Process for the preparation of low lithium content amidinate metal complexes

Abstract

The application relates to a preparation method of an amidine metal complex with low lithium content, and belongs to the technical field of chemical synthesis. The preparation method comprises the following steps: S1, under a protective atmosphere, a solvent is added into a potassium source to obtain a potassium source solution; S2, an amidine-based compound is added dropwise into the potassium source solution in S1 at-78 DEG C to-30 DEG C, and a reaction liquid is obtained through reaction; S3, a metal halide is added into the reaction liquid in S2 at-78 DEG C to-30 DEG C, and a mixed liquid is obtained through reaction; and S4, the mixed liquid in S3 is subjected to product collection, and the amidine metal complex with low lithium content is obtained. The preparation method replaces an organic lithium reagent with a potassium source, controls the introduction of product metal lithium impurities from the source, greatly reduces the purification difficulty and cost, is favorable for obtaining an ALD precursor source product with high purity, is favorable for growing a high-quality thin film with nanometer thickness through an atomic layer deposition technology, and meets the requirements of an ALD precursor preparation process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical synthesis, and particularly relates to a preparation method of an amidine metal complex with low lithium content. BACKGROUND

[0002] The amidine group is a kind of compound with an N=C-N skeleton, and the two bonds can be interchanged through resonance forms, resulting in the formation of a delocalized conjugated system, so that the H atom connected to N has certain acidity. The amidine ligand is a single negative charge ligand, which can be generated by deprotonation of the corresponding precursor amidine compound, and is a kind of diverse ligand. The N=C-N skeleton is conjugated, and the delocalization of the double bond and the negative charge promotes the formation of the Π3 4 system. On the other hand, the three substituents on the skeleton can be exchanged, which greatly adjusts the steric hindrance effect and charge effect of the ligand. Through this means, this kind of conjugated chelated ligand can be combined with almost all metal elements in the periodic table.

[0003] The amidine metal complex has low activity and low melting point, and is an important ALD precursor source. For example, bis (N, N-diisopropylacetamidine) cobalt (II) has a melting point of 84℃; bis (N, N-diisopropylacetamidine) calcium (II) dimer has a melting point of 110℃-116℃; bis (N, N-di-tert-butylacetamidine) iron (II) has a melting point of 107℃; and bis (N, N-di-tert-butylacetamidine) nickel (II) has a melting point of 95℃-96℃. The unique physical and chemical properties determine that the amidine metal compound has a broad application prospect in ALD application.

[0004] The most common synthesis method of the amidine metal compound is the reaction of lithiated amidine group with metal halide to generate the amidine metal compound and lithium halide salt. Due to the low reactivity of the amidine lithium compound, the reaction is incomplete, and the generated lithium halide salt has weak metallicity, which makes the lithium impurity more exist in the form of covalent compound, relatively easy to volatilize and dissolve, and easy to transfer in the product purification process and difficult to remove, which will affect the purity of the product. The amidine metal compound prepared by using this method usually contains more than 50ppm of metal lithium impurity. Using this product for ALD deposition process will cause a large amount of lithium impurity to enter the semiconductor device, and since the lithium atom has a small size, it is easy to move in the semiconductor device, causing damage to the electrical performance of the semiconductor device. Therefore, when preparing the ALD precursor source material, the introduction of lithium impurity should be avoided as much as possible.

[0005] The traditional preparation method of metal amidinate complex is exemplified by the preparation method of bis(N,N-di-isopropylacetamidinate) cobalt (II). N,N-di-isopropylcarbodiimide is first reacted with methyllithium to synthesize N,N-di-isopropylacetamidinate lithium, and then the N,N-di-isopropylacetamidinate lithium is reacted with cobalt dichloride to obtain bis(N,N-di-isopropylacetamidinate) cobalt (II) and lithium chloride salt. The problems of this method are: first, a large amount of organic lithium reagent is introduced in the reaction process; second, the activity of methyllithium and N,N-di-isopropylacetamidinate lithium is relatively low, and there is incomplete reaction in the reaction process of N,N-di-isopropylcarbodiimide and metal halide, which leads to low yield, and it is difficult to separate because the chemical properties of them are close to the product; third, a small amount of impurities is dissolved in the organic solvent because the size of lithium chloride is small; fourth, the metal lithium has weak metallicity, which makes the lithium impurities exist in the form of covalent compound, and it is relatively easy to volatilize, and it is easy to mix in the product during the purification process of the product, and it is difficult to remove.

[0006] The atomic layer deposition process is usually applied in the field of advanced chip process. As a precursor raw material, part of the metal amidinate compound will enter the chip, and these lithium impurities will also enter the chip. As known, lithium will seriously damage the electrical properties of the semiconductor and reduce the yield of the chip. Therefore, it is necessary to develop a preparation process of ALD precursor metal amidinate complex with low lithium content. SUMMARY

[0007] To solve the above technical problems, the present application provides a preparation method of metal amidinate complex with low lithium content. An optimized process of one-pot preparation at low temperature by using a high-activity potassium source raw material instead of organic lithium reagent is proposed. The activity of the potassium source is higher than that of lithium, and the activity of the generated amidinate potassium complex is also higher than that of the amidinate lithium complex, so there is no incomplete reaction phenomenon. The size of the generated potassium chloride is larger than that of lithium chloride, and it is an ionic compound, which is easier to form a precipitate and has a small solubility in an organic solvent. The potassium salt usually exists in the form of ionic compound, which is difficult to volatilize and is easier to be distinguished from the product, and will not contaminate the product with potassium.

[0008] The purpose of the present application is to provide a preparation method of metal amidinate complex with low lithium content, which comprises the following steps,

[0009] S1, under a protective atmosphere, a potassium source is added with a solvent to obtain a potassium source solution;

[0010] S2, at-78℃ to-30℃, an amidinate compound is added dropwise into the potassium source solution of S1 to obtain a reaction liquid;

[0011] S3, at-78℃ to-30℃, a metal halide is added into the reaction liquid of S2 to obtain a mixed liquid;

[0012] S4, collecting the product from the mixture prepared in S3 to obtain the amidine metal complex with low lithium content.

[0013] In an embodiment of the present application, since the raw materials and products are prone to react with water and oxygen, the whole preparation process is carried out in a protective atmosphere to protect the raw materials and target products from being destroyed by any water and oxygen in the reaction system.

[0014] Further, the protective atmosphere includes but is not limited to nitrogen atmosphere and inert gas atmosphere.

[0015] In an embodiment of the present application, in S1, the potassium source includes but is not limited to one or more of potassium carbide, potassium hydride and organometallic potassium.

[0016] Further, the potassium carbide is a dispersion of metallic potassium with carbon as the carrier, i.e., carbon octapotassium KC8, which has a specific structure. When the number of carbon atoms is 8, it appears golden yellow and is a high-activity solid substance that burns quickly in air. It is used in a glove box.

[0017] Further, KC8 and potassium hydride are inorganic metal potassium sources and are not dissolved in any ether solvent. Therefore, KC8 and potassium hydride must be weighed into a reaction bottle in a glove box before the solvent is added.

[0018] In an embodiment of the present application, the organometallic potassium includes but is not limited to one or more of potassium bis(trimethylsilyl)amide, potassium dimethylamide, potassium diisopropylamide (CAS: 67459-71-6) and potassium diethylamide (CAS: 2245-68-3).

[0019] Further, the potassium bis(trimethylsilyl)amide is dissolved in any ether solvent, and the order does not affect.

[0020] Further, the potassium dimethylamide can be dissolved in tetrahydrofuran, but cannot be dissolved in diethyl ether and ethylene glycol dimethyl ether.

[0021] In an embodiment of the present application, in S1, the solvent includes but is not limited to one or more of tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether and 1,4-dioxane.

[0022] In an embodiment of the present application, in S2, the amidine-based compound includes but is not limited to one or more of N,N-diisopropylacetamidine, N,N-di-tert-butylpropylacetamidine, N,N-diisopropylformamidine and N,N-diisopropylvaleramide.

[0023] In one embodiment of the present application, in S3, the metal halide includes, but is not limited to, one or more of cobalt dichloride, ferrous chloride, calcium chloride, and nickel bromide.

[0024] In one embodiment of the present application, in S3, the metal halide is added to the reaction system through a solid sample injector, and other solvents such as tetrahydrofuran, diethyl ether, toluene, etc. can be used for dissolution or preparation of a suspension before being added to the reaction system, which is also within the protection scope of the present application; or the amidine potassium complex in the reaction bottle is added to the metal halide system, which is also within the protection scope of the present application.

[0025] In one embodiment of the present application, in S2 and S3, after the amidine compound and the metal halide are introduced, the reaction is continuously stirred at room temperature until the reaction is completed.

[0026] In one embodiment of the present application, the time for continuously stirring the reaction in S2 is 2h-4h; and the time for continuously stirring the reaction in S3 is 8h-12h.

[0027] In one embodiment of the present application, the molar ratio of the potassium source, the amidine compound, and the metal halide is 2-2.5:2-2.5:1.

[0028] In one embodiment of the present application, in S4, the product is collected by removing the solvent under vacuum, adding a solvent to the mixture and shaking it thoroughly, then filtering through diatomite, washing with an organic solvent, collecting the filtrate, and drying the filtrate to obtain the product.

[0029] In one embodiment of the present application, the organic solvent includes, but is not limited to, one or more of n-hexane, n-pentane, n-heptane, toluene, and diethyl ether.

[0030] In one embodiment of the present application, in S4, after the product is collected, a step of purifying the amidine metal complex by sublimation under reduced pressure or recrystallization is further included; the temperature for sublimation under reduced pressure is 75℃-120℃, and the vacuum degree is 0.5Torr-0.8Torr; the organic solvent used for recrystallization includes, but is not limited to, one or more of n-hexane, toluene, and diethyl ether.

[0031] The technical solution of the present application has the following advantages compared with the prior art:

[0032] (1) The preparation method of the present application uses a potassium source instead of an organic lithium reagent, which controls the introduction of product metal lithium impurities from the source, greatly reduces the purification difficulty and cost, is conducive to obtaining high-purity ALD precursor source products, and is conducive to growing nanometer-thickness high-quality thin films through atomic layer deposition technology, which meets the requirements of the ALD precursor preparation process.

[0033] (2) The preparation method generates potassium chloride, which has stronger metallicity than lithium chloride, and the size of potassium chloride is relatively large. The outermost electron number of potassium ion and chloride ion is 8, and there are 3 layers of electron number, which is combined relatively firmly, usually exists in the form of ionic compound, is difficult to volatilize, and is more easily distinguished from the product, and does not bring potassium pollution to the product.

[0034] (3) The preparation method improves the reaction activity of the compound, makes the reaction thorough, reduces the influence of raw materials, and improves the product yield.

[0035] (4) The preparation method uses raw materials with wide sources and low cost, and the target product is obtained by one-pot method. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments of the present application and in combination with the drawings, in which:

[0037] Figure 1 Process flow chart of the low lithium content amidine metal complex of embodiment 1 of the present application;

[0038] Figure 2 NMR spectrum of bis (N, N-diisopropylethyl amidine) cobalt (II) prepared in embodiment 1 of the present application;

[0039] Figure 3 NMR spectrum of bis (N, N-di-tert-butylethyl amidine) nickel (II) prepared in embodiment 5 of the present application;

[0040] Figure 4 NMR spectrum of bis (N, N-di-tert-butylethyl amidine) iron (II) prepared in embodiment 6 of the present application. DETAILED DESCRIPTION

[0041] The present application will be further described below in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the present application and implement it, but the embodiments are not limiting to the present application.

[0042] In the present application, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as understood by those skilled in the art to which the present application belongs.

[0043] In the present application, unless otherwise specified, the term "and / or" used in the present application includes any and all combinations of one or more related listed items.

[0044] In the present application, unless otherwise specified, the experimental methods used in the embodiments of the present application are conventional methods, and the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0045] Example 1

[0046] Referring to Figure 1 The preparation method of the low-lithium-content metal amidine complex of the present application specifically comprises the following steps:

[0047] In a glove box, the reactant KC8 (13.5 g, 0.1 moL) was added to a 500 mL reaction bottle, and tetrahydrofuran (300 mL) was added under nitrogen protection (using double-tube). The reaction bottle was placed in a cold bath at -78°C. N,N-diisopropylacetamidine (CAS: 106500-93-0) (14.24 g, 0.1 moL) was slowly added dropwise to the reaction bottle, and after the addition was completed, it was slowly restored to room temperature and stirred for 3 h. The reaction bottle was placed in a cold bath at -78°C. Solid sample was used to slowly add cobalt dichloride (6.49 g, 0.05 moL) to the reaction bottle, and after the addition was completed, it was slowly restored to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and it was shaken thoroughly. Filtration was performed on diatomite, and n-hexane (50 mL) was used for washing. The filtrate was collected and the filtrate was dried to obtain a crude product. After the crude product was subjected to reduced pressure sublimation (85°C, 0.5 Torr), a green solid product bis(N,N-diisopropylacetamidinate) cobalt (II) (CAS: 635680-58-9) (14.51 g, 0.0425 moL) was obtained, and the yield was 85%.

[0048] The sample was characterized by nuclear magnetic resonance, and the results are shown in Figure 2 The nuclear magnetic resonance results are as follows: 1 H-NMR (C6D6, 400, MHz, 298K): δ (ppm) = 330.28 (br, 4H), 304.32 (br, 6H), -70.55 (br, 24H).

[0049] The product purity was detected by inductively coupled plasma mass spectrometry (ICP-MS), and the results showed that the metal purity of the product was 5N (ICP-MS): Li (402.011 ppb), Na (30.66 ppb), K (33.22 ppb), Mg (60.978 ppb), Ca (27.316 ppb).

[0050] Example 2

[0051] The preparation method of the low-lithium-content metal amidine complex of the present application specifically comprises the following steps:

[0052] In a glove box, reactant KC8 (13.5 g, 0.1 moL) was added to a 500 mL reaction flask, tetrahydrofuran (300 mL) was added under nitrogen protection (double-tube was used), and stirred uniformly. The reaction flask was placed in a cold bath at -78 °C. N,N-diisopropylethylamine (CAS: 106500-93-0) (17.07 g, 0.12 moL) was slowly added dropwise to the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 3 h. The reaction flask was placed in a cold bath at -78 °C. Solid sample was used to slowly add cobalt dichloride (6.49 g, 0.05 moL) to the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and shaken thoroughly. Filtration was performed on diatomite, washed with n-hexane (50 mL), the filtrate was collected, and the filtrate was dried to obtain a crude product. After the crude product was sublimed under reduced pressure (85 °C, 0.5 Torr), green solid product bis(N,N-diisopropylethylamino) cobalt (II) (CAS: 635680-58-9) (14.68 g, 0.043 moL) was obtained, and the yield was 86%.

[0053] Metal purity: 5N.

[0054] Example 3

[0055] The preparation method of the low-lithium-content amidine metal complex of the present application specifically comprises the following steps:

[0056] In a glove box, reactant KC8 (13.5 g, 0.1 moL) was added to a 500 mL reaction flask, tetrahydrofuran (300 mL) was added under nitrogen protection (double-tube was used), and stirred uniformly. The reaction flask was placed in a cold bath at -78 °C. N,N-diisopropylethylamine (CAS: 106500-93-0) (17.07 g, 0.12 moL) was slowly added dropwise to the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 3 h. The reaction flask was placed in a cold bath at -78 °C. Solid sample was used to slowly add cobalt dichloride (6.49 g, 0.05 moL) to the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and shaken thoroughly. Filtration was performed on diatomite, washed with n-hexane (50 mL), the filtrate was collected, and the filtrate was dried to obtain a crude product. After the crude product was sublimed under reduced pressure (85 °C, 0.5 Torr), green solid product bis(N,N-diisopropylethylamino) cobalt (II) (CAS: 635680-58-9) (14.68 g, 0.043 moL) was obtained, and the yield was 86%.

[0057] Metal purity: 5N.

[0058] Example 4

[0059] The method for preparing the low-lithium-content metal amidinate complex of the present application specifically comprises the following steps:

[0060] In a glove box, the reactant potassium diisopropylamide (14.13 g, 0.1 moL) was added into a 500 mL reaction flask, and tetrahydrofuran (300 mL) was added under nitrogen protection (double-tube was used) and stirred uniformly. The reaction flask was placed in a cold bath at -78 °C. N,N-diisopropylacetamidine (CAS: 106500-93-0) (14.24 g, 0.1 moL) was slowly added dropwise into the reaction flask, after the dropwise addition was completed, it was slowly recovered to room temperature and stirred for 3 h. The reaction flask was placed in a cold bath at -78 °C. Solid sample feeder was used to slowly add cobalt dichloride (6.49 g, 0.05 moL) into the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and it was shaken thoroughly. Filtration was performed on diatomite, and n-hexane (50 mL) was used for washing, the filtrate was collected, and the filtrate was dried by suction to obtain a crude product. After the crude product was subjected to reduced pressure sublimation (85 °C, 0.5 Torr), green solid finished product bis(N,N-diisopropylacetamidinate) cobalt (II) (CAS: 635680-58-9) (12.8 g, 0.0375 moL) was obtained, and the yield was 75%.

[0061] Metal purity: 5N.

[0062] Example 5

[0063] The method for preparing the low-lithium-content metal amidinate complex of the present application specifically comprises the following steps:

[0064] In a glove box, add 13.5 g (0.1 mol) of reactant KC8 to a 500 mL reaction flask. Under nitrogen protection (using a double-row tube), add 300 mL of tetrahydrofuran and stir until homogeneous. Place the reaction flask in a -78°C cold bath. Slowly add 17.00 g (0.1 mol) of N,N-di-tert-butylacetamidine (CAS: 54838-72-1) to the reaction flask. After the addition is complete, slowly restore the temperature to room temperature and stir for 3 h. Place the reaction flask in a -78°C cold bath. Using a solid sampler, slowly add 10.92 g (0.05 mol) of nickel bromide to the reaction flask. After the addition is complete, slowly restore the temperature to room temperature and stir for 10 h. After the reaction is complete, remove the solvent under vacuum, add 200 mL of n-hexane, and shake thoroughly. Filter on diatomaceous earth, wash with 50 mL of n-hexane, collect the filtrate, and dry the filtrate to obtain the crude product. The crude product was sublimated under reduced pressure (98℃, 0.5 Torr) to obtain a blackish-purple solid product, bis(N,N-di-tert-butylethamidinyl)nickel(II) (CAS: 940895-79-4) (17.48 g, 0.044 mol), yield: 88%.

[0065] The sample was characterized by NMR, and the results are as follows: Figure 3 As shown, the NMR results are as follows: 1 H-NMR (C6D6, 400MHz, 298K): δ (ppm) = 98.80 (br, 6H), 17.83 (br, 36H).

[0066] The purity of the product was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The results showed the following metal purity of the product: 5N (ICP-MS): Li (112.595ppb), Na (35.938ppb), K (16.387ppb), Mg (31.503ppb), Ca (18.421ppb).

[0067] Example 6

[0068] The method for preparing the low-lithium-content amidine-based metal complex of the present invention specifically includes the following steps:

[0069] In a glove box, reactant KC8 (13.5 g, 0.1 moL) was added to a 500 mL reaction flask, tetrahydrofuran (300 mL) was added under nitrogen protection (double manifold was used), and stirred well. The reaction flask was placed in a cold bath at -78 °C. N,N-di-tert-butylethanimidamide (CAS: 54838-72-1) (17.00 g, 0.1 moL) was slowly added dropwise to the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 3 h. The reaction flask was placed in a cold bath at -78 °C. Iron (II) chloride (6.34 g, 0.05 moL) was slowly added to the reaction flask using a solid sample injector, after the addition was completed, it was slowly recovered to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and shaken well. Filtered on diatomite, washed with n-hexane (50 mL), collected the filtrate, and the filtrate was dried to obtain a crude product. The crude product was subjected to reduced pressure distillation (110 °C, 0.5 Torr) to obtain a black gray solid final product bis(N,N-di-tert-butylethanimidamido)iron(II) (CAS: 635680-56-7) (16.96 g, 0.043 moL), yield: 86%.

[0070] The sample was characterized by nuclear magnetic resonance, and the results are shown in Table 1, and the nuclear magnetic resonance results are shown in Table 2. Figure 4 1 H-NMR (C6D6, 400 MHz, 298 K): δ (ppm) = 154.61 (br, 6H), 15.81 (br, 36H).

[0071] Metal purity: 5N.

[0072] Comparative Example 1

[0073] n-Butyllithium (40 mL, 2.5 M, 0.1 moL) was added to a 500 mL reaction flask, ether (300 mL) was added under nitrogen protection (double manifold was used), and stirred well. The reaction flask was placed in a cold bath at -78 °C. N,N-diisopropylethanimidamide (14.24 g, 0.1 moL) was slowly added dropwise to the reaction flask, after the addition was completed, it was slowly recovered to room temperature and stirred for 3 h. The reaction flask was placed in a cold bath at -78 °C. Cobalt dichloride (6.49 g, 0.05 moL) was slowly added to the reaction flask using a solid sample injector, after the addition was completed, it was slowly recovered to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and shaken well. Filtered on diatomite, washed with n-hexane (50 mL), collected the filtrate, and the filtrate was dried to obtain a crude product. The crude product was subjected to reduced pressure sublimation to obtain a green solid final product bis(N,N-diisopropylethanimidamido)cobalt(II) (11.1 g, 0.0325 moL), yield: 65%.

[0074] ​The purity of the product was analyzed by inductively coupled plasma mass spectrometer (ICP-MS), and the results showed that the metal purity of the product was: 4N (ICP-MS): Li (57182.458 ppb), Na (121.78 ppb), K (97.443 ppb), Mg (357.432 ppb), Ca (324.517 ppb).

[0075] Comparative Example 2

[0076] N,N-diisopropylcarbodiimide (12.62 g, 0.1 moL) was added to a 500 mL reaction bottle, and tetrahydrofuran (300 mL) was added under nitrogen protection (double-tube was used), and stirred uniformly. The reaction bottle was placed in a cold bath at -78°C. Methyl lithium (62.5 mL, 1.6 M, 0.1 moL) was slowly added dropwise to the reaction bottle, after the dropwise addition was completed, it was slowly recovered to room temperature and stirred for 3 h. The reaction bottle was placed in a cold bath at -78°C. Cobalt dichloride (6.49 g, 0.05 moL) was slowly added to the reaction bottle using a solid feeder, after the addition was completed, it was slowly recovered to room temperature and stirred for 10 h. After the reaction was completed, the solvent was removed under vacuum, n-hexane (200 mL) was added, and it was shaken thoroughly. Filtration was performed on diatomite, and n-hexane (50 mL) was used for washing, the filtrate was collected, and the filtrate was dried to obtain a crude product. After the crude product was subjected to sublimation under reduced pressure, green solid product bis(N,N-diisopropylacetamidine) cobalt (II) (10.58 g, 0.031 moL) was obtained, and the yield was 62%.

[0077] The purity of the product was analyzed by inductively coupled plasma mass spectrometer (ICP-MS), and the results showed that the metal purity of the product was: 3N (ICP-MS): Li (701067.336 ppb), Na (112.385 ppb), K (125.503 ppb), Mg (219.306 ppb), Ca (524.394 ppb).

[0078] From the results of Examples 1-6, it can be seen that the preparation method of the present application improves the reactivity of the compound, makes the reaction thorough, reduces the influence of raw materials, and improves the product yield. Among them, the activity of KC8 and potassium hydride is relatively high, the reaction is relatively thorough, and the product yield is relatively high. The activity of the organic metal potassium source is relatively weak, and the product yield is slightly lower. The use of potassium source instead of organic lithium reagent controls the introduction of metal lithium impurities in the product from the source, greatly reduces the purification difficulty and cost, is conducive to obtaining high-purity ALD precursor source product, and is conducive to growing nanometer-thickness high-quality thin film through atomic layer deposition technology, which meets the requirements of ALD precursor preparation process.

[0079] As can be seen from the results of Comparative Example 1-2, the reaction is not complete due to the low activity of the organic lithium reagent, and the yield of the product is relatively low, and the raw material increases the influence on the product. The lithium content of the product synthesized by the organic lithium reagent is very high, and the use of such a product in the ALD deposition process will cause a large amount of lithium impurities to enter the semiconductor device. Since the lithium atom is small in size, it is easy to move in the semiconductor device, causing damage to the electrical performance of the semiconductor device. Therefore, when preparing the ALD precursor source material, the introduction of lithium impurities should be avoided as much as possible.

[0080] Obviously, the above examples are only examples for the sake of clarity, and are not limitations on the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A process for the preparation of a low lithium content amidinato metal complex, characterized in that, The method comprises the following steps: S1, under a protective atmosphere, adding a solvent to a potassium source to obtain a potassium source solution; the potassium source is KC8; S2, at -78℃ to -30℃, adding an amidine-based compound to the potassium source solution of S1 dropwise to obtain a reaction solution; the amidine-based compound is selected from one or more of N,N-diisopropylethyl amidine, N,N-di-tert-butylpropyl amidine, and N,N-diisopropyl methyl amidine; S3, at -78℃ to -30℃, adding a metal halide to the reaction solution of S2 to obtain a mixture; the metal halide is selected from one or more of cobalt dichloride, ferrous chloride, calcium chloride, and nickel bromide; S4, collecting the product from the mixture of S3 to obtain the amidine metal complex with low lithium content.

2. The process for the preparation of low lithium content metal amidinate complexes according to claim 1, characterized in that, In S1, the solvent is selected from one or more of tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, and 1,4-dioxane.

3. The method for preparing the low-lithium-content amidine-based metal complex according to claim 1, characterized in that, In S2 and S3, after the amidine-based compound and the metal halide are introduced, the reaction is continued to be stirred at room temperature until the reaction is completed.

4. The process for the preparation of low lithium content metal amidinate complexes according to claim 3, characterized in that, The time for continuing to stir the reaction in S2 is 2h-4h; the time for continuing to stir the reaction in S3 is 8h-12h.

5. The method for preparing the low-lithium-content amidine-based metal complex according to claim 1, characterized in that, The molar ratio of the potassium source, the amidine-based compound, and the metal halide is 2-2.5:2-2.5:

1.

6. The method for preparing the low-lithium-content amidine-based metal complex according to claim 1, characterized in that, In S4, after the product is collected, a step of purifying the amidine metal complex by sublimation under reduced pressure or recrystallization is further included; the temperature for sublimation under reduced pressure is 75℃-120℃, and the vacuum degree is 0.5Torr-0.8Torr; the organic solvent used for recrystallization is selected from one or more of n-hexane, toluene, and diethyl ether.

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