Preparation method of high-purity diiodosilane

Abstract

The invention relates to a preparation method of high-purity diiodosilane, and belongs to the technical field of preparation of organosilicon compounds. The preparation method comprises the following steps: adding iodoethane, bis (diethylamino) silane and a solvent into a three-neck flask, and carrying out stirring reaction under the protection of argon; in the reaction process, yellow white precipitate is slowly generated, and a yellow reaction product is finally obtained; filtering the yellow product through a filter column to obtain colorless transparent liquid and yellowish white solid tetraethylammonium iodide; carrying out atmospheric distillation on the obtained colorless transparent liquid; carrying out adsorption refining on the residual reaction liquid, adding a polystyrene-based complexing active agent, filtering, and carrying out reduced pressure rectification on the filtrate to obtain diiodosilane; the polystyrene-based complexing active agent is prepared from styrene, allylidene triphenylphosphine, trans-2-butene-1, 4-dicarboxylic acid, divinyl benzene, water, potassium persulfate and gelatin; the purity of the prepared diiodosilane reaches 99.5% or above, and the purity grade of metal ions reaches 6N grade.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of organosilicon compounds, in particular to a method for preparing high-purity diiodosilane. Background Art

[0002] Diiodosilane, with the chemical formula SiH2I2, is an important silicon-based precursor for chemical vapor deposition (CVD). It has the characteristics of high deposition rate and low reaction temperature. Therefore, it can achieve high-precision silicon film deposition on a variety of substrates (such as semiconductor wafers and metal oxides). It has high application value in advanced semiconductor manufacturing (such as high-k gate dielectrics and three-dimensional stacked devices) and functional coatings. There are several methods for preparing diiodosilane:

[0003] Currently, the more mature method for synthesizing diiodosilane is mainly the method first proposed by Fritz and Kummer in 1960 to generate diiodosilane by reacting phenylsilane with elemental iodine.

[0004] Patent CN110606491B discloses a method for preparing high-purity diiodosilane. The initial raw material uses non-toxic phenyldichlorosilane as a raw material instead of the highly toxic chemical phenyltrichlorosilane, and after reacting with lithium aluminum tetrahydride, the reaction raw material phenylsilane is obtained. This is added to elemental iodine, and an oxygen-containing organic compound is added as a catalyst, and diiodosilane is obtained after reactive distillation. Patent CN114656497A states that phenyldichlorosilane is expensive and has high production costs. Phenylsilane is prepared using sodium hydrogen sulfide, lithium aluminum tetrahydride, and phenyltrichlorosilane as raw materials. However, the phenylsilane raw material explodes when exposed to water, is highly hygroscopic, and is difficult to store. The problem of its easy deterioration has not been fundamentally solved, and this route produces the carcinogen benzene.

[0005] At present, the reaction raw materials of phenylsilane and iodine usually need pre-cooling treatment in the early stage, and the temperature of the reaction process needs to be strictly controlled to avoid side reactions. A synthetic method for manufacturing diiodosilane on a scale suitable for industry is disclosed in patent CN111072030B. Phenylsilane reacts with iodine at low temperatures, and the reaction mixture is taken out from the reaction tank in a small amount continuously or intermittently and transferred while heating it, and phenylsilane and iodine are reacted to realize the industrial-scale manufacture of diiodosilane safely and efficiently. In addition, in patent CN111592565B, the contact between the raw material phenylsilane and the intermediate product HI is reduced to reduce the occurrence of side reactions, and the intermediate product HI and Ph-SiH2I are transferred to the second reactor to carry out the second step reaction, thereby improving the purity and raw material conversion of the product. Although these patents have improved the safety and reaction conversion of the reaction to a certain extent, the process is more complicated and requires special design of the equipment.

[0006] Another method is to synthesize diiodosilane by reacting dichlorosilane and iodine or inorganic iodide as raw materials.

[0007] The reaction has high requirements for the metal ions and moisture of lithium iodide, and the cost of lithium iodide is high. In patent CN116081626B, relatively expensive lithium iodide is replaced by relatively cheap raw materials sodium iodide and potassium iodide. After adding an amine catalyst, diiodosilane is synthesized by reacting with dichlorosilane. In patent CN111592565B, it is believed that the use of lithium iodide as an iodine source is expensive. Using cheap NaI and KI as an iodine source has achieved the recycling of LiCl. However, this method introduces other metal ions, making later purification treatment more demanding.

[0008] Other synthesis methods: Patent WO2022087036A1 provides a method for preparing iodosilanes such as H2SiI2 and HSiI3 by reacting alkylaminosilanes with substituted acyl iodides. It specifically describes the reaction of bis(diethylamino)silane with benzoyl iodide to produce diiodosilane. However, the synthesis of acyl iodide reagents is very difficult and unstable, and this method cannot be scaled up for process production.

[0009] In view of the problems existing in the above synthesis methods, such as expensive or difficult to obtain raw materials, difficult to stably control the reaction process, low safety factor, high requirements for device design, and difficulty in industrialization, it is of great significance to invent a new synthesis method for diiodosilane with cheap reaction raw materials, mild reaction conditions, simple steps, and applicable to industrial production. Summary of the Invention

[0010] In order to solve the above problems, the present invention provides a simple and efficient method for preparing high-purity diiodosilane, the operating steps of which are as follows:

[0011] S1 Reaction process: 20-30 parts of iodoethane, 20-30 parts of bis(diethylamino)silane, and 80-120 parts of solvent are added to a three-necked flask and stirred under the protection of argon for reaction; during the reaction, a yellow-white precipitate is slowly generated, and a yellow reaction product is finally obtained;

[0012] S2 Product Separation: Filter the yellow product through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; distill the obtained colorless transparent liquid under normal pressure at 90-100°C, collect the fraction at 50-60°C as monoiodosilane, and collect the fraction at 70-80°C as the solvent;

[0013] S3: The remaining reaction liquid is subjected to adsorption purification, and 2-8 parts of polystyrene-based complexing active agent are added. The mixture is stirred at 50-60° C. for 0.5-2 hours, and then filtered. The filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0014] As a preferred embodiment of the present invention, the S1 solvent is n-hexane.

[0015] As a preferred embodiment of the present invention, the S1 reaction temperature is 30-60° C. and the reaction time is 16-24 hours.

[0016] As a preferred embodiment of the present invention, the operating pressure of the S3 vacuum distillation is 1000-1300 Pa and the temperature is 70-80°C.

[0017] As a preferred embodiment of the present invention, the preparation method of the polystyrene-based complexing active agent is:

[0018] By weight, 100-150 parts of styrene, 0.03-0.5 parts of allyl triphenylphosphine, 1-5 parts of trans-2-butene-1,4-dicarboxylic acid, 5-10 parts of divinylbenzene, 1000-1500 parts of water, 0.3-2 parts of potassium persulfate and 0.2-2 parts of gelatin are stirred and reacted at 80-90° C. for 6-10 hours, filtered, washed with water and dried to obtain a polystyrene-based complexing active agent.

[0019] Reaction mechanism:

[0020] Nucleophilic substitution reaction is dominant: the amino group (-N(C2H5)2) in bis(diethylamino)silane acts as a nucleophile, attacks the α-carbon of the iodine atom in iodoethane, undergoes a nucleophilic substitution reaction, gradually removes the ethylamino group, and finally generates diiodosilane.

[0021] By-product formation pathway: During the reaction, after the ethylamino group is replaced by an iodine atom, the released triethylamine further reacts with ethyl iodide to form tetraethylammonium iodide ((C2H5)4NI) as a yellow-white precipitate.

[0022] Technical effects:

[0023] The present invention provides a method for preparing high-purity diiodosilane. Compared with the prior art, the present invention has the following significant effects:

[0024] 1. Purity and metal ion control: The purity of the prepared diiodosilane is ≥99.5%, and the metal ion purity grade reaches 6N (99.9999%), meeting the requirements of semiconductor CVD process for high-purity precursors.

[0025] 2. Process and environmental advantages: The raw material cost is lower than that of the phenylsilane route, the reaction does not introduce metal ions, the solvent recovery rate is high, and the by-product tetraethylammonium iodide can be recycled as an ionic liquid raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart.

[0027] Figure 2 This is the NMR spectrum of diiodosilane.

[0028] Figure 3 This is the GC spectrum of diiodosilane. DETAILED DESCRIPTION

[0029] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0030] GC was used to characterize the purity of the product; H NMR was used to verify the purity of the product and the analysis of impurities.

[0031] Example 1

[0032] A method for preparing high-purity diiodosilane, comprising the following steps:

[0033] S1 Reaction process: 20 g of iodine ethane, 20 g of bis(diethylamino)silane, and 80 g of solvent were added to a three-necked flask and stirred under argon protection for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0034] S2 Product Separation: The yellow product was filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid was distilled at 90°C under normal pressure, and the fraction at 50°C was collected as monoiodosilane; the fraction at 70°C was collected as the solvent;

[0035] S3: The remaining reaction liquid is subjected to adsorption purification, 2 g of polystyrene-based complexing active agent is added, stirred at 50° C. for 0.5 hour, filtered, and the filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0036] The S1 solvent is n-hexane.

[0037] The S1 reaction temperature is 30° C. and the reaction time is 16 hours.

[0038] The operating pressure of the S3 vacuum distillation is 1000 Pa and the temperature is 70°C.

[0039] The preparation method of the polystyrene-based complexing active agent is:

[0040] 100 g of styrene, 0.03 g of allyl triphenylphosphine, 1 g of trans-2-butene-1,4-dicarboxylic acid, 5 g of divinylbenzene, 1000 g of water, 0.3 g of potassium persulfate, and 0.2 g of gelatin were stirred and reacted at 80° C. for 6 hours, filtered, washed with water, and dried to obtain a polystyrene-based complexing active agent.

[0041] Example 2

[0042] A method for preparing high-purity diiodosilane, comprising the following steps:

[0043] S1 Reaction process: 23g of iodine ethane, 23g of bis(diethylamino)silane, and 90g of solvent were added to a three-necked flask and stirred under the protection of argon for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0044] S2 Product Separation: The yellow product is filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid is distilled at 95°C under atmospheric pressure, and the fraction at 55°C is collected as monoiodosilane; the fraction at 70°C is collected as iodoethane; and the fraction at 80°C is collected as the solvent;

[0045] S3: The remaining reaction liquid is subjected to adsorption purification, 4 g of polystyrene-based complexing active agent is added, stirred at 55° C. for 1 hour, and then filtered. The filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0046] The S1 solvent is n-hexane.

[0047] The S1 reaction temperature is 40° C. and the reaction time is 18 hours.

[0048] The operating pressure of the S3 vacuum distillation is 1100 Pa and the temperature is 75°C.

[0049] The preparation method of the polystyrene-based complexing active agent is:

[0050] 110 g of styrene, 0.2 g of allyl triphenylphosphine, 2 g of trans-2-butene-1,4-dicarboxylic acid, 6 g of divinylbenzene, 1100 g of water, 1 g of potassium persulfate, and 1 g of gelatin were stirred and reacted at 85° C. for 7 hours, filtered, washed with water, and dried to obtain a polystyrene-based complexing active agent.

[0051] Example 3

[0052] A method for preparing high-purity diiodosilane, comprising the following steps:

[0053] S1 Reaction process: 28 g of iodine ethane, 28 g of bis(diethylamino)silane, and 110 g of solvent were added to a three-necked flask and stirred under argon protection for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0054] S2 Product Separation: The yellow product is filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid is distilled at 95°C under atmospheric pressure, and the fraction at 55°C is collected as monoiodosilane; the fraction at 70°C is collected as iodoethane; and the fraction at 80°C is collected as the solvent;

[0055] S3: The remaining reaction liquid is subjected to adsorption purification, and 6 g of polystyrene-based complexing active agent is added. The mixture is stirred at 55° C. for 1.5 hours, filtered, and the filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0056] The S1 solvent is n-hexane.

[0057] The S1 reaction temperature is 50° C. and the reaction time is 22 hours.

[0058] The operating pressure of the S3 vacuum distillation is 1200 Pa and the temperature is 75°C.

[0059] The preparation method of the polystyrene-based complexing active agent is:

[0060] 140 g of styrene, 0.4 g of allyl triphenylphosphine, 4 g of trans-2-butene-1,4-dicarboxylic acid, 8 g of divinylbenzene, 1400 g of water, 1.5 g of potassium persulfate, and 1.5 g of gelatin were stirred and reacted at 85° C. for 9 hours, filtered, washed with water, and dried to obtain a polystyrene-based complexing active agent.

[0061] Example 4

[0062] A method for preparing high-purity diiodosilane, comprising the following steps:

[0063] S1 Reaction process: 30 g of iodine ethane, 30 g of bis(diethylamino)silane, and 120 g of solvent were added to a three-necked flask and stirred under the protection of argon for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0064] S2 Product Separation: The yellow product was filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid was distilled at 100°C under normal pressure, and the fraction at 60°C was monoiodosilane; the fraction at 70°C was collected as the solvent;

[0065] S3: The remaining reaction liquid is subjected to adsorption purification, 8 g of polystyrene-based complexing active agent is added, stirred at 60° C. for 2 hours, and then filtered. The filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0066] The S1 solvent is n-hexane.

[0067] The S1 reaction temperature is 60° C. and the reaction time is 24 hours.

[0068] The operating pressure of the S3 vacuum distillation is 1300 Pa and the temperature is 80°C.

[0069] The preparation method of the polystyrene-based complexing active agent is:

[0070] 150g of styrene, 0.5g of allyl triphenylphosphine, 5g of trans-2-butene-1,4-dicarboxylic acid, 10g of divinylbenzene, 1500g of water, 2g of potassium persulfate, and 2g of gelatin were stirred and reacted at 90°C for 10 hours, filtered, washed with water, and dried to obtain a polystyrene-based complexing active agent.

[0071] Comparative Example 1

[0072] A method for preparing high-purity diiodosilane, comprising the following steps:

[0073] S1 Reaction process: 20 g of iodine ethane, 20 g of bis(diethylamino)silane, and 80 g of solvent were added to a three-necked flask and stirred under argon protection for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0074] S2 Product Separation: The yellow product was filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid was distilled at 90°C under normal pressure, and the fraction at 50°C was collected as monoiodosilane; the fraction at 70°C was collected as the solvent;

[0075] S3: The remaining reaction liquid is subjected to vacuum distillation to finally obtain diiodosilane.

[0076] The S1 solvent is n-hexane.

[0077] The S1 reaction temperature is 30° C. and the reaction time is 16 hours.

[0078] The operating pressure of the S3 vacuum distillation is 1000 Pa and the temperature is 70°C.

[0079] Comparative Example 2

[0080] A method for preparing high-purity diiodosilane, comprising the following steps:

[0081] S1 Reaction process: 20 g of iodine ethane, 20 g of bis(diethylamino)silane, and 80 g of solvent were added to a three-necked flask and stirred under argon protection for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0082] S2 Product Separation: The yellow product was filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid was distilled at 90°C under normal pressure, and the fraction at 50°C was collected as monoiodosilane; the fraction at 70°C was collected as the solvent;

[0083] S3: The remaining reaction liquid is subjected to adsorption purification, and the amount of active agent added is 2 g. The mixture is stirred at 50° C. for 0.5 hour, and then filtered. The filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0084] The S1 solvent is n-hexane.

[0085] The S1 reaction temperature is 30° C. and the reaction time is 16 hours.

[0086] The operating pressure of the S3 vacuum distillation is 1000 Pa and the temperature is 70°C.

[0087] The preparation method of the active agent is:

[0088] 100 g of styrene, 1 g of trans-2-butene-1,4-dicarboxylic acid, 5 g of divinylbenzene, 1000 g of water, 0.3 g of potassium persulfate, and 0.2 g of gelatin were stirred and reacted at 80° C. for 6 hours, filtered, washed with water, and dried to obtain an active agent.

[0089] Comparative Example 3

[0090] A method for preparing high-purity diiodosilane, comprising the following steps:

[0091] S1 Reaction process: 20 g of iodine ethane, 20 g of bis(diethylamino)silane, and 80 g of solvent were added to a three-necked flask and stirred under argon protection for reaction; during the reaction, a yellow-white precipitate was slowly generated, and a yellow reaction product was finally obtained;

[0092] S2 Product Separation: The yellow product was filtered through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; the obtained colorless transparent liquid was distilled at 90°C under normal pressure, and the fraction at 50°C was collected as monoiodosilane; the fraction at 70°C was collected as the solvent;

[0093] S3: The remaining reaction liquid is subjected to adsorption purification, and the amount of active agent added is 2 g. The mixture is stirred at 50° C. for 0.5 hour, and then filtered. The filtrate is subjected to vacuum distillation to finally obtain diiodosilane.

[0094] The S1 solvent is n-hexane.

[0095] The S1 reaction temperature is 30° C. and the reaction time is 16 hours.

[0096] The operating pressure of the S3 vacuum distillation is 1000 Pa and the temperature is 70°C.

[0097] The preparation method of the active agent is:

[0098] 100 g of styrene, 0.03 g of allyl triphenylphosphine, 5 g of divinylbenzene, 1000 g of water, 0.3 g of potassium persulfate, and 0.2 g of gelatin were stirred and reacted at 80° C. for 6 hours, filtered, washed with water, and dried to obtain an active agent.

[0099] Table 1: Test results of Examples and Comparative Examples

[0100]

[0101]

[0102] Through the data analysis of the above examples and comparative examples, the diiodosilane prepared by the present invention has a purity of more than 99.5%, and the metal ion purity grade reaches 6N level.

[0103] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing high-purity diiodosilane, comprising the following steps: S1 Reaction process: 20-30 parts of iodoethane, 20-30 parts of bis(diethylamino)silane, and 80-120 parts of solvent are added to a three-necked flask and stirred under the protection of argon for reaction; during the reaction, a yellow-white precipitate is slowly generated, and a yellow reaction product is finally obtained; S2 Product Separation: Filter the yellow product through a filter column to obtain a colorless transparent liquid and a yellow-white solid tetraethylammonium iodide; distill the obtained colorless transparent liquid under normal pressure at 90-100°C, collect the fraction at 50-60°C as monoiodosilane, and collect the fraction at 70-80°C as the solvent; S3: The remaining reaction liquid is subjected to adsorption purification, and 2-8 parts of a polystyrene-based complexing active agent are added, stirred at 50-60° C. for 0.5-2 hours, filtered, and the filtrate is subjected to vacuum distillation to finally obtain diiodosilane; The polystyrene-based complexing active agent is prepared by reacting styrene, allyl triphenylphosphine, trans-2-butene-1,4-dicarboxylic acid, divinylbenzene, water, potassium persulfate and gelatin.

2. The method for preparing high-purity diiodosilane according to claim 1, wherein: The S1 solvent is n-hexane.

3. The method for preparing high-purity diiodosilane according to claim 1, wherein: The S1 reaction temperature is 30-60°C and the reaction time is 16-24 hours.

4. The method for preparing high-purity diiodosilane according to claim 1, wherein: The operating pressure of the S3 vacuum distillation is 1000-1300 Pa and the temperature is 70-80°C.

5. The method for preparing high-purity diiodosilane according to claim 1, wherein: The preparation method of the polystyrene-based complexing active agent is: By weight, 100-150 parts of styrene, 0.03-0.5 parts of allyl triphenylphosphine, 1-5 parts of trans-2-butene-1,4-dicarboxylic acid, 5-10 parts of divinylbenzene, 1000-1500 parts of water, 0.3-2 parts of potassium persulfate and 0.2-2 parts of gelatin are stirred and reacted at 80-90° C. for 6-10 hours, filtered, washed with water and dried to obtain a polystyrene-based complexing active agent.

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