Preparation method of tantalum pentachloride

Abstract

The invention discloses a preparation method of tantalum pentachloride, and belongs to the technical field of materials.According to the method, crude tantalum pentachloride serves as a raw material, specific pressure maintaining hydrogen reduction treatment is conducted in a closed system, then sublimation purification is conducted, and a tantalum pentachloride product with the purity up to 6N can be obtained. The requirements on equipment and process conditions are low, and industrial large-scale implementation can be carried out.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a method for preparing tantalum pentachloride. Background Art

[0002] In the semiconductor field, tantalum materials represented by tantalum carbide are currently mainly prepared using tantalum pentachloride as raw material. The purity of tantalum pentachloride directly affects the quality of the finished product. Therefore, the purity of tantalum pentachloride needs to be strictly controlled at the front end of the production line.

[0003] There are two main traditional methods for preparing tantalum pentachloride: directly chlorinating elemental tantalum under high temperature, or converting tantalum oxide into finished products by mixing chlorine and a reducing agent. However, the products prepared by these two methods both contain a large amount of unreacted substances and by-products, and therefore require additional purification treatment. However, the current purification treatment has high requirements for equipment and operating processes, making it difficult to implement on a large scale in industrial plants. In addition, the degree of improvement in the purity of tantalum pentachloride is very limited, and it is basically impossible to reach 5N. Summary of the invention

[0004] Based on the defects of the prior art, the purpose of the present invention is to provide a method for preparing tantalum pentachloride. The method uses crude tantalum pentachloride as a raw material, performs a specific pressure-maintaining hydrogen reduction treatment in a closed system, and then performs sublimation purification to obtain a tantalum pentachloride product with a purity of up to 6N. The method has simple operating steps, low requirements on equipment and process conditions, and can be implemented on an industrial scale.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing tantalum pentachloride comprises the following steps:

[0007] (1) placing crude tantalum pentachloride into a closed system and performing an atmosphere replacement treatment in the system with an inert atmosphere;

[0008] (2) Open the exhaust system of the closed system and heat the closed system to 200-240°C for insulation treatment;

[0009] (3) The tail gas system of the closed system is closed, and the closed system is evacuated, and then hydrogen is introduced until the pressure in the closed system reaches 10 kPa or more, and then the pressure is maintained;

[0010] (4) Open the condensation system of the closed system, then heat the closed system to 200-450°C for insulation treatment, and exhaust and release the pressure to below 10KPa after the pressure in the closed system reaches above 15KPa;

[0011] (5) Introduce hydrogen into the closed system while keeping the temperature constant until the pressure in the closed system reaches above 15 kPa, then exhaust the gas to release the pressure to below 10 kPa;

[0012] (6) Repeat step (5) 2 to 5 times and cool down to obtain the tantalum pentachloride.

[0013] Preferably, the purity of the crude tantalum pentachloride is ≤3N, and the content of iron is ≥10ppm.

[0014] The crude tantalum pentachloride prepared by the traditional process has low purity and high impurity concentration (especially iron elements that affect semiconductor applications) due to the defects of the production process. The conventional fractionation or sublimation purification means have high requirements for equipment and implementation conditions, and the degree of purification is very limited, generally difficult to reach 5N or more. Therefore, in the technical solution of the present invention, in order to ensure the convenience of implementation and product quality of product production, the cheap crude tantalum pentachloride is used as a raw material, and is pre-placed in a closed device for ventilation treatment, and then sealed and heated to 200-240°C for insulation treatment to separate some low-boiling impurities in the crude product, and then vacuumed and hydrogen is introduced for the first time to a high pressure degree to maintain pressure so as to perform the first hydrogen reduction and impurity removal treatment. After the treatment is completed, the condensation system is turned on and heated and heat-insulated, and then the hydrogen pressure is repeatedly charged-depressurized and then cooled, and finally the sublimation-deposition and impurity separation of tantalum pentachloride are realized, and the obtained tantalum pentachloride product has high purity quality; at the same time, the method only uses conventional hydrogen as the impurity removal atmosphere, does not need to set up special devices, is simple to operate, and can be implemented on an industrial scale.

[0015] Preferably, the closed system includes a tail gas exhaust system, a condensation system and a sublimation system, and the crude tantalum pentachloride is placed in the sublimation system of the closed system.

[0016] Preferably, in step (1), the steps of atmosphere replacement treatment are:

[0017] The closed system is vacuumed until the pressure is ≤-0.08MPa, and then an inert atmosphere is introduced until the pressure of the closed system returns to normal pressure;

[0018] Repeat the above steps 3 to 5 times.

[0019] Preferably, the insulation treatment time in step (2) is 8 to 12 hours.

[0020] Before the hydrogen pressure reduction treatment, high temperature insulation treatment can effectively convert the low boiling point impurities in the crude tantalum pentachloride into gas phase and discharge it from the tail gas system, thereby initially improving the purity of the product.

[0021] Preferably, in step (3), the closed system is evacuated until the pressure is ≤-0.08 MPa.

[0022] Preferably, in step (3), the pressure treatment time is 0.5 to 1.5 hours.

[0023] Preferably, before implementing step (4), step (3) is repeated several times.

[0024] More preferably, in the step (3), hydrogen is introduced until the pressure in the closed system reaches 40 KPa or above and then the pressure is maintained.

[0025] In step (3), hydrogen is introduced for pressure treatment, which can effectively reduce the impurities in the crude tantalum pentachloride to low-valent substances or single substances under normal conditions, so as to separate and treat them in the subsequent sublimation process. The technicians in this field can repeat the operation of step (3) multiple times according to the actual requirements and the purity of the crude tantalum pentachloride to ensure the degree of impurity treatment. In particular, during the hydrogen pressure treatment, when the pressure reaches 40 KPa or above, the purity of the product can be further improved.

[0026] Preferably, in step (4), the insulation treatment time is 15 to 30 hours.

[0027] Preferably, in step (4), after the pressure in the closed system reaches 15-50 KPa, the pressure is released to below 10 KPa.

[0028] During the sublimation purification process, the intermediate product that has been subjected to hydrogen pressure maintenance treatment is heated in advance, then pressurized to a higher level and then released, which can effectively sublime and discharge the impurities.

[0029] Preferably, in step (5), the insulation temperature is 200-450°C.

[0030] Preferably, in step (5), hydrogen is introduced into the closed system while maintaining temperature until the pressure in the closed system reaches 15-50 KPa and then exhausted to reduce the pressure to below 10 KPa.

[0031] More preferably, in the step (5), hydrogen is introduced into the closed system while maintaining temperature until the pressure in the closed system reaches 30-50 KPa and then the pressure is released to below 10 KPa.

[0032] After multiple hydrogen charging and depressurization under the preferred conditions of high temperature and high pressure in step (5), the residual trace impurities in the product can be further reduced and separated, and ultimately the product can be extremely pure, especially the iron impurity content can be less than 0.3ppm, meeting the application standards in the semiconductor field.

[0033] The raw material used in the actual operation of the method of the present invention is low-quality crude tantalum pentachloride, which has low cost and does not require additional operating equipment. It can be implemented with a closed atmosphere system. Through hydrogen reduction and sublimation purification treatment under specific conditions, efficient impurity removal of the crude product can be achieved without introducing additional expensive additives, thereby preparing a high-quality product with a purity of up to 6N and a minimum iron impurity of less than 0.1ppm.

[0034] The beneficial effect of the present invention is that the present invention provides a method for preparing tantalum pentachloride, which uses crude tantalum pentachloride as a raw material, performs a specific pressure-maintaining hydrogen reduction treatment in a closed system, and then performs sublimation purification to obtain a tantalum pentachloride product with a purity of up to 6N. The method has simple operating steps, low requirements on equipment and process conditions, and can be implemented on an industrial scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a closed system used in the method described in Example 1 of the present invention, wherein 1 is a condensation system, 2 is an exhaust system, 3 is a furnace, 4 is a purification furnace, 5 is crude tantalum pentachloride, and 6 is the prepared tantalum pentachloride. DETAILED DESCRIPTION

[0036] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention, unless otherwise specified, are all commonly used common reagents and instruments.

[0037] Example 1

[0038] The method for preparing tantalum pentachloride of the present invention comprises the following steps:

[0039] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1 In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0040] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 200°C for insulation treatment for 10 hours;

[0041] (3) Close the exhaust system of the closed system, evacuate the closed system until the pressure is -0.08 MPa, then introduce hydrogen until the pressure in the closed system reaches 40 KPa, close the gas charging end, and maintain the pressure for 1 hour;

[0042] (4) Open the condensation system (i.e., cooling water pipe) of the closed system, then heat the closed system to 280°C for 20 hours, and after the pressure in the closed system reaches 45 kPa, open the exhaust system to release the pressure to below 10 kPa;

[0043] (5) Close the exhaust system, keep the temperature in the closed system at 280°C and introduce hydrogen until the pressure in the closed system reaches 45KPa, then exhaust and release the pressure to below 10KPa;

[0044] (6) Repeat step (5) twice and cool down to obtain the tantalum pentachloride.

[0045] Example 2

[0046] The method for preparing tantalum pentachloride of the present invention comprises the following steps:

[0047] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1 In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0048] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 220°C for 10 hours;

[0049] (3) Close the exhaust system of the closed system, evacuate the closed system until the pressure is -0.08 MPa, then introduce hydrogen until the pressure in the closed system reaches 40 KPa, close the gas charging end, and maintain the pressure for 1 hour;

[0050] (4) Open the condensation system (i.e., cooling water pipe) of the closed system, then heat the closed system to 280°C for 20 hours, and after the pressure in the closed system reaches 45 kPa, open the exhaust system to release the pressure to below 10 kPa;

[0051] (5) Close the exhaust system, keep the temperature in the closed system at 280°C and introduce hydrogen until the pressure in the closed system reaches 45KPa, then exhaust and release the pressure to below 10KPa;

[0052] (6) Repeat step (5) 5 times and cool down to obtain the tantalum pentachloride.

[0053] Example 3

[0054] The method for preparing tantalum pentachloride of the present invention is different from that of Example 2 only in that it comprises the following steps:

[0055] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1 In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0056] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 220°C for 10 hours;

[0057] (3) Close the exhaust system of the closed system, evacuate the closed system until the pressure is -0.08 MPa, then introduce hydrogen until the pressure in the closed system reaches 40 KPa, close the gas charging end, and maintain the pressure for 1 hour;

[0058] (4) Open the condensation system (i.e., cooling water pipe) of the closed system, then heat the closed system to 280°C for 20 hours, and after the pressure in the closed system reaches 25KPa, open the exhaust system to release the pressure to below 10KPa;

[0059] (5) Close the exhaust system, keep the temperature in the closed system at 280°C and introduce hydrogen until the pressure in the closed system reaches 25KPa, then exhaust and release the pressure to below 10KPa;

[0060] (6) Repeat step (5) 5 times and cool down to obtain the tantalum pentachloride.

[0061] Example 4

[0062] The method for preparing tantalum pentachloride of the present invention is different from that of Example 2 only in that it comprises the following steps:

[0063] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0064] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 220°C for 10 hours;

[0065] (3) Close the exhaust system of the closed system, evacuate the closed system until the pressure is -0.08 MPa, then introduce hydrogen until the pressure in the closed system reaches 10 KPa, close the gas charging end, and maintain the pressure for 1 hour;

[0066] (4) Open the condensation system (i.e., cooling water pipe) of the closed system, then heat the closed system to 280°C for 20 hours, and after the pressure in the closed system reaches 45 kPa, open the exhaust system to release the pressure to below 10 kPa;

[0067] (5) Close the exhaust system, keep the temperature in the closed system at 280°C and introduce hydrogen until the pressure in the closed system reaches 45KPa, then exhaust and release the pressure to below 10KPa;

[0068] (6) Repeat step (5) 5 times and cool down to obtain the tantalum pentachloride.

[0069] Comparative Example 1

[0070] A method for preparing tantalum pentachloride, which differs from Example 2 only in that it comprises the following steps:

[0071] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1 In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0072] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 220°C for 10 hours;

[0073] (3) Open the condensation system (i.e., cooling water pipe) of the closed system, then heat the closed system to 280°C for 20 hours of heat preservation, and after the pressure in the closed system reaches 45KPa, open the exhaust system to release the pressure to below 10KPa;

[0074] (4) Close the tail gas system, keep the temperature in the closed system at 280°C and introduce hydrogen until the pressure in the closed system reaches 45KPa, then exhaust and release the pressure to below 10KPa;

[0075] (5) Repeat step (4) 5 times and cool down to obtain the tantalum pentachloride.

[0076] Comparative Example 2

[0077] A method for preparing tantalum pentachloride, which differs from Example 2 only in that it comprises the following steps:

[0078] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1 In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0079] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 220°C for 10 hours;

[0080] (3) closing the tail gas system of the closed system, evacuating the closed system until the pressure is -0.08 MPa, then introducing hydrogen until the pressure in the closed system reaches 40 KPa, closing the gas charging end, maintaining the pressure for 1 hour, and cooling to obtain the tantalum pentachloride.

[0081] Comparative Example 3

[0082] A method for preparing tantalum pentachloride, which differs from Example 2 only in that it comprises the following steps:

[0083] (1) 200 kg of crude tantalum pentachloride with a purity of 3N and an iron impurity content of 9.8 ppm was placed in a Figure 1 In the furnace of the closed system, close the discharge valve, detect the air tightness of the system, fill with argon until the pressure in the system reaches 25KPa and then maintain for 30 minutes, the pressure drop does not exceed 3%, and the air tightness is qualified, then evacuate the system to a pressure of -0.08MPa, then fill with argon atmosphere to normal pressure, and repeat the evacuation and filling with argon 4 times to complete the atmosphere replacement treatment;

[0084] (2) Open the exhaust system (i.e., the exhaust pipe) of the closed system and heat the closed system to 220°C for 10 hours;

[0085] (3) Close the exhaust system of the closed system, evacuate the closed system until the pressure is -0.08 MPa, then introduce nitrogen until the pressure in the closed system reaches 40 KPa, close the inflation end, and maintain the pressure for 1 hour;

[0086] (4) Open the condensation system (i.e., cooling water pipe) of the closed system, then heat the closed system to 280°C for 20 hours, and after the pressure in the closed system reaches 45 kPa, open the exhaust system to release the pressure to below 10 kPa;

[0087] (5) Close the exhaust system, keep the temperature in the closed system at 280°C and introduce nitrogen until the pressure in the closed system reaches 45 kPa, then exhaust and release the pressure to below 10 kPa;

[0088] (6) Repeat step (5) 5 times and cool down to obtain the tantalum pentachloride.

[0089] Effect example

[0090] In order to verify the preparation effect of the preparation method of tantalum pentachloride of the present invention, the purity and iron impurity content of the tantalum pentachloride obtained in each embodiment and comparative example were analyzed by ICP-MS / MS. The results are shown in Table 1

[0091] Table 1

[0092] product Purity(N) Iron impurity content (ppm) Example 1 6 0.07 Example 2 6 0.03 Example 3 5.5 0.2 Example 4 5.5 0.22 Comparative Example 1 4.5 1.25 Comparative Example 2 4 2.65 Comparative Example 3 3 6.85

[0093] It can be seen from the test results that the tantalum pentachloride product prepared by the preparation method of the present invention has high purity and extremely low impurity content, and can reach a quality of 6N at most, and the implementation effect is very excellent. Without relying on special equipment or processing aids, this is mainly due to the special hydrogen pressure reduction treatment and the subsequent hydrogen atmosphere sublimation purification treatment. In contrast, the two key steps are not carried out in Comparative Examples 1 and 2. Therefore, although the purity of the product is slightly improved compared with the crude product, it still cannot meet the standard. Comparative Example 3 uses nitrogen as the working atmosphere. Obviously, the crude product cannot be removed from impurities only under mild conditions of pressurized heating, and the purity of the product is still 3N.

[0094] According to the comparison of Examples 2 to 4, it can be seen that during the preparation process of the product of the present invention, the pressure setting range during the hydrogen pressure maintenance and sublimation purification process is very critical to the purity of the product. If the pressure is too low, it may lead to insufficient impurity removal reaction.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the present invention.

Claims

1. A method for preparing tantalum pentachloride, characterized in that: The following steps are involved: (1) placing crude tantalum pentachloride into a closed system and performing an atmosphere replacement treatment in the system with an inert atmosphere; (2) Open the exhaust system of the closed system and heat the closed system to 200-240°C for insulation treatment; (3) The tail gas system of the closed system is closed, and the closed system is evacuated, and then hydrogen is introduced until the pressure in the closed system reaches 10 kPa or more, and then the pressure is maintained; (4) Open the condensation system of the closed system, then heat the closed system to 200-450°C for insulation treatment, and exhaust and release the pressure to below 10KPa after the pressure in the closed system reaches above 15KPa; (5) Introduce hydrogen into the closed system while keeping the temperature constant until the pressure in the closed system reaches above 15 kPa, then exhaust the gas to release the pressure to below 10 kPa; (6) Repeat step (5) 2 to 5 times and cool down to obtain the tantalum pentachloride.

2. The method for preparing tantalum pentachloride according to claim 1, characterized in that: The purity of the crude tantalum pentachloride is ≤3N, and the content of iron is ≥10ppm.

3. The method for preparing tantalum pentachloride according to claim 1, characterized in that: In the step (1), the steps of atmosphere replacement treatment are: The closed system is vacuumed until the pressure is ≤-0.08MPa, and then an inert atmosphere is introduced until the pressure of the closed system returns to normal pressure; Repeat the above steps 3 to 5 times.

4. The method for preparing tantalum pentachloride according to claim 1, characterized in that: Before the step (4) is implemented, the step (3) is repeated several times.

5. The method for preparing tantalum pentachloride according to claim 4, characterized in that: In the step (3), hydrogen is introduced until the pressure in the closed system reaches 40 KPa or above, and then pressure maintenance treatment is performed.

6. The method for preparing tantalum pentachloride according to claim 1, characterized in that: In the step (4), after the pressure in the closed system reaches 15-50 KPa, the pressure is released to below 10 KPa.

7. The method for preparing tantalum pentachloride according to claim 1, characterized in that: In the step (5), the insulation temperature is 200 to 450°C.

8. The method for preparing tantalum pentachloride according to claim 1, characterized in that: In the step (5), hydrogen is introduced into the closed system while maintaining temperature until the pressure in the closed system reaches 15-50 KPa and then the pressure is released to below 10 KPa.

9. The method for preparing tantalum pentachloride according to claim 8, characterized in that: In the step (5), hydrogen is introduced into the closed system while maintaining temperature until the pressure in the closed system reaches 30-50 KPa and then the pressure is released to below 10 KPa.

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