A preparation method and production system of high-purity ethyl orthosilicate

Abstract

A preparation method and production system is disclosed for high-purity ethyl orthosilicate, which comprises the following steps: (1) performing a first distillation of crude ethyl orthosilicate to ob

Description

TECHNICAL FIELD The present invention belongs to the field of semiconductor technology, in particular to a preparation method and production system of high-purity ethyl orthosilicate. BACKGROUND Electronic grade ethyl orthosilicate (TEOS) is widely used in chemical vapor deposition processes to form a silicon dioxide deposition film, which blocks pollutants and impurities from entering semiconductor components. At the same time, it can generate a conductive or insulating layer, produce an anti reflection film to improve absorbance, and temporarily block etching. The preparation of electronic grade tetraethyl orthosilicate is mainly achieved by purifying industrial grade raw materials. The purity of industrial tetraethyl orthosilicate is generally 99%, and it still contains 1% impurities. Impurities include electronic active impurities and non electronic impurities, among which electronic active impurities are metal ions that can reduce the insulation performance of SiO2 thin film layers deposited in semiconductor devices, leading to interconnection of circuits at the micron level, and thus leading to circuit board scrapping; The non electronic impurities in ethyl orthosilicate include organic matter and water, which affect the physical properties of the membrane by altering the structural integrity and planar uniformity of the membrane surface Patent US5840953 uses gas chromatography to prepare tetraethyl orthosilicate, and lithium hydride is used to remove impurities. The resulting product has a purity of not less than 99.999999% and a water content of less than 2ppm. However, the gas chromatograph is mainly used for the analysis and detection of trace elements, and the equipment is expensive, which increases production costs. CN109748931B provides a preparation method for high-purity ethyl orthosilicate, which includes: SI) mixing high-purity silicon tetrachloride with high-purity ethanol for reactive distillation to obtain crude ethyl orthosilicate and crude hydrogen chloride; S2) The crude orthosilicate ethyl ester is subjected to decolorization and adsorption treatment, followed by alkaline adsorption treatment, and then subjected to de light distillation treatment to obtain the de light treated orthosilicate ethyl ester and the removed light component; S3) After the de lightness treated ethyl orthosilicate is treated with boron phosphorus adsorption resin and metal ion adsorption resin, the weight is removed and rectified to obtain high-purity ethyl orthosilicate. However, in actual production, the reaction between high-purity silicon tetrachloride and high-purity ethanol has a significant impact on purity and yield due to side reactions. Therefore, a new method for preparing high-purity ethyl orthosilicate is needed to improve the purity of ethyl orthosilicate while reducing production costs. SUMMARY OF THE INVENTION The present invention provides a preparation method and production system for electronic grade tetraethyl orthosilicate with a purity of not less than 99.999999% (W / W), using conventional manufacturing equipment, simple operation, and low production cost of the product. In order to achieve the above objectives, the present invention provides the following technical solutions: The first aspect of the present invention provides a preparation method for high-purity orthosilicate ethyl ester, which comprises the following steps: (1) Perform the first distillation of the crude orthosilicate ethyl ester to obtain the product after the first distillation; (2) Pass the product after the first distillation through the adsorption tower to obtain the adsorbed product; (3) Perform a second distillation of the adsorbed product to obtain the product after the second distillation; (4) Distill the product after the second distillation to obtain high-purity ethyl orthosilicate. In a preferred embodiment, the reflux ratio of the first distillation is 7-10 times larger than the reflux ratio of the second distillation. In a preferred embodiment, the reflux ratio of the first distillation is 15-20. In a preferred embodiment, the reflux ratio of the second distillation is 7-13. Preferably, the reflux ratio of the first distillation is 18. The reflux ratio of the second distillation is 10. The reflux ratio is the ratio of the reflux liquid flow rate returned from the top of the distillation tower to the product flow rate at the top of the tower during distillation operations. The magnitude of the reflux ratio has a significant impact on the separation effect of the distillation process. The inventor discovered that the reflux ratio of the first distillation of the present invention is 7-10 higher than that of the second distillation, which can improve the purity of ethyl orthosilicate. The speculated reason is that under this condition, two distillation processes can maximize the removal of non electronic impurities in ethyl orthosilicate, while also removing some metal ions. In a preferred embodiment, the temperature of the first distillation is 90-110 °C, and the pressure of the first distillation is -0.8—1.2 bar. In a preferred embodiment, the temperature of the second distillation is 130-150 °C, and the pressure of the second distillation is -0.3—0.7 bar. In order to better remove impurities from the system, it is preferred that the temperature of the first distillation is 95 °C, and the pressure of the first distillation is -0.9 bar; The temperature of the second distillation is 140 °C, and the pressure of the second distillation is -0.5bar. In a preferred embodiment, the adsorption tower is sequentially filled with coconut shell activated carbon, cation exchange resin, and carbon nanotubes. In a preferred embodiment, the volume ratio of coconut shell activated carbon, cation exchange resin, and carbon nanotubes is 1:1 to 5:1. Preferably, the volume ratio of coconut shell activated carbon, cation exchange resin, and carbon nanotubes is 1:2:1. The inventor found that the purity of ethyl orthosilicate was significantly improved by sequentially using coconut shell activated carbon, cation exchange resin, and carbon nanotubes for adsorption. Coconut shell activated carbon has a small molecular pore structure with developed pore structures, and the surface of coconut shell activated carbon has acidic functional groups. Its special pore structure makes it highly capable of adsorbing both electronic and non electronic impurities in this system. After being adsorbed by coconut shell activated carbon, it is further removed by cation exchange resin to remove various metal ions, Then, carbon nanotubes can be used to further adsorb residual metal ions, which gradually progress and play a synergistic role in this system. The inventor found through extensive experiments that the volume ratio of coconut shell activated carbon, ion exchange resin, and carbon nanotubes is 1:2:1, which has the best adsorption effect on impurities. It is speculated that the three components in this ratio can absorb different types of impurities separately. With a reasonable volume ratio, the impurities in the system can be more completely adsorbed, resulting in the highest purity of the product. In a preferred embodiment, the particle size of the coconut shell activated carbon is 12-30 mesh, the filling density is 0.45-0.55g / mL, the moisture content is < 10%, and the specific surface area is 950-1200m2 / g. Purchased from Yixing Huahai Activated Carbon Co., Ltd. In a preferred embodiment, the carbon nanotubes are single walled and functionalized with octadecylamine. Diameter 2-10 nm, length 0.5-2 p M. Purchased from Merck, model 652482. In a preferred embodiment, the cation exchange resin is selected from a styrene based strong acidic cation exchange resin, with a functional group of sulfonic acid, a total exchange capacity of > 1.8mmol / mL (wet), and a particle size range of 0.3-1.25mm. Purchased from Tianjin Yunkai Resin Technology Co., Ltd., 001 x 7 strong acidic cation exchange resin model Styrene DVB. The particle size and specific surface area of coconut shell activated carbon affect its adsorption capacity. The coconut shell activated carbon selected in the present invention has extremely strong adsorption capacity for both electronic and non electronic impurities. The inventor discovered the use of styrene based strong acidic cation exchange resin with a functional group of sulfonic acid, a total exchange capacity of > 1.8mmol / mL, and a particle size range of 0.3-1.25mm, which has stronger adsorption ability for various metal ions. After being adsorbed by coconut shell activated carbon and cation exchange resin, the inventor discovered that single-walled carbon nanotubes modified with octadecylamine can efficiently adsorb the remaining metal ions. It is speculated that after the oxidation modification of carbon nanotubes, the acidic adsorption sites increase and the adsorption energy increases. At the same time, the electrostatic attraction between single-walled carbon nanotubes and metal ions is stronger, and the adsorption amount is high, The inventor can achieve the best adsorption effect by selecting an adsorption tower composed of these three materials. The second aspect of the present invention provides a production system for high-purity ethyl orthosilicate, comprising: The first distillation tower is used for the first distillation of crude ethyl orthosilicate; An adsorption tower, wherein the first distillation tower is connected to the adsorption tower, and the adsorption tower is used to adsorb the products after the first distillation; A second distillation tower, wherein the adsorption tower is connected to the second distillation tower, and the second distillation tower is used to perform a second distillation of the adsorbed product; A distillation tower, wherein the second distillation tower is connected to the distillation tower, and the distillation tower is used to distill the product after the second distillation to obtain high-purity ethyl orthosilicate. Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention provides a preparation method for high-purity tetraethyl orthosilicate, which is simple in operation. By reasonably designing various steps and exerting synergistic effects, electronic grade tetraethyl orthosilicate of not less than 99.999999% (W / W) can be prepared. 2.The present invention greatly improves the purity of the product by designing the reflux ratio of the first distillation and the reflux ratio of the second distillation. 3.The absorption tower of the present invention is filled with coconut shell activated carbon, cation exchange resin, and carbon nanotubes with specific structure and performance. The three materials synergistically enhance the adsorption of electronic active impurities and non electronic impurities. 4.This aspect provides a production system for high-purity ethyl orthosilicate, using conventional manufacturing equipment to reduce production costs. DESCRIPTION OF DRAWINGS Figure 1 is a schematic diagram of the structure of a high-purity ethyl orthosilicate production system. DETAILED DESCRIPTION OF THE INVENTION The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the art without creative labor fall within the scope of protection of the present invention. Example 1 This embodiment provides a preparation method for high-purity ethyl orthosilicate, which comprises the following steps: (1) Perform the first distillation of the crude orthosilicate ethyl ester to obtain the product after the first distillation; The purity of the crude orthosilicate ethyl ester is 99.9%, purchased from Shanghai Duyin Industrial Co., Ltd. (2) Pass the product after the first distillation through the adsorption tower to obtain the adsorbed product; (3) Perform a second distillation of the adsorbed product to obtain the product after the second distillation; (4) Distill the product after the second distillation to obtain high-purity ethyl orthosilicate. The reflux ratio of the first distillation is 18. The reflux ratio of the second distillation is 10. The temperature of the first distillation is 95 °C, and the pressure of the first distillation is -0.9 bar; The temperature of the second distillation is 140 °C, and the pressure of the second distillation is -0.5bar. The adsorption tower is sequentially filled with coconut shell activated carbon, cation exchange resin, and carbon nanotubes. The volume ratio of coconut shell activated carbon, cation exchange resin, and carbon nanotubes is 1:2:1. The particle size of the coconut shell activated carbon is 12-30 mesh, the filling density is 0.45-0.55g / mL, the moisture content is < 10%, and the specific surface area is 950-1200m2 / g. Purchased from Yixing Huahai Activated Carbon Co., Ltd. The carbon nanotubes, single walled, octadecyl amine functionalized. Diameter 2-10 nm, length 0.5-2 p M. Purchased from Merck, model 652482. The cation exchange resin is selected from a styrene based strong acidic cation exchange resin, with a functional group of sulfonic acid, a total exchange capacity of > 1.8mmol / mL (wet), and a particle size range of 0.3-1.25mm. Purchased from Tianjin Yunkai Resin Technology Co., Ltd., 001 x 7 strong acidic cation exchange resin model Styrene DVB. As shown in Figure 1, this embodiment provides a production system for high-purity ethyl orthosilicate, which includes: The first distillation tower is used for the first distillation of crude ethyl orthosilicate; An adsorption tower, wherein the first distillation tower is connected to the adsorption tower, and the adsorption tower is used to adsorb the products after the first distillation; A second distillation tower, wherein the adsorption tower is connected to the second distillation tower, and the second distillation tower is used to perform a second distillation of the adsorbed product; A distillation tower, wherein the second distillation tower is connected to the distillation tower, and the distillation tower is used to distill the product after the second distillation to obtain high-purity ethyl orthosilicate. Example 2 The difference between this embodiment and Example 1 is that the reflux ratio of the first distillation is 15; The reflux ratio of the second distillation is 8. Example 3 The difference between this embodiment and Example 1 is that the carbon nanotubes are multi walled, carboxylic acid functionalized, purchased from Merck, model 755125. Proportion 1 The difference between this ratio and Example 1 is that the adsorption tower is sequentially filled with coconut shell activated carbon and cation exchange resin. The volume ratio of coconut shell activated carbon and cation exchange resin is 1:2. Ratio 2 The difference between this ratio and Example 1 is that the adsorption tower is sequentially filled with non coconut shell activated carbon, cation exchange resin, and carbon nanotubes. The non coconut shell activated carbon has a particle size of 20-40 mesh, purchased from Merck, 242268. Ratio 3 The difference between this ratio and Example 1 is that the volume ratio of coconut shell activated carbon, cation exchange resin, and carbon nanotubes is 1:1:5. Proportion 4 The difference between this ratio and Example 1 is that the temperature of the first distillation is 145 °C, and the pressure of the first distillation is -0.8 bar; The temperature of the second distillation is 90 °C, and the pressure of the second distillation is -1.1 bar. performance testing The purity and elemental content of ethyl orthosilicate prepared in accordance with the sample and ratio were detected using GC and ICP-MS analysis methods, respectively. The results are shown in Table 1. Table 1 Measurement Results item unit Example 1 Example 2 Example 3 proportion 1 proportion 2 proportion 3 proportion 4 purity 0 / / 0 99.9999999 99.9999999 99.9999999 99.999999 99.999999 99.999999 99.999999 water PPm 1.5 1.6 1.8 3.5 3.3 2.5 2.8 aluminium PPb 0.05 0.06 0.06 0.12 0.09 0.10 0.08 antimony PPb 0.07 0.08 0.09 0.15 0.14 0.12 0.13 arsenic PPb 0.01 0.01 0.01 0.03 0.03 0.02 0.03 boron PPb 0.05 0.07 0.08 0.15 0.14 0.13 0.12 chrome PPb 0.01 0.01 0.01 0.05 0.03 0.04 0.04 cobalt PPb 0.01 0.01 0.01 0.05 0.02 0.04 0.02 copper PPb 0.01 0.01 0.01 0.04 0.02 0.04 0.03 iron PPb 0.01 0.01 0.01 0.06 0.03 0.04 0.05 manganese PPb 0.01 0.01 0.01 0.03 0.01 0.02 0.01 molybdenu PPb 0.01 0.01 0.01 0.04 0.02 0.01 0.03 m nickel PPb 0.01 0.01 0.01 0.05 0.02 0.02 0.04 titanium PPb 0.01 0.01 0.01 0.02 0.02 0.02 0.03 vanadium PPb 0.01 0.01 0.01 0.06 0.03 0.01 0.02 zinc PPb 0.01 0.01 0.01 0.03 0.01 0.01 0.02 The above are the preferred embodiments of the present invention. It should be pointed out that for ordinary technical personnel in the field of this technology, several improvements and embellishments can be made without departing from the principles described in the present invention. These improvements and embellishments should also be considered as the scope of protection of the present invention.

Claims

l.A preparation method for high-purity ethyl orthosilicate, characterized in that the preparation method comprises the following steps:(1) Perform the first distillation of the crude orthosilicate ethyl ester to obtain the product after the first distillation;(2) Pass the product after the first distillation through the adsorption tower to obtain the adsorbed product;(3) Perform a second distillation of the adsorbed product to obtain the product after the second distillation;(4) Distill the product after the second distillation to obtain high-purity ethyl orthosilicate.2.A preparation method for high-purity orthosilicate ethyl ester according to claim 1, characterized in that the reflux ratio of the first distillation is 7-10 times larger than the reflux ratio of the second distillation.3.A preparation method for high-purity orthosilicate ethyl ester according to claim 2, characterized in that the reflux ratio of the first distillation is 15-20.4.A preparation method for high-purity orthosilicate ethyl ester according to claim 3, characterized in that the reflux ratio of the second distillation is 7-13.5.A preparation method for high-purity orthosilicate ethyl ester according to claim 1, characterized in that the temperature of the first distillation is 90-110 °C, and the pressure of the first distillation is -0.8-1.2 bar.

6. A preparation method for high-purity ethyl orthosilicate according to claim 5, characterized in that the temperature of the second distillation is 130-150 °C, and the pressure of the second distillation is -0.3—0.7 bar.

7. A preparation method for high-purity ethyl orthosilicate according to claim 1, characterized in that the adsorption tower is sequentially filled with coconut shell activated carbon, cation exchange resin, and carbon nanotubes.

8. A preparation method for high-purity ethyl orthosilicate according to claim 7, characterized in that the particle size of the coconut shell activated carbon is 12-30 mesh, the filling density is 0.45-0.55g / mL, the moisture content is 10%, and the specific surface area is 950-1200m2 / g.9.A preparation method for high-purity orthosilicate ethyl ester according to claim 7, characterized in that the volume ratio of coconut shell activated carbon, ion exchange resin, and carbon nanotubes is 1:1 to 5:1.

10. A production system based on the preparation method of high-purity ethyl orthosilicate according to any one of claims 1-9, characterized in that the production system comprises:The first distillation tower is used for the first distillation of crude ethyl orthosilicate;An adsorption tower, wherein the first distillation tower is connected to the adsorption tower, and the adsorption tower is used to adsorb the products after the first distillation;A second distillation tower, wherein the adsorption tower is connected to the second distillation tower, and the second distillation tower is used to perform a second distillation of the adsorbed product;A distillation tower, wherein the second distillation tower is connected to the distillation tower, and the distillation tower is used to distill the product after the second distillation to obtain high-purity ethyl orthosilicate.