Metal complex precursor and method for preparing metal oxide thin film

Abstract

This invention relates to a method for preparing a metal complex precursor and a metal oxide thin film. The method for preparing the metal complex precursor includes the following steps: reacting a Grignard reagent with an alkylamine; after the reaction is complete, adding MCl4 to the reaction system to continue the reaction, thereby preparing the metal complex precursor; wherein the alkylamine has the structural formula HNR1R2, R1 and R2 each independently include a C1-C3 alkyl group, M includes one or more of Ge and Sn, and the metal complex precursor has the structural formula M(NR1R2)4. This preparation method can improve reaction safety while increasing yield and purity, and is easy to scale up for industrial production.

Description

Technical Field

[0001] This invention relates to the field of organometallic compounds, and in particular to a method for preparing a metal complex precursor and a metal oxide thin film. Background Technology

[0002] With the development of the very large-scale integrated circuit (VLSI) industry, people have placed more stringent requirements on the properties of semiconductor materials and their fabrication processes. According to Moore's Law, as the size of individual electronic devices shrinks, integrated circuit technology continues to evolve, and the thickness of the gate dielectric layer is one of the decisive factors affecting the size of electronic devices. Currently, the integrated circuit industry commonly uses SiO2 as the gate dielectric material for electronic devices. However, as the feature size of devices decreases, when the thickness of the SiO2 gate dielectric layer decreases to the nanometer scale, the leakage current through SiO2 increases exponentially with the decrease in the thickness of the SiO2 gate dielectric layer. This huge leakage current not only seriously affects device performance but also ultimately causes SiO2 to fail to perform its insulating function. Finding high-dielectric-constant materials (high-k materials) to replace traditional SiO2, and reducing the tunneling effect by increasing the physical thickness of the dielectric layer, is an effective technical means to improve the stability of electronic devices. Therefore, finding high-k and metal gate material precursors suitable for ALD (Atomic Layer Deposition) and CVD (Chemical Vapor Deposition) is crucial. Based on this, in recent years, germanium complex precursors and tin complex precursors have gradually come into the view of researchers. For example, tetra(dimethylamino)germanium is a liquid at room temperature and is a compound that is very sensitive to air and water vapor. It is soluble in organic solvents such as hydrocarbons and carbon tetrachloride. It not only has good stability and high vapor pressure, but also exhibits quite high reactivity.

[0003] However, there are currently few methods for preparing germanium and tin complex precursors. The preparation process usually requires the use of highly flammable raw materials, butyllithium and intermediate dimethylaminolithium, which poses significant safety hazards. At the same time, the reaction byproduct lithium chloride is prone to remain in the product, affecting the metal purity of the product. To meet the requirements of semiconductor purity, multiple purifications are required, which leads to a decrease in product yield and limits the industrial-scale production of germanium and tin complex precursors. Summary of the Invention

[0004] Based on this, some embodiments of the present invention provide a method for preparing a metal complex precursor, which can improve the yield and purity while improving the safety of the reaction, and is easy to scale up for industrial production.

[0005] In addition, some other embodiments of the present invention also provide a method for preparing a metal oxide thin film.

[0006] A method for preparing a metal complex precursor includes the following steps:

[0007] The Grignard reagent was reacted with an alkylamine. After the reaction was completed, MCl4 was added to the reaction system to continue the reaction and prepare the metal complex precursor.

[0008] The alkylamine has the structural formula HNR1R2, where R1 and R2 each independently include C1 to C3 alkyl groups, M includes one or more of Ge and Sn, and the metal complex precursor has the structural formula M(NR1R2)4.

[0009] In some embodiments, the Grignard reagent includes one or more of acetylenyl magnesium bromide, vinyl magnesium bromide, n-propyl magnesium bromide, 1-propynyl magnesium bromide, isopropenyl magnesium bromide, propenyl magnesium bromide, cyclopropenyl magnesium bromide, n-butyl magnesium bromide, sec-butyl magnesium bromide, 3-butenyl magnesium bromide, hexyl magnesium bromide, methyl magnesium chloride, ethyl magnesium chloride, acetylenyl magnesium chloride, vinyl magnesium chloride, propenyl magnesium chloride, n-butyl magnesium chloride, isobutyl magnesium chloride, sec-butyl magnesium chloride, and tert-butyl magnesium chloride.

[0010] Optionally, the Grignard reagent includes n-propylmagnesium bromide.

[0011] In some embodiments, the molar ratio of the Grignard reagent to the alkylamine is 1:(1 to 1.5).

[0012] In some embodiments, the alkylamine includes one or more of dimethylamine, diethylamine, and methyl ethylamine.

[0013] In some embodiments, the step of reacting the Grignard reagent with the alkylamine includes: first adding the alkylamine to the Grignard reagent and anhydrous hydrocarbon solvent at -15°C to 0°C under a protective atmosphere, and then reacting at 20°C to 30°C for 6 to 10 hours after the addition is completed.

[0014] In some embodiments, the anhydrous hydrocarbon solvent includes anhydrous n-hexane.

[0015] In some embodiments, the step of adding MCl4 to the reaction system to continue the reaction includes: cooling the reaction system to -15°C to 0°C, adding the MCl4 to the reaction system under a protective atmosphere, and stirring the reaction at 20°C to 30°C for 10 to 14 hours after the addition is completed.

[0016] In some embodiments, the molar ratio of the alkylamine to the MCl4 is (4-5):1.

[0017] In some embodiments, after the step of adding MCl4 to continue the reaction, steps of filtration and distillation are also included.

[0018] A method for preparing a metal oxide thin film includes the following steps:

[0019] Metal complex precursors were prepared using the above-described preparation method;

[0020] The metal complex precursor is reacted with an oxygen source to form a film, thereby preparing a metal oxide thin film.

[0021] The method for preparing the aforementioned metal complex precursor involves first reacting a Grignard reagent with an alkylamine, followed by the addition of MCl4 to continue the reaction. Since germanium and tin have much higher electronegativity than magnesium, an exchange reaction is conducted between the intermediate resulting from the reaction of the Grignard reagent with the alkylamine and a salt compound of the metal to obtain the metal complex precursor. Furthermore, using a Grignard reagent instead of butyllithium results in a milder and safer reaction process. In addition, no intermediate separation is required during the reaction, allowing for a one-pot yield of the target product. The byproducts obtained using this method have larger particles than lithium chloride particles, making them easier to remove through filtration. The product has high metal purity, readily meeting the needs of the semiconductor industry, and boasts a high yield, facilitating industrial-scale production. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of a method for preparing a metal complex precursor according to one embodiment. Detailed Implementation

[0023] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] Unless otherwise stated or in case of contradiction, the terms or phrases used in this invention shall have the following meanings:

[0026] In this invention, "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0027] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this invention, "one or several" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0029] In this invention, unless otherwise specified, all percentage concentrations refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0030] The terms "preferred" and similar expressions used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0031] When a numerical range is disclosed in this invention, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Further, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed in this invention should be understood to include any and all subranges to which they are incorporated.

[0032] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0033] The terms "comprising" and "having," and any variations thereof, used in embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0034] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0035] Unless otherwise specified, room temperature in this article refers to a temperature of 20℃ to 30℃.

[0036] The first aspect of this invention provides a method for preparing a metal complex precursor; please refer to [link to relevant documentation]. Figure 1 It includes the following steps:

[0037] Step S110: React the Grignard reagent with an alkylamine.

[0038] In some embodiments, Grignard reagents include one or more of ethynyl magnesium bromide, vinyl magnesium bromide, n-propyl magnesium bromide, 1-propynyl magnesium bromide, isopropenyl magnesium bromide, propenyl magnesium bromide, cyclopropenyl magnesium bromide, n-butyl magnesium bromide, sec-butyl magnesium bromide, 3-butenyl magnesium bromide, hexyl magnesium bromide, methyl magnesium chloride, ethyl magnesium chloride, ethynyl magnesium chloride, vinyl magnesium chloride, propenyl magnesium chloride, n-butyl magnesium chloride, isobutyl magnesium chloride, sec-butyl magnesium chloride, and tert-butyl magnesium chloride.

[0039] Preferably, the Grignard reagent includes n-propylmagnesium bromide.

[0040] In some embodiments, the alkylamine has the structural formula HNR1R2, where R1 and R2 each independently comprise a C1-C3 alkyl group. In some embodiments, the alkylamine includes one or more of dimethylamine, diethylamine, and methyl ethylamine.

[0041] In some embodiments, the molar ratio of the Grignard reagent to the alkylamine is 1:(1 to 1.5). For example, the molar ratio of the Grignard reagent to the alkylamine may be, but is not limited to, 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, 1:1.3, 1:1.35, 1:1.4, 1:1.45, 1:1.5, or any range of two of these values.

[0042] In some embodiments, step S110 includes: first, adding alkylamine to Grignard reagent and anhydrous hydrocarbon solvent at -15℃ to 0℃ under a protective atmosphere; after the addition is complete, reacting at 20℃ to 30℃ for 6h to 10h.

[0043] Optionally, the temperature at which the alkylamine is added can be, but is not limited to, -15°C, -14°C, -13°C, -12°C, -11°C, -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, or any combination of these values. Because alkylamines have low boiling points, adding them at low temperatures reduces their volatility, which is beneficial for the reaction between the alkylamine and the Grignard reagent.

[0044] Alternatively, the protective atmosphere may include nitrogen or argon.

[0045] Optionally, anhydrous hydrocarbon solvents include anhydrous n-hexane.

[0046] Optionally, the Grignard reagent is added in the form of a tetrahydrofuran solution of the Grignard reagent.

[0047] Optionally, in step S110, the reaction temperature may be, but is not limited to, 20°C, 22°C, 25°C, 28°C, 30°C, or any combination of these values.

[0048] Optionally, in step S110, the reaction time may be, but is not limited to, 6h, 7h, 8h, 9h, 10h or any combination of these values.

[0049] Step S120: After the reaction is complete, MCl4 is added to the reaction system to continue the reaction and prepare the metal complex precursor.

[0050] M includes one or more of Ge and Sn. The structural formula of the metal complex precursor is M(NR1R2)4.

[0051] Similar to tetradimethylaminogermanium and tetradimethylaminotin, the traditional synthesis process for tetradimethylaminozirconium involves first preparing a dimethylaminolithium intermediate, which is then reacted with zirconium tetrachloride. When this process was attempted for the preparation of tetradimethylaminozirconium, it was found that because germanium (2.01) and tin (1.96) have much higher electronegativity than magnesium (1.31), an exchange reaction can be performed between the intermediate obtained from the reaction of Grignard reagents with alkylamines and the salts of these metals to yield another organometallic compound. However, zirconium (1.33) has a similar electronegativity to magnesium (1.31), so tetradimethylaminozirconium cannot be prepared using this method.

[0052] In some embodiments, the molar ratio of alkylamine to MCl4 is (4-5):1. For example, the molar ratio of alkylamine to MCl4 may be, but is not limited to, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5:1, or any range of two of these values.

[0053] In some embodiments, step S120 includes: cooling the reaction system to -15°C to 0°C, adding MCl4 to the reaction system under a protective atmosphere, and stirring the reaction at 20°C to 30°C for 10 to 14 hours after the addition is completed.

[0054] Optionally, the temperature at which MCl4 is added may be, but is not limited to, -15°C, -14°C, -13°C, -12°C, -11°C, -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, or any combination of these values.

[0055] Alternatively, the protective atmosphere may include nitrogen or argon.

[0056] Optionally, in step S120, the reaction temperature may be, but is not limited to, 20°C, 22°C, 25°C, 28°C, 30°C, or any combination of these values.

[0057] Optionally, in step S120, the reaction time may be, but is not limited to, 10h, 11h, 12h, 13h, 14h or any combination of these values.

[0058] In some embodiments, after the reaction in step S110 is completed, MCl4 is added directly to the reaction system to continue the reaction without separation and purification.

[0059] In some embodiments, after step S120, a filtration and distillation step is further included. Insoluble byproducts are removed by filtration, and solvents and other byproducts are removed by distillation.

[0060] Taking n-propylmagnesium bromide as the Grignard reagent and GeCl4 as the MCl4 as an example, the synthetic route of the metal complex precursor is as follows:

[0061] CH3CH2CH2MgBr+HNR1R2→MgBrNR1R2+CH3CH2CH3

[0062] MgBrNR1R2+GeCl4→Ge(NR1R2)4+MgClBr.

[0063] It is understandable that if the Grignard reagent is replaced with other reagents and MCl4 is replaced with SnCl4, the synthetic route can be adjusted accordingly, which will not be elaborated further.

[0064] The above-mentioned method for preparing metal complex precursors has at least the following advantages:

[0065] (1) The above-mentioned method for preparing the metal complex precursor involves reacting a Grignard reagent with an alkylamine, followed by the addition of MCl4 to continue the reaction. No intermediate separation is required during the reaction, allowing for a one-pot yield of the target product. Furthermore, the use of a Grignard reagent instead of a butyllithium reagent results in a gentler and safer reaction process. In addition, the byproducts of this method are easier to remove compared to lithium chloride, resulting in a product with high metal purity, easily meeting the needs of the semiconductor industry. The high product yield also facilitates industrial-scale production.

[0066] (2) The reaction raw materials for the above-mentioned metal complex precursor preparation method are simple and readily available, and the operation is convenient. It avoids the use of n-butyllithium required in conventional processes, which is both safe and environmentally friendly. At the same time, there is no need to separate intermediates. MCl4 is directly added to the reaction system to obtain the target product in one pot. The process is simple, and the by-products are easy to remove. The post-processing process is simple, and the product yield is high, which is suitable for industrial scale-up production.

[0067] (3) In the traditional preparation method, butyllithium is usually used. On the one hand, there are certain safety hazards. On the other hand, butyllithium products are generally diluted in alkane solvents, which will generate a large amount of waste liquid during use. It is not green and environmentally friendly and increases the cost of hazardous waste disposal. In the above preparation method, Grignard reagent is used instead of butyllithium reagent, which reduces the cost of hazardous waste disposal.

[0068] A second aspect of the present invention provides a method for preparing a metal oxide thin film, comprising the following steps:

[0069] Metal complex precursors were prepared using the above-described preparation method;

[0070] Metal oxide thin films are prepared by reacting metal complex precursors with oxygen sources to form films.

[0071] In some embodiments, chemical vapor deposition (CVD) or atomic layer deposition (ALD) is used to react the metal complex precursor with an oxygen source to form a film. The specific CVD or ALD process can be one commonly used in the art.

[0072] In some embodiments, the oxygen source may be, but is not limited to, water.

[0073] In some embodiments, the preparation steps of the metal oxide thin film include: using an atomic layer deposition (ALD) process, heating the ALD chamber to 250°C–350°C and evacuating it; then, pulse-introducing a metal complex precursor into the ALD chamber using argon gas; after the metal complex precursor introduction is complete, continuing to introduce argon gas to clean residual metal complex precursor and reaction byproducts. Next, pulse-introducing water into the ALD chamber using argon gas; after the water introduction is complete, continuing to introduce argon gas to clean residual water and reaction byproducts. Repeating the above steps prepares the metal oxide thin film.

[0074] Optionally, the pulse time of the metal complex precursor may be, but is not limited to, 0.2 s, and the pulse time of water may be, but is not limited to, 0.3 s.

[0075] Optionally, the duration of argon gas introduction may be, but is not limited to, 10 seconds.

[0076] Experiments have shown that the metal oxide films prepared by the above method are of good quality and have high uniformity.

[0077] To make the objectives and advantages of the present invention clearer, the preparation method and effects of the metal complex precursor of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and should not be used to limit the present invention. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods in the embodiments that do not specify specific conditions are implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0078] Example 1

[0079] This embodiment provides a method for preparing a germanium complex precursor, including the following steps:

[0080] Under a nitrogen atmosphere, a 2 mol / L solution of n-propylmagnesium bromide in tetrahydrofuran (400 mL, 0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately 0 °C, followed by the dropwise addition of a 20% dimethylamine n-hexane solution (180.4 g, 0.8 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. After the reaction was complete, the reaction solution was cooled to 0 °C again, and germanium tetrachloride (42.8 g, 0.2 mol) was slowly added dropwise under nitrogen protection. After the addition was complete, the mixture was brought back to room temperature and stirred for 12 hours. The mixture was filtered, the solvent was removed, and the residue was distilled under reduced pressure to obtain 41.8 g of tetradimethylaminogermanium, with a yield of 84%. The characterization data of tetradimethylaminogermanium are as follows:

[0081] 1 HNMR (C6D6): 2.66 (s, 24H);

[0082] The purity of the product was analyzed using inductively coupled plasma mass spectrometry (ICP-MS), and the results showed that the magnesium content was 0.3 ppm and the metal purity of the product was 5N.

[0083] Example 2

[0084] This embodiment provides a method for preparing a germanium complex precursor. The preparation steps are similar to those in Example 1, except that the amount of dimethylamine n-hexane solution in Example 1 is changed to 225.4 grams. The specific steps are as follows:

[0085] Under a nitrogen atmosphere, 400 mL of 2 mol / L n-propylmagnesium bromide tetrahydrofuran solution (0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately 0 °C, followed by the dropwise addition of a 20% (w / w) dimethylamine solution in n-hexane (225.4 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. The reaction mixture was then cooled to 0 °C again, and germanium tetrachloride (0.2 mol, 42.8 g) was slowly added dropwise under nitrogen protection. The mixture was brought back to room temperature and stirred for another 12 hours. The mixture was filtered, the solvent was removed, and the residue was distilled under reduced pressure to obtain 43.8 g of tetradimethylaminogermanium, with a yield of 88%. The characterization of tetradimethylaminogermanium was the same as in Example 1 and will not be repeated.

[0086] Example 3

[0087] This embodiment provides a method for preparing a germanium complex precursor. The preparation steps are similar to those in Example 2, except that the reaction temperature in Example 2 is changed to -10℃. The specific steps are as follows:

[0088] Under a nitrogen atmosphere, a 2 mol / L solution of n-propylmagnesium bromide in tetrahydrofuran (400 mL, 0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately -10 °C, followed by the dropwise addition of a 20% (w / w) dimethylamine solution in n-hexane (225.4 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. The reaction mixture was then cooled again to -10 °C, and germanium tetrachloride (42.8 g, 0.2 mol) was slowly added dropwise under nitrogen protection. The mixture was brought back to room temperature and stirred for another 12 hours. The mixture was filtered, the solvent was removed, and the residue was distilled under reduced pressure to obtain 46.3 g of tetradimethylaminogermanium, with a yield of 93%. The characterization of tetradimethylaminogermanium is as follows:

[0089] The purity of the product was analyzed using inductively coupled plasma mass spectrometry (ICP-MS), and the results showed that the magnesium content was 0.22 ppm and the metal purity of the product was 5N.

[0090] Example 4

[0091] This embodiment provides a method for preparing a germanium complex precursor. The preparation steps are similar to those in Example 3, except that the dimethylamine in Example 3 is replaced with an equivalent amount of diethylamine. The specific steps are as follows:

[0092] Under a nitrogen atmosphere, a 2 mol / L solution of n-propylmagnesium bromide in tetrahydrofuran (400 mL, 0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately -10 °C, followed by the dropwise addition of diethylamine (73.14 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. The reaction solution was then cooled again to -10 °C, and germanium tetrachloride (42.8 g, 0.2 mol) was slowly added dropwise under nitrogen protection. The mixture was brought back to room temperature and stirred for another 12 hours. The mixture was filtered, the solvent was removed, and the residue was distilled under reduced pressure to obtain 63.6 g of tetradiethylaminogermanium, with a yield of 88%. The characterization data of tetradiethylaminogermanium are as follows:

[0093] 1 HNMR(C6D6):3.34(q,16H),1.15(t,24H);

[0094] The purity of the product was determined by ICP-MS analysis, and the results showed that the metal purity of the product was 5N.

[0095] Example 5

[0096] This embodiment provides a method for preparing a germanium complex precursor. The preparation steps are similar to those in Example 3, except that the dimethylamine in Example 3 is replaced with an equivalent amount of methyl ethylamine. The specific steps are as follows:

[0097] Under a nitrogen atmosphere, a 2 mol / L solution of n-propylmagnesium bromide in tetrahydrofuran (400 mL, 0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately -10 °C, followed by the dropwise addition of methyl ethylamine (59.1 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted at room temperature for 8 hours. After the reaction was complete, the reaction solution was cooled to -10 °C again, and germanium tetrachloride (42.8 g, 0.2 mol) was slowly added dropwise under nitrogen protection. After the addition was complete, the mixture was brought back to room temperature and stirred for 12 hours. The mixture was filtered, the solvent was dried under vacuum, and the residue was distilled under reduced pressure to obtain 51.9 g of tetramethylethylaminogermanium, with a yield of 85%. The characterization data of tetramethylethylaminogermanium are as follows:

[0098] 1 HNMR(C6D6):3.24(q,8H),2.97(s,12H),1.15(t,12H);

[0099] The purity of the product was determined by ICP-MS analysis, and the results showed that the metal purity of the product was 5N.

[0100] Example 6

[0101] This embodiment provides a method for preparing a germanium complex precursor. The preparation steps are similar to those in Example 3, except that the tetrahydrofuran solution of n-propyl magnesium bromide in Example 3 is replaced with an equivalent amount of tetrahydrofuran solution of ethyl magnesium bromide. The preparation steps are as follows:

[0102] Under a nitrogen atmosphere, 800 mL (0.8 mol) of a tetrahydrofuran solution of ethyl magnesium bromide per liter and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately -10 °C, followed by the dropwise addition of a 20% dimethylamine n-hexane solution (225.4 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. After the reaction was complete, the reaction solution was cooled to -10 °C again, and germanium tetrachloride (42.8 g, 0.2 mol) was slowly added dropwise under nitrogen protection. After the addition was complete, the mixture was brought back to room temperature and stirred for 12 hours. The mixture was filtered, the solvent was dried, and the residue was distilled under reduced pressure to obtain 44.3 g of tetradimethylaminogermanium, with a yield of 89%. The characterization of tetradimethylaminogermanium was the same as in Example 1 and will not be repeated.

[0103] As can be seen from Examples 6 and 3, tetradimethylaminogermanium can also be obtained by using ethyl magnesium bromide instead of n-propyl magnesium bromide. However, from the perspective of process safety, the explosion limit of propane, a reaction byproduct of Example 3, is 2.1% to 9.5%, while the explosion limit of ethane, a reaction byproduct of Example 6, is 3.0% to 16.0%. Therefore, the preferred Grignard reagent is n-propyl magnesium bromide.

[0104] Example 7

[0105] This embodiment provides a method for preparing a tin complex precursor. The difference from Example 3 is that germanium tetrachloride in Example 3 is replaced with an equivalent amount of tin tetrachloride. The specific preparation steps are as follows:

[0106] Under a nitrogen atmosphere, a 2 mol / L solution of n-propylmagnesium bromide in tetrahydrofuran (400 mL, 0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately -10 °C, followed by the dropwise addition of a 20% (w / w) dimethylamine solution in n-hexane (225.4 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. After the reaction was complete, the reaction solution was cooled to -10 °C again, and 52.1 g (0.2 mol) of tin tetrachloride was slowly added dropwise under nitrogen protection. After the addition was complete, the mixture was brought back to room temperature and stirred for 12 hours. The mixture was filtered, the solvent was dried under vacuum, and the residue was distilled under reduced pressure to obtain 50.2 g of tetradimethylaminotin, with a yield of 85%. The characterization data of tetradimethylaminotin are as follows:

[0107] 1 HNMR (C6D6): 2.81 (s, 24H);

[0108] The purity of the product was determined by ICP-MS analysis, and the results showed that the metal purity of the product was 5N.

[0109] Comparative Example 1

[0110] Comparative Example 1 provides a conventional method for preparing a germanium complex precursor, comprising the following steps:

[0111] Under a nitrogen atmosphere, a 2.5 mol / L solution of n-butyllithium in n-hexane (320 mL, 0.8 mol) and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The mixture was cooled to approximately -10 °C, followed by the dropwise addition of a 20% (w / w) solution of dimethylamine in n-hexane (225.4 g, 1.0 mol). After the addition was complete, the mixture was slowly brought back to room temperature and reacted for 8 hours. The reaction mixture was then cooled to -10 °C again, and germanium tetrachloride (42.8 g, 0.2 mol) was slowly added dropwise under nitrogen protection. The mixture was brought back to room temperature and stirred for 12 hours. The mixture was filtered, the solvent was removed, and the residue was distilled under reduced pressure to obtain 40.8 g of tetradimethylaminogermanium, with a yield of 82%.

[0112] The purity of the product was determined by inductively coupled plasma mass spectrometry (ICP-MS), and the results showed that the lithium content was 72 ppm and the metal purity of the product was 4N.

[0113] As can be seen from the comparison between Comparative Example 1 and Example 3, in the process of preparing germanium complex precursors, replacing butyllithium with Grignard reagents not only improves the safety of the reaction, but also improves the metal purity and reaction yield of the germanium complex precursors, which is beneficial for industrial scale-up production.

[0114] Comparative Example 2

[0115] Comparative Example 2 provides a method for preparing a zirconium precursor complex. The difference between Comparative Example 2 and Example 3 is that only the germanium tetrachloride in Example 3 is replaced with an equivalent amount of zirconium tetrachloride. The specific preparation steps are as follows:

[0116] Under a nitrogen atmosphere, 400 mL of tetrahydrofuran solution of 2 mol / L n-propylmagnesium bromide and 400 mL of n-hexane were added to a 2000 mL Schlenk flask. The flask was cooled to approximately -10 °C, and then a 20% (w / w) dimethylamine solution in n-hexane (225.4 g, 1.0 mol) was added dropwise. After the addition was complete, the flask was slowly brought back to room temperature and reacted for 8 hours. After the reaction was complete, the flask was cooled to -10 °C again, and zirconium tetrachloride (46.6 g, 0.2 mol) was slowly added under nitrogen protection. After the addition was complete, the flask was brought back to room temperature and stirred for 12 hours. The flask was filtered, and the solvent was dried to obtain a brown residue. NMR characterization confirmed that the residue was not tetradimethylaminozirconium.

[0117] As can be seen from Examples 3, 7, and Comparative Example 2, germanium (2.01) has a much higher electronegativity than magnesium (1.31), and tin (1.96) has a much higher electronegativity than magnesium (1.31). By using the intermediate resulting from the reaction of a Grignard reagent with an alkylamine and an exchange reaction with a salt compound of this metal, another organometallic compound can be obtained. However, zirconium (1.33) has a similar electronegativity to magnesium (1.31), and tetradimethylaminozirconium cannot be obtained using the above method.

[0118] Example 8

[0119] This embodiment provides a method for preparing germanium oxide thin films, including the following steps:

[0120] Using atomic layer deposition (ALD), tetramethylaminogermanium from Example 1 was used as a precursor for depositing germanium oxide thin films. The ALD chamber was heated from room temperature to 300°C and evacuated. Precursor molecules were introduced into the ALD chamber using high-purity argon gas (pulse time 0.2 s). After the germanium source molecules were introduced, argon gas was continued for 10 s to clean residual germanium source and reaction byproducts. H2O was then pulsed into the ALD chamber using argon gas (pulse time 0.3 s). After the pulsed H2O molecules were introduced, argon gas was continued for 10 s to clean residual H2O molecules and reaction byproducts. This process was repeated for 100 cycles to obtain a good germanium oxide thin film. The film thickness was measured to be 5 nm using an ellipsometry, and the film inhomogeneity was 0.88%.

[0121] Example 9

[0122] This embodiment provides a method for preparing germanium oxide thin films. The difference from Example 8 is that the precursor used is tetradiethylaminogermanium prepared in Example 4.

[0123] The thickness of the germanium oxide thin film prepared in this embodiment was measured to be 4.8 nm using an ellipsometry, and the film's non-uniformity was 0.91%.

[0124] Example 10

[0125] This embodiment provides a method for preparing germanium oxide thin films. The difference from Example 8 is that the precursor used is tetramethylethylaminogermanium prepared in Example 5.

[0126] The thickness of the germanium oxide thin film prepared in this embodiment was measured to be 5.1 nm using an ellipsometry, and the film non-uniformity was 0.85%.

[0127] Example 11

[0128] This embodiment provides a method for preparing a tin oxide thin film. The difference from Example 8 is that the precursor used is tetradimethylamine tin prepared in Example 7.

[0129] The thickness of the tin oxide film prepared in this embodiment was measured to be 6.4 nm using an ellipsometry, and the film's non-uniformity was 0.82%.

[0130] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0131] The above-described embodiments are merely illustrative of several implementation methods of the present invention, facilitating a detailed understanding of the technical solutions of the present invention, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this invention patent should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a metal complex precursor, characterized in that, Includes the following steps: The Grignard reagent was reacted with an alkylamine. After the reaction was completed, MCl4 was added to the reaction system to continue the reaction and prepare the metal complex precursor. The alkylamine has the structural formula HNR1R2, where R1 and R2 each independently include C1-C3 alkyl groups, M includes one or both of Ge and Sn, and the metal complex precursor has the structural formula M(NR1R2)4.

2. The method for preparing the metal complex precursor according to claim 1, characterized in that, The Grignard reagents include one or more of the following: acetylenyl magnesium bromide, vinyl magnesium bromide, n-propyl magnesium bromide, 1-propynyl magnesium bromide, isopropenyl magnesium bromide, propenyl magnesium bromide, cyclopropenyl magnesium bromide, n-butyl magnesium bromide, sec-butyl magnesium bromide, 3-butenyl magnesium bromide, hexyl magnesium bromide, methyl magnesium chloride, ethyl magnesium chloride, acetylenyl magnesium chloride, vinyl magnesium chloride, propenyl magnesium chloride, n-butyl magnesium chloride, isobutyl magnesium chloride, sec-butyl magnesium chloride, and tert-butyl magnesium chloride.

3. The method for preparing the metal complex precursor according to claim 2, characterized in that, The Grignard reagent includes n-propylmagnesium bromide.

4. The method for preparing the metal complex precursor according to claim 1, characterized in that, The molar ratio of the Grignard reagent to the alkylamine is 1:(1~1.5).

5. The method for preparing the metal complex precursor according to claim 1, characterized in that, The alkylamine includes one or more of dimethylamine, diethylamine, and methyl ethylamine.

6. The method for preparing the metal complex precursor according to any one of claims 1 to 5, characterized in that, The steps for reacting Grignard reagent with alkylamine include: first, adding the alkylamine to the Grignard reagent and anhydrous hydrocarbon solvent at -15℃ to 0℃ under a protective atmosphere; after the addition is complete, reacting at 20℃ to 30℃ for 6h to 10h.

7. The method for preparing the metal complex precursor according to claim 6, characterized in that, The anhydrous hydrocarbon solvent includes anhydrous n-hexane.

8. The method for preparing the metal complex precursor according to claim 1, characterized in that, The steps of adding MCl4 to the reaction system to continue the reaction include: cooling the reaction system to -15℃ to 0℃, adding MCl4 to the reaction system under a protective atmosphere, and stirring the reaction at 20℃ to 30℃ for 10h to 14h after the addition is completed.

9. The method for preparing the metal complex precursor according to claim 1 or 8, characterized in that, The molar ratio of the alkylamine to the MCl4 is (4~5):

1.

10. The method for preparing the metal complex precursor according to any one of claims 1-5 and 7-8, characterized in that, Following the step of adding MCl4 to continue the reaction, the process also includes filtration and distillation.

11. A method for preparing a metal oxide thin film, characterized in that, Includes the following steps: The metal complex precursor was prepared by the preparation method according to any one of claims 1 to 10; The metal complex precursor is reacted with an oxygen source to form a film, thereby preparing a metal oxide thin film.

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