to claim 6, characterized in that: During the natural cooling process, when the reactor is cooled to below 100°C, the introduction of hydrogen is stopped and nitrogen is introduced for more than 30 minutes. Then, the upper cover is opened and the intact block of high-purity antimony is taken out.

8. The method for preparing high-purity metallic antimony according to claim 6, characterized in that: In the mixed gas, the molar ratio of hydrogen to antimony trichloride is 5:1 to 30:

1.

9. The method for preparing high-purity metallic antimony according to claim 6, characterized in that: In step (6), during the heating and melting process of the solid antimony element, the temperature of the heater on the outer peripheral side is increased to 750-800°C, and the temperature of the heater on the bottom is increased to 700-750°C.

10. The method for preparing high-purity metallic antimony according to claim 6, characterized in that: High-purity antimony material with a purity of 7.5N or above is prepared using 8N antimony trichloride as raw material.

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