Purification process of electronic-grade dimethyldimethoxysilane

Abstract

The invention discloses dimethyldimethoxysilane purification equipment and a process system, and the purification system comprises the following equipment: an industrial-grade raw material tank (1), a primary dehydrating tower A (2), a primary dehydrating tower B (3), a buffer tank (4), a primary rectifying tower (5), a heavy component flash tank (6), a secondary rectifying tower (7), a light component flash tank (8), a temporary storage tank (9), a gas chromatograph (10), a buffer tank (11), a resin tower A (12) and a resin tower B (13). The device comprises a first-stage dehydration tower (11), a second-stage dehydration tower A (14), a second-stage dehydration tower B (15), a filter A (16), a filter B (17) and an electronic-grade product tank (18). The process devices are connected in sequence, reasonable material recovery is carried out, the process comprises the processes of removing water, anions, cations, particle impurities, light and heavy component impurities and the like, the removed light and heavy components are subjected to secondary flash evaporation and then are pumped back to a buffer tank to be reused, the good yield of electronic-grade products can be guaranteed, and the production cost is reduced. In addition, on-line organic component analysis is carried out on the materials after two times of rectification, the organic purity of the materials can be fully guaranteed to be maintained at 99.99% or above, and finally electronic-grade qualified products are obtained.

Description

Technical Field

[0001] The invention relates to the purification and refining of electronic-grade dimethyldimethoxysilane, and in particular to equipment and a purification process system in the production process of dimethyldimethoxysilane. Background Art

[0002] Dimethyldimethoxysilane ((CH3O)2Si(CH3)2) is usually a low-viscosity liquid with high volatility and certain solubility. It is soluble in a variety of organic solvents. It is widely used in the fields of chemical industry, materials, semiconductor manufacturing, etc., especially in thin film deposition and surface treatment. Its unique chemical properties make it an important precursor and intermediate. In the semiconductor field, dimethyldimethoxysilane is mainly used as a precursor or intermediate in the manufacturing and processing process. The specific uses are as follows: (1) Used as an insulating layer in semiconductor devices to reduce the capacitance effect and improve the speed and performance of the device. (2) Used as a silicon source material in the chemical vapor deposition (CVD) process to form thin films or nanostructures. These silicon-based films or structures can be used as insulating layers, passivation layers or other functional layers in chip manufacturing. (3) Used for surface treatment in electronic packaging to improve the adhesion and stability of packaging materials and improve the durability and reliability of packaging. (4) It can be used as an additive in photoresist to optimize the performance of photoresist and enhance the accuracy of pattern transfer.

[0003] At present, dimethyldimethoxysilane is mainly produced in industrial grade purity. Due to the special properties of the synthetic raw materials, dimethyldimethoxysilane is only 30-40% during synthesis, so even industrial purity needs to be purified. Chinese patents CN101712691B, CN109251221A, CN116444557A, and CN214346486U disclose the preparation method and reaction device of dimethyldimethoxysilane, which also include the purification method of industrial grade dimethyldimethoxysilane, but it is far from meeting the electronic grade standard. Not only is the organic purity not reached, but the impurity content of anions, cations, moisture, particles, etc. is too high, and it cannot be used in chip manufacturing.

[0004] At present, there is no related electronic grade dimethyldimethoxysilane purification device and process system in the reported literature. This invention patent introduces the process of removing water, removing light and heavy components, removing anions and cations, secondary dehydration, removing particles, etc. from industrial grade dimethyldimethoxysilane. It not only introduces the relevant process parameters in detail, but also can recycle part of dimethyldimethoxysilane to ensure the product yield. After a series of purification processes, qualified electronic grade dimethyldimethoxysilane is finally obtained. Summary of the invention

[0005] In order to obtain electronic grade dimethyldimethoxysilane, the present invention provides a purification device and process system for electronic grade dimethyldimethoxysilane, which realizes the purification of electronic grade dimethyldimethoxysilane by organically combining the processes of removing water, removing light and heavy components, removing anions and cations, secondary dehydration, removing particles and the like.

[0006] The dimethyldimethoxysilane purification process system includes a primary dehydration tower dehydration process, a primary distillation process, a secondary distillation process, a secondary flash distillation process, an anion and cation removal process, a secondary dehydration process, and a particle removal process. The specific process is as follows: the industrial-grade raw material tank is nitrogen-pressed, and after flowing out from the bottom of the industrial-grade raw material tank, it is pumped to the primary dehydration tower A and the primary dehydration tower B. After dehydration, the material enters the buffer tank and continues to enter the primary distillation tower. The material at the top of the distillation tower enters the secondary distillation tower. The material at the bottom of the primary distillation tower and the material at the top of the secondary distillation tower are flashed and then enter the temporary storage tank together, and enter the buffer tank at the appropriate time; the material coming out of the bottom of the secondary distillation tower is tested by gas chromatography and then enters the buffer tank after passing the gas chromatography test, and then goes to the resin tower A and the resin tower B in turn to remove anions and cations, enter the secondary dehydration tower A, the secondary dehydration tower B removes moisture, enters the filter A, and the filter B removes particulate impurities. Finally, the qualified electronic-grade dimethyldimethoxysilane enters the electronic-grade product tank. This process system not only purifies the industrial-grade dimethyldimethoxysilane into electronic-grade products by removing moisture, anions and cations, and impurities such as particles. In addition, a post-distillation flash material recovery system is designed, because the light and heavy components of the first and second distillation towers still contain a large amount of dimethyldimethoxysilane, which can still be used as an industrial-grade raw material for distillation and purification after flash evaporation.

[0007] In the dehydration process of the first-level dehydration tower, the first-level dehydration tower is divided into two sets of equipment, A and B, one for use and one for standby. When one set is in use, the other set performs high-temperature nitrogen dehydration to restore performance. Each dehydration tower is divided into three layers, and three types of fillers, 3A, silica gel, and polyacrylamide absorbent resin, are filled from top to bottom. By filling specific fillers and a certain amount of use, moisture can be removed according to different levels. Finally, after adsorption by three layers of fillers, the moisture of the material can be reduced to 40ppm. Preliminary dehydration of the material can not only prevent the corrosion of the material to the pipeline, but also the influence of moisture on subsequent processes.

[0008] In some preferred embodiments, the volume ratio of each filler is 4:2:1 from top to bottom, and the diameter ratio of each section of filler is 1:1:1.

[0009] The primary distillation process is characterized in that: the feed pressure of the first-stage distillation tower is 1-5 bar, the feed temperature is 40-50°C, the feed position is the 18th tower plate, the feed gas-liquid state is liquid phase, the theoretical number of plates of the distillation tower is 42, the packing type is theta ring packing, the reflux ratio is 3-5, the tower top pressure is 1.5-3.5 bar, the tower top extraction ratio is 0.90-0.950, the first-stage distillation equipment and the material contact parts are all made of stainless steel and the stainless steel material is mechanically or electrolytically polished, with a roughness of ≤0.2um, and the pipelines and instruments are made of fluorine-lined materials.

[0010] In the secondary distillation process, the feed pressure of the second-stage distillation tower is 10-12 bar, the feed temperature is 100-110 ° C, the feed position is the 55th tower plate, the feed gas-liquid state is liquid phase, the theoretical number of plates of the distillation tower is 63, the packing type is the West Tower ring, the reflux ratio is 10-15, the tower top pressure is 8-10 bar, the tower bottom extraction ratio is 0.926-0.955, the second-stage distillation equipment and the material contact part are all made of stainless steel and the stainless steel material is mechanically or electrolytically polished, the roughness is ≤0.2um, and the pipelines and instruments are made of fluorine-lined materials. After the secondary distillation, the content of dimethyldimethoxysilane reaches 99.99%, wherein the anion concentration is controlled below 10ppb, and the single cation concentration is controlled below 30ppt.

[0011] In the secondary flash process, the flash tank at the bottom of the primary distillation tower is mainly used to collect the dimethyldimethoxysilane in the removed heavy components and collect it into a temporary storage tank. The pressure of the flash tank is 1.7 bar and the temperature is 100°C. After flash distillation, its purity can be purified from 0.9600 to 0.9878; the flash tank at the top of the secondary distillation tower is mainly used to collect the dimethyldimethoxysilane in the removed light components and collect it into a temporary storage tank. The pressure of the flash tank is 10 bar and the temperature is 179°C. After flash distillation, its purity can be purified from 0.9838 to 0.9869; because the purity of industrial-grade dimethyldimethoxysilane has reached more than 99%, a large amount of dimethyldimethoxysilane will flow out from the light components and the heavy components during the process of removing light and heavy components, so it needs to be recovered, and the recovered dimethyldimethoxysilane has a purity of 99.68%.

[0012] In the process of removing anions and cations, different resins are used for exchange removal of anions and cations, and specifically, a mixed resin is formed by mixing a cationic resin and an anionic resin, wherein the cationic resin is selected from XO1300-H and XO1310-H; the anionic resin is selected from XO1600-OH resin; The resin types filled in the upper and lower fillers are cation resin and anion resin with a filling volume ratio of 3-5:1-2. The working pressure of the resin tower is 2-5 bar and the working temperature is room temperature. After the resin cation exchange, the anion concentration in dimethyldimethoxysilane is controlled below 50ppb, and the single cation concentration is controlled below 30ppt; however, the water content exceeds 20ppm, and the dehydration process needs to be carried out again.

[0013] In the secondary dehydration process, the types of mixed fillers in the secondary dehydration tower are two types of fillers, silica gel and water-absorbing resin. The above conditions are used to dehydrate dimethyldimethoxysilane. The moisture content of dimethyldimethoxysilane after dehydration can also be controlled at 20ppm through moisture detection.

[0014] In some preferred cases, the volume ratio of the upper and lower packings is 1:1, and the diameter ratio of the upper and lower packing beds is 1:1.

[0015] In the particle removal process, the dimethyldimethoxysilane after resin filtration in the filter is circulated and filtered, and the filtration is carried out in series using microporous folded filter elements with pore sizes of 120-100nm, 50-40nm, and 10-5nm (in some preferred cases, the filtration is carried out using microporous folded filter elements with pore sizes of 100nm, 50nm, and 10nm), and the filter element material is one of polytetrafluoroethylene and polyvinylidene fluoride membrane (PVDF). After filtration, the concentration of particles of dimethyldimethoxysilane greater than 0.2 microns is less than 50 particles / ml, the concentration of particles greater than 0.1 microns is less than 100 particles / ml, and the concentration of particles greater than 0.05 microns is less than 200 particles / ml. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the process scheme of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention will be briefly introduced below. The following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a process flow diagram of the purification process of electronic grade dimethyldimethoxysilane in the present invention.

[0018] Description of the markings in the figure: Industrial-grade raw material tank (1), primary dehydration tower A (2), primary dehydration tower B (3), buffer tank (4), primary distillation tower (5), heavy component flash tank (6), secondary distillation tower (7), light component flash tank (8), temporary storage tank (9), gas chromatograph (10), buffer tank (11), resin tower A (12), resin tower B (13), secondary dehydration tower A (14), secondary dehydration tower B (15), filter A (16), filter B (17), electronic-grade product tank (18) DETAILED DESCRIPTION The present invention is further described below by way of examples. It is worth noting that the given examples cannot be understood as limiting the scope of protection of the present invention, and some non-essential improvements and adjustments made by technicians in the field of the present invention based on the content of the present invention should still fall within the scope of protection of the present invention.

[0019] The industrial-grade dimethyldimethoxysilane described in the present invention has a main content of ≥99%, a water content of ≤800ppm, a chloride ion content of ≤300ppm, and a total metal ion content of ≤700ppb, and the metal ions mainly include K, Ga, Na, Mg, Al, Zn, Fe, Cr, Mn, Ni, Pb, Cu, etc.

[0020] Example 1 A device for purifying electronic-grade dimethyldimethoxysilane, wherein an industrial-grade raw material tank 1 is nitrogen-pressed, and the material flows out from the bottom of the industrial-grade raw material tank 1 and is pumped to a primary dehydration tower A2 and a primary dehydration tower B3, and the material enters a buffer tank 4 after being dehydrated, and then continues to enter a primary distillation tower 5, and the material at the top of the distillation tower enters a secondary distillation tower 7, and the material at the bottom of the primary distillation tower 5 and the material at the top of the secondary distillation tower 7 are flashed and then enter a temporary storage tank 9 together, and enter the buffer tank 4 at an appropriate time; the material coming out of the bottom of the secondary distillation tower 7 is tested by a gas chromatograph 10 and enters a buffer tank 11 after being qualified, and then successively goes through a resin tower A 12 and a resin tower B 13 to remove anions and cations, enters a secondary dehydration tower A 14, and a secondary dehydration tower B 15 to remove moisture, and enters a filter A 16, and a filter B 17 to remove particulate impurities, and finally the qualified electronic-grade dimethyldimethoxysilane enters an electronic-grade product tank 18.

[0021] Example 2 Using the process apparatus of Example 1, industrial-grade dimethyldimethoxysilane continuously enters the purification system.

[0022] The first-stage dehydration tower is divided into two sets of equipment, A and B. Each set of dehydration tower is divided into three layers, and three types of fillers are filled from top to bottom: 3A, silica gel, and polyacrylamide absorbent resin. The volume ratio of each filler is 4:2:1 from top to bottom, and the diameter ratio of each section of filler is 1:1:1. After adsorption, the moisture content of the material can be reduced to 40ppm.

[0023] The dehydrated material enters the first-stage distillation tower for weight removal, with a feed pressure of 2 bar, a feed temperature of 50 ° C, a feed position of the 18th tower plate, a feed state of liquid phase, a theoretical number of plates of 42, a packing of the West Tower ring, a reflux ratio of 3, a top pressure of 1.8 bar, and a top extraction ratio of 0.950. The weight-removed material enters the secondary distillation tower, with a feed pressure of 12 bar, a feed temperature of 103 ° C, a feed position of the 55th tower plate, a feed state of liquid phase, a theoretical number of plates of 63, a packing of the West Tower ring, a reflux ratio of 10, a top pressure of 10 bar, and a bottom extraction ratio of 0.926. After the secondary distillation, the content of dimethyldimethoxysilane reaches 99.99%.

[0024] Flash evaporation is mainly used to recover dimethyldimethoxysilane. The pressure of the flash tank at the bottom of the primary distillation tower is 1.7 bar and the temperature is 100°C; the pressure of the flash tank at the top of the secondary distillation tower is 10 bar and the temperature is 179°C; the content of dimethyldimethoxysilane in the temporary storage tank reaches 99.68%.

[0025] The material after light removal enters the resin tower for removal of anions and cations. Experiments show that the types of mixed resins are two of XO1300-H and XO1600-OH resins, and the resin types filled in the upper and lower fillers are cation resin and anion resin with a filling volume ratio of 3:2. When the working pressure of the resin tower is 2 bar and the working temperature is 25°C, after the resin cation exchange, the anion concentration in dimethyldimethoxysilane is controlled below 50ppb, and the single cation concentration is controlled below 30ppt.

[0026] The material enters the secondary dehydration tower from the resin tower. The types of mixed fillers are two types of fillers, silica gel and polyacrylamide absorbent resin. The volume ratio of the upper and lower fillers is 1:1, and the diameter ratio of the upper and lower filler beds is 1:1. The above conditions are used to dehydrate dimethyldimethoxysilane. The moisture content of dimethyldimethoxysilane after dehydration can also be controlled at 20ppm through moisture detection.

[0027] The material is finally subjected to particle removal. The dimethyldimethoxysilane filtered by the resin in the filter is then circulated and filtered. The filtration is carried out in series using microporous folded filter elements with pore sizes of 100nm, 50nm, and 10nm respectively. The filter element material is one of polytetrafluoroethylene and polyvinylidene fluoride membrane (PVDF). The concentration of particles of dimethyldimethoxysilane greater than 0.2 microns is less than 50 particles / ml, the concentration of particles greater than 0.1 microns is less than 100 particles / ml, and the concentration of particles greater than 0.05 microns is less than 200 particles / ml.

[0028] Example 3 This embodiment is also carried out using the process system of Example 1. The difference from Example 2 is that this embodiment mainly has different process parameters of the primary dehydration tower, and other process details are consistent with Example 2.

[0029] The first-level dehydration tower in this example is divided into two sets of equipment, A and B. Each set of dehydration tower has only one layer, and the interior is still the same three kinds of the same volume of fillers. The difference from Example 2 is that the three fillers are mixed and loaded into the dehydration tower together, rather than loaded in layers. After the mixed fillers absorb moisture, the moisture content of the material can be reduced to 60ppm after testing. If the moisture content of the material is reduced to the standard value, the material flow rate needs to be reduced by one quarter, and the filler replacement cycle is shortened by half.

[0030] Example 4 This embodiment is also carried out using the process system of Example 1. The difference between this embodiment and Example 2 lies in that the parameters of the two-stage distillation process are different. Other process details are consistent with Example 2.

[0031] The parameters of the secondary distillation tower remain unchanged. The feed pressure, feed temperature, feed position, feed state and theoretical plate number of the primary distillation tower remain unchanged. The packing is changed to wire mesh corrugated regular packing, the reflux ratio, the top pressure and the bottom extraction ratio remain unchanged. The content of dimethyldimethoxysilane after distillation is 99.98%. The packing type has a great influence on distillation separation.

[0032] The parameters of the primary distillation tower remain unchanged, the feed pressure of the secondary distillation tower is 5 bar, the feed temperature, feed position, feed state, theoretical plate number filling, reflux ratio, top pressure and bottom extraction ratio remain unchanged, and the content of dimethyldimethoxysilane after distillation is 99.63%. The removal of light components is related to the distillation pressure.

[0033] Example 5 This embodiment is also carried out using the process system of Example 1. The difference from Example 2 is that this embodiment mainly differs in the resin tower process parameters, and other process details are consistent with Example 2.

[0034] The type of mixed resin in this example is the same type and volume filler as above. The difference from Example 2 is that the filling method of this example is that the two fillers selected in Example 2 are mixed in a certain volume ratio and then uniformly filled into the resin tower, that is, the resin tower has only one layer. When the working pressure of the resin tower is 2 bar and the working temperature is 25°C, after the resin cation exchange, the anion concentration in dimethyldimethoxysilane is controlled between 90-100ppb, and the single cation concentration is controlled between 60-80ppt.

[0035] The above are only some embodiments of the present application and are not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have other forms of changes and variations. Any modifications, near-meaning substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0036] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily make changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims. In addition, when dimethyldimethoxysilane is replaced with methyldiethoxydimethylsilane, it is also within the protection scope of this patent.

[0037] Industrial-grade raw material data, electronic-grade product requirements, and data results of Examples 2 to 5:

Claims

1. A dimethyldimethoxysilane purification process, characterized in that: It includes the first-level dehydration tower dehydration process, the first-level distillation process, the second-level distillation process, the second-level flash distillation process, the anion and cation removal process, the second-level dehydration process, and the particle removal process; the process is as follows: The industrial-grade raw material tank (1) is nitrogen-pressed, and the industrial-grade dimethyldimethoxysilane raw material flows out from the bottom of the industrial-grade raw material tank (1) and is pumped to the primary dehydration tower A (2) and the primary dehydration tower B (3). After dehydration, the material enters the buffer tank (4) and continues to enter the primary distillation tower (5). The material at the top of the distillation tower enters the secondary distillation tower (7); The material coming out from the bottom of the secondary distillation tower (7) is tested by gas chromatography (10) and then enters a buffer tank (11). The material is then successively tested by resin tower A (12) and resin tower B (13) to remove anions and cations, enters a secondary dehydration tower A (14), and a secondary dehydration tower B (15) to remove moisture, enters a filter A (16), and a filter B (17) to remove particulate impurities. The obtained electronic grade dimethyldimethoxysilane enters an electronic grade product tank (18).

2. The dimethyldimethoxysilane purification process according to claim 1, characterized in that: There are two sets of equipment, the first-stage dehydration tower A (2) and the first-stage dehydration tower B (3), one for use and the other for standby. When one set is in use, the other set performs medium-high temperature nitrogen dehydration to restore performance. Each dehydration tower is divided into three layers, which are filled with three types of fillers, namely molecular sieve, silica gel and polyacrylamide absorbent resin, from top to bottom.

3. The dimethyldimethoxysilane purification process according to claim 2, characterized in that: The feed pressure in the primary distillation tower (5) is 1-5 bar, the feed temperature is 40-50°C, the reflux ratio is 3-5, the tower top pressure is 1.5-3.5 bar, and the tower top extraction ratio is 0.90-0.

950.

4. The dimethyldimethoxysilane purification process according to claim 2, characterized in that: The feed pressure in the secondary distillation tower (7) is 10-12 bar, the feed temperature is 100-110° C., the reflux ratio is 10-15, the tower top pressure is 8-10 bar, and the tower bottom extraction ratio is 0.926-0.

955.

5. The dimethyldimethoxysilane purification process according to claim 1, characterized in that: The bottom material of the primary distillation tower (5) and the top material of the secondary distillation tower (7) are respectively flashed and then enter the temporary storage tank (9) together, and then enter the buffer tank (4).

6. The dimethyldimethoxysilane purification process according to claim 5, characterized in that: In the secondary flash process, the flash tank at the bottom of the primary distillation tower is used to collect the dimethyldimethoxysilane in the removed heavy components and collect it into a temporary storage tank. The pressure of the flash tank is 1.5-1.7 bar and the temperature is 100-120°C. The flash tank at the top of the secondary distillation tower is used to collect the dimethyldimethoxysilane in the removed light components and collect it into a temporary storage tank. The pressure of the flash tank is 10-15 bar and the temperature is 179-185°C.

7. The dimethyldimethoxysilane purification process according to claim 1, characterized in that: In the process of removing anions and cations, different resins are used for exchange removal of anions and cations, and the cationic resin and the anionic resin are mixed to form a mixed resin, wherein the cationic resin is selected from XO1300-H and XO1310-H; the anionic resin is selected from XO1600-OH resin; The resin types filled in the upper and lower packings are cation resin and anion resin respectively with a filling volume ratio of 3-5:1-2. The working pressure of the resin tower is 2-5 bar, and the working temperature is room temperature to carry out resin exchange to remove anions and cations.

8. The dimethyldimethoxysilane purification process according to claim 1, characterized in that: In the secondary dehydration process, the types of mixed fillers in the secondary dehydration tower are two types of fillers, namely, silica gel and polyacrylamide absorbent resin. The above conditions are used to dehydrate dimethyldimethoxysilane.

9. The dimethyldimethoxysilane purification process according to claim 2, characterized in that: In the particle removal process, the dimethyldimethoxysilane after resin filtration in the filter is circulated and filtered, and the filtration is carried out in series using microporous folded filter elements with pore sizes of 120-100nm, 50-40nm, and 10-5nm, respectively. The filter element material is one of polytetrafluoroethylene and polyvinylidene fluoride membranes.

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