Preparation method of electronic-grade triethyl phosphate, triethyl phosphate and application

Abstract

The application discloses a preparation method of electronic-grade triethyl phosphate, the triethyl phosphate and application, wherein the preparation method sequentially comprises the following steps: raw material pretreatment, so as to obtain 99 wt.% industrial-grade raw material of TEPO; catalytic reaction, in a fixed bed reaction with a catalyst, the catalyst adopted is selected from spinel-type aluminum oxide, gamma-aluminum oxide, spinel-type iron oxide and gamma-copper oxide; multi-stage rectification, including light-removing rectification and heavy-removing rectification; and precision filtration. The application optimizes a purification preparation process, so that the separation and post-processing efficiency are effectively improved, and the particle size and metal ion concentration are reduced.

Description

Technical Field

[0001] This invention belongs to the field of electronic-grade chemical preparation technology, specifically relating to a method for preparing electronic-grade triethyl phosphate, triethyl phosphate, and its applications. Background Technology

[0002] In recent years, with the accelerated development of electronic specialty gases and electronic-grade wet chemicals, the variety of related products has become increasingly rich. Among them, organophosphorus compounds, as an important precursor material, are widely used in advanced semiconductor manufacturing processes due to their key role in the preparation of boro-phospho-silicate glass (BPSG).

[0003] BPSG is a boron- and phosphorus-doped silicon dioxide commonly used in integrated circuit (IC) manufacturing as a pre-metal dielectric (PMD) and inter-metal dielectric (MD) layer. The originally ordered network structure of silicon dioxide becomes porous due to the doping of boron and phosphorus impurities (B₂O₃, P₂O₅), giving it a certain degree of fluidity at high temperatures. This structure endows BPSG films with excellent via-filling ability and planarization effect, providing greater process margin for photolithography and subsequent processes. Simultaneously, BPSG also possesses excellent sodium ion blocking ability, significantly improving device stability and reliability. With the continuous shrinking of semiconductor device dimensions, the requirements for via-filling ability in PMD layers are becoming increasingly stringent, making BPSG, especially its application as a PMD in advanced DRAM products, particularly important. BPSG films are mainly prepared using sub-atmospheric pressure chemical vapor deposition (SACVD) and plasma-enhanced chemical vapor deposition (PECVD), with SACVD being more favored due to its superior via-filling performance. In the SACVD process, by precisely controlling the flow rate and pressure of the reactive gases, a uniform and dense BPSG film can be formed on the substrate. Therefore, the yield and purity of triethyl phosphate, a key precursor for BPSG preparation, have attracted great attention from the industry.

[0004] Currently, there are numerous manufacturers of triethyl phosphate (TEPO) in my country, mainly used as a flame retardant, green solvent, and heat-resistant coating for polyurethane. Therefore, the purity is relatively low. The national standard for industrial-grade TEPO (GB / T33106-2016) typically only requires a purity of 99.5% or higher, far below the requirements of advanced IC manufacturing processes. Due to the late start of electronic-grade TEPO development in China, only two domestic manufacturers, Guizhou Weidun Jinglin and Aipeike, produce TEPO with a purity exceeding 99.99%. The majority of the market is still dominated by foreign companies such as Versum Materials, Entegris, and Yamanaka Ceradyne, hindering the development of high-end electronic products in my country. In the production case of Guizhou Weidun Jinglin (CN116251535B), extractive distillation is used, resulting in high energy consumption and pollution. In case CN114057787A, only distillation is used after obtaining the crude product, leading to poor control over the metal content of electronic-grade chemicals. In case CN104447855B, additional antioxidants are required, which presents a cost issue in the subsequent separation and purification stages.

[0005] To promote the healthy, stable, and sustainable development of my country's integrated circuit industry, enhance the independent innovation capabilities and market competitiveness of my country's integrated circuit equipment, processes, and materials, and address the industry's reliance on imported advanced electronic materials and gases, it is imperative to vigorously develop and improve the overall level of electronic gases. Therefore, this project focuses on the purification process of TEPO, exploring suitable purification routes to provide the semiconductor industry with high-quality and low-cost electronic-grade TEPO (99.99% based on main component concentration and 99.9999995% based on metal ion concentration), thus driving the continuous development of the semiconductor industry.

[0006] Therefore, in view of the above-mentioned technical problems, it is necessary to provide a method for preparing electronic-grade triethyl phosphate, triethyl phosphate, and its applications. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing electronic-grade triethyl phosphate, triethyl phosphate, and its applications.

[0008] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0009] The preparation method of electronic grade triethyl phosphate includes, in sequence: raw material pretreatment to obtain industrial grade raw material of TEPO 99wt.%; catalytic reaction in a fixed bed reaction with a catalyst, wherein the catalyst is selected from spinel alumina, γ-alumina, spinel iron oxide, and γ-copper oxide; multi-stage distillation, including light distillation and heavy distillation; and precision filtration.

[0010] In one or more embodiments of the present invention, the catalyst is spinel-type alumina, which is obtained by mixing aluminum tert-butoxide, ethanol, and a template agent, slowly adding nitric acid and stirring to form a sol, heating to form a gel, and then drying and heating.

[0011] Preferably, the catalyst is spinel-type alumina, which is obtained by mixing aluminum tert-butoxide, ethanol, and a template agent, slowly adding nitric acid, stirring for 24 hours to form a sol, heating at 100°C to form a gel, drying in an oven at 120°C for 12 hours, and then heating in a muffle furnace at 700°C for 2 hours.

[0012] In one or more embodiments of the present invention, the template agent is P123.

[0013] In one or more embodiments of the present invention, the mass ratio of aluminum tert-butoxide, ethanol, and template agent is 1:4:0.1.

[0014] In one or more embodiments of the present invention, the dropping rate of nitric acid is 50-100 drops / min, the dropping amount is 5-10 mL / L, and the molar ratio of nitric acid to aluminum tert-butoxide is 1:0.5-2.25.

[0015] In one or more embodiments of the present invention, the conditions for light distillation are: temperature 120–140°C and vacuum degree 0.095–0.1 MPa.

[0016] In one or more embodiments of the present invention, the conditions for de-heavy distillation are: temperature 120–140°C, vacuum degree 0.093–0.1 MPa, and collection of the fraction in the temperature range of 115°C–120°C.

[0017] In one or more embodiments of the present invention, precision filtration is microfiltration, with a pore size not greater than 0.05 μm.

[0018] In one or more embodiments of the present invention, electronic-grade triethyl phosphate is obtained by the aforementioned preparation method. The product purity is ≥99.999%, and the metal impurities are ≤0.093 ppb.

[0019] In one or more embodiments of the present invention, the aforementioned electronic-grade triethyl phosphate is used in the manufacture of semiconductor BPSG doping sources and chips (such as IC chips).

[0020] Compared with existing technologies, the preparation method, application, and use of electronic-grade triethyl phosphate of the present invention utilize a fixed-bed catalysis and two-stage distillation scheme, which can effectively separate light and heavy components from TEPO feedstock. Pre-treatment of some light components with a catalyst avoids the generation of byproducts and reduces the pressure on subsequent distillation. The catalyst selection does not introduce other metal ions, which is beneficial for the production of electronic-grade products. No other impurities such as extractants or antioxidants are introduced during distillation, effectively improving separation and post-processing efficiency. The final product obtained is the product obtained through distillation and filtration, which can effectively reduce particle size and metal ion concentration. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the preparation process of electronic-grade triethyl phosphate in one embodiment of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments disclosed herein. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0024] Example 1

[0025] In this embodiment, the preparation of electronic-grade triethyl phosphate is as follows: industrial-grade raw materials (containing 99% TEPO) are fed into a fixed bed of spinel-type alumina packed with catalyst at a mass ratio of approximately 1:300. The fixed-bed reaction temperature is 130°C, the material flow rate is 0.8 L / h, and the reaction is run for 10 h. The preparation of spinel-type alumina is as follows: aluminum tert-butoxide, ethanol, and template agent P123 are mixed at a mass ratio of 1:4:0.1. Nitric acid is slowly added dropwise and stirred for 24 h to form a sol. The nitric acid is added at a rate of 50 drops / min and a volume of 5 mL / L. The molar ratio of nitric acid to aluminum tert-butoxide is 1:0.7. The mixture is then heated at 100°C to form a gel, dried in an oven at 120°C for 12 h, and then heated in a muffle furnace at 700°C for 2 h to obtain spinel-type alumina.

[0026] The material then directly enters the first distillation column, where the vacuum level is controlled at 0.095 MPa-0.1 MPa and the reboiler temperature is controlled at 120℃-140℃. Light components are removed at a certain reflux ratio. The heavy components at the bottom of the column are then transferred to the second distillation column, where the reboiler vacuum level is controlled at 0.093 MPa-0.1 MPa and the reboiler temperature is controlled at 120-140℃. The fraction in the 115℃-120℃ temperature range is then collected. Finally, the top fraction is filtered through a precision filter to remove particulate impurities, yielding electronic-grade TEPO.

[0027]

[0028] Example 2

[0029] The only difference between this embodiment and Example 1 is that the nitric acid is added at a rate of 70 drops / min, the amount added is 5 mL / L, and the molar ratio of nitric acid to aluminum tert-butoxide is 1:0.5.

[0030]

[0031] Example 3

[0032] The only difference between this embodiment and Example 1 is that the nitric acid is added at a rate of 100 drops / min, the amount added is 5 mL / L, and the molar ratio of nitric acid to aluminum tert-butoxide is 1:2.25.

[0033]

[0034] Example 4

[0035] The only difference between this embodiment and Example 1 is that the amount of nitric acid added is 8 mL / L.

[0036]

[0037] Comparative Example 1

[0038] The only difference between this comparative example and Example 1 is that the catalyst was replaced with commercially available γ-alumina.

[0039]

[0040] Comparative Example 2

[0041] The only difference between this comparative example and Example 1 is that the catalyst was replaced with commercially available spinel-type iron oxide.

[0042]

[0043] Comparative Example 3

[0044] The only difference between this comparative example and Example 1 is that the catalyst was replaced with commercially available γ-copper oxide.

[0045]

[0046] Comparing Examples 1-4 with Comparative Examples 1-3, it was found that when using spinel-type alumina, its compact lattice structure resulted in less aluminum ion precipitation during the reaction, effectively reducing the difficulty of subsequent metal ion impurity removal. Furthermore, comparing Examples 1-4 revealed that increasing the amount of nitric acid added led to a higher overall oxidation state of the catalyst after sintering, reducing catalytic activity; while excessively rapid dropping resulted in poor dispersion of aluminum tert-butoxide during sol formation, similarly reducing catalytic performance.

[0047] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing electronic-grade triethyl phosphate, comprising, in sequence: Raw material pretreatment yields industrial-grade raw material with 99 wt.% TEPO; The catalytic reaction is a fixed-bed reaction with a catalyst, the catalyst of which is selected from spinel alumina, γ-alumina, spinel iron oxide, and γ-copper oxide; Multistage distillation, including light distillation and heavy distillation; Precision filtration.

2. The preparation method according to claim 1, characterized in that, The catalyst is spinel-type alumina, which is obtained by mixing aluminum tert-butoxide, ethanol, and a template agent, slowly adding nitric acid and stirring to form a sol, heating to form a gel, and then drying and heating.

3. The preparation method according to claim 2, characterized in that, The template agent is P123.

4. The preparation method according to claim 2, characterized in that, The mass ratio of aluminum tert-butoxide, ethanol, and template agent is 1:4:0.

1.

5. The preparation method according to claim 2, characterized in that, The nitric acid is added at a rate of 50-100 drops / min and at a volume of 5-10 mL / L. The molar ratio of nitric acid to aluminum tert-butoxide is 1:0.5-2.

25.

6. The preparation method according to claim 1, characterized in that, The conditions for light-light distillation are: temperature 120–140℃, vacuum degree 0.095–0.1MPa.

7. The preparation method according to claim 1, characterized in that, The conditions for the de-gravity distillation are: temperature 120–140℃, vacuum degree 0.093–0.1MPa, and collection of the fraction in the temperature range of 115℃–120℃.

8. The preparation method according to claim 1, characterized in that, The precision filter is a microporous filter with a pore size of no more than 0.05 μm.

9. Electronic-grade triethyl phosphate, obtained by the preparation method according to any one of claims 1-8. The product purity is ≥99.999%, and the metal impurities are ≤0.093 ppb.

10. The application of the electronic-grade triethyl phosphate according to claim 9 in semiconductor BPSG doping source and chip manufacturing.

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