Deep dechlorination method of tetraethoxysilane
By combining molecular sieve adsorption with distillation, the problem of reducing chloride ion content in tetraethoxysilane has been solved, achieving efficient and low-cost purification, which is suitable for the production of high-purity tetraethoxysilane in the semiconductor field.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-29
- Publication Date
- 2026-03-31
AI Technical Summary
Existing technologies are insufficient to efficiently and cost-effectively reduce the chloride ion content in tetraethoxysilanes to below 50 ppb. Traditional methods are prone to introducing impurities and are costly.
The molecular sieve adsorption method was adopted. The activated molecular sieve was added to tetraethoxysilane, and after adsorbing trace amounts of chlorine impurities by stirring, it was then subjected to distillation. The molecular sieve selectively adsorbed chloride ions to below 20 ppb.
This technology reduces the chlorine content in tetraethoxysilane from 100-200 ppb to below 20 ppb, simplifying the process, lowering costs, and making it suitable for the high purity requirements of the semiconductor industry.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of purification technology for tetraethoxysilanes, and particularly to a method for deep dechlorination of tetraethoxysilanes. Background Technology
[0002] Tetraethoxysilane (TEOS), also known as tetraethyl orthosilicate, is an important chemical raw material widely used in materials and chemical industries, electronics and semiconductor industries, building and industrial materials, as well as high-end materials and special fields. It is a colorless, transparent liquid with a slight odor, relatively stable properties, slightly soluble in water and benzene, soluble in diethyl ether, and miscible with ethanol.
[0003] In the semiconductor field, high-purity tetraethoxysilane is mainly used in chemical vapor deposition (CVD and ALD) processes to grow silicon dioxide thin films. Therefore, the purity requirements of the TEOS raw materials used are relatively high. For example, the chloride ion content must be below 50 ppb or even lower. This is because a high chloride ion content can lead to film defects and corrode the reaction chamber, causing cross-contamination. Therefore, it is of great significance to prepare TEOS with low chloride ion content.
[0004] Currently, there are two main methods for producing tetraethoxysilane both domestically and internationally: the silicon tetrachloride method and the silicon powder method. The former accounts for more than 90% of the production capacity, while a few companies use the silicon powder method.
[0005] Both of the above methods produce TEOS containing varying amounts of chlorine. In the silicon tetrachloride method, incomplete reactions produce byproducts such as triethoxychlorosilane (Si(OC2H5)3Cl), which has a boiling point of 157°C, while TEOS has a boiling point of 168.1°C. Because their boiling points are similar, multi-stage distillation is traditionally used to remove chlorine to a low level. However, when the chlorine content is in the hundreds of ppb, distillation becomes even more difficult, leading to a longer production cycle and higher costs. Furthermore, patent CN117551124 mentions using inorganic fluorides and triethoxychlorosilane for halogen removal followed by further distillation to obtain low-chlorine TEOS. Patent CN110498811 uses sodium ethoxide and triethoxychlorosilane for affinity substitution to remove chlorine. Both patents employ chemical methods for impurity removal. A significant problem with chemical methods is the easy introduction of impurities, which is detrimental to subsequent stable production. Summary of the Invention
[0006] The main objective of this invention is to propose a deep dechlorination method for tetraethoxysilane to solve the aforementioned technical problems.
[0007] To achieve the above objectives, this invention proposes a deep dechlorination method for tetraethoxysilanes, comprising the following steps: S1. After activating the molecular sieve by heating, cool it to room temperature; S2. Add the activated molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 1-12 h. S3. After the reaction, the material is filtered to obtain a liquid phase, which is then distilled to obtain purified tetraethoxysilane.
[0008] This invention employs a molecular sieve adsorption method. After activation, the molecular sieve is added to TEOS and stirred, which can remove chlorine from TEOS at a concentration of several hundred ppb to less than 20 ppb. Following distillation, purified tetraethoxysilane is obtained. The entire process is simple, efficient, and inexpensive.
[0009] Preferably, in step S1, the heating temperature is 250~400℃ and the activation time is 8~16 h.
[0010] Preferably, the molecular sieve is at least one of 4A molecular sieve and 13X molecular sieve.
[0011] Preferably, the molecular sieve is a 4A molecular sieve.
[0012] Preferably, the amount of molecular sieve used is 5-20% based on the mass of the tetraethoxysilane raw material being 100%.
[0013] Preferably, the amount of molecular sieve used is 15-20% based on the mass of the tetraethoxysilane raw material being 100%.
[0014] Preferably, in step S2, the stirring time is 6~12 h.
[0015] Preferably, the distillation specifically includes: using a light component removal column for distillation, setting the column bottom temperature to 170~175℃, and the reflux time to 4~6h, removing 10%~20% of light components, and finally obtaining high-purity tetraethoxysilane.
[0016] Preferably, the chlorine content in the tetraethoxysilane raw material is in the range of 100~200 ppb.
[0017] Compared to existing technologies, this invention utilizes molecular sieve adsorption, taking advantage of the porous structure of molecular sieves to selectively adsorb trace amounts of chlorine impurities (including inorganic and organic chlorine) in the system. It can remove chlorine from TEOS containing 100-200 ppb to below 20 ppb, more preferably, to below 10 ppb. Following adsorption, a subsequent distillation process yields purified tetraethoxysilane. The entire process is simple, easy to operate, and low in cost, making it suitable for the deep purification of raw materials with low chlorine content. Detailed Implementation
[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. At the same time, the raw materials mentioned below, unless otherwise specified, are all commercially available products; the process steps or preparation methods not mentioned in detail are all process steps or preparation methods known to those skilled in the art.
[0019] This invention provides a method for deep dechlorination of tetraethoxysilane, comprising the following steps: S1. After activating the molecular sieve by heating, cool it to room temperature; Specifically, in step S1, the heating temperature is 250~400℃, and the activation time is 8~16 h. After the molecular sieve is activated by heating, it is cooled to room temperature while maintaining a nitrogen atmosphere.
[0020] S2. Add the activated molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 1-12 h. Understandably, the activated molecular sieve is added to TEOS for liquid-phase adsorption, utilizing the porous structure of the molecular sieve to selectively adsorb trace chlorine impurities in the system, including free chloride ions and organic chlorine. During this process, chlorine content between 100 and 200 ppb can be removed to below 20 ppb. More preferably, with a stirring time and adsorption time of 6 to 12 hours, the chlorine content can be further removed to below 10 ppb.
[0021] S3. After the reaction, the material is filtered to obtain a liquid phase, which is then distilled to obtain purified tetraethoxysilane.
[0022] It should be noted that molecular sieve adsorption can effectively remove organic and free chlorine from TEOS, with good adsorption efficiency, avoiding the complex process of multi-stage distillation, which has a longer production cycle and higher cost. However, molecular sieve adsorption can easily introduce a small amount of new metal ion impurities, so further purification by distillation is required to obtain high-purity tetraethoxysilane that meets the requirements of semiconductor manufacturing processes without affecting subsequent production stability.
[0023] Understandably, conventional methods for producing tetraethoxysilanes easily generate chlorine-containing byproducts, such as triethoxychlorosilane, with a boiling point of 157°C, very close to the boiling point of TEOS (168.1°C). Therefore, it is difficult to remove them to a low level through distillation, making them unsuitable for direct application in the semiconductor field. Therefore, this invention first uses molecular sieve liquid-phase adsorption to further remove the chlorine content in TEOS from 100-200 ppb to below 20 ppb. Although this avoids introducing new metal ion impurities, these impurities can be separated by distillation, ultimately yielding purified tetraethoxysilane. The entire process is simple and efficient.
[0024] The distillation process specifically includes: using a light component removal column for distillation, setting the column bottom temperature to 170~175℃, and the reflux time to 4~6h, removing 10%~20% of light components, and finally obtaining high-purity tetraethoxysilane.
[0025] In some preferred embodiments, the molecular sieve may optionally include at least one of 4A molecular sieve and 13X molecular sieve. 4A molecular sieve is particularly effective. It can further remove chlorine content to below 10 ppb.
[0026] In some preferred embodiments, the amount of molecular sieve is 5-20% of the total mass of the tetraethoxysilane feedstock. More preferably, the amount of molecular sieve is 15-20%. In particular, when the amount of molecular sieve is 20%, the chlorine content can be further removed to less than 10 ppb.
[0027] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters in the following examples are merely one example within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values in the examples below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply.
[0028] It should be noted that, for ease of comparison, the tetraethoxysilane raw materials in Examples 1-2 and Comparative Examples 1-2 were all taken from the same group of raw materials. Therefore, the parameter measurements of the raw materials all came from the same sampling results.
[0029] Example 1 A method for deep dechlorination of tetraethoxysilane includes the following steps: S1. Activate the 4A molecular sieve by heating it to 300 °C for 12 h, and then cool it to room temperature while maintaining a nitrogen atmosphere; S2. Add the activated 4A molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 12 h; the amount of 4A molecular sieve added accounts for 20% of the total mass of the tetraethoxysilane raw material; S3. Collect the reaction material and use a light component removal column for distillation. Set the column temperature to 170℃ and the reflux time to 5h to remove 10%~20% of the light components and obtain purified tetraethoxysilane.
[0030] Example 2 A method for deep dechlorination of tetraethoxysilane includes the following steps: S1. Activate 13X molecular sieve by heating it to 300 °C for 12 h, and then cool it to room temperature while maintaining a nitrogen atmosphere; S2. Add the activated 13X molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 12 h; the amount of 13X molecular sieve added accounts for 20% of the total mass of the tetraethoxysilane raw material; S3. Collect the reaction material and use a light component removal column for distillation. Set the column temperature to 175℃ and the reflux time to 4h to remove 10%~20% of the light components and obtain purified tetraethoxysilane.
[0031] Comparative Example 1 A method for removing chlorine from tetraethoxysilane includes the following steps: S1. Activate the activated carbon by heating it to 300 °C for 12 h, and then cool it to room temperature while maintaining a nitrogen atmosphere. S2. Add the activated carbon obtained in step S1 to the tetraethoxysilane raw material and stir for 12 h; the amount of activated carbon added accounts for 20% of the total mass of the tetraethoxysilane raw material. S3. Collect the reaction material and use a light component removal column for distillation. Set the column temperature to 170℃ and the reflux time to 5h to remove 10%~20% of the light components and obtain purified tetraethoxysilane.
[0032] Comparative Example 2 A method for removing chlorine from tetraethoxysilane includes the following steps: S1. Activate the 5A molecular sieve by heating it to 300 °C for 12 h, and then cool it to room temperature while maintaining a nitrogen atmosphere; S2. Add the activated 5A molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 12 h; the amount of 5A molecular sieve added accounts for 20% of the total mass of the tetraethoxysilane raw material; S3. Collect the reaction material and use a light component removal column for distillation. Set the column temperature to 175℃ and the reflux time to 4h to remove 10%~20% of the light components and obtain purified tetraethoxysilane.
[0033] The tetraethoxysilane raw materials in Examples 1-2 and Comparative Examples 1-2, the tetraethoxysilane treated in step S2, and the tetraethoxysilane treated in step S3 were tested, and the results are shown in Tables 1-4.
[0034] Table 1. Measurement results of Example 1 Table 2. Measurement results of Example 2 Table 3. Measurement results of Comparative Example 1 Table 4. Measurement results of Comparative Example 2 As shown in Tables 1-4, after adsorption using activated 4A and 13X molecular sieves, the chlorine content decreased from 102.85 ppb to 9.85 ppb and 10.72 ppb, respectively. After further distillation in step S3, the chlorine contents were reduced to 8.86 ppb and 10.32 ppb, respectively. The results were superior to those of activated carbon and 5A molecular sieves. The simple distillation in step S3 removed newly introduced metal ion impurities, yielding high-purity tetraethoxysilane.
[0035] Example 3 A method for deep dechlorination of tetraethoxysilane includes the following steps: S1. Activate the 4A molecular sieve by heating it to 300 °C for 12 h, and then cool it to room temperature while maintaining a nitrogen atmosphere; S2. Add the activated 4A molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 12 h; the amount of 4A molecular sieve added is shown in Table 5. S3. Collect the reaction material and use a light component removal column for distillation. Set the column temperature to 170℃ and the reflux time to 6h to remove 10%~20% of the light components and obtain purified tetraethoxysilane.
[0036] Table 5 To save space, only the tetraethoxysilane raw material in Example 3 and the tetraethoxysilane after step S3 were tested, and the results are shown in Table 6.
[0037] Table 6 Table 6 shows that adjusting the dosage of 4A molecular sieve achieves the optimal adsorption effect. A dosage of 15% 4A molecular sieve can reduce the chlorine content to 10.83 ppb, with a dosage of 20% showing a more significant chlorine removal effect, achieving a removal rate below 10 ppb. This also indicates that when the dosage of 4A molecular sieve reaches a certain level (15%), further increasing the dosage has little effect on further reducing the chlorine content in TEOS. Therefore, when using 4A molecular sieve, a dosage of 15-20% provides good chlorine removal, reducing the chlorine content to approximately 9 ppb.
[0038] Example 4 A method for deep dechlorination of tetraethoxysilane includes the following steps: S1. Activate the 4A molecular sieve by heating it to 300 °C for 12 h, and then cool it to room temperature while maintaining a nitrogen atmosphere; S2. Add the activated 4A molecular sieve from step S1 to the tetraethoxysilane raw material, and stir for the time shown in Table 7; the amount of 4A molecular sieve added accounts for 20% of the total mass of the tetraethoxysilane raw material; S3. Collect the reaction material and use a light component removal column for distillation. Set the column temperature to 175℃ and the reflux time to 5h to remove 10%~20% of the light components and obtain purified tetraethoxysilane.
[0039] Table 7 To save space, only the tetraethoxysilane raw material in Example 4 and the tetraethoxysilane after step S3 were tested, and the results are shown in Table 8.
[0040] Table 8 Table 8 shows that different adsorption times have varying effects on the removal of chlorine from TEOS. When the adsorption time is 3 h, the chlorine content is close to 10 ppb. The data indicates that the chlorine removal effect is relatively significant when the adsorption time is 3–12 h. When the adsorption time reaches 6 h, the chlorine content decreases to below 10 ppb, showing even better results. However, compared to Examples 4-4, when the adsorption time is 12 h, the chlorine removal effect is not significantly improved compared to Examples 4-3. Therefore, further increasing the adsorption time has little effect on further reducing the chlorine content in TEOS. The chlorine removal effect is most significant when the adsorption time is 6–12 h.
[0041] In summary, this invention utilizes the adsorption effect of molecular sieves combined with simple distillation to achieve deep dechlorination of TEOS, resulting in a simple, efficient, and low-cost process. The dechlorination effect is most significant when using 4A molecular sieves at a dosage of 15-20% and an adsorption time of 6-12 hours.
[0042] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
Claims
1. A method for deep dechlorination of tetraethoxysilane, characterized in that, Includes the following steps: S1. After activating the molecular sieve by heating, cool it to room temperature; S2. Add the activated molecular sieve from step S1 to the tetraethoxysilane raw material and stir for 1-12 h. S3. After the reaction, the material is filtered to obtain a liquid phase, which is then distilled to obtain purified tetraethoxysilane.
2. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, In step S1, the heating temperature is 250~400℃ and the activation time is 8~16 h.
3. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, The molecular sieve is at least one of 4A molecular sieve and 13X molecular sieve.
4. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, The molecular sieve is a 4A molecular sieve.
5. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, Based on the mass of the tetraethoxysilane raw material being 100%, the amount of the molecular sieve used is 5-20%.
6. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, Based on the mass of the tetraethoxysilane raw material being 100%, the amount of the molecular sieve used is 15-20%.
7. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, In step S2, the stirring time is 6~12 h.
8. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, The distillation specifically includes: using a light component removal column for distillation, with the column bottom temperature set at 170~175℃ and the reflux time at 4~6h, to remove 10%~20% of light components, ultimately obtaining high-purity tetraethoxysilane.
9. The method for deep dechlorination of tetraethoxysilane according to claim 1, characterized in that, The chlorine content in the tetraethoxysilane raw material ranges from 100 to 200 ppb.