A process for the preparation of trimethylsilane
By controlling the reaction conditions and subsequent processing steps of trimethylchlorosilane with lithium aluminum hydride solution, the problems of low yield and purity in the preparation of trimethylsilane were solved, and the preparation of high-purity trimethylsilane was achieved, which is suitable for integrated circuit film forming materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LINGGAS MATERIALS TIANJIN LTD
- Filing Date
- 2024-08-12
- Publication Date
- 2026-07-07
AI Technical Summary
The existing preparation process for trimethylsilane has low yield and purity, and there are problems such as silane rearrangement and excessive metal elements.
High-purity trimethylsilane was obtained by reacting trimethylchlorosilane with lithium aluminum hydride solution at a specific molar ratio and temperature, followed by steps such as condensation, alkali treatment, ion exchange, and distillation to control the reaction conditions and subsequent impurity removal processes.
A high-yield and high-purity preparation of trimethylsilane was achieved, meeting the purity requirements of electronic specialty gases, simplifying the subsequent purification process and reducing the risk of environmental pollution.
Smart Images
Figure CN118994225B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic specialty gas preparation technology, and in particular to a method for preparing trimethylsilane. Background Technology
[0002] Currently, trimethylsilane has become an important material for integrated circuit film formation. It is mainly used in the preparation of carbon silicon nitrogen thin films via PECVD process to deposit copper diffusion barrier layers or etching stop layers with low dielectric constant.
[0003] The integrated circuit industry has high requirements for product purity, especially the content of trace metal element impurities in the product, which is usually required to be below 5 ppb, which greatly increases the difficulty of product purification.
[0004] The technology for preparing trimethylsilane via metal hydrides is currently quite mature.
[0005] For example, CN117567496A discloses a method for preparing high-purity trimethylsilane, including the following steps: S1, placing a catalyst in a reactor and an adsorbent in an adsorber, and purging the reaction apparatus with high-purity nitrogen; S2, introducing hydrogen and trimethylchlorosilane into the reactor containing the catalyst at a ratio of 2-6:1, and reacting to obtain a mixed gas; S3, buffering the mixed gas, and then washing it with alkali to obtain crude trimethylsilane; S4, subjecting the crude trimethylsilane to a series of heavy weight removal, light weight removal, and adsorption processes to obtain high-purity trimethylsilane.
[0006] However, existing preparation processes often involve silane rearrangement, with the generation of dimethyldichlorosilane having a particularly significant impact. Free chlorine can cause irreversible corrosion to integrated circuits under certain conditions, so excessive chlorine levels have become a common problem for electronic specialty gases. At the same time, the use of large amounts of metal hydrides has also resulted in serious exceedances of metal content in the products, posing significant challenges to subsequent purification and use.
[0007] In summary, the existing processes for preparing trimethylsilane still suffer from low yields and low purity of the obtained trimethylsilane. Summary of the Invention
[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing trimethylsilane, so as to solve the problem that the yield and purity of the obtained trimethylsilane are still low in the preparation process.
[0009] To achieve this objective, the present invention adopts the following technical solution:
[0010] This invention provides a method for preparing trimethylsilane, the method comprising:
[0011] Trimethylchlorosilane was added dropwise to a lithium aluminum hydride solution to react and obtain trimethylsilane;
[0012] In the reaction, the molar ratio of trimethylchlorosilane to lithium aluminum hydride is (3.8-4.2):1;
[0013] The temperature of the lithium aluminum hydride solution in the reaction is 80-100℃.
[0014] The preparation method provided by this invention achieves the preparation of high-quality trimethylsilane by using specific preparation process parameters, controlling specific molar ratios and reaction system temperatures, and the obtained trimethylsilane has a high purity yield.
[0015] As a preferred embodiment of the present invention, the solvent of the lithium aluminum hydride solution includes xylene and / or toluene.
[0016] As a preferred embodiment of the present invention, the mass concentration of the lithium aluminum hydride solution is 4-5%.
[0017] As a preferred embodiment of the present invention, the dropping rate of trimethylchlorosilane in the reaction is 1-2 mL / min.
[0018] Preferably, the reaction is maintained at a constant temperature for 1-1.5 hours after the trimethylchlorosilane is added dropwise.
[0019] As a preferred embodiment of the present invention, the trimethylsilane obtained from the reaction is a gaseous product that is condensed to obtain trimethylsilane liquid.
[0020] As a preferred embodiment of the present invention, the condensation temperature is -40℃ to -20℃.
[0021] As a preferred technical solution of the present invention, the trimethylsilane liquid obtained by condensation is subjected to alkali treatment, ion exchange and distillation in sequence to obtain electronic grade trimethylsilane.
[0022] As a preferred embodiment of the present invention, the alkaline treatment involves washing the trimethylsilane liquid with an alkaline solution.
[0023] Preferably, the molar ratio of trimethylsilane liquid to the volume ratio of alkali solution in the alkali treatment is 1 mol:(50-60 mL).
[0024] Preferably, the alkaline solution comprises sodium hydroxide and / or potassium hydroxide.
[0025] Preferably, the mass concentration of the alkaline solution is 10-20%.
[0026] As a preferred embodiment of the present invention, the ion exchange is performed by treating the feed solution with anion exchange resin and cation exchange resin.
[0027] Preferably, the adsorption temperature of the ion exchange is 25-45℃.
[0028] As a preferred embodiment of the present invention, the distillation includes processing the feed liquid using a distillation column.
[0029] Preferably, the pressure in the distillation column reboiler is 0.02-0.03 MPa.
[0030] Preferably, the temperature of the distillation column reboiler is 40-45°C.
[0031] Preferably, the pressure at the top of the distillation column is 0.005-0.02 MPa.
[0032] Preferably, the temperature at the top of the distillation column is 2-9°C.
[0033] Preferably, the temperature of the reflux condenser in the distillation process is 8-10°C.
[0034] Compared with existing technical solutions, the present invention has the following beneficial effects:
[0035] (1) The preparation of trimethylsilane is carried out under mild conditions and with a high yield.
[0036] (2) The subsequent impurity removal and adsorption processes are simple to operate and do not cause environmental pollution.
[0037] (3) It facilitates the construction of equipment and large-scale production in subsequent industries. Attached Figure Description
[0038] Figure 1 This is the gas chromatogram of the trimethylsilane product obtained in Example 1 of the present invention;
[0039] Figure 2 This is the mass spectrum of the trimethylsilane product obtained in Example 1 of the present invention.
[0040] In the figure, the peak at 8-9 minutes is the nitrogen peak, and purity is not considered.
[0041] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation
[0042] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:
[0043] This embodiment provides a method for preparing trimethylsilane, the method comprising:
[0044] Trimethylchlorosilane was added dropwise to a lithium aluminum hydride solution to react and obtain trimethylsilane;
[0045] In the reaction, the molar ratio of trimethylchlorosilane to lithium aluminum hydride is (3.8-4.2):1;
[0046] The temperature of the lithium aluminum hydride solution in the reaction is 80-100℃.
[0047] In this invention, the molar ratio of trimethylchlorosilane to lithium aluminum hydride in the reaction is (3.8-4.2):1, for example, it can be 3.8:1, 3.82:1, 3.84:1, 3.86:1, 3.88:1, 3.9:1, 3.92:1, 3.94:1, 3.96:1, 3.98:1, 4:1, 4.02:1, 4.04:1, 4.06:1, 4.08:1, 4.1:1, 4.12:1, 4.14:1, 4.16:1, 4.18:1, or 4.2:1, etc., but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0048] In this invention, the temperature of the lithium aluminum hydride solution in the reaction is 80-100℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃ or 100℃, etc., but is not limited to the listed values, and other unlisted values within this range are also acceptable.
[0049] The solvent of the lithium aluminum hydride solution includes xylene and / or toluene.
[0050] The mass concentration of the lithium aluminum hydride solution is 4-5%, for example, it can be 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9% or 5%, etc., but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0051] The dropping rate of trimethylchlorosilane in the reaction is 1-2 mL / min, for example, it can be 1 mL / min, 1.1 mL / min, 1.2 mL / min, 1.3 mL / min, 1.4 mL / min, 1.5 mL / min, 1.6 mL / min, 1.7 mL / min, 1.8 mL / min, 1.9 mL / min or 2 mL / min, but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0052] In the reaction, after the trimethylchlorosilane is added dropwise, the temperature is maintained for 1-1.5 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, or 1.5 hours, but not limited to the listed values. Other unlisted values within this range are also acceptable.
[0053] The trimethylsilane obtained from the reaction is a gaseous product that is condensed to obtain a liquid trimethylsilane.
[0054] The condensation temperature is -40℃ to -20℃, for example, it can be -40℃, -38℃, -36℃, -34℃, -32℃, -30℃, -28℃, -26℃, -24℃, -22℃ or -20℃, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.
[0055] The trimethylsilane liquid obtained by condensation is subjected to alkali treatment, ion exchange and distillation in sequence to obtain electronic grade trimethylsilane.
[0056] Specifically, the alkaline treatment involves washing the trimethylsilane liquid with an alkaline solution.
[0057] Specifically, the alkaline solution includes sodium hydroxide and / or potassium hydroxide.
[0058] Specifically, the mass concentration of the alkaline solution is 10-20%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0059] Specifically, the ion exchange involves treating the feed solution with anion exchange resin and cation exchange resin.
[0060] In this invention, the anion exchange resin used in the ion exchange is first washed with a 5%-10% NaOH solution and then washed with water before use; the cation exchange resin is washed with a 0.8-1.1 mol / L hydrochloric acid solution and then washed with water before contacting the feed solution to perform ion exchange.
[0061] Specifically, the treatment sequence of anion exchange resin and cation exchange resin in ion exchange can be designed according to the conventional requirements in this field, such as sequentially passing the feed solution through anion exchange resin and cation exchange resin for ion exchange treatment, or sequentially passing the feed solution through cation exchange resin and anion exchange resin for ion exchange treatment.
[0062] In this invention, the anion exchange resin can be a commercially available ion exchange resin or an ion exchange resin synthesized according to the prior art. For example, it can be a 201×7 anion exchange resin, D201 anion exchange resin, or other commonly used strong base anion exchange resins in the art.
[0063] In this invention, the cation exchange resin can be a commercially available ion exchange resin or an ion exchange resin synthesized according to the prior art. For example, it can be a 001×7 cation exchange resin, 003×7 cation exchange resin, 004×7 cation exchange resin, or other commonly used strong acid cation exchange resins in the art.
[0064] Specifically, the adsorption temperature of the ion exchange is 25-45℃, for example, it can be 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃ or 45℃, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.
[0065] Specifically, the distillation includes processing the feed liquid using a distillation column.
[0066] Specifically, the pressure in the distillation column reboiler is 0.02-0.03 MPa, for example, it can be 0.02 MPa, 0.022 MPa, 0.024 MPa, 0.026 MPa, 0.028 MPa or 0.03 MPa, but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0067] Specifically, the temperature of the distillation column reboiler is 40-45℃, for example, it can be 40℃, 41℃, 42℃, 43℃, 44℃ or 45℃, etc., but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0068] Specifically, the pressure at the top of the distillation column is 0.005-0.02 MPa, for example, it can be 0.005 MPa, 0.006 MPa, 0.008 MPa, 0.01 MPa, 0.012 MPa, 0.014 MPa, 0.016 MPa, 0.018 MPa or 0.02 MPa, but is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0069] Specifically, the temperature at the top of the distillation column is 2-9°C, for example, it can be 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C or 9°C, but is not limited to the listed values. Other unlisted values within this range also meet the requirements.
[0070] Specifically, the temperature of the reflux condenser in the distillation process is 8-10°C, for example, it can be 8°C, 9°C or 8°C, but it is not limited to the listed values. Other unlisted values within this range are also acceptable.
[0071] Furthermore, to illustrate the beneficial effects of the method for preparing trimethylsilane provided by this invention, practical examples are used for analysis and explanation, as follows:
[0072] Example 1
[0073] This embodiment provides a method for preparing trimethylsilane, as detailed below:
[0074] 1. Weigh 42.30 g (1.11 mol) of lithium aluminum hydride and dissolve it in 1000 mL of xylene solution. Stir well and heat the reaction apparatus to 80 °C. Maintain the temperature.
[0075] 2. 470 g (4.33 mol) of trimethylchlorosilane was slowly added dropwise (at a rate of 1.5 mL / min) until a large amount of gas was generated in the reaction solution. After the addition was completed, the mixture was kept at this temperature for 1.2 h. The generated gas was collected using a condenser at -40 °C to obtain crude trimethylsilane. 296 g (4.01 mol) of crude trimethylsilane was collected. The molar ratio of trimethylchlorosilane to lithium aluminum hydride during the reaction was 3.9:1.
[0076] 3. Prepare a 10% sodium hydroxide solution. The ratio of solution volume to crude trimethylsilane is 50 mL of sodium hydroxide solution per 1 mol of trimethylsilane, i.e., a total of 200 mL of sodium hydroxide alkali solution. Pass the prepared crude trimethylsilane into the alkali solution to remove chlorine-containing impurities from the product.
[0077] 4. The hydroxide-type anion exchange resin (201×7 anion exchange resin) was washed with a 5% NaOH solution and then pretreated with ultrapure water. The hydrogen-type cation exchange resin (001×7 cation exchange resin) was washed with a 1 mol / L hydrochloric acid solution and then pretreated with ultrapure water. The crude trimethylsilane product that had passed through the alkaline solution was then passed through the hydroxide-type anion exchange resin and the hydrogen-type cation exchange resin sequentially at 45°C to remove trace metal elements from the crude product. The concentration of metal ions in the resulting solution after ion exchange treatment is shown in Table 1 below.
[0078] Table 1
[0079]
[0080] 5. The crude trimethylsilane, after adsorption treatment with ion exchange resin, was distilled in a distillation column (pressure at the bottom of the column was 0.02 MPa, temperature at the bottom was 40℃, pressure at the top was 0.005 MPa, temperature at the top was 2℃, and temperature of the reflux condenser was 10℃) to obtain trimethylsilane. Gas chromatography-mass spectrometry analysis was performed, and the results are as follows: Figure 1 and Figure 2 As shown, 264 g (3.57 mol) of electronic-grade trimethylsilane with a purity of 99.99% was obtained, with a yield of 82.45%.
[0081] Example 2
[0082] This embodiment provides a method for preparing trimethylsilane, as detailed below:
[0083] 1. Weigh 42.30 g (1.11 mol) of lithium aluminum hydride and dissolve it in 1000 mL of toluene solution. Stir well and heat the reaction apparatus to 80 °C. Maintain the temperature.
[0084] 2. 470 g (4.33 mol) of trimethylchlorosilane was slowly added dropwise (at a rate of 2 mL / min) until a large amount of gas was generated in the reaction solution. After the addition was completed, the solution was kept warm for 1 hour. The generated gas was collected through a condenser at -40℃, which is the crude product of trimethylsilane. 308 g (4.17 mol) of crude product was collected. The molar ratio of trimethylchlorosilane to lithium aluminum hydride during the reaction was 3.9:1.
[0085] 3. Prepare a 20% sodium hydroxide solution. The volume ratio of the solution to the crude trimethylsilane is 50 mL of sodium hydroxide solution for every 1 mol of trimethylsilane, i.e., a total of 200 mL of sodium hydroxide alkali solution. Pass the prepared crude trimethylsilane into the alkali solution to remove chlorine-containing impurities from the product.
[0086] 4. The hydroxide-type anion exchange resin (201×7 anion exchange resin) was washed with a 10% NaOH solution and then pretreated with ultrapure water. The hydrogen-type cation exchange resin (001×7 cation exchange resin) was washed with a 1 mol / L hydrochloric acid solution and then pretreated with ultrapure water. The crude trimethylsilane product that had passed through the alkaline solution was then passed through the hydroxide-type anion exchange resin and the hydrogen-type cation exchange resin sequentially at 45°C to remove trace metal elements from the crude product. The content of metal elements in the resulting solution after ion exchange treatment is shown in Table 2 below.
[0087] Table 2
[0088]
[0089]
[0090] 5. The crude trimethylsilane treated by ion exchange resin adsorption was distilled in a distillation column (pressure at the bottom of the column was 0.03 MPa, temperature at the bottom of the column was 45℃, pressure at the top of the column was 0.02 MPa, temperature at the top of the column was 9℃, and temperature of the reflux condenser was 8℃) to obtain 287 g (3.88 mol) of electronic-grade trimethylsilane with a purity of 99.99% by gas chromatography-mass spectrometry analysis, with a yield of 89.61%.
[0091] Comparative Example 1
[0092] The difference from Example 1 is that ion exchange resin adsorption is not performed. After alkali washing, the product is directly fed into a distillation column for distillation, yielding 293g (3.97mol) of trimethylsilane with a purity of 99.99% and a yield of 91.69%. The concentration of metal ions in the obtained trimethylsilane is shown in Table 3 below, indicating that the metal ion concentration is seriously excessive.
[0093] Table 3
[0094]
[0095]
[0096] Comparative Example 2
[0097] The only difference from Example 1 is that lithium aluminum hydride is replaced with an equal amount of calcium hydride.
[0098] Comparative Example 3
[0099] The only difference from Example 1 is that lithium aluminum hydride is replaced with equal amounts of lithium aluminum hydride and calcium hydride in a molar ratio of 1:11.
[0100] Comparative Example 4
[0101] The only difference from Example 1 is that the temperature of the lithium aluminum hydride solution in the reaction is 50°C.
[0102] Comparative Example 5
[0103] The only difference from Example 1 is that the temperature of the lithium aluminum hydride solution in the reaction is 120°C.
[0104] Comparative Example 6
[0105] The only difference from Example 1 is that the xylene solution is replaced with an equal amount of diethylene glycol dibutyl ether solution.
[0106] In this invention, the yield and purity of the products in the examples and comparative examples are detailed in Table 4.
[0107] Table 4
[0108]
[0109]
[0110] As can be seen from the data of the examples and comparative examples in Table 4, calcium hydride has no promoting effect on the reaction under these reaction conditions, and the final reaction solvent is an aromatic solvent containing a benzene ring. The suitable reaction temperature is 80-100℃. Excessively high temperature will cause the lithium aluminum hydride catalyst to decompose and reduce its catalytic activity. Most importantly, after adsorption by ion exchange resin, its metal ion content is significantly reduced, meeting the requirements of electronic grade special gas standards.
[0111] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
[0112] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0113] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0114] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A method for preparing trimethylsilane, characterized in that, The preparation method includes: Trimethylchlorosilane was added dropwise to a lithium aluminum hydride solution to react with the resulting trimethylsilane gaseous product. The resulting trimethylsilane gaseous product was condensed to obtain a liquid trimethylsilane. The liquid trimethylsilane was then subjected to alkali treatment, ion exchange, and distillation to obtain electronic-grade trimethylsilane with a purity of 99.99%. The molar ratio of trimethylchlorosilane to lithium aluminum hydride in the reaction was (3.8-4.2):
1. The temperature of the lithium aluminum hydride solution in the reaction is 80-100℃; The alkaline treatment involves washing the trimethylsilane liquid with an alkaline solution, wherein the molar ratio of the trimethylsilane liquid to the volume of the alkaline solution is 1 mol: (50-60 mL). The ion exchange involves treating the feed solution with anion exchange resin and cation exchange resin. Before use, the anion exchange resin is first washed with a 5%-10% NaOH solution and then washed with water; the cation exchange resin is first washed with a 0.8-1.1 mol / L hydrochloric acid solution and then washed with water. The distillation includes processing the feed liquid using a distillation column; The pressure at the bottom of the distillation column is 0.02-0.03 MPa, the temperature at the bottom is 40-45℃, the pressure at the top is 0.005-0.02 MPa, the temperature at the top is 2-9℃, and the temperature of the condenser in the reflux distillation process is 8-10℃.
2. The preparation method according to claim 1, characterized in that, The solvent for the lithium aluminum hydride solution includes xylene and / or toluene.
3. The preparation method according to claim 1, characterized in that, The mass concentration of the lithium aluminum hydride solution is 4-5%.
4. The preparation method according to claim 1, characterized in that, The dropping rate of trimethylchlorosilane in the reaction was 1-2 mL / min.
5. The preparation method according to any one of claims 1-3, wherein the reaction is maintained at a constant temperature for 1-1.5 h after the addition of trimethylchlorosilane.
6. The preparation method according to claim 1, characterized in that, The condensation temperature is -40℃ to -20℃.
7. The preparation method according to claim 1, characterized in that, The alkaline solution includes sodium hydroxide and / or potassium hydroxide.
8. The preparation method according to claim 1, characterized in that, The mass concentration of the alkaline solution is 10-20%.
9. The preparation method according to claim 1, characterized in that, The adsorption temperature of the ion exchange is 25-45℃.