Preparation method of electronic-grade penta (dimethylamino) tantalum

Abstract

The invention discloses a preparation method of electronic-grade penta (dimethylamino) tantalum, and belongs to the technical field of materials.According to the method, tantalum pentachloride and dimethylamine react in advance to form an intermediate, then a penta (dimethylamino) tantalum product is formed through a trialkylamine complexation reaction, finally purification is achieved in a low-temperature recrystallization mode, the product purity is high, and the product purity is high. And moreover, product decomposition caused by a traditional purification mode is avoided, and the yield of the product is relatively high.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a method for preparing electronic-grade penta(dimethylamino)tantalum. Background Art

[0002] In the semiconductor field, tantalum nitride and tantalum pentoxide are both important application materials. Both are mainly prepared from the raw material tantalum penta(dimethylamino) by chemical vapor deposition or atomic layer deposition. Therefore, the initial purity of the raw material tantalum penta(dimethylamino) directly affects the quality of the obtained tantalum nitride and tantalum pentoxide.

[0003] At present, tantalum penta(dimethylamino) is mainly prepared using tantalum pentachloride as raw material. However, in the preparation process, it is inevitable to use organic lithium reagents. Such reagents are not only costly and risky, but also the residues and by-products (such as lithium chloride) after the preparation of tantalum penta(dimethylamino) will be coated by tantalum penta(dimethylamino) in the form of fine particles, making separation difficult. At the same time, due to the low thermal stability of tantalum penta(dimethylamino) itself, if the conventional sublimation purification method is used to separate impurities, part of the product will decompose and the yield will be reduced.

[0004] For this reason, people have tried to prepare tantalum penta(dimethylamino) by using other process systems. For example, CN 110698347B provides a preparation method, in which butyl magnesium chloride is dissolved in tetrahydrofuran solution, a co-catalyst (copper iodide) is added, dimethylamine gas is introduced to react to obtain di(dimethylamino) magnesium, and finally reacted with tantalum pentachloride, and the final product is obtained by sublimation under reduced pressure. This method is based on the use of Grignard reagents to participate in nucleophilic reactions, which can avoid the use of organic lithium reagents, but the introduction of di(dimethylamino) magnesium and cuprous iodide will bring new metal element impurities Mg and Cu, and the difficulty of removing impurities from the product has not been reduced; in addition, this method requires the pre-preparation of Mg-based Grignard reagents, and the preparation process is cumbersome, the cycle is long, and it is difficult to achieve industrial production. Summary of the invention

[0005] Based on the defects of the prior art, the purpose of the present invention is to provide a method for preparing electronic grade penta(dimethylamino)tantalum, which comprises reacting tantalum pentachloride and dimethylamine to form an intermediate, then forming a penta(dimethylamino)tantalum product through a trialkylamine complex reaction, and finally purifying the product through low-temperature recrystallization. The product has high purity and will not cause product decomposition like traditional purification methods, and the product yield is high.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing electronic grade pentakis(dimethylamino)tantalum comprises the following steps:

[0008] (1) Under a protective atmosphere, tantalum pentachloride is dispersed in an organic solvent, the resulting mixed solution is cooled to -30 to -10°C, and dimethylamine is introduced to react to obtain an intermediate solution;

[0009] (2) cooling the intermediate solution to -30 to -10°C, adding trialkylamine to react, filtering the resulting reaction solution, and subjecting the resulting filtrate to reduced pressure distillation to obtain a crude product;

[0010] (3) adding the crude product to a good solvent at 35-70°C and mixing until completely dissolved, then gradually cooling to below -40°C and maintaining for 2-4 hours, filtering, washing, and obtaining a filter residue;

[0011] (4) After the filter residue is repeatedly treated 2 to 4 times according to the crude product treatment method of step (3), the obtained solid is heated and decompressed to remove the solvent, thereby obtaining the electronic grade penta(dimethylamino)tantalum.

[0012] In order to take into account both the purity and yield indicators of the product during the preparation process, the technical solution of the present invention does not use an organic reagent containing metal ions during the preparation of tantalum penta(dimethylamino), and tantalum pentachloride and dimethylamine are reacted in advance to generate an intermediate containing HCl molecules, and then a specific trialkylamine is introduced as a complexing agent to react with the intermediate, complexing with the HCl molecules in the intermediate to form a trialkylamine salt precipitate, thereby promoting the conversion of tantalum penta(dimethylamino). Based on the difference in solubility, the salt precipitate and the unreacted tantalum pentachloride can be separated by simple filtration. On the other hand, the method uses low-temperature recrystallization to purify the crude product. Compared with traditional sublimation purification or distillation, the process of the present invention will not cause the target product to decompose during the purification process, thereby effectively improving the product yield (the product yield of the method of the present invention can reach more than 65%).

[0013] Preferably, in step (1), the protective atmosphere includes at least one of a nitrogen atmosphere and an argon atmosphere.

[0014] Preferably, in step (1), the organic solvent comprises at least one of n-pentane, n-hexane, n-heptane and toluene.

[0015] More preferably, in the step (1), the ratio of the mole of tantalum pentachloride to the volume of the organic solvent is (0.3-0.45) mol: (1-2) L.

[0016] More preferably, the ratio of the mole of tantalum pentachloride to the volume of the organic solvent is in the range of one or any two of 0.3 mol: (1-2) L, 0.32 mol: (1-2) L, 0.35 mol: (1-2) L, 0.38 mol: (1-2) L, 0.4 mol: (1-2) L, 0.42 mol: (1-2) L, and 0.45 mol: (1-2) L.

[0017] When the mixed solution prepared under the above concentration system reacts with dimethylamine in a low temperature environment, the reaction process can be ensured to be more fully uniform without the occurrence of problems such as precipitation, and the by-product content when the subsequent intermediate continues to react with trialkylamine is always maintained at a low level, which is more conducive to ensuring the purity of the product.

[0018] Preferably, in step (1), the molar ratio of tantalum pentachloride to dimethylamine is 1:(5-5.5).

[0019] In the method of the present invention, tantalum pentachloride and dimethylamine are added in the above molar ratio range to carry out the following reaction:

[0020]

[0021] Since the reaction is violent, it needs to be carried out at a relatively low temperature to avoid excessive heat release. At the same time, at the molar ratio, the by-products can be effectively controlled at a relatively low content level.

[0022] Preferably, after dimethylamine is introduced into the mixed solution in step (1) for reaction, the temperature is raised to 23-28° C. and stirring is continued for 2-4 hours.

[0023] Preferably, the trialkylamine in step (2) includes at least one of triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine and triisobutylamine.

[0024] More preferably, the trialkylamine is at least one of triethylamine, tri-n-propylamine and triisopropylamine.

[0025] Different trialkylamines, after being mixed with the intermediate, have different complexing activities for HCl molecules, and the probability of generating by-products is also different. In addition, due to the violent reaction, the products will also have different degrees of decomposition. The inventors have found through experimental optimization that the above trialkylamines can be used for the reaction to further increase the yield of the product to a higher level.

[0026] Preferably, the molar ratio of the trialkylamine in step (2) to the tantalum pentachloride in step (1) is (6-6.5):1.

[0027] In the preparation method of the present invention, after the trialkylamine is introduced, the following complexation reaction occurs in the reaction system:

[0028]

[0029] When the above molar ratio is further optimized, the reaction can be fully guaranteed to be complete without excessive residual raw materials, and without product decomposition and increase of by-products due to excessive heat release of the reaction system.

[0030] Preferably, the reaction solution in step (2) is pre-heated to 50-75° C. and stirred for 4-12 hours before filtering.

[0031] More preferably, the reaction solution in step (2) is pre-heated to 50-75° C. and stirred for 8-12 h before filtering.

[0032] The inventors have found through experiments that after the trialkylamine and the intermediate react completely at low temperature, if the temperature is continued to be raised and the reaction is stirred for a period of time, the forward generation of penta(dimethylamine)tantalum will continue, thereby further improving the yield of the product without affecting the purity level of the product.

[0033] Preferably, the temperature of the filtrate obtained in step (2) during the reduced pressure distillation treatment is ≤60°C.

[0034] Since tantalum penta(dimethylamino) has poor stability, in order to prevent the product from deteriorating or being distilled out with the solvent, the temperature during the reduced pressure distillation treatment needs to be controlled at a low level.

[0035] Preferably, in step (3), the good solvent includes at least one of n-pentane and n-hexane.

[0036] More preferably, the ratio of the mole of tantalum pentachloride in step (1) to the volume of the good solvent in step (3) is (0.2-4) mol: (0.5-1) L.

[0037] Preferably, in step (3), the specific steps of the gradient cooling are: cooling the good solvent for dissolving the crude product by 5 to 10°C, then keeping it warm for 10 to 15 minutes, and then repeating the operation until the temperature of the good solvent drops to -40°C.

[0038] Gradient cooling can ensure that the product maintains a uniform rate during recrystallization and that the crystallization is sufficient, thereby achieving a higher yield.

[0039] Preferably, in step (3), washing is carried out using a good solvent at -40 to -20°C.

[0040] Preferably, in step (4), the temperature during heating and decompression is 30-45°C.

[0041] The preparation method of electronic-grade pentakis(dimethylamino)tantalum described in the present invention is based on the fact that no metal-containing organic reagents are used, so the metal purity of the product can reach 99.9999%, and no additional metal impurity separation treatment is required after the product is synthesized, and the operation is simple; in the purification stage, the scheme described in the present invention adopts a low-temperature recrystallization method instead of traditional sublimation or distillation purification to avoid decomposition loss of the product, and the yield of the product is relatively high, which can reach more than 65%, and the comprehensive application prospect is good. In addition, the method has no additional equipment and environmental requirements, and can realize industrial-scale production.

[0042] The beneficial effect of the present invention is that the present invention provides a method for preparing electronic grade penta(dimethylamino)tantalum, which first reacts tantalum pentachloride and dimethylamine to form an intermediate, then forms a penta(dimethylamino)tantalum product through a trialkylamine complex reaction, and finally purifies it through low-temperature recrystallization. The product has high purity and will not cause product decomposition like traditional purification methods, and the product yield is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the NMR spectrum of penta(dimethylamino)tantalum prepared by the method described in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] 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.

[0045] Example 1

[0046] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum according to the present invention comprises the following steps:

[0047] (1) In an anhydrous and oxygen-free nitrogen atmosphere, 138 g (0.385 mol) of tantalum pentachloride was dispersed in 1.5 L of n-hexane, and the resulting mixed solution was cooled to -10°C, and then 88 g (1.96 mol) of dimethylamine was introduced to react, and then the temperature was raised to 25°C and stirred for 2 hours to obtain an intermediate solution;

[0048] (2) After cooling the intermediate solution to -10°C, 237 g of triethylamine (2.35 mol) was added dropwise using a constant pressure dropping funnel to react, and then the temperature was raised to 50°C and stirred for 4 hours. The resulting reaction solution was filtered, and the filtrate was treated with reduced pressure distillation at 50°C and 1300 Pa to remove the solvent, thereby obtaining a dark brown crude product;

[0049] (3) The crude product was added to 0.8 L of good solvent n-pentane at 40°C and mixed until completely dissolved, then cooled by 10°C, and then kept warm for 10 min. The operation was then repeated until the temperature of the good solvent dropped to -40°C and maintained for 2 h, filtered, and washed with the same good solvent cooled to -20°C to obtain a filter residue;

[0050] (4) After the filter residue is treated twice according to the crude product treatment method of step (3), the obtained solid is heated at 40° C. and 300 Pa to remove the solvent under reduced pressure to obtain the electronic grade penta(dimethylamino)tantalum.

[0051] The product was subjected to nuclear magnetic resonance testing, and the results were as follows Figure 1 As shown, 1 HNMR (400 MHz, C 6 D 6 ):3.26(s,30H)。

[0052] Example 2

[0053] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum according to the present invention comprises the following steps:

[0054] (1) In an anhydrous and oxygen-free nitrogen atmosphere, 138 g (0.385 mol) of tantalum pentachloride was dispersed in 1.5 L of n-hexane, and the resulting mixed solution was cooled to -20°C, and then 88 g (1.96 mol) of dimethylamine was introduced to react, and then the temperature was raised to 25°C and stirred for 2 hours to obtain an intermediate solution;

[0055] (2) After cooling the intermediate solution to -20°C, 237 g of triethylamine (2.35 mol) was added dropwise using a constant pressure dropping funnel to react, and then the temperature was raised to 60°C and stirred for 6 hours. The resulting reaction solution was filtered, and the resulting filtrate was treated with reduced pressure distillation at 50°C and 1300Pa to remove the solvent, thereby obtaining a dark brown crude product;

[0056] (3) The crude product was added to 0.7 L of good solvent n-hexane at 60°C and mixed until completely dissolved, then cooled by 10°C, and then kept warm for 10 min. The operation was then repeated until the temperature of the good solvent dropped to -40°C and maintained for 2 h, filtered, and washed with the same good solvent cooled to -20°C to obtain a filter residue;

[0057] (4) After the filter residue is treated twice according to the crude product treatment method of step (3), the obtained solid is heated at 40° C. and 300 Pa to remove the solvent under reduced pressure to obtain the electronic grade penta(dimethylamino)tantalum.

[0058] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0059] Example 3

[0060] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum of the present invention differs from Embodiment 2 only in that the triethylamine in step (2) is replaced by 335.6 g (2.34 mol) of tri-n-propylamine.

[0061] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0062] Example 4

[0063] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum of the present invention differs from Embodiment 2 only in that the triethylamine in step (2) is replaced by 335.6 g (2.34 mol) of triisopropylamine.

[0064] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0065] Example 5

[0066] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum of the present invention differs from Embodiment 2 only in that the triethylamine in step (2) is replaced by 434.2 g (2.34 mol) of tri-n-butylamine.

[0067] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0068] Example 6

[0069] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum of the present invention differs from Embodiment 2 only in that the triethylamine in step (2) is replaced by 434.2 g (2.34 mol) of triisobutylamine.

[0070] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0071] Example 7

[0072] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum of the present invention differs from embodiment 5 only in that in step (2), the intermediate solution is cooled to -20°C and then tri-n-butylamine is added dropwise with a constant pressure dropping funnel for reaction, and then the temperature is raised to 60°C and stirred for 12 hours.

[0073] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0074] Example 8

[0075] An embodiment of the method for preparing electronic grade penta(dimethylamino)tantalum of the present invention differs from embodiment 6 only in that in step (2), the intermediate solution is cooled to -20°C and triisobutylamine is added dropwise with a constant pressure dropping funnel for reaction, and then the temperature is raised to 60°C and stirred for 12 hours.

[0076] The product was subjected to nuclear magnetic resonance testing, and the result was similar to that of Example 1.

[0077] Comparative Example 1

[0078] A method for preparing pentakis(dimethylamino)tantalum comprises the following steps:

[0079] (1) In an anhydrous and oxygen-free nitrogen atmosphere, 765 mL (2.5 mol) of n-butyl lithium and 1.2 L of n-hexane were mixed, the resulting mixture was cooled to -20°C, and then 88 g (1.96 mol) of dimethylamine was introduced, the temperature was raised to 25°C and stirred for 4 hours to obtain a precursor solution;

[0080] (2) After cooling the precursor solution to -20°C, 138 g (0.385 mol) of tantalum pentachloride was slowly added to react, and then the temperature was raised to 60°C and stirred for 8 hours. The resulting reaction solution was filtered, and the resulting filtrate was treated with reduced pressure distillation at 50°C and 1300 Pa to remove the solvent, thereby obtaining a dark brown crude product;

[0081] (3) The crude product is transferred to a vacuum sublimator for sublimation purification (0.02 mmHg, 86° C.) to obtain the penta(dimethylamino)tantalum.

[0082] Comparative Example 2

[0083] A method for preparing pentakis(dimethylamino)tantalum comprises the following steps:

[0084] (1) In an anhydrous and oxygen-free nitrogen atmosphere, 765 mL (2.5 mol) of n-butyl lithium and 1.2 L of n-hexane were mixed, the resulting mixture was cooled to -20°C, and then 88 g (1.96 mol) of dimethylamine was introduced, the temperature was raised to 25°C and stirred for 4 hours to obtain a precursor solution;

[0085] (2) After cooling the precursor solution to -20°C, 138 g (0.385 mol) of tantalum pentachloride was slowly added to react, and then the temperature was raised to 60°C and stirred for 8 hours. The resulting reaction solution was filtered, and the resulting filtrate was treated with reduced pressure distillation at 50°C and 1300 Pa to remove the solvent, thereby obtaining a dark brown crude product;

[0086] (3) The crude product is transferred to a vacuum sublimator for primary sublimation purification (0.02 mmHg, 86° C.), and then the resulting crystals are collected for secondary sublimation purification (0.02 mmHg, 75° C.) to obtain the penta(dimethylamino)tantalum.

[0087] Effect Example 1

[0088] In order to verify the application effect of the preparation method of the present invention, the metal purity of the products obtained in each embodiment and comparative example was analyzed by ICP-MS / MS method, and the product output was recorded and the yield was calculated. The results are shown in Table 1.

[0089] Table 1

[0090] product Metal purity (%) Yield (g) Yield (%) Example 1 99.9999 112.8 72 Example 2 99.9999 130 83 Example 3 99.9999 122.2 78 Example 4 99.9999 117.5 75 Example 5 99.9999 106.5 68 Example 6 99.9999 103.4 66 Example 7 99.9999 119 76 Example 8 99.9999 114.4 73 Comparative Example 1 99.99 89.1 58 Comparative Example 2 99.999 78.3 51

[0091] It can be clearly seen from the test results that the preparation method of pentyl (dimethylamino) tantalum of the present invention can prepare electronic grade products with a metal purity of up to 99.9999%, and the product yield is high. Under the condition of the same raw material addition amount, the yield can reach more than 65%. In contrast, the products prepared in the methods of Comparative Examples 1 and 2 using the traditional organic lithium reagent system have low purity, and the lithium residue in the product cannot be effectively removed even after multiple sublimation purifications, and the initial yield of the method is only 58%. After secondary sublimation purification, the purity of the product is still not as good as that of the embodiment product, and the product is lost, and the yield is reduced to 51%.

[0092] From the comparison of Examples 1 to 6, it can be seen that different trialkylamines have a certain influence on the yield of the product when used as complexing reaction agents. When triethylamine, tri-n-propylamine and triisopropylamine are used, the yield of the obtained product is higher, reaching more than 75%.

[0093] At the same time, it can be seen from the comparison of Examples 5 to 8 that after the trialkylamine reacts with the intermediate, continuing to stir the mixed solution under a heating environment can further promote the complete formation of the product, thereby improving the product yield.

[0094] 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 electronic grade pentyl(dimethylamino)tantalum, characterized in that: The following steps are involved: (1) Under a protective atmosphere, tantalum pentachloride is dispersed in an organic solvent, the resulting mixed solution is cooled to -30 to -10°C, and dimethylamine is introduced to react to obtain an intermediate solution; (2) cooling the intermediate solution to -30 to -10°C, adding trialkylamine to react, filtering the resulting reaction solution, and subjecting the resulting filtrate to reduced pressure distillation to obtain a crude product; (3) adding the crude product to a good solvent at 35-70°C and mixing until completely dissolved, then gradually cooling to below -40°C and maintaining for 2-4 hours, filtering, washing, and obtaining a filter residue; (4) After the filter residue is repeatedly treated 2 to 4 times according to the crude product treatment method of step (3), the obtained solid is heated and decompressed to remove the solvent, thereby obtaining the electronic grade penta(dimethylamino)tantalum.

2. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: In the step (1), the organic solvent includes at least one of n-pentane, n-hexane, n-heptane and toluene.

3. The method for preparing electronic grade penta(dimethylamino)tantalum as claimed in claim 2, wherein in step (1), the ratio of the mole of tantalum pentachloride to the volume of the organic solvent is (0.3-0.45) mol: (1-2) L.

4. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: In the step (1), the molar ratio of tantalum pentachloride to dimethylamine is 1:(5-5.5).

5. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: After dimethylamine is introduced into the mixed solution in step (1) for reaction, the temperature is raised to 23-28° C. and stirring is continued for 2-4 hours.

6. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: The trialkylamine in step (2) includes at least one of triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine and triisobutylamine.

7. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: The molar ratio of the trialkylamine in step (2) to the tantalum pentachloride in step (1) is (6-6.5):

1.

8. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: Before filtering, the reaction solution in step (2) is preheated to 50-75° C. and stirred for 4-12 hours.

9. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: In the step (3), the good solvent includes at least one of n-pentane and n-hexane.

10. The method for preparing electronic grade pentakis(dimethylamino)tantalum as claimed in claim 1, characterized in that: In the step (3), the specific steps of the gradient cooling are: cooling the good solvent for dissolving the crude product by 5 to 10°C, then keeping the temperature for 10 to 15 minutes, and then repeating the operation until the temperature of the good solvent drops to -40°C.

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