Solid metal precursor and method for purifying the same

Abstract

This invention provides a solid metal precursor and its purification method, belonging to the field of semiconductor precursor purification technology. The purification method includes the following steps: adding an auxiliary agent to the crude solid metal precursor and sublimating it at a temperature ≤150℃ to obtain a pure product; the auxiliary agent has a boiling point ≥250℃ at atmospheric pressure, and during sublimation, it generates intermolecular forces with at least one organic impurity in the crude solid metal precursor, promoting their separation. This application uses an auxiliary agent to avoid the influence of organic impurities generated by water and oxygen on the precursor sublimation process, effectively changing the sublimation state. Combined with the sublimation process, it achieves a purification yield of over 75% for tantalum-based solid metal precursors, reducing the content of difficult-to-remove organic impurities generated by water and oxygen in the product to below 0.1%; the purification operation is simple and can be scaled up.

Description

Technical Field

[0001] This invention relates to the field of semiconductor precursor purification technology, specifically to a solid metal precursor and its purification method. Background Technology

[0002] Tantalum-based solid metal precursors are key raw materials in atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes. They are widely used in advanced semiconductor fields as core precursors for high-k dielectrics, tantalum-based barrier layers, and conductive thin films. Their purity directly determines the density, uniformity, and electrical properties of the thin film. As semiconductor technology advances to more advanced process nodes, the industry's purity requirements for semiconductor precursors, including tantalum-based solid metal precursors, have been raised to 99.999% (5N) or 99.9999% (6N) and above, with metal impurities (such as Li, Cl, Fe, Ni, etc.) required to be ≤0.05ppm.

[0003] Currently, the main methods for purifying tantalum-based solid metal precursors are recrystallization or sublimation. However, traditional single vacuum sublimation processes are difficult to effectively remove various impurities, and fluctuations in operating temperature can easily lead to thermal decomposition of the product, thus restricting the industrial purification of the product. For example, patent CN118307585A discloses a penta(dimethylamino)tantalum product and its preparation method, which uses multiple sublimation combined with adsorption processes to remove by-products and metal impurities. Sublimation is carried out at 50-90℃ and 0.02-0.05mmHg. Although this method can obtain good product purity, its yield on a laboratory scale is less than 50%, which is difficult to meet the needs of industrial production. Patent CN120309651A discloses a recrystallization purification process for high-purity ALD precursor penta(dimethylamino)tantalum, specifically: first, the crude product is dissolved in an alkane solvent treated with n-butyllithium, and then insoluble impurities are filtered out. Then, crystallization is slowly precipitated through gradient cooling (-15~0℃). The NMR purity of the product obtained by this method is 99.2%-99.85%, and the yield is 67%-78.4%. Both purity and yield have room for improvement. Furthermore, this method requires the use of a large amount of organic solvent, generating a significant amount of waste liquid containing penta(dimethylamino)tantalum. This waste liquid is flammable upon contact with water and oxygen, posing a serious safety hazard during scale-up production. It also increases waste liquid treatment costs, hindering market competitiveness and industrialization. In summary, existing technologies for purifying tantalum-based solid metal precursors such as penta(dimethylamino)tantalum generally suffer from low yield, poor process stability, cumbersome operation, and high costs.

[0004] The applicant has discovered that trace amounts of water and oxygen are unavoidable during the synthesis of tantalum-based solid metal precursors such as penta(dimethylamino)tantalum, resulting in the formation of small amounts of oily impurities. These impurities, when mixed with penta(dimethylamino)tantalum, affect the sublimation efficiency of the crude product, and prolonged heating can lead to product deterioration, further reducing the purification yield. Therefore, there is an urgent need to develop a simple, efficient, and yield-ideal method for purifying solid metal precursors suitable for large-scale production. Summary of the Invention

[0005] To address the shortcomings of existing technologies in purifying solid metal precursors, such as poor purification efficiency, low purification yield, and complex operating procedures, this application provides a solid metal precursor and its purification method. This application overcomes the limitations of existing technologies (avoiding the introduction of foreign substances, which increases the difficulty of product impurity removal) by adding specific types and amounts of additives to the traditional sublimation purification method. The intermolecular forces generated between the additives and organic impurities in the crude product during sublimation promote the separation of organic impurities from the solid metal precursor, thus avoiding the influence of organic impurities on the sublimation process. Simultaneously, the additives can effectively change the sublimation state of the crude product, avoiding product deterioration caused by prolonged heating or excessively high local temperatures. Combined with the optimization of the sublimation process, the purification yield of the solid metal precursor is synergistically achieved to be above 75%, and even above 90%, reducing the content of organic impurities generated by water and oxygen in the product to below 0.1%. Furthermore, the purification operation is simple and can be scaled up.

[0006] The technical solution provided in this application is as follows:

[0007] A method for purifying a solid metal precursor includes the following steps: adding an auxiliary agent to the crude solid metal precursor and sublimating it at a temperature of ≤150℃ to obtain a pure product.

[0008] Further, the solid metal precursor is an alkylamine metal precursor; preferably, the solid metal precursor is penta(dialkylamine)tantalum, wherein the alkyl group has 1-5 carbon atoms; more preferably, the solid metal precursor is penta(dimethylamine)tantalum or penta(methylethylamine)tantalum.

[0009] Furthermore, the boiling point of the additive under normal pressure is ≥250℃.

[0010] Furthermore, during the sublimation process, the additive generates intermolecular forces with at least one organic impurity in the crude solid metal precursor, thereby promoting the separation of the organic impurity from the solid metal precursor.

[0011] Furthermore, the structure of the organic impurity includes at least one of MO bond, MON bond, and MOM bond, where M is a metal atom of the solid metal precursor; specifically, M is tantalum (Ta).

[0012] Further, the additive includes at least one of alcohol ethers, aromatic ethers, aromatic hydrocarbons, and C12-C32 alkylamines; preferably, the additive includes at least one of tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, triethylene glycol monoethyl ether, diethylene glycol hexyl ether, polyethylene glycol dimethyl ether, diphenyl ether, dibenzyl ether, benzylphenyl ether, 3-methyl diphenyl ether, biphenyl-biphenyl ether azeotropic mixture, biphenyl, n-dodecylbenzene, and C12-C32 alkylamines.

[0013] More preferably, the additive includes at least one of tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, triethylene glycol monoethyl ether, diethylene glycol hexyl ether, diphenyl ether, dibenzyl ether, benzylphenyl ether, 3-methyl diphenyl ether, and at least one of C12-C32 alkylamines.

[0014] Further, the amount of the additive accounts for 1-25% of the crude solid metal precursor mass, preferably 5-20%; more preferably, the amount of the additive accounts for 15-20% of the crude solid metal precursor mass.

[0015] Further, the sublimation temperature is ≤100℃, and the sublimation pressure is 0.01-100Pa. Preferably, the sublimation temperature is 40-100℃, and the sublimation pressure is 0.01-100Pa. More preferably, the sublimation temperature is 40-70℃, and the sublimation pressure is 1-20Pa.

[0016] Furthermore, in the purification method, the sublimation is performed once, twice, or multiple times.

[0017] Furthermore, the sublimation is performed two or more times. The sublimation temperature of the first sublimation is 40-99℃ and the sublimation pressure is 0.01-100Pa. The sublimation temperature of the second or more sublimations is 40-60℃ and the sublimation pressure is 1-40Pa.

[0018] Preferably, the sublimation is performed twice. The first sublimation is performed at a sublimation temperature of 50-70°C and a sublimation pressure of 1-10 Pa. The second or subsequent sublimation is performed at a sublimation temperature of 40-60°C and a sublimation pressure of 1-20 Pa.

[0019] Furthermore, the sublimation is carried out in an environment with an oxygen content of <1 ppm and a water content of <0.01 ppm.

[0020] Furthermore, the particle size of the crude solid metal precursor powder is not less than 40 mesh.

[0021] Furthermore, the content of organic impurities generated by water and oxygen in the crude solid metal precursor is ≤30%, preferably ≤25%. Unless otherwise specified, the content of organic impurities mentioned in this application is determined by proton nuclear magnetic resonance spectroscopy (NMR). 1 Obtained by H NMR (H NMR) test.

[0022] A solid metal precursor, which is a pure product prepared according to the above purification method, wherein the content of organic impurities generated by water and oxygen is <0.1%.

[0023] Furthermore, the solid metal precursor is pentapentan(dialkylamino)tantalum.

[0024] Preferably, the solid metal precursor is pentapenta(dimethylamino)tantalum.

[0025] Furthermore, the organic purity of the solid metal precursor is ≥99.5%; the organic purity is determined by... 1 Obtained by H NMR testing.

[0026] Furthermore, the metal purity of the solid metal precursor is ≥99.9999%; the metal purity is measured by ICP-MS / MS or ICP-MS.

[0027] The beneficial effects of this invention are:

[0028] This invention, by adding specific types and amounts of modifiers during the sublimation process, enables impurities to be firmly fixed in the solid residue through intermolecular forces such as coordination complexation, hydrogen bonding, and physical adsorption. This allows for the acquisition of high-purity products with only one or two sublimation cycles, overturning the traditional understanding that the purification of solid metal precursors must rely on a combination of recrystallization and sublimation. Furthermore, by combining low-temperature sublimation process parameters, it can effectively separate tantalum-based solid metal precursors from various impurities, especially difficult-to-remove water, oxygen, and organic impurities, effectively eliminating the adverse effects of oily water, oxygen, and organic impurities on the sublimation of the product into the gas phase. Results show that the purification method of this application achieves a yield of over 75%, even exceeding 90%, significantly better than the yield levels of existing technologies (generally below 50%), making it suitable for large-scale production.

[0029] The purification method of the present invention can reduce the content of organic impurities generated by water and oxygen to below 0.1%, achieving an organic purity of ≥99.5% and a metal purity of ≥99.9999%, which can meet the stringent requirements of advanced semiconductor and other fields for ultra-high purity precursors.

[0030] This invention requires only two sublimation steps, eliminating the need for complex recrystallization, solvent treatment, or multi-step adsorption processes found in traditional technologies. It avoids cumbersome steps such as low-temperature crystallization, large-volume solvent use, and waste liquid treatment. The addition of a modifier effectively reduces the impact of byproducts on sublimation efficiency, prevents product decomposition due to prolonged heating, and ensures good process reproducibility and ease of industrial scale-up. Attached Figure Description

[0031] Figure 1 In the examples, crude PDMAT... 1H NMR spectrum.

[0032] Figure 2 The pure PDMAT in Example 1 1 H NMR spectrum.

[0033] Figure 3 : Pure PDMAT in Comparative Example 1 1 H NMR spectrum. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] A method for purifying a solid metal precursor includes the following steps: adding an auxiliary agent to the crude solid metal precursor and sublimating it at a temperature of ≤150℃ to obtain a pure product.

[0036] Furthermore, the solid metal precursor is an alkylamine metal precursor.

[0037] Preferably, the solid metal precursor is penta(dialkylamino)tantalum, wherein the alkyl group has 1-5 carbon atoms. Optional examples of solid metal precursors include, but are not limited to, penta(dimethylamino)tantalum, penta(diethylamino)tantalum, penta(dipropylamino)tantalum, and penta(methylethylamino)tantalum. Preferably, the solid metal precursor is penta(dimethylamino)tantalum (PDMAT) or penta(methylethylamino)tantalum (PEMAT).

[0038] Furthermore, the boiling point of the additive is ≥250℃ at atmospheric pressure (760 mmHg). The additive is a high-boiling-point substance, which is not easily sublimated and volatilized, thus avoiding contamination of the pure product. Preferably, the boiling point of the additive is at least 120℃ higher than the boiling point of the solid metal precursor, more preferably at least 150℃ higher. In a preferred embodiment, the boiling point of the additive is at least 200℃ higher than the boiling point of the solid metal precursor. In another preferred embodiment, the boiling point of the additive is at least 300℃ higher than the boiling point of the solid metal precursor. Specifying the boiling point difference between the additive and the solid metal precursor ensures that no additive evaporates simultaneously with the product at low sublimation temperatures and pressures.

[0039] Furthermore, during the sublimation process, the additive generates intermolecular forces with at least one organic impurity in the crude solid metal precursor, thereby promoting the separation of the organic impurity from the solid metal precursor.

[0040] Furthermore, the structure of the organic impurity includes at least one of MO bond, MON bond, and MOM bond, where M is a metal atom of the solid metal precursor, specifically, M is tantalum (Ta). Taking PDMAT as an example, trace amounts of water and oxygen are unavoidably encountered during the synthesis of PDMAT, resulting in a small amount of organic impurities. Exemplary structures of some organic impurities are shown in the following chemical formulas (I) to (III): Chemical formula (Ⅰ): ; Chemical formula (II): ; Chemical formula (Ⅲ): ; The organic impurities, when mixed with PDMAT, exhibit an oily morphology. This not only encapsulates the PDMAT, affecting its extraction, but also, due to their similar boiling points, they readily sublimate and escape simultaneously with PDMAT, leading to poor PDMAT purification efficiency, low purification yield, and low product purity. When the additive described in this application is used, the additive generates stronger intermolecular forces (including electrostatic adsorption, hydrogen bonding, and coordination complexation) with the electron-containing element O (derived from MO bonds, MON bonds, MOM bonds, etc.) in the organic impurities (compared to those with PDMAT). These intermolecular forces firmly bind and fix various impurities in the solid residue, significantly reducing their saturated vapor pressure and volatilization migration ability, making them difficult to sublimate simultaneously with the gas phase. Simultaneously, the low-temperature, non-sublimation characteristic of the additive allows for the retention of the organic impurities within it. When heated, PDMAT has a stable and suitable saturated vapor pressure. Under the set temperature and pressure conditions, it can be smoothly vaporized into gaseous molecules, which migrate directionally to the condenser end to crystallize and precipitate. This achieves the gas-phase sublimation and enrichment of high-purity PDMAT components and the solid-phase retention and separation of harmful impurities, thereby achieving the purpose of deep purification and reducing the content of metal and organic impurities.

[0041] Further, the additive includes at least one of alcohol ethers, aromatic ethers, aromatic hydrocarbons, and C12-C32 alkylamines; preferably, the additive includes at least one of tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, triethylene glycol monoethyl ether, diethylene glycol hexyl ether, polyethylene glycol dimethyl ether, diphenyl ether, dibenzyl ether, benzylphenyl ether, 3-methyl diphenyl ether, biphenyl-biphenyl ether azeotropic mixture, biphenyl, n-dodecylbenzene, and C12-C32 alkylamines.

[0042] In one embodiment, the adjuvant includes at least one of tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, triethylene glycol monoethyl ether, diethylene glycol hexyl ether, diphenyl ether, dibenzyl ether, benzylphenyl ether, 3-methyl diphenyl ether, and at least one of C12-C32 alkylamines.

[0043] Further, the C12-C32 alkylamines include, but are not limited to, at least one of the following: n-dodecylamine, n-tetrazine, n-tetradecylamine, n-pentadecanylamine, n-hexadecylamine, n-heptadecylamine, n-heptadecylamine, n-octadecylamine, n-octadecylamine, n-octadecylamine, n-nonadecanylamine, n-eicosylamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, 1,18-octadecanediamine, 1,20-eicosyldiamine, tri(dodecyl)amine, tri(hexadecyl)amine, a mixture of tri(C14-C18)alkylamines, trioctylamine, tri-nonylamine, and tri-decylamine; preferably, the adjuvants include C19-C32 alkylamines.

[0044] Further, the amount of the additive accounts for 1-25% of the crude solid metal precursor mass, preferably 5-20%; in one embodiment, the amount of the additive accounts for 15-20% of the crude solid metal precursor mass.

[0045] Further, the sublimation temperature is ≤100℃, and the sublimation pressure is 0.01-100Pa. Preferably, the sublimation temperature is 40-100℃, and the sublimation pressure is 0.01-100Pa. In one embodiment, the sublimation temperature is 40-70℃, and the sublimation pressure is 1-20Pa.

[0046] Further, in the purification method, the sublimation is performed once, twice, or multiple times. Preferably, the sublimation is performed twice or multiple times, and the auxiliary agent is added during the first sublimation of the solid metal precursor. In one embodiment, the sublimation is performed twice, and the auxiliary agent is added during the first sublimation of the solid metal precursor, while no auxiliary agent is added during the second sublimation. In one embodiment, the sublimation is performed three times, and the auxiliary agent is added during the first sublimation of the solid metal precursor, while no auxiliary agent is added during the second and third sublimation. In one embodiment, the sublimation is performed three times, and the auxiliary agent is added during the first and second sublimation of the solid metal precursor, while no auxiliary agent is added during the third sublimation.

[0047] Furthermore, the sublimation is performed two or more times. The first sublimation is performed at a sublimation temperature of 40-99℃ and a sublimation pressure of 0.01-100 Pa. The second or subsequent sublimations are performed at a sublimation temperature of 40-60℃ and a sublimation pressure of 1-40 Pa. Multiple sublimations are more conducive to improving product purity, and the number of sublimations can be adjusted according to the required product purity.

[0048] In one embodiment, the sublimation is performed twice. The first sublimation is performed at a sublimation temperature of 50-70°C and a sublimation pressure of 1-10 Pa. The second or subsequent sublimation is performed at a sublimation temperature of 40-60°C and a sublimation pressure of 1-20 Pa.

[0049] Furthermore, the sublimation is carried out in an environment with an oxygen content of <1 ppm and a water content of <0.01 ppm. To minimize the impact of product contact with water and oxygen on the sublimation process, the oxygen and water content in the sublimation environment should be controlled at low levels.

[0050] Furthermore, the particle size of the crude solid metal precursor powder is not less than 40 mesh; grinding the crude solid metal precursor before sublimation obtains raw material powder with more uniform particle size and smaller dimensions, thereby avoiding localized excessive temperature and uneven sublimation of the product. Preferably, the particle size of the crude solid metal precursor powder is not less than 50 mesh, and exemplary particle sizes of the crude solid metal precursor powder include 50 mesh, 75 mesh, 80 mesh, 100 mesh, 120 mesh, 150 mesh, and 170 mesh.

[0051] Furthermore, the content of organic impurities generated by water and oxygen in the crude solid metal precursor is ≤30%, preferably ≤25%. Unless otherwise specified, the content of organic impurities mentioned in this application is determined by proton nuclear magnetic resonance spectroscopy (NMR). 1 According to H NMR (hydrogen spectroscopy) tests, organic impurities generated by water oxygen in [the following is a possible interpretation]: 1 The chemical shifts on the H NMR spectrum are approximately 3.98-3.28 ppm, 3.19 ppm, and 2.11 ppm. Their contents can be calculated based on the proportion of the peak area corresponding to the above chemical shifts to the total peak area of ​​all hydrogen components (excluding the hydrogen peak area of ​​the deuterated reagent).

[0052] A solid metal precursor, which is a pure product prepared according to the above purification method, wherein the content of organic impurities generated by water and oxygen is <0.1%.

[0053] Furthermore, the solid metal precursor is penta(dialkylamino)tantalum, wherein the alkyl group has 1-5 carbon atoms. Optional examples of solid metal precursors include, but are not limited to, penta(dimethylamino)tantalum, penta(diethylamino)tantalum, penta(dipropylamino)tantalum, and penta(methylethylamino)tantalum.

[0054] In one embodiment, the solid metal precursor is pentapentan(dimethylamino)tantalum or pentapentan(methylethylamino)tantalum.

[0055] Furthermore, the organic purity of the solid metal precursor is ≥99.5%; the organic purity is determined by... 1 Obtained by H NMR testing.

[0056] Furthermore, the metal purity of the solid metal precursor is ≥99.9999%; the metal purity is measured by ICP-MS / MS and ICP-MS.

[0057] In the following examples and comparative examples, the present invention does not impose any particular limitation on the use of crude penta(dimethylamino)tantalum, including penta(dimethylamino)tantalum prepared by known methods or commercially available penta(dimethylamino)tantalum.

[0058] Example 1

[0059] This embodiment provides a purification method for penta(dimethylamino)tantalum (PDMAT), including the following steps:

[0060] S1. In a glove box with oxygen content <1ppm and water content <0.01ppm, grind 300g of crude PDMAT into a 50-mesh powder using a mortar and pestle, and evenly place it into the crude product receiving end of the sublimator. 1 According to H NMR analysis, the organic purity of crude PDMAT was 79.97%, and the content of organic impurities produced by water and oxygen was 20.03%.

[0061] S2. Add 20% (by weight of crude PDMAT) of tetratetramine to S1 and mix thoroughly; sublimate at 65°C and 15 Pa for 4 hours to obtain 216g of the first-sublimation product. 1 ¹H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first sublimation product was 0.49%.

[0062] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 50°C and 1 Pa for 6 hours to obtain 213g of pure product. The calculated yield was 88.8%. 1 H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was less than 0.1%.

[0063] Process yield = {pure product mass / [crude product mass * (1 - content of organic impurities produced by water and oxygen)]} * 100%.

[0064] Appendix Figure 1 For crude PDMAT 1 The 1H NMR spectrum shows that the organic impurity peaks generated by water and oxygen in the crude product appear at chemical shifts of 3.98 ppm, 3.42 ppm, 3.30 ppm, 3.19 ppm, 3.28 ppm and 2.11 ppm.

[0065] Appendix Figure 2 This is the purified PDMAT product from this embodiment. 1 H NMR spectrum, attached Figure 2The sample showed only a methyl hydrogen peak at 3.26 ppm, with no other obvious impurity peaks. This comparison demonstrates that the purification method in Example 1 of this application can essentially completely remove water, oxygen, and organic impurities that are difficult to remove with ordinary sublimation.

[0066] Example 2

[0067] This embodiment provides a method for purifying PDMAT, including the following steps:

[0068] S1, Same as in Example 1.

[0069] S2. Add 10% (by weight of crude PDMAT) of tetratetramine to S1 and mix thoroughly; sublimate at 65°C and 15 Pa for 4 hours to obtain 209 g of the first-sublimation product. 1 H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first sublimation product was 0.57%.

[0070] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 50°C and 1 Pa for 6 hours to obtain 198.9 g of pure product. The calculated yield was 82.9%. 1 H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was less than 0.1%.

[0071] Example 3

[0072] This embodiment provides a method for purifying PDMAT, including the following steps:

[0073] S1, Same as in Example 1.

[0074] S2. Add 20% (by weight of crude PDMAT) of tetratetramine and tetraethylene glycol dimethyl ether (mass ratio 3:1) to S1, mix thoroughly, and sublimate at 65°C and 15 Pa for 4 hours to obtain 221g of the first-sublimation product. 1 ¹H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first-sublimation product was 0.31%.

[0075] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 50°C and 1 Pa for 6 hours to obtain 219.26 g of pure product. The calculated yield was 91.40%. 1 H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was less than 0.1%.

[0076] Example 4

[0077] This embodiment provides a method for purifying PDMAT, including the following steps:

[0078] S1, Same as in Example 1.

[0079] S2. Add tetraethylene glycol dimethyl ether at 20% of the crude PDMAT mass to S1 and mix thoroughly; sublimate at 65℃ and 15Pa for 4 hours to obtain 192g of the first-sublimation product. 1 ¹H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first sublimation product was 0.67%.

[0080] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 50°C and 1 Pa for 6 hours to obtain 180.1 g of pure product. The calculated yield was 75.1%. 1 H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was less than 0.1%.

[0081] Example 5

[0082] This embodiment provides a method for purifying PDMAT, including the following steps:

[0083] S1, Same as in Example 1.

[0084] S2. Add 25% (by weight of crude PDMAT) of n-nonadecanine and tetraethylene glycol diethyl ether (mass ratio 4:1) to S1, mix thoroughly, and sublimate at 50°C and 10 Pa for 8 hours to obtain 225g of the single-sublimation product. 1 ¹H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first sublimation product was 0.64%.

[0085] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 40°C and 20 Pa for 8 hours to obtain 214 g of pure product. The calculated yield was 89.2%. 1 H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was less than 0.1%.

[0086] Example 6

[0087] This embodiment provides a method for purifying PDMAT, including the following steps:

[0088] S1, Same as in Example 1.

[0089] S2. Add 5% (by weight of crude PDMAT) of tri-n-decylamine to S1 and mix thoroughly; sublimate at 65°C and 15 Pa for 4 hours to obtain 208 g of the first-sublimation product. 1 H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first sublimation product was 0.71%.

[0090] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 50°C and 1 Pa for 6 hours to obtain 192.4 g of pure product. The calculated yield was 80.2%. 1 H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was less than 0.1%.

[0091] Comparative Example 1

[0092] This comparative example provides a method for purifying PDMAT, including the following steps:

[0093] S1, Same as in Example 1.

[0094] S2. Sublimation was carried out at 90℃ and 10Pa for 4 hours to obtain 145g of the single-sublimation product. 1 H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first sublimation product was 18.9%.

[0095] S3. The sublimation product from S2 was placed back into the sublimator and sublimated at 40°C and 1 Pa for 6 hours to obtain 134g of pure product. The calculated yield was 55.8%. 1H NMR analysis showed that the content of organic impurities generated by water and oxygen in the pure product was 12.3%.

[0096] Comparative Example 1, without using any additives, adaptively increased the primary sublimation temperature and decreased the primary sublimation pressure. However, its process yield was far lower than any of the embodiments in this application, and even after two sublimation processes, it could not completely remove organic impurities caused by trace amounts of water and oxygen in the product. (Appendix) Figure 3 For this comparative example, pure PDMAT 1 The 1H NMR spectrum shows peaks with chemical shifts of 3.99 ppm and 3.30 ppm, which are organic impurity peaks produced by water and oxygen.

[0097] Comparative Example 2

[0098] This comparative example provides a method for purifying PDMAT, including the following steps:

[0099] S1, Same as in Example 1.

[0100] S2. Sublimation was carried out at 80℃ and 1Pa for 4 hours to obtain 137g of the single-sublimation product. 1 ¹H NMR analysis showed that the content of organic impurities generated by water and oxygen in the first-sublimation product was 15.7%.

[0101] S3. The sublimated product from S2 was placed back into the sublimator and sublimated at 40°C and 1 Pa for 6 hours to obtain 129g of pure product. The calculated yield was 53.8%. 1H NMR testing showed that the content of organic impurities produced by water and oxygen in the pure product was 11.5%.

[0102] Comparative Example 3

[0103] The process is basically the same as in Example 1, except that tetratetramine was not added in S2, and 116g of the first sublimation product was obtained; the second sublimation yielded 103g of pure PDMAT. The calculated process yield was 42.9%, and the content of organic impurities generated by water and oxygen in the pure product was 10.2%.

[0104] Based on the experimental data of Comparative Examples 1-3, it can be demonstrated that no matter how the sublimation process is adjusted, a single sublimation process cannot completely remove organic impurities caused by trace amounts of water and oxygen in the product, and the yield of the sublimation process is also relatively poor, which cannot meet the needs of large-scale production.

[0105] Comparative Example 4

[0106] The process is basically the same as in Example 1, except that n-tetratetramine in S2 is replaced with n-dodecane, and 132g of the first sublimation product is obtained by sublimation; 120g of pure PDMAT product is obtained by second sublimation. The calculated process yield is 50.0%, and the content of organic impurities generated by water and oxygen in the pure product is 8.2%.

[0107] In Comparative Example 4, n-dodecane, which has a low boiling point and cannot selectively generate intermolecular forces with organic impurities, was used as an additive. Based on the test results, it is speculated that the addition of n-dodecane has a very weak improvement on the sublimation state, but this improvement is not enough to effectively remove organic impurities generated by water and oxygen in the product.

[0108] Comparative Example 5

[0109] The process is basically the same as in Example 1, except that the tetratetramine in S2 is replaced with dimethyl ethylene glycol ether. Sublimation yields 196.5g of the first sublimation product; secondary sublimation yields 173.4g of pure PDMAT. The calculated process yield is 72.3%, and the content of organic impurities generated by water and oxygen in the pure product is 10.5%.

[0110] In Comparative Example 5, ethylene glycol dimethyl ether, which has a relatively low boiling point, was used. During sublimation, it was found that it was released along with the product, resulting in poor product purity and sublimation yield.

[0111] Comparative Example 6

[0112] This comparative example provides a method for purifying PDMAT, including the following steps:

[0113] S1. In a glove box with oxygen content <1ppm and water content <0.01ppm, 300g of crude PDMAT (consistent with the crude product in Example 1) was dissolved in 300g of n-hexane at room temperature; crystallization was slowly precipitated by gradient cooling (-20 to 0℃), filtered, and the filter cake was dried to obtain 114g of recrystallized product. The content of impurities caused by water and oxygen in the crystallized product was 1.04% as determined by 1H NMR.

[0114] S2. The recrystallized product was placed in a sublimator and sublimated at 40°C and 1 Pa for 6 hours to obtain 102.2 g of product. The calculated process yield was 42.6%. 1 According to H NMR testing, the impurity content generated by water and oxygen in the product is 0.33%.

[0115] Comparative Example 6 uses a purification scheme commonly used in the prior art, namely recrystallization followed by sublimation. According to the test results, the above scheme has inherent defects in the recrystallization method, resulting in a very low purification yield, and the method still cannot completely remove difficult-to-remove water, oxygen and organic impurities.

[0116] Based on the purification results of Examples 1-6 of this application, it can be seen that by introducing an auxiliary agent with a boiling point ≥250℃ during the sublimation process, and utilizing the intermolecular forces between the auxiliary agent and organic impurities, metal ions, organic residues, etc. (generated by water and oxygen) in the product, as well as the low-temperature non-sublimation characteristic of the auxiliary agent, and further combined with the low-temperature sublimation process, the separation of the organic impurities from the product can be basically completely achieved. In the prepared pure product, the content of organic impurities generated by water and oxygen is less than 0.1%, the organic purity of the pure product is ≥99.5%, the metal purity reaches 6N and above (≥99.9999%), and the process yield can reach more than 90%, which can be used for industrial purification.

[0117] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0118] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of purifying a solid-state metal precursor, characterized by, Includes the following steps: Adding an auxiliary agent to a crude solid metal precursor and sublimating it at a temperature ≤150℃ yields a pure product; the boiling point of the auxiliary agent is ≥250℃ under normal pressure, and during the sublimation process, it generates intermolecular forces with at least one organic impurity in the crude solid metal precursor, thereby promoting the separation of the organic impurity from the solid metal precursor. The solid metal precursor is penta(dialkylamino)tantalum, wherein the alkyl group has 1-5 carbon atoms; The auxiliary agent is at least one selected from tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, triethylene glycol monoethyl ether, diethylene glycol hexyl ether, and C12-C32 alkylamines; The C12-C32 alkylamines are at least one of the following: n-dodecylamine, n-tetrazine, n-tetradecylamine, n-pentadecanylamine, n-hexadecylamine, n-heptadecylamine, n-heptadecylamine, n-octadecylamine, n-octadecylamine, n-octadecylamine, n-nonadecanylamine, n-eicosylamine, n-eicosylamine, n-eicosylamine, n-eicosylamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, 1,18-octadecanediamine, 1,20-eicosyldiamine, tri(dodecyl)amine, tri(hexadecyl)amine, trioctylamine, tri-nonylamine, and tri-decylamine.

2. The purification method according to claim 1, characterized in that, The structure of the organic impurity includes at least one of MO bond, MON bond, and MOM bond, where M is a metal atom of the solid metal precursor. And / or, sublimation temperature ≤100℃; And / or, the sublimation pressure is 0.01-100 Pa; And / or, the amount of the additive is 1-25% of the crude mass of the solid metal precursor.

3. The purification method according to claim 1, characterized in that, The sublimation temperature is 40-100℃, and the sublimation pressure is 0.01-100Pa.

4. The purification method according to claim 1, characterized in that, The amount of the additive is 5-20% of the crude mass of the solid metal precursor.

5. The purification method according to claim 1, characterized in that, The amount of the additive is 15-20% of the crude solid metal precursor. And / or, the adjuvant is at least one of tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, triethylene glycol monoethyl ether, diethylene glycol hexyl ether, and at least one of C12-C32 alkylamines.

6. The purification method according to claim 1, characterized in that, The sublimation may be performed once, twice, or more; And / or, when two or more sublimations are performed, the additive is added during the first sublimation process of the solid metal precursor; And / or, the sublimation temperature for the first sublimation is 40-99℃ and the sublimation pressure is 0.01-100Pa, and the sublimation temperature for the second or subsequent sublimations is 40-60℃ and the sublimation pressure is 1-40Pa.

7. The purification method according to claim 1, characterized in that, The solid metal precursor is pentapenta(dimethylamino)tantalum or pentapenta(methylethylamino)tantalum; And / or, the particle size of the coarse solid metal precursor powder is not less than 40 mesh; And / or, the content of organic impurities generated by water and oxygen in the crude solid metal precursor is ≤30%; And / or, the sublimation temperature is 40-70℃, and the sublimation pressure is 1-20Pa.

8. The purification method according to any one of claims 1-7, characterized in that, The sublimation was carried out in an environment with an oxygen content of <1 ppm and a water content of <0.01 ppm.

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