An electronic-grade boric acid, its purification method and application

Abstract

The present invention discloses an electronic-grade boric acid and its purification method and application, belonging to the technical field of chemical processes. The purification method of the electronic-grade boric acid of the present invention comprises the following steps: S1, degreasing: passing the crude boric acid solution through an adsorbent for degreasing to obtain a degreased boric acid solution; S2, ion exchange: purifying the degreased boric acid solution through an ion exchanger to obtain an electronic-grade boric acid solution. The purification method of the present invention is simple and efficient. Through the steps of degreasing and ion exchange, impurities in the crude boric acid solution can be effectively removed, and an electronic-grade boric acid solution with a low total metal impurity content and a low total organic carbon content can be obtained. It has stable and good use performance, and has wide applications especially in the field of nano-scale chip integrated circuits.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical processes, and particularly relates to an electronic-grade boric acid and its purification method and application. Background Art

[0002] Boric acid (H3BO3), as an important inorganic compound, is widely used in many fields such as electronics, chemical industry, medicine, and agriculture. In the electronics industry, electronic-grade boric acid is used in key steps such as cleaning, etching, and doping in the semiconductor manufacturing process due to its high purity and specific physical and chemical properties.

[0003] Although the application of boric acid in the electronics industry is becoming increasingly widespread, there are still some limitations in the existing methods for producing electronic-grade boric acid. Traditional methods for producing boric acid usually involve the acidification treatment of boron ore. This process not only has a high cost but also may introduce impurities, making it difficult to meet the high-purity requirements for electronic applications.

[0004] In addition, existing methods also face challenges in purifying and refining boric acid. For example, removing heavy metal ions and other organic or inorganic impurities in boric acid requires complex purification processes, which not only increase the production cost but also make it difficult to achieve good purification effects. Summary of the Invention

[0005] In order to overcome at least one of the above problems existing in the prior art, one of the purposes of the present invention is to provide a purification method for boric acid, which has a simple process, and the obtained boric acid has high purity and low impurity content.

[0006] Another purpose of the present invention is to provide an electronic-grade boric acid solution obtained by the above purification method.

[0007] Another purpose of the present invention is to provide an application of the above electronic-grade boric acid solution in the field of nano-scale chip integrated circuits.

[0008] In order to achieve the above purposes, the technical solutions adopted by the present invention are as follows:

[0009] The first aspect of the present invention provides a purification method for electronic-grade boric acid, comprising the following steps:

[0010] S1, degreasing: Passing the crude boric acid solution through an adsorbent for degreasing to obtain a degreased boric acid solution;

[0011] S2, ion exchange: Passing the degreased boric acid solution through an ion exchanger for purification to obtain an electronic-grade boric acid solution.

[0012] In the purification method of the present invention, through the degreasing step, organic impurities in the crude boric acid solution can be effectively removed, significantly reducing the total organic carbon (TOC) content in the obtained degreased boric acid solution; through the ion exchange step, metal impurities in the solution can be effectively removed, significantly reducing the total content of metal impurities in the obtained electronic-grade boric acid solution. The finally obtained electronic-grade boric acid solution has a low total content of metal impurities and a low total organic carbon content.

[0013] In some specific embodiments of the present invention, in step S1, the B concentration of the crude boric acid solution is 2 - 20 g / L.

[0014] In some specific embodiments of the present invention, in step S1, the crude boric acid solution contains metal impurities and / or organic impurities.

[0015] In some specific embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include at least one element of Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl, or Hg.

[0016] In some specific embodiments of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is ≥ 500 μg / L.

[0017] In some specific embodiments of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is ≥ 8 mg / L.

[0018] In some specific embodiments of the present invention, in step S1, the adsorbent is activated carbon.

[0019] In some specific embodiments of the present invention, the activated carbon is obtained by a impurity removal method including the following steps: primary cleaning: cleaning the activated carbon raw material with dilute sulfuric acid and soaking for 20 - 30 h to obtain primary activated carbon; secondary cleaning: cleaning the primary activated carbon with ultrapure water to obtain secondary activated carbon and a washing solution, and in this step, cleaning until the conductivity of the washing solution ≤ 10 μS; tertiary cleaning: cleaning the secondary activated carbon with a boric acid solution to obtain the impurity-removed activated carbon and a boric acid washing solution, and in this step, cleaning until the difference between the total content of metal impurities in the boric acid washing solution and the total content of metal impurities in the boric acid solution is ≤ 30 μg / L.

[0020] In some specific embodiments of the present invention, in step S2, the flow rate of the degreased boric acid solution through the ion exchanger is 80 - 220 L / h.

[0021] In some specific embodiments of the present invention, in step S2, the ion exchanger is selected from cation exchange resins.

[0022] In some specific embodiments of the present invention, in step S2, the particle size of the ion exchanger is 0.3 to 2 mm.

[0023] In some specific embodiments of the present invention, in step S2, the exchange capacity of the ion exchanger is 10 to 30 mol / L.

[0024] The second aspect of the present invention provides an electronic-grade boric acid solution obtained by the purification method described in the first aspect of the present invention.

[0025] In some specific embodiments of the present invention, the B concentration of the electronic-grade boric acid solution is 2 to 20 g / L.

[0026] In some specific embodiments of the present invention, the total metal impurity content of the electronic-grade boric acid solution is ≤ 100 μg / L.

[0027] In some specific embodiments of the present invention, the total organic carbon content of the electronic-grade boric acid solution is ≤ 5 mg / L.

[0028] In some specific embodiments of the present invention, the pH value of the electronic-grade boric acid solution is 3.5 to 5.

[0029] The third aspect of the present invention provides an application of the electronic-grade boric acid solution described in the second aspect of the present invention in the field of nano-scale chip integrated circuits.

[0030] The beneficial effects of the present invention are as follows: The purification method of the present invention is simple and efficient. Through the steps of degreasing and ion exchange, impurities in the crude boric acid solution can be effectively removed, and an electronic-grade boric acid solution with a low total metal impurity content and a low total organic carbon content can be obtained. It has stable and good performance, and has a wide range of applications especially in the field of nano-scale chip integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic flow chart of the purification method of boric acid in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following details the embodiments of the present invention. The embodiments are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0033] The first aspect of the embodiments of the present invention provides a purification method of boric acid, which specifically includes the following steps:

[0034] S1. Degreasing: Passing the crude boric acid solution through an adsorbent for degreasing to obtain a degreased boric acid solution;

[0035] S2. Ion exchange: The boric acid degreasing solution is purified through an ion exchanger to obtain an electronic-grade boric acid solution.

[0036] In the purification method of the embodiment of the present invention, through the degreasing step, organic impurities in the crude boric acid solution can be effectively removed, and the total organic carbon (TOC) content in the obtained boric acid degreasing solution is greatly reduced; through the ion exchange step, metal impurities in the solution can be effectively removed, and the total content of metal impurities in the obtained electronic-grade boric acid solution is greatly reduced. Finally, the obtained electronic-grade boric acid solution has a low total content of metal impurities and a low total organic carbon content.

[0037] In some embodiments of the present invention, in step S1, the B concentration of the crude boric acid solution is 2-20 g / L; in some specific embodiments of the present invention, in step S1, the B concentration of the crude boric acid solution is 3-15 g / L; in some examples of the present invention, in step S1, the B concentration of the crude boric acid solution is 5-10 g / L; non-limiting specific examples are 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0038] The B concentration of the crude boric acid solution refers to the concentration of B element in the solution. The present invention controls the B concentration of the crude boric acid solution within the range of 2-20 g / L, which is beneficial to controlling the impurity content within a controllable range and effectively removing it through subsequent purification steps to obtain high-purity boric acid.

[0039] In some embodiments of the present invention, in step S1, the crude boric acid solution is obtained by mixing crude boric acid with water.

[0040] In some embodiments of the present invention, in the crude boric acid solution, the mass ratio of crude boric acid to water is 1:(15-35); in some specific embodiments of the present invention, in the crude boric acid solution, the mass ratio of crude boric acid to water is 1:(18-32); in some examples of the present invention, in the crude boric acid solution, the mass ratio of crude boric acid to water is 1:(20-30); non-limiting specific examples are 1:22, 1:24, 1:26 or 1:28.

[0041] The specific mass ratio of crude boric acid to water needs to be determined according to the purity of the crude boric acid. Adjust the mass ratio of crude boric acid to water so that the prepared crude boric acid solution meets the requirements, especially so that the crude boric acid solution has a specific concentration. At the same time, the purity of the crude boric acid also affects the impurity content in the purification system. If the purity of the crude boric acid is high, the introduced impurity content is low and the purification difficulty is small; otherwise, the purification difficulty is large.

[0042] In some embodiments of the present invention, in step S1, the crude boric acid solution contains metal impurities and / or organic impurities; in some specific embodiments of the present invention, in step S1, the crude boric acid solution contains metal impurities and organic impurities.

[0043] The metal impurities of the present invention include all kinds of metal elements that may exist in the crude boric acid product.

[0044] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include at least one element of Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl or Hg.

[0045] In some embodiments of the present invention, in step S1, the metal impurity in the crude boric acid solution includes Ca, and the content of Ca element in the crude boric acid solution ≥ 200 μg / L; in some specific embodiments of the present invention, the content of Ca element in the crude boric acid solution is 200 - 400 μg / L; in some examples of the present invention, the content of Ca element in the crude boric acid solution is 300 - 400 μg / L; non-limiting specific examples are 320 μg / L, 340 μg / L, 360 μg / L, 380 μg / L or 390 μg / L.

[0046] In some embodiments of the present invention, in step S1, the metal impurity in the crude boric acid solution includes Fe, and the content of Fe element in the crude boric acid solution ≥ 20 μg / L; in some specific embodiments of the present invention, the content of Fe element in the crude boric acid solution is 20 - 50 μg / L; in some examples of the present invention, the content of Fe element in the crude boric acid solution is 30 - 50 μg / L; non-limiting specific examples are 32 μg / L, 35 μg / L, 38 μg / L, 40 μg / L, 42 μg / L or 45 μg / L.

[0047] In some embodiments of the present invention, in step S1, the metal impurity in the crude boric acid solution includes Mg, and the content of Mg element in the crude boric acid solution ≥ 40 μg / L; in some specific embodiments of the present invention, the content of Mg element in the crude boric acid solution is 40 - 200 μg / L; in some examples of the present invention, the content of Mg element in the crude boric acid solution is 50 - 100 μg / L; non-limiting specific examples are 60 μg / L, 70 μg / L, 80 μg / L or 90 μg / L.

[0048] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Mn, and the content of Mn element in the crude boric acid solution is ≥ 20 μg / L; in some specific embodiments of the present invention, the content of Mn element in the crude boric acid solution is 20 - 150 μg / L; in some examples of the present invention, the content of Mn element in the crude boric acid solution is 30 - 100 μg / L; non-limiting specific examples are 40 μg / L, 50 μg / L, 60 μg / L, 70 μg / L, 80 μg / L or 90 μg / L.

[0049] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Na, and the content of Na element in the crude boric acid solution is ≥ 20 μg / L; in some specific embodiments of the present invention, the content of Na element in the crude boric acid solution is 20 - 50 μg / L; in some examples of the present invention, the content of Na element in the crude boric acid solution is 30 - 50 μg / L; non-limiting specific examples are 32 μg / L, 35 μg / L, 38 μg / L, 40 μg / L, 42 μg / L or 45 μg / L.

[0050] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Zn, and the content of Zn element in the crude boric acid solution is ≥ 10 μg / L; in some specific embodiments of the present invention, the content of Zn element in the crude boric acid solution is 10 - 50 μg / L; in some examples of the present invention, the content of Zn element in the crude boric acid solution is 15 - 40 μg / L; non-limiting specific examples are 20 μg / L, 25 μg / L, 30 μg / L or 35 μg / L.

[0051] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include Al, and the content of Al element in the crude boric acid solution is ≥ 30 μg / L; in some specific embodiments of the present invention, the content of Al element in the crude boric acid solution is 30 - 55 μg / L; in some examples of the present invention, the content of Al element in the crude boric acid solution is 35 - 55 μg / L; non-limiting specific examples are 40 μg / L, 45 μg / L, 50 μg / L or 53 μg / L.

[0052] In some embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include K, and the content of K element in the crude boric acid solution is ≥ 15 μg / L; in some specific embodiments of the present invention, the content of K element in the crude boric acid solution is 15 - 50 μg / L; in some examples of the present invention, the content of K element in the crude boric acid solution is 20 - 40 μg / L; non-limiting specific examples are 22 μg / L, 25 μg / L, 28 μg / L, 30 μg / L, 35 μg / L or 38 μg / L.

[0053] In some specific embodiments of the present invention, in step S1, the metal impurities in the crude boric acid solution include elements such as Ca, Fe, Mg, Mn, Na, Zn, Al, K, and at least one element among Cd, Cr, Mo, Ni, As, Cu, Pb, Au, Ti, In, Sn, Tl, or Hg; in some examples of the present invention, in step S1, the metal impurities in the crude boric acid solution include elements such as Ca, Cr, Fe, Mg, Mn, Na, Ni, Zn, Al, As, Cu, K, and Ti.

[0054] In some embodiments of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution ≥ 500 μg / L; in some specific embodiments of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is 500 - 1800 μg / L; in some examples of the present invention, in step S1, the total content of metal impurities in the crude boric acid solution is 550 - 1500 μg / L; non-limiting specific examples are 600 μg / L, 700 μg / L, 800 μg / L, 900 μg / L, 1000 μg / L, 1200 μg / L, or 1400 μg / L.

[0055] In some embodiments of the present invention, in step S1, the crude boric acid solution contains organic impurities. The total content of organic impurities is expressed as the total organic carbon (TOC) content.

[0056] In some embodiments of the present invention, in step S1, the total organic carbon content in the crude boric acid solution ≥ 8 mg / L; in some specific embodiments of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is 8 - 15 mg / L; in some examples of the present invention, in step S1, the total organic carbon content in the crude boric acid solution is 9 - 14 mg / L; non-limiting specific examples are 10 mg / L, 11 mg / L, 12 mg / L, or 13 mg / L.

[0057] In some embodiments of the present invention, in step S1, the crude boric acid solution includes the following components in the following contents:

[0058] B 2 - 20 g / L Total Organic Carbon (TOC) ≥ 8 mg / L Metal Impurities ≥ 500 μg / L

[0059] In some specific embodiments of the present invention, in step S1, the crude boric acid solution includes the following components in the following contents:

[0060]

[0061]

[0062] In some examples of the present invention, in step S1, the crude boric acid solution includes the following components in the following contents:

[0063] B 2 - 20 g / L Total Organic Carbon (TOC) 9 - 14 mg / L Metal Impurities 550 - 1500 μg / L

[0064] In some specific examples of the present invention, in step S1, the crude boric acid solution includes the following components:

[0065] B 2 - 20 g / L Total Organic Carbon (TOC) 9 - 14 mg / L Ca 200 - 400 μg / L Cd 0.001 - 100 μg / L Cr 0.1 - 100 μg / L Fe 20 - 50 μg / L Mg 40 - 200 μg / L Mn 20 - 150 μg / L Mo 0.001 - 50 μg / L Na 20 - 50 μg / L Ni 1 - 50 μg / L Zn 10 - 50 μg / L Al 30 - 55 μg / L As 1 - 50 μg / L Cu 0.01 - 50 μg / L Pb 0.001 - 50 μg / L K 15 - 50 μg / L Au 0.001 - 50 μg / L Ti 0.1 - 50 μg / L In 0.001 - 50 μg / L Sn 0.001 - 50 μg / L Tl 0.001 - 50 μg / L Hg 0.001 - 50 μg / L

[0066] In some embodiments of the present invention, in step S1, the adsorbent is activated carbon.

[0067] In some embodiments of the present invention, in step S1, activated carbon is obtained by an impurity removal method comprising the following steps: primary cleaning: using dilute sulfuric acid to clean the activated carbon raw material and soaking it for 20 to 30 hours to obtain primary activated carbon; secondary cleaning: using ultrapure water to clean the primary activated carbon to obtain secondary activated carbon and a water washing liquid, and this step is performed until the conductivity of the water washing liquid is ≤10μS; tertiary cleaning: using a boric acid solution to clean the secondary activated carbon to obtain activated carbon and a boric acid washing liquid after impurities are removed, and this step is performed until the difference between the total content of metal impurities in the boric acid washing liquid and the total content of metal impurities in the boric acid solution is ≤30μg / L.

[0068] Since conventional activated carbon raw materials contain a large amount of impurities, especially a large amount of metal impurities, if the activated carbon raw materials are directly used for oil removal, more impurities will be introduced. The activated carbon obtained by the above impurity removal method has a low content of metal impurities. When deoiling the crude boric acid solution, it can not only achieve a good oil removal effect and significantly reduce the total organic carbon content, but also ensure that no new metal impurities are introduced into the purification system, which increases the difficulty of subsequent purification.

[0069] In the above impurity removal method, firstly, dilute sulfuric acid is used for thorough washing to soak out some acid-soluble metal impurities, then ultrapure water is used for washing to further remove impurities and wash away residual acid to avoid affecting subsequent steps, and finally, boric acid solution is used for washing. Since boric acid is relatively high in the activated carbon adsorption order, it can replace a large amount of metal impurities contained in the activated carbon raw material, so that the metal impurities are desorbed from the activated carbon, thereby achieving the effect of further purification of the activated carbon. The difference between the total content of metal impurities in the boric acid washing solution and the total content of metal impurities in the boric acid solution is ≤30μg / L, indicating that the impurities can basically no longer be desorbed from the activated carbon. The crude boric acid solution is deoiled using the activated carbon after impurities removal, and no new metal impurities are introduced into the purification system.

[0070] In some embodiments of the present invention, in the method for removing impurities from activated carbon, the concentration of dilute sulfuric acid is 0.1-1 mol / L; in some embodiments of the present invention, in the method for removing impurities from activated carbon, the concentration of dilute sulfuric acid is 0.3-0.7 mol / L.

[0071] In some embodiments of the present invention, in the method for removing impurities from activated carbon, the boric acid solution used may be the same as the crude boric acid solution in step S1, or a boric acid solution prepared with higher purity boric acid. As long as the solution contains boric acid, there is no specific requirement for its purity.

[0072] In the present invention, an oil removal step is first adopted to remove organic impurities in the crude boric acid solution, which can avoid the influence of organic impurities on the ion exchange step, enable the ion exchanger to fully perform ion exchange with metal impurities in the crude boric acid solution, and thus facilitate the removal of metal impurities in subsequent steps. After the oil removal step of step S1, a boric acid oil removal solution with a low total organic carbon content can be obtained.

[0073] In some embodiments of the present invention, in step S1, the pH value of the crude boric acid solution during oil removal is 3.5 - 4.5; in some specific embodiments of the present invention, in step S1, the pH value of the crude boric acid solution during oil removal is 3.6 - 4.3; in some examples of the present invention, in step S1, the pH value of the crude boric acid solution during oil removal is 3.7 - 4.2; non-limiting specific examples are 3.8, 3.9, 4, or 4.1.

[0074] In some embodiments of the present invention, in step S1, the residence time of the crude boric acid solution in the activated carbon column during oil removal is 0.5 - 2 h; in some specific embodiments of the present invention, in step S1, the residence time of the crude boric acid solution in the activated carbon column during oil removal is 0.6 - 1.8 h; in some examples of the present invention, in step S1, the residence time of the crude boric acid solution in the activated carbon column during oil removal is 0.7 - 1.5 h; non-limiting specific examples are 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, or 1.4 h.

[0075] In some embodiments of the present invention, in step S1, the flow rate of the crude boric acid solution through the activated carbon column during oil removal is 10 - 100 L / h; in some specific embodiments of the present invention, in step S1, the flow rate of the crude boric acid solution through the activated carbon column during oil removal is 20 - 80 L / h; in some examples of the present invention, in step S1, the flow rate of the crude boric acid solution through the activated carbon column during oil removal is 30 - 70 L / h; non-limiting specific examples are 35 L / h, 40 L / h, 45 L / h, 50 L / h, 55 L / h, 60 L / h, or 65 L / h.

[0076] By controlling parameters such as the residence time and flow rate of the crude boric acid solution in the activated carbon column during oil removal, a good TOC removal effect is ensured, which is also beneficial to achieving a good metal impurity removal effect in subsequent steps.

[0077] In some embodiments of the present invention, in step S1, the B concentration of the boric acid degreasing solution is 2-20 g / L; in some specific embodiments of the present invention, in step S1, the B concentration of the boric acid degreasing solution is 3-15 g / L; in some examples of the present invention, in step S1, the B concentration of the boric acid degreasing solution is 5-10 g / L; non-limiting specific examples are 6 g / L, 7 g / L, 8 g / L, or 9 g / L.

[0078] In some embodiments of the present invention, in step S1, the total organic carbon content in the boric acid degreasing solution is ≤ 5 mg / L; in some specific embodiments of the present invention, in step S1, the total organic carbon content in the boric acid degreasing solution is 1-5 mg / L; in some examples of the present invention, in step S1, the total organic carbon content in the boric acid degreasing solution is 1-2 mg / L; non-limiting specific examples are 1.1, 1.2, 1.3 mg / L, 1.4 mg / L, 1.5 mg / L, 1.6 mg / L, 1.7 mg / L, 1.8 mg / L, or 1.9 mg / L.

[0079] In some embodiments of the present invention, in step S1, the total content of metal impurities in the boric acid degreasing solution is ≥ 500 μg / L; in some specific embodiments of the present invention, in step S1, the total content of metal impurities in the boric acid degreasing solution is 500-1800 μg / L; in some examples of the present invention, in step S1, the total content of metal impurities in the boric acid degreasing solution is 550-1500 μg / L; non-limiting specific examples are 600 μg / L, 700 μg / L, 800 μg / L, 900 μg / L, 1000 μg / L, 1200 μg / L, or 1400 μg / L.

[0080] In some embodiments of the present invention, in step S1, the boric acid degreasing solution includes the following components in the following contents:

[0081] B 2 - 20 g / L Total Organic Carbon (TOC) ≤ 5 mg / L Metal Impurities ≥ 500 μg / L

[0082] In some specific embodiments of the present invention, in step S1, the boric acid degreasing solution includes the following components in the following contents:

[0083] B 2 - 20 g / L Total Organic Carbon (TOC) 1 - 5 mg / L Metal Impurities 500 - 1800 μg / L

[0084] In some examples of the present invention, in step S1, the boric acid degreasing solution includes the following components in the following contents:

[0085]

[0086]

[0087] In some specific examples of the present invention, in step S1, the boric acid degreasing solution includes the following components in the following contents:

[0088] B 2 - 20 g / L Total Organic Carbon (TOC) 1 - 2 mg / L Ca 200 - 400 μg / L Cd 0.001 - 100 μg / L Cr 0.1 - 100 μg / L Fe 20 - 50 μg / L Mg 40 - 200 μg / L Mn 20 - 150 μg / L Mo 0.001 - 50 μg / L Na 20 - 50 μg / L Ni 1 - 50 μg / L Zn 10 - 50 μg / L Al 30 - 55 μg / L As 1 - 50 μg / L Cu 0.01 - 50 μg / L Pb 0.001 - 50 μg / L K 15 - 50 μg / L Au 0.001 - 50 μg / L Ti 0.1 - 50 μg / L In 0.001 - 50 μg / L Sn 0.001 - 50 μg / L Tl 0.001 - 50 μg / L Hg 0.001 - 50 μg / L

[0089] In some embodiments of the present invention, in step S2, the flow rate of the boric acid degreasing solution through the ion exchanger is 80 - 220 L / h; in some embodiments of the present invention, in step S2, the flow rate of the boric acid degreasing solution through the ion exchanger is 90 - 210 L / h; in some embodiments of the present invention, in step S2, the flow rate of the boric acid degreasing solution through the ion exchanger is 100 - 190 L / h; non-limiting specific examples are 120 L / h, 140 L / h, 160 L / h, or 180 L / h.

[0090] By controlling the flow rate of the boric acid degreasing solution through the ion exchanger, it is ensured that sufficient ion exchange reaction occurs between the ion exchanger and metal impurities, and the metal impurities are adsorbed onto the ion exchanger to be removed from the solution, achieving a good boric acid purification effect.

[0091] In some embodiments of the present invention, the ion exchanger is selected from cation exchange resins; in some specific embodiments of the present invention, the cation exchange resin is selected from D001, LSC850, D860, D851, D401, D412, or 732.

[0092] Compared with anion exchange resins, using cation exchange resins in the present invention can achieve a better impurity removal effect and is more conducive to removing metal impurities in the system.

[0093] In some embodiments of the present invention, the particle size of the ion exchanger is 0.3 - 2 mm; in some specific embodiments of the present invention, the particle size of the ion exchanger is 0.5 - 1.8 mm; in some examples of the present invention, the particle size of the ion exchanger is 0.6 - 1.5 mm; non-limiting specific examples are 0.710 - 1.250 mm, 0.7 mm, 0.8 mm, 1 mm, or 1.2 mm.

[0094] In some embodiments of the present invention, the exchange capacity of the ion exchanger is 10 - 30 mol / L; in some specific embodiments of the present invention, the exchange capacity of the ion exchanger is 12 - 28 mol / L; in some examples of the present invention, the exchange capacity of the ion exchanger is 15 - 25 mol / L; non-limiting specific examples are 18 mol / L, 2 mol / L, or 22 mol / L.

[0095] Ion exchangers with specific particle sizes and exchange capacities are beneficial for better adsorbing metal impurities in the system and achieving a better purification and impurity removal effect.

[0096] Through the ion exchange step of step S2, metal impurities in the solution can be effectively removed, and an electronic-grade boric acid solution with a low total metal impurity content can be obtained.

[0097] The second aspect of the embodiments of the present invention provides an electronic-grade boric acid solution obtained by the purification method of the first aspect of the embodiments of the present invention.

[0098] Through the degreasing and ion exchange steps in the purification method of the present invention, the obtained electronic-grade boric acid solution has the characteristics of low total metal impurity content and low total organic carbon content, and has good application performance.

[0099] In some embodiments of the present invention, the B concentration of the electronic-grade boric acid solution is 2-20 g / L; in some specific embodiments of the present invention, the B concentration of the electronic-grade boric acid solution is 3-15 g / L; in some examples of the present invention, the B concentration of the electronic-grade boric acid solution is 5-10 g / L; non-limiting specific examples are 6 g / L, 7 g / L, 8 g / L or 9 g / L.

[0100] In some embodiments of the present invention, the total metal impurity content of the electronic-grade boric acid solution ≤ 100 μg / L; in some specific embodiments of the present invention, the total metal impurity content of the electronic-grade boric acid solution is 20-100 μg / L; in some examples of the present invention, the total metal impurity content of the electronic-grade boric acid solution is 30-80 μg / L; non-limiting specific examples are 40 μg / L, 50 μg / L, 60 μg / L or 70 μg / L.

[0101] The purification method of the present invention can effectively remove metal impurities in the solution, especially can remove a large amount of Ca element and relatively more Fe, Mg, Mn, Na, Zn, Al, K elements contained in the original crude boric acid solution, and obtain an electronic-grade boric acid solution with relatively low contents of Ca, Fe, Mg, Mn, Na, Zn, Al, K elements.

[0102] In some embodiments of the present invention, the Ca element content in the electronic-grade boric acid solution ≤ 10 μg / L; in some specific embodiments of the present invention, the Ca element content in the electronic-grade boric acid solution is 1-10 μg / L; in some examples of the present invention, the Ca element content in the electronic-grade boric acid solution is 1.5-7 μg / L; non-limiting specific examples are 2 μg / L, 3 μg / L, 4 μg / L, 5 μg / L or 6 μg / L.

[0103] In some embodiments of the present invention, the Fe element content in the electronic-grade boric acid solution ≤ 10 μg / L; in some specific embodiments of the present invention, the Fe element content in the electronic-grade boric acid solution is 0.001-10 μg / L; in some examples of the present invention, the Fe element content in the electronic-grade boric acid solution is 0.001-1 μg / L; non-limiting specific examples are 0.005 μg / L, 0.01 μg / L, 0.05 μg / L, 0.1 μg / L or 0.5 μg / L.

[0104] In some embodiments of the present invention, the content of Mg element in the electronic-grade boric acid solution is ≤ 10 μg / L; in some specific embodiments of the present invention, the content of Mg element in the electronic-grade boric acid solution is 1 - 10 μg / L; in some examples of the present invention, the content of Mg element in the electronic-grade boric acid solution is 4 - 9 μg / L; non-limiting specific examples are 5 μg / L, 6 μg / L, 7 μg / L, or 8 μg / L.

[0105] In some embodiments of the present invention, the content of Mn element in the electronic-grade boric acid solution is ≤ 10 μg / L; in some specific embodiments of the present invention, the content of Mn element in the electronic-grade boric acid solution is 0.1 - 10 μg / L; in some examples of the present invention, the content of Mn element in the electronic-grade boric acid solution is 0.2 - 3 μg / L; non-limiting specific examples are 0.3 μg / L, 0.5 μg / L, 1 μg / L, 1.5 μg / L or 2 μg / L.

[0106] In some embodiments of the present invention, the content of Na element in the electronic-grade boric acid solution is ≤ 45 μg / L; in some specific embodiments of the present invention, the content of Na element in the electronic-grade boric acid solution is 20 - 45 μg / L; in some examples of the present invention, the content of Na element in the electronic-grade boric acid solution is 25 - 40 μg / L; non-limiting specific examples are 28 μg / L, 30 μg / L, 32 μg / L, 35 μg / L or 38 μg / L.

[0107] In some embodiments of the present invention, the content of Zn element in the electronic-grade boric acid solution is ≤ 10 μg / L; in some specific embodiments of the present invention, the content of Zn element in the electronic-grade boric acid solution is 0.001 - 10 μg / L; in some examples of the present invention, the content of Zn element in the electronic-grade boric acid solution is 0.001 - 1 μg / L; non-limiting specific examples are 0.005 μg / L, 0.01 μg / L, 0.05 μg / L, 0.1 μg / L or 0.5 μg / L.

[0108] In some embodiments of the present invention, the content of Al element in the electronic-grade boric acid solution is ≤ 10 μg / L; in some specific embodiments of the present invention, the content of Al element in the electronic-grade boric acid solution is 0.001 - 10 μg / L; in some examples of the present invention, the content of Al element in the electronic-grade boric acid solution is 0.001 - 1 μg / L; non-limiting specific examples are 0.005 μg / L, 0.01 μg / L, 0.05 μg / L, 0.1 μg / L or 0.5 μg / L.

[0109] In some embodiments of the present invention, the content of K element in the electronic grade boric acid solution is ≤ 10 μg / L; in some specific embodiments of the present invention, the content of K element in the electronic grade boric acid solution is 3 - 10 μg / L; in some examples of the present invention, the content of K element in the electronic grade boric acid solution is 5 - 8 μg / L; non-limiting specific examples are 5.5 μg / L, 6 μg / L, 6.5 μg / L, 7 μg / L or 7.5 μg / L.

[0110] In some embodiments of the present invention, the total organic carbon content of the electronic grade boric acid solution is ≤ 5 mg / L; in some specific embodiments of the present invention, the total organic carbon content of the electronic grade boric acid solution is 0.5 - 5 mg / L; in some examples of the present invention, the total organic carbon content of the electronic grade boric acid solution is 1 - 2 mg / L; non-limiting specific examples are 1.1, 1.2, 1.3 mg / L, 1.4 mg / L, 1.5 mg / L, 1.6 mg / L, 1.7 mg / L, 1.8 mg / L or 1.9 mg / L.

[0111] In some embodiments of the present invention, the electronic grade boric acid solution comprises components with the following contents:

[0112] B 2 - 20 g / L Total Organic Carbon (TOC) ≤ 5 mg / L Metal Impurities ≤ 100 μg / L

[0113] In some specific embodiments of the present invention, the electronic grade boric acid solution comprises components with the following contents:

[0114] B 2 - 20 g / L Total Organic Carbon (TOC) 0.5 - 5 mg / L Metal Impurities 20 - 100 μg / L

[0115] In some examples of the present invention, the electronic grade boric acid solution comprises components with the following contents:

[0116] B 2 - 20 g / L Total Organic Carbon (TOC) 1 - 2 mg / L Metal Impurities 30 - 80 μg / L

[0117] In some specific examples of the present invention, the electronic grade boric acid solution comprises components with the following contents:

[0118]

[0119]

[0120] In some embodiments of the present invention, the pH value of the electronic grade boric acid solution is 3.5 - 5; in some specific embodiments of the present invention, the pH value of the electronic grade boric acid solution is 3.8 - 4.5; in some embodiments of the present invention, the pH value of the electronic grade boric acid solution is 4 - 4.2; non-limiting specific examples are 4.05, 4.1 or 4.15.

[0121] The fourth aspect of the embodiments of the present invention provides an application of the electronic grade boric acid solution in the second aspect of the embodiments of the present invention in the field of nano-scale chip integrated circuits.

[0122] The electronic-grade boric acid solution obtained by using the purification method of the present invention has a low total content of metal impurities and a low total organic carbon content, and thus has stable and good performance in use, especially in the field of nano-scale chip integrated circuits, it has a wide range of applications.

[0123] The content of the present invention will be further described in detail through specific embodiments below. It should also be understood that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles described in the present invention all fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description in this article, rather than being limited to the specific data in the following examples. The raw materials, reagents or devices used in the following examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing known methods without special instructions.

[0124] In the following examples, ND means that when the content of a certain substance is lower than the lowest detection limit of the detection equipment, the substance will be marked as "ND" in the detection report, indicating that the content of the substance ≤ 0.01 μg / L.

[0125] In the following examples, metal impurities include Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl and Hg elements, and the total content of metal impurities (total metal impurities) refers to the sum of the contents of the above metal impurities.

[0126] In the following examples, the water used in each step is ultrapure water, and the conductivity of the ultrapure water < 1 μS and the total content of metal impurities < 10 μg / L.

[0127] Example 1

[0128] A purification method of electronic-grade boric acid, the process schematic diagram is as Figure 1 shown, including the following steps:

[0129] S1. Preparation of crude product solution: Prepare a boric acid crude product solution with a B concentration of 7 g / L according to the mass ratio of boric acid crude product to ultrapure water of 1:24.29.

[0130] S2. Oil removal: Adsorb and remove oil from the boric acid crude product solution through an activated carbon column to obtain a boric acid oil-removed solution; in this step, the pH value of the boric acid crude product solution is 3.9, the residence time of the boric acid crude product solution in the activated carbon column is 1 h, the flow rate of the boric acid crude product solution through the activated carbon column is 50 L / h, and the column passing method is from bottom to top.

[0131] In this step, before degreasing, the activated carbon column is prepared by the following steps: cleaning the activated carbon raw material with dilute sulfuric acid (0.5 mol / L) - ultrapure water - boric acid solution in three levels. Specifically, soak it in dilute sulfuric acid (0.5 mol / L) for 20 - 30 h; wash with ultrapure water until the conductivity of the washing liquid ≤ 10 μS; wash with boric acid solution until the difference between the total content of metal impurities in the boric acid washing liquid and the total content of metal impurities in the boric acid solution ≤ 30 μg / L, obtaining the purified activated carbon, and filling it into the column body to obtain the activated carbon column for degreasing.

[0132] S3. Ion exchange: At room temperature (25 ± 5 °C), purify the boric acid degreasing solution through a cation exchange resin column to obtain an electronic-grade boric acid solution; in this step, the model of the cation exchange resin is D001, the resin particle size is 0.710 - 1.250 mm, and the exchange capacity is 20 mol / L; the column body volume of the cation exchange resin column is 200 L, the effective volume is 175 L, the passing speed of the boric acid degreasing solution through the cation exchange resin column is 175 L / h, and the passing method is from top to bottom.

[0133] S4. Packaging: Fill the electronic-grade boric acid solution into the product packaging barrel.

[0134] Measure the components and their contents in the solution systems of each step in Example 1, and the results are shown in Table 1:

[0135] Table 1 Components and Their Contents in the Solution Systems of Each Step in Example 1

[0136]

[0137]

[0138] As can be seen from Table 1, in the purification method of Example 1 of the present invention, the crude boric acid solution contains a large amount of metal impurities and organic impurities. The total content of metal impurities reaches 657.71 μg / L, among which the Ca content is above 300 μg / L, the contents of Mg and Al are both above 50 μg / L, and the TOC content reaches 10.57 mg / L; through the degreasing step, the organic impurities in the solution can be effectively removed, and the TOC content in the obtained boric acid degreasing solution is greatly reduced; through the ion exchange step, the metal impurities in the solution can be effectively removed, and the total content of metal impurities in the obtained boric acid purification solution is greatly reduced. The pH value of the electronic-grade boric acid solution in this example is 4.1.

[0139] In addition, the ion exchange in this example is carried out at room temperature (25 ± 5 °C). If the temperature is too high, the exchange groups in the resin may be damaged, thus reducing the exchange capacity of the resin; if the temperature is too low, the activity of the exchange groups of the resin decreases, resulting in a slow exchange process and reducing the purification effect.

[0140] Example 2

[0141] A purification method of electronic-grade boric acid, which is different from Example 1. In step S3 of this example, the ion exchange resin is replaced with an anion exchange resin, with the model D301 and the particle size of 0.315 - 1.25 mm. Other steps are the same as those in Example 1.

[0142] Detect the total content of metal impurities in the electronic-grade boric acid solution obtained by ion exchange in different ion exchange resins to characterize the influence of the ion exchange resin on the impurity removal effect of the ion exchange step. The results are shown in Table 2.

[0143] Table 2 Influence of ion exchange resin on the impurity removal effect of the ion exchange step

[0144] Resin Type D301 Anion Exchange Resin D001 Cation Exchange Resin Resin Particle Size (mm) 0.315～1.25 0.710-1.250 Total Metal Impurities in Boric Acid Degreasing Solution (μg / L) 640.61 640.61 Total Metal Impurities in Electronic Grade Boric Acid Solution (μg / L) 437.91 49.28 Total Metal Impurities Removal Rate (%) 31.62 92.30

[0145] As can be seen from Table 2, the type of ion exchange resin has a great influence on the impurity removal effect. Compared with the anion exchange resin, the cation exchange resin has a better effect on removing metal impurities from the boric acid degreasing solution.

[0146] Example 3

[0147] A purification method of electronic-grade boric acid, which is different from Example 1. In step S3 of this example, the speed of the boric acid degreasing solution passing through the cation exchange resin column (column passing speed) is changed. The specific column passing speeds are shown in Table 3. Other steps are the same as those in Example 1.

[0148] Detect the total content of metal impurities in the electronic-grade boric acid solution obtained at different column passing speeds to characterize the influence of the column passing speed on the impurity removal effect of the ion exchange step. The results are shown in Table 3.

[0149] Table 3 Influence of column passing speed on the impurity removal effect of the ion exchange step

[0150] Column Passing Rate (L / h) 100 125 150 175 190 Total Metal Impurities in Boric Acid Degreasing Solution (μg / L) 640.61 640.61 640.61 640.61 640.61 Total Metal Impurities in Electronic Grade Boric Acid Solution (μg / L) 46.28 47.30 48.52 49.28 68.79 Total Metal Impurities Removal Rate (%) 92.77 92.61 92.42 92.30 89.26

[0151] As can be seen from Table 3, the column passing speed affects the impurity removal effect of the ion exchange step. The column passing speed within the scope of the embodiments of the present invention (such as 100 - 190 L / h) has a good impurity removal effect. If the column passing speed is too fast, the impurity removal effect is poor. By adopting an appropriate column passing speed, an electronic-grade boric acid solution with a low total content of metal impurities can be obtained.

[0152] In summary, the purification method of the present invention is simple and efficient. Through the steps of degreasing and ion exchange, the impurities in the crude boric acid solution can be effectively removed, and an electronic-grade boric acid solution with a low total content of metal impurities and a low total organic carbon content can be obtained. It has stable and good use performance, and has a wide application especially in the field of nano-scale chip integrated circuits.

Claims

1. A purification method for electronic-grade boric acid, characterized in that, It includes the following steps: S1. Degreasing: Pass the crude boric acid solution through an adsorbent for degreasing to obtain a degreased boric acid solution; S2. Ion exchange: Purify the degreased boric acid solution through an ion exchanger to obtain an electronic-grade boric acid solution; In step S1, the B concentration of the crude boric acid solution is 5-8 g / L; the crude boric acid solution contains metal impurities and organic impurities; the total content of metal impurities in the crude boric acid solution is 500-1800 μg / L; the total organic carbon content in the crude boric acid solution is 8-15 mg / L; the adsorbent is activated carbon; the pH value of the crude boric acid solution during degreasing is 3.5-4.5; the residence time of the crude boric acid solution in the activated carbon during degreasing is 0.5-2 h; the flow rate of the crude boric acid solution through the activated carbon during degreasing is 10-100 L / h; In step S2, the flow rate of the degreased boric acid solution through the ion exchanger is 80-220 L / h; the ion exchanger is selected from cation exchange resins; the particle size of the ion exchanger is 0.3-2 mm; the exchange capacity of the ion exchanger is 10-30 mol / L; In step S1, the activated carbon is obtained by an impurity removal method including the following steps: Primary cleaning: Wash the activated carbon raw material with dilute sulfuric acid and soak for 20-30 h to obtain primary activated carbon; Secondary cleaning: Wash the primary activated carbon with ultrapure water to obtain secondary activated carbon and a washing solution. In this step, the washing is carried out until the conductivity of the washing solution ≤ 10 μS; Tertiary cleaning: Wash the secondary activated carbon with a boric acid solution to obtain the impurity-removed activated carbon and a boric acid washing solution. In this step, the washing is carried out until the difference between the total content of metal impurities in the boric acid washing solution and the total content of metal impurities in the boric acid solution ≤ 30 μg / L.

2. The purification method of electronic grade boric acid according to claim 1, characterized in that, In step S1, the metal impurities in the crude boric acid solution include at least one element of Ca, Cd, Cr, Fe, Mg, Mn, Mo, Na, Ni, Zn, Al, As, Cu, Pb, K, Au, Ti, In, Sn, Tl or Hg.

3. The purification method of electronic grade boric acid according to claim 1, characterized in that The B concentration of the electronic-grade boric acid solution is 2-20 g / L; and / or, the total content of metal impurities in the electronic-grade boric acid solution ≤ 100 μg / L; and / or, the total organic carbon content in the electronic-grade boric acid solution ≤ 5 mg / L; and / or, the pH value of the electronic-grade boric acid solution is 3.5-5.

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