Rectification and purification method of electronic-grade diiodosilane

Abstract

The invention discloses a rectification and purification method of electronic-grade diiodosilane, and the rectification and purification method of the electronic-grade diiodosilane provided by the invention treats a diiodosilane crude product through rectification-adsorption combination, and some low-boiling-point substances can be removed through reduced-pressure rectification light component removal treatment. An organic solvent such as an aromatic organic solvent, hydrogen iodide, phenylsilane, monoiodobenzene silane; a polymer or macromolecular structure formed in the reaction process can be removed through vacuum distillation heavy component removal treatment; however, in the rectification process, benzene in a diiodosilane crude product can form an azeotrope with diiodosilane, so that a part of impurity benzene cannot be separated from diiodosilane all the time, and the residual benzene and metal impurities in diiodosilane are adsorbed and separated by adopting an adsorption treatment method, so that the electronic-grade diiodosilane is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of diiodosilane purification, and in particular to a distillation and purification method for electronic grade diiodosilane. Background Art

[0002] Diiodosilane (DIS, molecular formula H2I2Si) is an important chemical vapor deposition silicon source and has received widespread attention in the semiconductor field in recent years. This compound can effectively generate silicon radicals with higher reactivity in a plasma-enhanced environment, thereby achieving a reduction in the reaction chamber temperature and controllable pressure operation while maintaining a high deposition rate. These characteristics make DIS an ideal choice to meet the trend of modern semiconductor devices, especially chip ultra-miniaturization. With the advancement of science and technology, it has become increasingly important to break through the limitations of Moore's Law, which requires improvements to the structure of traditional semiconductor substrates. As a silicon precursor, DIS can adapt to and successfully perform vapor deposition on a variety of substrates, including but not limited to gallium arsenide (GaAs), boron nitride (BN), crystalline silicon, polycrystalline silicon, amorphous silicon, epitaxial fragmented silicon layers, and various metal layers (such as copper Cu, aluminum Al), etc. In addition, DIS is also suitable for the deposition of various silicon dioxide (SiO2), silicon carbide (SiC), silicon nitride (SiN), carbon-nitrogen-silicon-oxygen materials (SiOC, SiCN), and new materials such as organic silicon glass (OSG) and fluorosilicone glass (FSG). This flexibility and wide applicability make DIS show a huge market prospect and receive extensive attention and research.

[0003] At present, in the synthesis of diiodosilane, the main method used by domestic and foreign companies is to react phenylsilane with iodine under low temperature and catalytic conditions. The reaction has strong exothermic characteristics. The mixing temperature of the reactants is usually controlled between -50°C and -20°C, while the actual reaction temperature is maintained at 0°C to 30°C. In this process, ethyl acetate is generally used as the catalyst, and the reaction lasts for 24 to 40 hours. In order to reduce the excess iodine free radicals produced in the reaction, some literature recommends adding an appropriate amount of copper powder for treatment after the reaction. The yield of diiodosilane produced by this synthesis and purification method can usually reach more than 75%, and the purity of the target product exceeds 90%. However, this traditional synthesis process also has some shortcomings, such as the high market prices of phenylsilane and iodine, and the difficulty in ensuring the long-term stability of their sources and quality, resulting in high overall costs and challenges in large-scale production. In addition, the existing process flow is complicated, involving ultra-low temperature reaction raw material mixing, catalyst addition, long-term reaction, filtration, and distillation. It has high requirements for equipment and automation control, which increases production costs. In particular, the cleanliness of the catalyst may not meet the requirements, and the long reaction time may cause a variety of side reactions, which makes the composition of the reaction product complex and affects the purity of diiodosilane. Therefore, how to optimize the synthesis process, reduce costs, and improve purity is still a current research hotspot and challenge.

[0004] Chinese patent document CN202311718867.6 discloses a synthesis and purification process of high-purity diiodosilane, which uses high-purity dichlorodihydrosilane as a silicon source and common anhydrous iodine metal compounds as an iodine source. The source and quality of the raw materials are both stably guaranteed. Reactive distillation is carried out under catalyst-free conditions. After the reaction is completed, the reaction product is obtained by multi-stage filtration, and finally a high-purity diiodosilane product is obtained through a two-stage vacuum distillation tower system. However, the purity of the diiodosilane product still needs to be further improved. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for distillation and purification of electronic grade diiodosilane.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0008] S1. Lightweight treatment

[0009] The crude diiodosilane is added to the first distillation tower for vacuum distillation to remove light substances, and the product after light removal is drawn out from the bottom of the tower.

[0010] In this step, the vacuum degree of the vacuum distillation is 20-30Pa. In some embodiments of the present invention, for example, 20Pa, 22Pa, 24Pa, 25Pa, 26Pa, 28Pa, and 30Pa can be selected; the temperature of the vacuum distillation is 40-50°C, for example, 40°C, 42°C, 44°C, 45°C, 46°C, 48°C, and 50°C can be selected; but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0011] In this step, some low-boiling-point substances, such as aromatic organic solvents, hydrogen iodide, phenylsilane, and monoiodophenylsilane, can be removed by vacuum distillation to remove light substances.

[0012] S2. Weight removal

[0013] The product after light removal is introduced into the second distillation tower for vacuum distillation to remove heavy gases, and the product after heavy removal is drawn out from the top of the tower.

[0014] In this step, the vacuum degree of the vacuum distillation is 20-30Pa. In some embodiments of the present invention, for example, 20Pa, 22Pa, 24Pa, 25Pa, 26Pa, 28Pa, and 30Pa can be selected; the temperature of the vacuum distillation is 56-60°C, for example, 56°C, 57°C, 58°C, 59°C, and 60°C can be selected; but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] In this step, the purpose of removing the polymer or macromolecular structure that may be formed during the reaction is to remove the weight removal treatment through vacuum distillation.

[0016] S3, obtain electronic grade diiodosilane

[0017] The product after deweighting is introduced into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is distilled and purified, and the fractions are collected to obtain electronic grade diiodosilane.

[0018] In this step, the preparation method of the composite modified adsorbent is as follows:

[0019] (1) adding a soluble nickel salt and terephthalic acid to an organic solvent, mixing them evenly, then adding activated carbon, dispersing them evenly and heating them for reaction, and after the reaction is completed, filtering, washing and drying to obtain a composite material;

[0020] (2) dispersing the composite material in an ethanol aqueous solution, then adding vinyl trimethoxysilane thereto, stirring for 1-3 hours, and after the reaction is completed, filtering, washing, and drying to obtain a vinyl composite material;

[0021] (3) dispersing the vinyl composite material in an organic solvent, then adding styrene, p-hydroxycinnamic acid and benzoyl peroxide thereto, reacting at a constant temperature, and after the reaction is completed, filtering, washing and drying to obtain a composite modified adsorbent.

[0022] Specifically, in step (1), the mass ratio of soluble nickel salt, terephthalic acid and activated carbon is 6-12:4-8:15-25. In some embodiments of the present invention, for example, 6:4:15, 6:6:20, 6:8:25, 10:4:15, 10:6:20, 12:6:20, 12:8:25 can be selected, but it is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0023] Specifically, in step (1), the temperature of the heating reaction is 120-150°C, for example, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C can be selected; the time of the heating reaction is 4-8h, for example, 4h, 5h, 6h, 7h, 8h can be selected; but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Specifically, in step (2), the mass ratio of the composite material to vinyltrimethoxysilane is 10-15:1-3, for example, 10:1, 10:2, 10:3, 12:1, 12:2, 12:3, 15:1, 15:2, 15:3 can be selected, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0025] Specifically, in step (3), the mass ratio of the vinyl composite material, styrene, p-hydroxycinnamic acid and benzoyl peroxide is 10-15:3-5:2-4:0.5-1.

[0026] Specifically, in step (3), the temperature of the isothermal reaction is 70-85°C. In some embodiments of the present invention, for example, 70°C, 75°C, 80°C, and 85°C can be selected; the time of the isothermal reaction is 2-4h, for example, 2h, 2.5h, 3h, 3.5h, and 4h can be selected; but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] In this step, during the distillation and purification process, the internal pressure of the distillation purifier is equal to the external atmospheric pressure, and the fraction collection temperature is 149-150°C.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The distillation and purification method of electronic grade diiodosilane provided by the present invention treats the crude diiodosilane by a combination of distillation and adsorption, wherein some low boiling point substances, such as aromatic organic solvents, hydrogen iodide, phenylsilane, and monoiodophenylsilane, can be removed by vacuum distillation to remove light substances; and polymers or macromolecular structures formed in the reaction process can be removed by vacuum distillation to remove heavy substances; however, during the distillation process, benzene in the crude diiodosilane can form an azeotrope with diiodosilane, thereby causing a portion of the impurity benzene to be unable to be separated from the diiodosilane. The present invention adopts an adsorption treatment method to adsorb and separate the residual benzene and metal impurities in the diiodosilane, thereby obtaining electronic grade diiodosilane.

[0030] (2) The composite modified adsorbent provided by the present invention uses activated carbon as an adsorption carrier. Activated carbon has a high specific surface area and porosity and is a commonly used adsorption material, but its adsorption performance for benzene molecules and metals is poor. The present invention first loads the nickel-based MOF material on the surface of the activated carbon through a heating synthesis method. On the one hand, the specific surface area of ​​the activated carbon is increased, and on the other hand, the nickel-based MOF material has a good adsorption effect on benzene, thereby improving the adsorption performance of the activated carbon for benzene; then, the composite material is treated with vinyltrimethoxysilane to introduce double bonds on the surface of the composite material, and then styrene and p-hydroxycinnamic acid are grafted on the composite material through the addition of the double bonds. Styrene and p-hydroxycinnamic acid contain benzene ring structures and can form conjugation with benzene, further improving the adsorption performance of the adsorbent for benzene impurities; at the same time, p-hydroxycinnamic acid contains functional groups such as carboxyl and hydroxyl groups, which can form coordination bonds with metal impurities, thereby improving the adsorption performance of the adsorbent for metal impurities, thereby improving the purity of diiodosilane to reach electronic grade. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0032] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0033] The crude diiodosilane used in the present invention has a purity of 99.5%; the activated carbon is coconut shell activated carbon with a mesh size of 400 meshes.

[0034] Example 1

[0035] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0036] S1. Add the crude diiodosilane to the first distillation tower, and perform vacuum distillation to remove light. The vacuum degree of the vacuum distillation is 25 Pa, the temperature of the vacuum distillation is 45° C., the theoretical plate number is 25, and the product after light removal is drawn out from the bottom of the tower;

[0037] S2, introducing the product after light removal into the second distillation tower, and performing vacuum distillation to remove heavy substances, the vacuum degree of vacuum distillation is 25Pa, the temperature of vacuum distillation is 58°C, the number of theoretical plates is 25, and the product after heavy removal is drawn out from the top of the tower;

[0038] S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is subjected to distillation and purification. The internal pressure of the distillation purifier is equal to the external atmospheric pressure. The fraction collection temperature is 149° C., the theoretical plate number is 20, and the fraction is collected to obtain electronic grade diiodosilane;

[0039] Wherein, the preparation method of the composite modified adsorbent is as follows:

[0040] (1) 10 g of nickel nitrate hexahydrate and 6 g of terephthalic acid were added to 150 mL of an organic solvent, DMF, and mixed evenly. Then, 20 g of activated carbon was added and heated to react after being evenly dispersed. The heating reaction temperature was 120° C. and the heating reaction time was 8 h. After the reaction was completed, the composite material was filtered, washed, and dried to obtain a composite material.

[0041] (2) dispersing 10 g of the composite material in 100 g of an 80 wt % ethanol aqueous solution, then adding 1 g of vinyltrimethoxysilane thereto, stirring for 1 h, and after the reaction is completed, filtering, washing, and drying to obtain a vinyl composite material;

[0042] (3) Disperse 10 g of the vinyl composite material in 150 mL of an organic solvent, DMF, and then add 3 g of styrene, 2 g of p-hydroxycinnamic acid, and 0.5 g of benzoyl peroxide. The mixture is reacted at 70 °C for 4 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified adsorbent.

[0043] Example 2

[0044] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0045] S1. Add the crude diiodosilane to the first distillation tower, and perform vacuum distillation to remove light. The vacuum degree of the vacuum distillation is 20 Pa, the temperature of the vacuum distillation is 40° C., the theoretical plate number is 25, and the product after light removal is drawn out from the bottom of the tower;

[0046] S2, introducing the product after light removal into the second distillation tower, and performing vacuum distillation to remove heavy substances, the vacuum degree of vacuum distillation is 20Pa, the temperature of vacuum distillation is 56°C, the number of theoretical plates is 25, and the product after heavy removal is drawn out from the top of the tower;

[0047] S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is subjected to distillation and purification. The internal pressure of the distillation purifier is equal to the external atmospheric pressure. The fraction collection temperature is 149° C., the theoretical plate number is 20, and the fraction is collected to obtain electronic grade diiodosilane;

[0048] Wherein, the preparation method of the composite modified adsorbent is as follows:

[0049] (1) 6 g of nickel nitrate hexahydrate and 4 g of terephthalic acid were added to 150 mL of an organic solvent, DMF, and mixed evenly. Then, 15 g of activated carbon was added and heated to react after being evenly dispersed. The temperature of the heating reaction was 150° C. and the heating reaction time was 4 h. After the reaction was completed, the composite material was filtered, washed, and dried to obtain a composite material.

[0050] (2) dispersing 12 g of the composite material in 100 g of an 80 wt% ethanol aqueous solution, then adding 2 g of vinyltrimethoxysilane thereto, stirring for 2 h, and after the reaction is completed, filtering, washing, and drying to obtain a vinyl composite material;

[0051] (3) Disperse 15 g of the vinyl composite material in 150 mL of an organic solvent, DMF, and then add 5 g of styrene, 4 g of p-hydroxycinnamic acid, and 1 g of benzoyl peroxide. The mixture is reacted at 85 °C for 2 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified adsorbent.

[0052] Example 3

[0053] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0054] S1. Add the crude diiodosilane to the first distillation tower, and perform vacuum distillation to remove light. The vacuum degree of vacuum distillation is 30 Pa, the temperature of vacuum distillation is 50° C., the theoretical plate number is 25, and the product after light removal is drawn out from the bottom of the tower;

[0055] S2, introducing the product after light removal into the second distillation tower, and performing vacuum distillation to remove heavy substances, the vacuum degree of vacuum distillation is 30Pa, the temperature of vacuum distillation is 60°C, the number of theoretical plates is 25, and the product after heavy removal is drawn out from the top of the tower;

[0056] S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is subjected to distillation and purification. The internal pressure of the distillation purifier is equal to the external atmospheric pressure. The fraction collection temperature is 149° C., the theoretical plate number is 20, and the fraction is collected to obtain electronic grade diiodosilane;

[0057] Wherein, the preparation method of the composite modified adsorbent is as follows:

[0058] (1) 12 g of nickel nitrate hexahydrate and 8 g of terephthalic acid were added to 150 mL of an organic solvent, DMF, and mixed evenly. Then, 25 g of activated carbon was added and heated to react after being evenly dispersed. The temperature of the heating reaction was 130° C. and the heating reaction time was 6 h. After the reaction was completed, the composite material was filtered, washed, and dried to obtain a composite material.

[0059] (2) dispersing 15 g of the composite material in 100 g of an 80 wt% ethanol aqueous solution, then adding 3 g of vinyl trimethoxysilane thereto, stirring for 2 h, and after the reaction is completed, filtering, washing, and drying to obtain a vinyl composite material;

[0060] (3) Disperse 12 g of the vinyl composite material in 150 mL of an organic solvent, DMF, and then add 4 g of styrene, 3 g of p-hydroxycinnamic acid, and 0.8 g of benzoyl peroxide. The mixture is reacted at 80 °C for 3 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified adsorbent.

[0061] Comparative Example 1

[0062] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0063] S1. Add the crude diiodosilane to the first distillation tower, and perform vacuum distillation to remove light. The vacuum degree of the vacuum distillation is 25 Pa, the temperature of the vacuum distillation is 45° C., the theoretical plate number is 25, and the product after light removal is drawn out from the bottom of the tower;

[0064] S2, introducing the product after light removal into the second distillation tower, and performing vacuum distillation to remove heavy substances, the vacuum degree of vacuum distillation is 25Pa, the temperature of vacuum distillation is 58°C, the number of theoretical plates is 25, and the product after heavy removal is drawn out from the top of the tower;

[0065] S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is subjected to distillation and purification. The internal pressure of the distillation purifier is equal to the external atmospheric pressure. The fraction collection temperature is 149° C., the theoretical plate number is 20, and the fraction is collected to obtain electronic grade diiodosilane;

[0066] Wherein, the preparation method of the composite modified adsorbent is as follows:

[0067] (1) Dispersing 10 g of activated carbon in 100 g of 80 wt% ethanol aqueous solution, then adding 1 g of vinyl trimethoxysilane thereto, stirring for 1 h, and after the reaction is completed, filtering, washing, and drying to obtain vinyl activated carbon;

[0068] (2) Disperse 10 g of vinyl activated carbon in 150 mL of organic solvent DMF, then add 3 g of styrene, 2 g of p-hydroxycinnamic acid and 0.5 g of benzoyl peroxide, and react at 70 ° C for 4 h. After the reaction is completed, filter, wash and dry to obtain a composite modified adsorbent.

[0069] Compared with Example 1, Comparative Example 1 does not treat the activated carbon with the nickel-based MOF material.

[0070] Comparative Example 2

[0071] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0072] S1. Add the crude diiodosilane to the first distillation tower, and perform vacuum distillation to remove light. The vacuum degree of the vacuum distillation is 25 Pa, the temperature of the vacuum distillation is 45° C., the theoretical plate number is 25, and the product after light removal is drawn out from the bottom of the tower;

[0073] S2, introducing the product after light removal into the second distillation tower, and performing vacuum distillation to remove heavy substances, the vacuum degree of vacuum distillation is 25Pa, the temperature of vacuum distillation is 58°C, the number of theoretical plates is 25, and the product after heavy removal is drawn out from the top of the tower;

[0074] S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is subjected to distillation and purification. The internal pressure of the distillation purifier is equal to the external atmospheric pressure. The fraction collection temperature is 149° C., the theoretical plate number is 20, and the fraction is collected to obtain electronic grade diiodosilane;

[0075] Wherein, the preparation method of the composite modified adsorbent is as follows:

[0076] 10g of nickel nitrate hexahydrate and 6g of terephthalic acid were added to 150mL of organic solvent DMF and mixed evenly. Then 20g of activated carbon was added and heated to react after being evenly dispersed. The heating reaction temperature was 120°C and the heating reaction time was 8h. After the reaction was completed, the composite modified adsorbent was obtained by filtering, washing and drying.

[0077] Compared with Example 1, Comparative Example 2 does not contain grafted styrene and p-hydroxycinnamic acid in the composite modified adsorbent.

[0078] Comparative Example 3

[0079] A method for distilling and purifying electronic grade diiodosilane comprises the following steps:

[0080] S1. Add the crude diiodosilane to the first distillation tower, and perform vacuum distillation to remove light. The vacuum degree of the vacuum distillation is 25 Pa, the temperature of the vacuum distillation is 45° C., the theoretical plate number is 25, and the product after light removal is drawn out from the bottom of the tower;

[0081] S2, introducing the product after light removal into the second distillation tower, and performing vacuum distillation to remove heavy substances, the vacuum degree of vacuum distillation is 25Pa, the temperature of vacuum distillation is 58°C, the number of theoretical plates is 25, and the product after heavy removal is drawn out from the top of the tower;

[0082] S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is subjected to distillation and purification. The internal pressure of the distillation purifier is equal to the external atmospheric pressure. The fraction collection temperature is 149° C., the theoretical plate number is 20, and the fraction is collected to obtain electronic grade diiodosilane;

[0083] Wherein, the preparation method of the composite modified adsorbent is as follows:

[0084] (1) 10 g of nickel nitrate hexahydrate and 6 g of terephthalic acid were added to 150 mL of an organic solvent, DMF, and mixed evenly. Then, 20 g of activated carbon was added and heated to react after being evenly dispersed. The heating reaction temperature was 120° C. and the heating reaction time was 8 h. After the reaction was completed, the composite material was filtered, washed, and dried to obtain a composite material.

[0085] (2) dispersing 10 g of the composite material in 100 g of an 80 wt % ethanol aqueous solution, then adding 1 g of vinyltrimethoxysilane thereto, stirring for 1 h, and after the reaction is completed, filtering, washing, and drying to obtain a vinyl composite material;

[0086] (3) Disperse 10 g of the vinyl composite material in 150 mL of an organic solvent, DMF, and then add 3 g of styrene and 0.5 g of benzoyl peroxide. The mixture is reacted at 70 °C for 4 h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified adsorbent.

[0087] Compared with Example 1, in Comparative Example 3, no p-hydroxycinnamic acid is grafted into the composite modified adsorbent.

[0088] The diiodosilane prepared in Example 1-3 and Comparative Example 1-3 was tested for purity, and the test results are shown in the following table:

[0089] Product Purity benzene Monoiodosilane Iron impurities Calcium impurities Diiodosilane crude product 99.5％ 478 ppm 246ppm 531ppb 857ppb Example 1 99.997％ 0.6ppb 4.8ppb 2.3ppb 8.1ppb Example 2 99.998％ 1.1ppb 5.2ppb 2.5ppb 8.6ppb Example 3 99.997％ 0.9ppb 5.5ppb 2.2ppb 8.3ppb Comparative Example 1 99.982％ 37 ppb 19ppb 34ppb 65ppb Comparative Example 2 99.939％ 51 ppb 23ppb 146ppb 192ppb Comparative Example 3 99.971％ 20 ppb 15ppb 67ppb 104ppb

[0090] It can be seen from the table that the impurity content in diiodosilane can be greatly reduced by the method of the present invention.

[0091] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of the present invention.

Claims

1. A method for distillation and purification of electronic grade diiodosilane, characterized in that: The steps include: S1, adding crude diiodosilane to a first distillation tower, performing vacuum distillation to remove light, and drawing the product after light removal from the bottom of the tower; S2, introducing the product after light removal into the second distillation tower, performing vacuum distillation to remove heavy substances, and drawing the product after heavy removal from the top of the tower; S3, introducing the deweighted product into an adsorption tank, which is filled with a composite modified adsorbent to adsorb impurities. After the adsorption is completed, the product is distilled and purified, and the fractions are collected to obtain electronic grade diiodosilane.

2. The rectification and purification method according to claim 1, characterized in that: In step S1, the vacuum degree of vacuum distillation is 20-30 Pa, and the temperature of vacuum distillation is 40-50°C.

3. The rectification and purification method according to claim 1, characterized in that: In step S2, the vacuum degree of vacuum distillation is 20-30 Pa, and the temperature of vacuum distillation is 56-60°C.

4. The distillation purification method according to claim 1, characterized in that: In step S3, the preparation method of the composite modified adsorbent is as follows: (1) adding a soluble nickel salt and terephthalic acid to an organic solvent, mixing them evenly, then adding activated carbon, dispersing them evenly and heating them for reaction, and after the reaction is completed, filtering, washing and drying to obtain a composite material; (2) dispersing the composite material in an ethanol aqueous solution, then adding vinyl trimethoxysilane thereto, stirring for 1-3 hours, and after the reaction is completed, filtering, washing, and drying to obtain a vinyl composite material; (3) dispersing the vinyl composite material in an organic solvent, then adding styrene, p-hydroxycinnamic acid and benzoyl peroxide thereto, reacting at a constant temperature, and after the reaction is completed, filtering, washing and drying to obtain a composite modified adsorbent.

5. The rectification and purification method according to claim 4, characterized in that: In step (1), the mass ratio of the soluble nickel salt, terephthalic acid and activated carbon is 6-12:4-8:15-25, and the soluble nickel salt is selected from nickel nitrate hexahydrate or nickel chloride hexahydrate.

6. The distillation purification method according to claim 4, characterized in that: In step (1), the heating reaction temperature is 120-150° C., and the heating reaction time is 4-8 hours.

7. The rectification and purification method according to claim 4, characterized in that: In step (2), the mass ratio of the composite material to vinyltrimethoxysilane is 10-15:1-3.

8. The rectification and purification method according to claim 4, characterized in that: In step (3), the mass ratio of the vinyl composite material, styrene, p-hydroxycinnamic acid and benzoyl peroxide is 10-15:3-5:2-4:0.5-1.

9. The rectification and purification method according to claim 4, characterized in that: In step (3), the temperature of the isothermal reaction is 70-85° C., and the time of the isothermal reaction is 2-4 h.

10. The distillation purification method according to claim 1, characterized in that: In step S3, during the distillation and purification process, the internal pressure of the distillation purifier is equal to the external atmospheric pressure, and the fraction collection temperature is 149-150°C.