A method for preparing diiodosilane

Abstract

The application relates to a preparation method of diiodosilane, which comprises the following steps: sequentially reacting dichlorosilane and lithium iodide at a first temperature and a second temperature; wherein the first temperature is 0-8 DEG C, and the second temperature is 25-30 DEG C. Compared with the existing preparation method, the preparation method of diiodosilane in one embodiment of the application can improve the purity and yield of diiodosilane products.

Description

Technical Field

[0001] This invention relates to the preparation of diiodosilanes, and more particularly to a method for preparing high-purity diiodosilanes. Background Technology

[0002] Diiodosilane, as an important organosilicon intermediate, possesses both high reactivity and specific structural characteristics, and has broad application prospects in semiconductor material doping, organosilicon compound synthesis, and functional thin film preparation. Its purity directly affects the performance of downstream products and the stability of the preparation process. Especially in advanced semiconductor processes, stringent requirements are placed on the impurity content and purity grade of diiodosilane.

[0003] Existing methods for preparing diiodosilanes mostly use halosilanes and iodides as raw materials, achieving synthesis through substitution reactions. The key lies in controlling reaction selectivity and product purification. However, existing preparation methods have the following drawbacks:

[0004] 1) Severe impurity residue: Existing methods for preparing diiodosilane require the use of solvents such as diethyl ether and toluene. These solvents are easily left in the product and are difficult to remove completely through conventional purification methods, resulting in insufficient purity of diiodosilane, which cannot meet the requirements of high-end semiconductor processes.

[0005] 2) Poor solid-liquid separation effect: The solid by-products (such as lithium chloride) generated by the reaction are mixed evenly with the liquid products. Existing separation methods such as filtration and sedimentation are inefficient and easily lead to the entrainment of solid impurities, further reducing the purity of the product. In addition, the product is easily exposed to air and deteriorates during the separation process.

[0006] 3) Low reaction selectivity: The existing process has a crude temperature control, which easily leads to side reactions that generate impurities such as polyiodosilanes and silane polymers, reducing the yield of the target product and increasing the difficulty of subsequent purification.

[0007] 4) Insufficient process safety: The reaction raw material dichlorosilane (DCS) is flammable and easily hydrolyzed. The existing feeding method and reaction process lack refined inert atmosphere control, which can easily lead to safety risks. In addition, the product is prone to decomposition upon contact with moisture. Summary of the Invention

[0008] To overcome at least one of the defects of the prior art, in a first aspect, one embodiment of the present invention provides a method for preparing diiodosilane, comprising: reacting dichlorosilane with lithium iodide sequentially at a first temperature and a second temperature; wherein the first temperature is 0 to 8°C and the second temperature is 25 to 30°C.

[0009] The present invention provides a method for preparing diiodosilane that, compared with existing methods, can improve the purity and yield of diiodosilane products. Detailed Implementation

[0010] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0011] One embodiment of the present invention provides a method for preparing diiodosilane, comprising: reacting dichlorosilane (DCS) with lithium iodide sequentially at a first temperature and a second temperature; wherein the first temperature is 0-8°C and the second temperature is 25-30°C.

[0012] In one embodiment, the reaction of dichlorosilane and lithium iodide is carried out in an inert gas atmosphere.

[0013] In one embodiment, the inert gas includes nitrogen and / or argon.

[0014] In one embodiment, the reaction of dichlorosilane and lithium iodide is carried out in a reaction vessel. The reaction vessel is first purged with an inert gas multiple times (e.g., three times) to ensure that there is no residual air or moisture in the system and to form a stable inert atmosphere.

[0015] In one embodiment, the reactor can be a stainless steel jacketed reactor, such as a stainless steel jacketed reactor with double-ended sealed stirring, to prevent gas leakage during the reaction. Cooling and heating during the reaction can be achieved through the jacket; for example, the system can be cooled by providing a cryogenic medium to the jacket through a cryogenic cooling system.

[0016] In one embodiment, inert gas can be provided to the reactor through an inert gas protection system that is compatible with the reactor.

[0017] In one embodiment, lithium iodide is added to the reactor under an inert gas atmosphere.

[0018] In one embodiment, dichlorosilane is added to a system containing lithium iodide at a temperature of -40 to -20°C. For example, the temperature at which dichlorosilane is added can be -38°C, -36°C, -35°C, -32°C, -30°C, -28°C, -26°C, -25°C, -23°C, or -21°C. Limiting the addition temperature of dichlorosilane to -40 to -20°C helps prevent side reactions caused by excessively high local temperatures.

[0019] In one embodiment, dichlorosilane is added to the reactor under an inert gas atmosphere.

[0020] In one embodiment, lithium iodide solid is added to the reactor under an inert gas atmosphere, and then the system temperature is lowered to -40 to -20°C (e.g., -40°C); dichlorosilane is liquefied by the low temperature, and then dichlorosilane gas is introduced through a gas pipeline, while the system temperature is controlled to be maintained at -40 to -20°C during the feeding process.

[0021] In one embodiment, after the dichlorosilane is added, the temperature of the reaction system is allowed to rise naturally to the first temperature for the reaction to proceed.

[0022] In one embodiment, the first temperature can be 0 to 8°C, for example, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, or 7°C.

[0023] In one embodiment, the reaction time of the dichlorosilane and lithium iodide reaction system at the first temperature can be 12 to 16 hours, for example 13 hours, 13.5 hours, 14 hours, 14.5 hours or 15 hours.

[0024] In one embodiment, the second temperature can be 25–30°C, for example 26°C, 27°C, 28°C, or 29°C.

[0025] In one embodiment, the reaction time of the dichlorosilane and lithium iodide reaction system at the second temperature can be 24 to 48 hours to ensure complete reaction, reduce unreacted raw material residue, and prevent product polymerization. The reaction time at the second temperature can be, for example, 25 hours, 28 hours, 30 hours, 32 hours, 35 hours, 36 hours, 37 hours, 38 hours, 40 hours, 42 hours, or 45 hours.

[0026] In one embodiment, the pressure of the reaction system of dichlorosilane and lithium iodide can be 0–30 kPa (gauge pressure), for example 0.01 kPa, 0.02 kPa, 0.05 kPa, 0.1 kPa, 0.5 kPa, 1 kPa, 2 kPa, 5 kPa, 10 kPa, 15 kPa, 20 kPa, or 25 kPa. More specifically, it can be atmospheric pressure.

[0027] In one embodiment, the reaction between dichlorosilane and lithium iodide is carried out under solvent-free conditions.

[0028] In one embodiment, the reaction system of dichlorosilane and lithium iodide is kept at 0-8°C for 12-16 hours, and then the system temperature is raised to 25-30°C and kept at 24-48 hours.

[0029] In one embodiment, the reacted materials are subjected to solid-liquid separation, which can be carried out in an inert gas atmosphere. This solid-liquid separation enables the separation of the liquid product diiodosilane from the solid product lithium chloride.

[0030] In one embodiment, centrifugal separation can be used to separate the solid and liquid components of the reacted material. Centrifugal separation can be carried out in a centrifuge with a rotation speed of 30–50 Hz, such as 32 Hz, 35 Hz, 38 Hz, 39 Hz, 40 Hz, 41 Hz, 42 Hz, 45 Hz, or 48 Hz.

[0031] In one embodiment, the centrifugation time can be 15 to 30 minutes, for example 18 minutes, 19 minutes, 20 minutes, 22 minutes, 25 minutes, 26 minutes or 28 minutes.

[0032] In one embodiment, after the reaction of dichlorosilane and lithium iodide is completed, the system is kept in an inert atmosphere, and the reacted material is directly introduced from the bottom of the reactor into a centrifuge protected by inert gas for processing.

[0033] In one embodiment, the centrifuge is equipped with an inert gas protection device to ensure that the centrifugation process is carried out in an inert atmosphere, thereby preventing product deterioration during the process.

[0034] In one embodiment, after centrifugation, the upper liquid product (diiodosilane product) is collected and stored in a sealed container under an inert atmosphere to prevent decomposition due to contact with air and moisture.

[0035] In one embodiment, the lithium iodide used is anhydrous lithium iodide solid.

[0036] In one embodiment, the lithium iodide has a particle size of 200-300 mesh, such as 220 mesh, 250 mesh, 260 mesh or 280 mesh.

[0037] In one embodiment, the molar ratio of dichlorosilane to lithium iodide can be 1:2.5 to 8, more preferably 1:2.5 to 3.5, and even more preferably 1:2.7 to 3.0, for example 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, 1:3.1, 1:3.2, 1:3.5, 1:4, 1:4.5, 1:5, 1:6 or 1:7.

[0038] In one embodiment, any step in the preparation process of diiodosilane is carried out in an inert gas atmosphere (i.e., the entire process is under inert gas protection), such as the addition of raw materials, the reaction step, and the solid-liquid separation step after the reaction are all carried out in an inert gas atmosphere.

[0039] This invention discloses a method for preparing diiodosilane, which, by carrying out the reaction at a first temperature and a second temperature respectively, allows for the control of the reaction rate, ensuring complete reaction and suppressing side reactions, thereby obtaining a product with high yield and high purity. Specifically, the low temperature of the first temperature suppresses the formation of byproducts, while carrying out the reaction at the second temperature improves reaction efficiency, significantly enhancing reaction selectivity and product yield.

[0040] The method for preparing diiodosilane according to one embodiment of the present invention can maintain a stable yield of over 87%, which is 10-15% higher than that of existing preparation methods.

[0041] The present invention discloses a method for preparing diiodosilane using a solvent-free reaction system, thereby eliminating residual impurities from organic solvents at the source.

[0042] The present invention provides a method for preparing diiodosilane in one embodiment, which can produce diiodosilane products with high purity and high yield in the reaction process.

[0043] This invention discloses a method for preparing diiodosilane, which achieves efficient removal of solid impurities by using centrifugation to separate the reaction materials from the solids. Compared with separation methods such as filtration and sedimentation, the separation efficiency is improved by 3 to 5 times. Furthermore, by conducting the separation process in a closed environment with inert gas, oxidation and hydrolysis of the product are avoided, reducing the complexity of operation and improving industrial applicability.

[0044] The present invention provides a method for preparing diiodosilane, wherein the centrifugal separation method can be scaled up synchronously with the increase of the reaction system scale, and the process parameters are highly stable.

[0045] The present invention discloses a method for preparing diiodosilane, which effectively avoids the safety risks of the flammability and hydrolysis of the raw material dichlorosilane by using an inert gas for protection, and avoids the decomposition and deterioration of the product upon contact with air and moisture.

[0046] The present invention discloses a method for preparing diiodosilane, which, by employing a stainless steel jacketed reactor, enables precise control of temperature and stirring rate.

[0047] The present invention discloses a method for preparing diiodosilane in one embodiment, wherein the reaction vessel and separation device are both modularly designed, which can be flexibly expanded according to production needs and reduce the equipment compatibility risk during the scale-up process.

[0048] The present invention discloses a method for preparing diiodosilane, which enables the obtained diiodosilane product to achieve a purity of over 99.5%, far exceeding the purity of products obtained by existing processes. This purity directly meets the requirements of high-end semiconductor manufacturing processes. Furthermore, the product purity and yield fluctuations can be maintained below 2%.

[0049] The present invention discloses a method for preparing diiodosilane, which has high selectivity and high separation efficiency, enabling the synthesis of diiodosilane products with high purity and high yield, while improving process safety and scalability, and meeting the needs of high-end application scenarios.

[0050] The preparation method of diiodosilane according to one embodiment of the present invention will be further described below with reference to specific embodiments. At least some of the raw materials and equipment used in each embodiment and comparative example are as follows: 1. The reactor is equipped with a stainless steel jacketed reactor with double-end sealed stirring, and is equipped with an inert gas protection system, a low-temperature cooling system and an inert atmosphere centrifuge (speed adjustable range 0-100Hz).

[0051] 2. Anhydrous lithium iodide (particle size 200-300 mesh, purity 99.9%), dichlorosilane (DCS, purity 99.99%), argon (purity 99.999%).

[0052] Example 1 S1: Close all valves of the reactor, introduce argon gas to replace the air in the reactor, maintain the pressure in the reactor at 0.2MPa, hold the pressure for 5 minutes and then release the gas. Repeat this operation three times.

[0053] S2: Under an argon atmosphere, add 5000g (37.36mol) of anhydrous lithium iodide through the solid feed port of the reactor, then close and lock the feed port; start the jacketed cryogenic cooling system, introduce a cryogenic medium into the jacket to lower the reactor temperature to -40℃, and adjust the stirring speed to 150r / min; slowly introduce 1397.5g (13.84mol) of dichlorosilane gas into the reactor through the gas pipeline, with a molar ratio of dichlorosilane to anhydrous lithium iodide of 1:2.7. During the feeding process, the temperature is controlled by the jacket to stabilize the reactor temperature at -30℃; after the dichlorosilane has been introduced, close the gas inlet valve and continue stirring the material system for 30min.

[0054] S3: Stop the supply of low-temperature medium to the cooling system and allow the temperature inside the vessel to rise naturally to 2°C. Maintain this temperature range for 14 hours. Then start the jacket heating system to raise the temperature inside the vessel to 28°C and continue the constant temperature reaction for 36 hours, during which the stirring rate is maintained at 150 r / min.

[0055] S4: After the reaction is complete, maintain the argon atmosphere in the vessel, open the bottom discharge valve, and directly introduce the reaction mixture (liquid diiodosilane and solid lithium chloride) into a centrifuge that has been purged with argon three times. Set the centrifugation speed to 40 Hz and the centrifugation time to 20 min to separate the solid product lithium chloride and the liquid product.

[0056] S5: After centrifugation, collect the clear liquid product at the top, which is the diiodosilane product. The yield was calculated to be 88%. Gas chromatography (GC) showed a product purity of 99.6%, with no obvious organic solvent impurity peaks or solid impurity entrainment; 1H NMR spectroscopy (NMR)... 1 ¹H NMR (solvent CDCl₃, internal standard TMS) showed clear target characteristic peaks, δ 4.22–4.26 ppm (s, 2H, Si-H), with no byproduct characteristic peaks.

[0057] Example 2 This embodiment uses the same raw materials and process as Example 1 to prepare diiodosilane. The difference is that the amount of raw materials used is different, and it is 10 times that of Example 1. That is, the amount of anhydrous lithium iodide used is 50 kg (373.6 mol), and the amount of dichlorosilane used is 13.975 kg (138.4 mol). At the same time, the centrifugation speed is 40 Hz and the centrifugation time is 25 min.

[0058] The obtained diiodosilane product was weighed, and the yield was calculated to be 87.5%. The purity of the product was determined to be 99.5% by gas chromatography, and the proton NMR spectrum was consistent with that of Example 1, indicating no obvious impurities were introduced.

[0059] Example 3 This embodiment uses the same raw materials and process as Example 1 to prepare diiodosilane, the difference being that the molar ratio of dichlorosilane to anhydrous lithium iodide is 1:3, that is, 5000g (37.36mol) of anhydrous lithium iodide is added, and 1258g (12.45mol) of dichlorosilane gas is introduced accordingly; at the same time, the first temperature is adjusted to 8°C.

[0060] The obtained diiodosilane product was weighed, and the yield was calculated to be 84.6%. The purity of the product was determined to be 99.5% by gas chromatography, and the proton NMR spectrum was consistent with that of Example 1, indicating no obvious impurities were introduced.

[0061] Example 4 This embodiment uses the same raw materials and process as Example 1 to prepare diiodosilane. The difference is that 10L of anhydrous diethyl ether is added to the reaction system as a solvent. After the reaction is completed, solid impurities are separated by filtration, and the filtration operation is carried out in air.

[0062] The obtained diiodosilane product was weighed, and the yield was calculated to be 72%. Gas chromatography (GC) determined the product purity to be 95.3%, and GC characterization showed a significant residual ether peak. During filtration, the product slightly deteriorated upon contact with air, becoming pale yellow and turbid, which does not meet the requirements of high-end applications. This demonstrates that the use of organic solvents easily introduces residual impurities, and that the separation method of filtration in air further reduces the product purity.

[0063] Example 5 This embodiment uses essentially the same raw materials and process as Example 1 to prepare diiodosilane, the difference being the separation method of the mixture after the reaction. In this embodiment, the mixture after the reaction is separated into solid and liquid phases by filtration in an inert gas atmosphere for 2 hours.

[0064] The obtained diiodosilane product was weighed, and the yield was calculated to be 75%. The purity of the product was determined to be 96.1% by gas chromatography.

[0065] Comparative Example 1 This example uses essentially the same raw materials and processes as Example 1 to prepare diiodosilane. The difference is that after dichlorosilane is introduced, the temperature of the system is directly raised to 28°C and reacted at a constant temperature for 50 hours.

[0066] The obtained diiodosilane product was weighed, and the yield was calculated to be 68%. The product was characterized by gas chromatography and proton nuclear magnetic resonance (NMR). Gas chromatography showed the presence of polyiodosilane byproduct peaks, and the proton NMR spectrum showed impurity peaks around the target peak. The purity of the product, determined by gas chromatography, was 93.9%.

[0067] Comparative Example 2 This example uses the same raw materials and processes as Example 1 to prepare diiodosilane. The difference is that the temperature inside the reactor is controlled at 0°C during the addition of dichlorosilane, and after the dichlorosilane is added and stirred, the temperature inside the reactor is directly raised and controlled at 28°C for 36 hours.

[0068] The obtained diiodosilane product was weighed, and the yield was calculated to be 63%. Gas chromatography characterization of the product revealed the presence of polyiodosilane byproduct peaks. The purity of the product, determined by gas chromatography, was 92.8%.

[0069] The results of Examples 1 to 5 show that the method for preparing diiodosilane according to the embodiments of the present invention has good adaptability for large-scale production, and the product purity and yield stability are excellent. The main difference between Comparative Examples 1 and 2 and Example 1 is that the reaction system was not carried out at a temperature of 0-8°C. The product purity and yield of Example 1 are significantly higher than those of Comparative Examples 1 and 2. Therefore, the method for preparing diiodosilane according to the embodiments of the present invention, by reacting dichlorosilane with lithium iodide sequentially at a first temperature and a second temperature, can significantly improve the purity and yield of the diiodosilane product. In contrast, a one-step isothermal reaction is prone to side reactions, which can impair reaction selectivity and lead to a significant decrease in product purity and yield.

[0070] Furthermore, the main difference between Example 1 and Example 4 is that a solvent was added to the reaction system of Example 4, and solid impurities were separated from the air by filtration. The main difference between Example 1 and Example 5 is that solid-liquid separation was performed by filtration in an inert gas atmosphere in Example 5. Based on the results of the above examples, the purity and yield of the product from Example 1 are higher than those from Examples 4 and 5. Therefore, the method for preparing diiodosilane according to the present invention, by not using a solvent during the reaction and by centrifuging under the protection of an inert gas atmosphere to separate the solid and liquid components after the reaction, can further improve the purity and yield of the diiodosilane product. Filtration separation results in relatively low product purity, indicating significant entrainment of solid impurities, proving that conventional filtration separation is ineffective and time-consuming, and cannot guarantee product stability.

[0071] Meanwhile, the diiodosilane product has high purity and good stability, and can be directly used in high-end doping processes without additional purification requirements. The comparative product, however, has low purity and requires secondary distillation purification, increasing process costs and operational complexity. Furthermore, higher purity crude products result in better yields of qualified products, thus the comparative product yield is also lower.

[0072] Furthermore, the high purity of diiodosilane products is more conducive to their application in devices. For example, the device doped with the product of Example 1 has an impurity content of <0.05at and stable electrical performance; while the device doped with the product of Comparative Example 1 has an impurity content of 1.2at and its electrical performance fluctuates significantly.

[0073] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0074] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A method for preparing diiodosilane, comprising: Dichlorosilane and lithium iodide are reacted sequentially at a first temperature and a second temperature; wherein the first temperature is 0–8°C and the second temperature is 25–30°C.

2. The preparation method according to claim 1, wherein, The reaction time of the dichlorosilane and lithium iodide reaction system at the first temperature is 12 to 16 hours.

3. The preparation method according to claim 1, wherein, The reaction time of the dichlorosilane and lithium iodide reaction system at the second temperature is 24 to 48 hours.

4. The preparation method according to claim 1, wherein, The reaction of dichlorosilane and lithium iodide is carried out in the absence of solvent; and / or, The reaction between dichlorosilane and lithium iodide is carried out in an inert gas atmosphere.

5. The preparation method according to claim 1, wherein, The dichlorosilane is added to a system containing the lithium iodide at a temperature of -40 to -20°C.

6. The preparation method according to claim 1, wherein, The lithium iodide has a particle size of 200–300 mesh; and / or, The molar ratio of the dichlorosilane to the lithium iodide is 1:2.5 to 8.

7. The preparation method according to claim 1, wherein, The reacted material is subjected to solid-liquid separation, which is carried out in an inert gas atmosphere; and / or, The molar ratio of the dichlorosilane to the lithium iodide is 1:2.5 to 3.

5.

8. The preparation method according to claim 7, wherein, The solid-liquid separation is performed by centrifugation.

9. The preparation method according to claim 8, wherein, The centrifugal separation is performed using a centrifuge with a rotation speed of 30–50 Hz; and / or, The centrifugation time is 15 to 30 minutes.

10. The preparation method according to claim 1, wherein, Each step in the preparation process is carried out in an inert gas atmosphere.