Process for the purification of diiodosilane

Abstract

The present application relates to the field of electronic precursor purification, and particularly relates to a purification method of diiodosilane, which comprises the following steps: (S.1) removing residual air in a rectification purifier; (S.2) placing crude diiodosilane in the rectification purifier, gradually reducing the temperature of the rectification purifier to the freezing critical temperature of diiodosilane, and continuously introducing a carrying gas into the crude diiodosilane under stirring; (S.3) further reducing the temperature of the rectification purifier so that diiodosilane is solidified, and the interior of the rectification purifier is subjected to a reduced pressure treatment, thereby removing low-boiling-point impurities; (S.4) subjecting diiodosilane to rectification treatment, and collecting a fraction to obtain electronic-grade diiodosilane. In the present application, the temperature in the rectification purifier is accurately reduced to the freezing critical temperature of diiodosilane and a temperature below the freezing point during the rectification process, so that the low-boiling-point impurity content in the crude diiodosilane can be effectively reduced, and finally electronic-grade diiodosilane is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic precursor purification, in particular to a purification method of diiodosilane. BACKGROUND

[0002] Diiodosilane is an organosilicon compound with the chemical formula SiI2H2. It is an organosilicon reagent with important chemical applications, which is a pink, light yellow and light red flammable liquid at room temperature and normal pressure, and has a pungent odor. It can be used as an important intermediate in organic synthesis and semiconductor materials.

[0003] In the field of organic synthesis, diiodosilane, as an important organosilicon reagent, can be used to synthesize various organosilicon compounds containing Si-I bonds (such as silane, silanol, siloxane, etc. Organosilicon compounds). These organosilicon compounds have important applications in the fields of drug synthesis, material science, etc.

[0004] In the field of semiconductors, due to the fact that diiodosilane can produce more active silicon radicals under plasma enhancement compared to other silicon precursors, this radical has the characteristics of low reaction chamber temperature and controllable pressure operation while maintaining high deposition rate. Therefore, compared to other silicon precursors, diiodosilane can significantly reduce the vapor deposition temperature and make the obtained silicon thin film have superior electrical properties, stability and durability. Therefore, diiodosilane is listed as a key silicon source material for processes from 10 nm line width to 6 nm line width.

[0005] The purity of diiodosilane is crucial in the field of semiconductors. High-purity diiodosilane can ensure the surface modification effect and chemical stability of semiconductor materials, reduce the introduction of impurities during the preparation process of semiconductor devices, and is beneficial to improve the performance and reliability of semiconductor devices. Therefore, for the preparation of semiconductor materials, high-purity diiodosilane is crucial.

[0006] At present, due to the limitation of preparation methods, in the process of preparing diiodosilane, impurities such as monoiodosilane, hydrogen iodide, benzene, etc. are often generated. In order to remove these impurities, the method commonly used is distillation. However, these methods have certain limitations in terms of purification efficiency, cost and environmental friendliness. For example, in the existing distillation process, the number of theoretical plates is relatively large, which needs to reach about 30-50 plates. Therefore, there are certain problems and limitations in the process of purifying diiodosilane in the existing technology, and further seeking more efficient, low-cost and environmentally friendly purification methods is needed. SUMMARY

[0007] The present application is to overcome the defects of low efficiency and high cost in the purification process of diiodosilane in the prior art, and provides a purification method of diiodosilane to overcome the above-mentioned defects.

[0008] To achieve the above-mentioned object of the application, the present application is implemented by the following technical solutions:

[0009] The purification method of diiodosilane comprises the following steps:

[0010] (S.1) performing a vacuum extraction and a circulation step of carrying gas in the rectification purifier to remove the residual air in the rectification purifier;

[0011] (S.2) placing the crude diiodosilane in the rectification purifier, gradually reducing the temperature of the rectification purifier to the freezing critical temperature of diiodosilane, and continuously introducing the carrying gas into the crude diiodosilane under stirring;

[0012] (S.3) further reducing the temperature of the rectification purifier to make the diiodosilane solidify, and simultaneously performing a pressure reduction treatment on the inside of the rectification purifier to remove the low-boiling-point impurities;

[0013] (S.4) simultaneously increasing the temperature and pressure in the rectification purifier to perform a rectification treatment on the diiodosilane, and collecting the fraction to obtain the electronic-grade diiodosilane.

[0014] The present inventors accidentally found during the process of purifying diiodosilane by using the rectification method that part of the impurities (such as moniodosilane and benzene) in diiodosilane can form azeotropes with diiodosilane during the rectification process, thereby causing part of the impurities to be unable to be separated from diiodosilane, and further unable to further improve the quality of diiodosilane.

[0015] The present application is directed to the technical problem, and the rectification method is improved. First, the temperature of the rectification purifier is lowered to the freezing critical temperature of diiodosilane. At this temperature, diiodosilane is at the critical point of solid and liquid. At this time, part of the diiodosilane in the rectification purifier is solid and part is liquid (i.e. similar to the ice-water mixture formed by water at 0℃). Under this condition, the saturated vapor pressure of diiodosilane decreases significantly, while the saturated vapor pressure of the impurities doped in diiodosilane does not decrease significantly. Therefore, although the total saturated vapor pressure in the rectification purifier decreases, the proportion of the partial pressure of the saturated vapor pressure of the impurities increases significantly.

[0016] In addition, at the freezing critical temperature of diiodosilane, diiodosilane does not completely condense into a solid, so the impurity gas is not covered by the diiodosilane solid, avoiding the problem that the impurities cannot be completely removed due to the covering of the diiodosilane solid.

[0017] Under this condition, continuously introducing the carrying gas into the crude diiodosilane can make the impurities in diiodosilane be continuously carried out of diiodosilane with the carrying gas, thereby greatly reducing the content of impurities in the crude diiodosilane.

[0018] Subsequently, in order to further reduce the impurity content in diiodosilane, the temperature of the rectification purifier is further reduced, so that the diiodosilane located inside the rectification purifier is solidified. Under this condition, the partial pressure of the vapor pressure of diiodosilane is further reduced, so that the total saturated vapor pressure inside the rectification purifier is mainly formed by the impurities doped inside the diiodosilane. At the same time, with the reduction of the pressure inside the rectification purifier, the low-boiling-point impurities in the diiodosilane can be further removed.

[0019] After two temperature reduction and impurity removal, most of the impurities in the diiodosilane have been removed, and only some high-boiling-point impurities remain inside the diiodosilane. Therefore, in order to remove this part of high-boiling-point impurities, the present application increases the pressure inside the rectification purifier, thereby increasing the boiling point difference between diiodosilane and high-boiling-point impurities, thereby reducing the difficulty of separating diiodosilane and high-boiling-point impurities by rectification treatment, and thereby ultimately obtaining electronic-grade diiodosilane.

[0020] As a preferred, the solidification critical temperature in the step (S.2) is -1℃~0℃.

[0021] In this temperature range, diiodosilane begins to solidify, and the volatility of diiodosilane will be relatively reduced, which is conducive to reducing the loss of diiodosilane and improving the purity of diiodosilane in the subsequent step of removing low-boiling-point substances. Moreover, nitrogen gas is introduced in the solidification critical temperature range, which can ensure that the nitrogen gas fully contacts the diiodosilane and is conducive to the removal of impurities during the solidification process.

[0022] As a preferred, the carrying gas flow rate in the step (S.2) is 1000 sccm~3000 sccm; the carrying gas introduction time is 1-5h.

[0023] By continuously introducing nitrogen gas, the mixing and diffusion of crude diiodosilane and nitrogen gas can be promoted, which is conducive to the removal of impurities during the solidification process and improves the purity. By controlling the carrying gas flow rate and time, the solidification speed of diiodosilane can be effectively controlled to avoid product quality problems caused by too fast or too slow, and the uniformity and stability of the impurity removal process during the solidification process can be ensured.

[0024] As a preferred, the temperature of the rectification purifier in the step (S.3) is -10℃~-5℃.

[0025] In this temperature range, diiodosilane will remain in a solid state, which is conducive to removing volatile impurities during distillation while maintaining the solidification state of diiodosilane.

[0026] As a preferred, the carrying gas flow rate in the step (S.3) is 4000 sccm~6000 sccm; the carrying gas introduction time is 1-5h.

[0027] Preferably, the vacuum degree in step (S.3) is 50-100 Pa.

[0028] Preferably, in step (S.4), the internal pressure of the distillation purifier is equal to the external atmospheric pressure, and the fraction collection temperature is 149-150℃.

[0029] Preferably, the carrier gas is any one of nitrogen, helium, or argon.

[0030] Preferably, the distillation purifier is also filled with a polyimide / silicate composite nanofiber membrane.

[0031] Preferably, the method for preparing the polyimide / silicate composite nanofiber membrane includes the following steps:

[0032] (1) The dianhydride monomer, diamine monomer and silicate are mixed with a solvent and reacted to obtain a polyamic acid / silicate mixed solution;

[0033] (2) Electrospinning of the polyamic acid / silicate mixed solution to obtain a polyamic acid / silicate nanofiber membrane;

[0034] (3) The polyamic acid / silicate nanofiber membrane is subjected to thermal imidization reaction to obtain a polyimide / silicate composite nanofiber membrane.

[0035] Preferably, the silicate is a layered silicate.

[0036] Preferably, the layered silicate is one or a combination of mica, talc, and montmorillonite.

[0037] Therefore, the present invention has the following beneficial effects:

[0038] In this application, by precisely reducing the temperature in the distillation purifier to the critical solidification temperature and below the solidification point of diiodosilane during the distillation process, the content of low-boiling-point impurities in crude diiodosilane can be effectively reduced. Subsequently, high-boiling-point impurities doped in diiodosilane are further removed by single-tower distillation, and finally electronic-grade diiodosilane is prepared. Attached Figure Description

[0039] Figure 1 This is an electron microscope image of the polyimide / silicate composite nanofiber membrane prepared in the embodiments of the present invention.

[0040] Figure 2 This is a gas phase detection spectrum of crude diiodosilane (purity 99.5%) that has not undergone purification in an embodiment of the present invention.

[0041] Figure 3This is a gas phase detection spectrum of purified electronic-grade diiodosilane in an embodiment of the present invention. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0043] Preparation of polyimide / silicate composite nanofiber membranes

[0044] Preparation Example 1

[0045] Preparation of polyimide / silicate composite nanofiber membrane (A): The preparation method includes the following steps:

[0046] (1) 4.0046 g (0.02 mol) 4,4'-diphenyl ether diamine (ODA), 8.0462 g (0.02 mol) 4,4'-terephthalic anhydride (HQDA) and 3 g of muscovite powder were added to a three-necked flask, and 60 mL of DMAc was added. The mixture was stirred vigorously and reacted at -5 °C for 6 h, and then heated to 10 °C for 6 h to obtain a polyamic acid / mica mixed solution.

[0047] (2) The polyamic acid / mica mixed solution prepared above was electrospun (voltage was 20kV, and the distance between the jet needle tip and the roller receiver was 20cm) to obtain a polyamic acid / silicate nanofiber membrane.

[0048] (3) The solvent was removed from the polyimide / silicate composite nanofiber membrane in a vacuum oven at 60°C for 4 hours, followed by thermal imidization at a heating rate of 1°C / min at 120°C / 1h, 200°C / 1h, and 250°C / 1h. After annealing and cooling to room temperature, the membrane was removed to obtain the polyimide / silicate composite nanofiber membrane (A). Electron micrographs of the prepared polyimide / silicate composite nanofiber membrane (A) are shown below. Figure 1 As shown.

[0049] Preparation Example 2

[0050] The difference between Preparation Example 2 and Preparation Example 1 is that the muscovite powder in step (1) is replaced with montmorillonite powder to obtain a polyimide / silicate composite nanofiber membrane (B).

[0051] Preparation Example 3

[0052] The difference between Preparation Example 3 and Preparation Example 1 is that the mica powder in step (1) is replaced with talc powder to obtain a polyimide / silicate composite nanofiber membrane (C).

[0053] Preparation Example 4

[0054] The difference between Preparation Example 4 and Preparation Example 1 is that the addition of mica powder in step (1) was omitted, and a polyimide nanofiber membrane (D) was obtained.

[0055] Preparation Example 5

[0056] The difference between Preparation Example 5 and Preparation Example 1 is that the muscovite powder in step (1) is replaced with beryl powder (a cyclic silicate mineral) to obtain a polyimide / silicate composite nanofiber membrane (E).

[0057] Preparation Example 6

[0058] The difference between Preparation Example 6 and Preparation Example 1 is that the muscovite powder in step (1) is replaced with feldspar powder (framework silicate mineral) to obtain a polyimide / silicate composite nanofiber membrane (F).

[0059] Example 1

[0060] The purification method for diiodosilane includes the following steps:

[0061] (S.1) Evacuate the distillation purifier to a low pressure (about 10 Pa), then introduce nitrogen into it until the internal pressure of the distillation purifier is equal to that of the outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0062] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0063] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0064] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier to cause diiodosilane to reflux. Control the number of plates in the distillation purifier to 20 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0065] Figure 2The image shows the gas phase detection spectrum of crude diiodosilane (99.5% purity) without purification in this embodiment of the invention. As can be seen from the image, the unpurified crude diiodosilane (99.5% purity) contains a large number of impurity peaks. The gas phase detection spectrum of the electronic-grade diiodosilane purified according to Example 1 of this invention is shown below. Figure 2 As shown in the figure, the original impurity peaks have been largely removed, leaving only the diiodosilane peak. Calculated using the gas chromatography area normalization method, the purity of diiodosilane is 99.99%.

[0066] Example 2

[0067] The purification method for diiodosilane includes the following steps:

[0068] (S.1) Evacuate the distillation purifier to a low pressure (about 10 Pa), then introduce nitrogen into it until the internal pressure of the distillation purifier is equal to that of the outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0069] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 1000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 5 hours.

[0070] (S.3) Further reduce the temperature of the distillation purifier to -5°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 100 Pa. At the same time, adjust the nitrogen flow rate to 4000 sccm and the nitrogen flow time to 5h to remove low-boiling-point impurities.

[0071] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier to cause diiodosilane to reflux. Control the number of plates in the distillation purifier to 20 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0072] Example 3

[0073] The purification method for diiodosilane includes the following steps:

[0074] (S.1) Evacuate the distillation purifier to a low pressure (about 10 Pa), then introduce nitrogen into it until the internal pressure of the distillation purifier is equal to that of the outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0075] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 3000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 1 hour.

[0076] (S.3) Further reduce the temperature of the distillation purifier to -10℃ to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 50Pa. At the same time, adjust the nitrogen flow rate to 6000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0077] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier to cause diiodosilane to reflux. Control the number of plates in the distillation purifier to 20 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0078] Example 4

[0079] The purification method for diiodosilane includes the following steps:

[0080] (S.1) Fill the interior of the distillation purifier with a polyimide / silicate composite nanofiber membrane (A), and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into the purifier until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0081] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0082] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0083] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier, so that the diiodosilane is refluxed and comes into contact with the polyimide / silicate composite nanofiber membrane (A). Control the number of plates in the distillation purifier to 15 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0084] Example 5

[0085] The purification method for diiodosilane includes the following steps:

[0086] (S.1) Fill the interior of the distillation purifier with a polyimide / silicate composite nanofiber membrane (B), and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into the purifier until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0087] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0088] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0089] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier, so that the diiodosilane is refluxed and comes into contact with the polyimide / silicate composite nanofiber membrane (B). Control the number of plates in the distillation purifier to 15 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0090] Example 6

[0091] The purification method for diiodosilane includes the following steps:

[0092] (S.1) Fill the interior of the distillation purifier with a polyimide / silicate composite nanofiber membrane (C), and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into the purifier until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0093] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0094] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0095] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier, so that the diiodosilane is refluxed and comes into contact with the polyimide / silicate composite nanofiber membrane (C). Control the number of plates in the distillation purifier to 15 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0096] Comparative Example 1

[0097] (S.1) Fill the interior of the distillation purifier with a polyimide / silicate composite nanofiber membrane (A), and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into the purifier until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0098] (S.2) Crude diiodosilane (commercially available, 99.5% purity) is placed in a distillation purifier, and the internal temperature of the distillation purifier is increased to allow the diiodosilane to reflux. The number of plates in the distillation purifier is controlled to be 30 for distillation. After discarding the low-boiling fraction, the fraction with a temperature of 149~150℃ is collected to obtain electronic grade diiodosilane.

[0099] Comparative Example 2

[0100] The purification method for diiodosilane includes the following steps:

[0101] (S.1) Evacuate the distillation purifier to a low pressure (about 10 Pa), then introduce nitrogen into it until the internal pressure of the distillation purifier is equal to that of the outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0102] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -10°C, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0103] (S.3) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier to cause diiodosilane to reflux. Control the number of plates in the distillation purifier to 20 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0104] Comparative Example 3

[0105] The purification method for diiodosilane includes the following steps:

[0106] (S.1) Fill the interior of the distillation purifier with polyimide nanofiber membrane (D) and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into it until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0107] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0108] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0109] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier to allow diiodosilane to reflux and contact with the polyimide nanofiber membrane (D). Control the number of plates in the distillation purifier to 15 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0110] Comparative Example 4

[0111] The purification method for diiodosilane includes the following steps:

[0112] (S.1) Fill the interior of the distillation purifier with a polyimide / silicate composite nanofiber membrane (E) and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into the purifier until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0113] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0114] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0115] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier, so that the diiodosilane is refluxed and comes into contact with the polyimide / silicate composite nanofiber membrane (E). Control the number of plates in the distillation purifier to 15 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0116] Comparative Example 5

[0117] The purification method for diiodosilane includes the following steps:

[0118] (S.1) Fill the interior of the distillation purifier with a polyimide / silicate composite nanofiber membrane (F), and evacuate the interior of the distillation purifier to a low pressure (about 10 Pa). Then, introduce nitrogen gas into the purifier until the pressure inside the distillation purifier is equal to that outside. Repeat this process 5 times to remove the residual air in the distillation purifier.

[0119] (S.2) Place crude diiodosilane (commercially available, purity 99.5%) in a distillation purifier, gradually lower the temperature of the distillation purifier to -1℃~0℃, and continuously introduce nitrogen gas at a flow rate of 2000 sccm into the crude diiodosilane at a stirring speed of 100 rpm for 3 hours.

[0120] (S.3) Further reduce the temperature of the distillation purifier to -8°C to solidify the diiodosilane. Evacuate the inside of the distillation purifier to a vacuum of 80 Pa. At the same time, adjust the nitrogen flow rate to 5000 sccm and the nitrogen flow time to 3h to remove low-boiling-point impurities.

[0121] (S.4) Simultaneously increase the internal pressure of the distillation purifier to match the external atmospheric pressure, and simultaneously increase the internal temperature of the distillation purifier, so that the diiodosilane is refluxed and comes into contact with the polyimide / silicate composite nanofiber membrane (F). Control the number of plates in the distillation purifier to 15 for distillation treatment. After discarding the low-boiling-point fraction, collect the fraction at a temperature of 149~150℃ to obtain electronic-grade diiodosilane.

[0122] The purity of the diiodosilanes prepared in Examples 1-6 and Comparative Examples 1-5 was tested, and the test results are shown in Table 1 below:

[0123] Table 1

[0124] .

[0125] The test results above show that the method in this application can significantly reduce the content of impurities (monoiodosilane, hydrogen iodide and benzene) in diiodosilane, indicating that the method in this application can effectively purify diiodosilane.

[0126] As can be seen from Comparative Example 1, since impurities can form azeotropes with diiodosilane, it is difficult to reduce the impurities in diiodosilane to the expected concentration using the conventional distillation method in Comparative Example 1.

[0127] Although Comparative Example 2 includes a step of freezing diiodosilane and then purging it with nitrogen, some impurities are coated by the frozen diiodosilane after the diiodosilane is directly applied. As a result, some impurities are co-doped with the diiodosilane, so the reduction of these impurities is limited. Even if distillation is performed later, the impurities cannot be removed due to the formation of azeotropes.

[0128] The difference between Comparative Examples 3-5 and the Examples lies in the replacement of the types of silicates in the polyimide / silicate composite nanofiber membranes. The original layered silicates were replaced with cyclic silicate minerals and framework silicate minerals. The results show that the original layered silicates (mica, talc, montmorillonite) have a better adsorption effect on impurities in diiodosilane than the cyclic silicate minerals and framework silicate minerals. This is beneficial for achieving higher purity of diiodosilane, which is conducive to its application in the electronics and semiconductor fields.

[0129] The examples provided in this invention are merely illustrative of the technical solutions of this invention. Any modifications, additions, or equivalent substitutions made by those skilled in the art based on these embodiments are within the scope of protection claimed in the claims of this invention.

Claims

1. A method for purifying diiodosilane, characterized in that, Includes the following steps: (S.1) Vacuuming and circulation of carrying gas are performed in the distillation purifier to remove residual air in the distillation purifier; (S.2) Place the crude diiodosilane in a distillation purifier, gradually lower the temperature of the distillation purifier to the critical solidification temperature of diiodosilane, and continuously introduce the carrier gas into the crude diiodosilane under stirring conditions. (S.3) Further reduce the temperature of the distillation purifier to solidify the diiodosilane, and at the same time reduce the pressure inside the distillation purifier to remove low-boiling-point impurities. (S.4) Simultaneously increase the internal temperature and pressure of the distillation purifier to distill diiodosilane and collect the fraction to obtain electronic grade diiodosilane. The distillation purifier is also filled with a polyimide / silicate composite nanofiber membrane; The preparation method of the polyimide / silicate composite nanofiber membrane includes the following steps: (1) The dianhydride monomer, diamine monomer and silicate are mixed with a solvent and reacted to obtain a polyamic acid / silicate mixed solution; (2) Electrospinning of the polyamic acid / silicate mixed solution to obtain a polyamic acid / silicate nanofiber membrane; (3) The polyamic acid / silicate nanofiber membrane is subjected to thermal imidization reaction to obtain a polyimide / silicate composite nanofiber membrane.

2. The method for purifying diiodosilane according to claim 1, characterized in that, The solidification critical temperature in step (S.2) is -1℃ to 0℃.

3. The method for purifying diiodosilane according to claim 1 or 2, characterized in that, In step (S.2), the flow rate of the carrier gas is 1000 sccm to 3000 sccm; the nitrogen introduction time is 1-5h.

4. The method for purifying diiodosilane according to claim 1, characterized in that, The temperature of the distillation purifier in step (S.3) is -10℃ to -5℃.

5. The method for purifying diiodosilane according to claim 1, characterized in that, In step (S.3), the flow rate of the carrier gas is 4000 sccm to 6000 sccm; the nitrogen gas introduction time is 3-5 hours.

6. The method for purifying diiodosilane according to claim 1, 4, or 5, characterized in that, The vacuum level in step (S.3) is 50~100 Pa.

7. The method for purifying diiodosilane according to claim 1, characterized in that, In step (S.4), the internal pressure of the distillation purifier is equal to the external atmospheric pressure, and the fraction collection temperature is 149~150℃.

8. The method for purifying diiodosilane according to claim 1, characterized in that, The carrier gas is any one of nitrogen, helium, or argon.

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