Preparation method of electronic-grade hydroxylamine solution

Abstract

The invention provides a method for preparing and purifying an electronic-grade hydroxylamine solution, which is suitable for meeting the requirements of the fields of electronic chemicals, medicines and the like on an ultra-clean high-purity hydroxylamine solution. The method comprises the following steps: S1, carrying out multi-stage feeding synthesis and concentration reaction on hydroxylamine salt; s2, adding a chelating agent and pre-filtering; s3, the chelate resin and the mixed bed resin are connected in series for adsorption; and S4, terminal ultrafiltration. Compared with a traditional process, the method does not need to distill hydroxylamine for concentration, so that the risk of rapid and violent decomposition of hydroxylamine is avoided. The chelating agent can settle a large amount of metal impurities with low energy consumption, and can be used as a hydroxylamine stabilizer. The concentration of the electronic-grade hydroxylamine obtained by preparation and purification of hydroxylamine salt is 35-45%, and the metal ion content is 1t; the number of particles with the particle size of 5 ppb and 0.2 mu m is smaller than or equal to 50 pcs / mL.

Description

Technical Field

[0001] This invention relates to a method for synthesizing and purifying electronic-grade chemicals, and more particularly to a method for preparing and purifying electronic-grade hydroxylamine solution. Background Technology

[0002] Hydroxylamine (NH₂OH) aqueous solution is an important chemical intermediate widely used in semiconductor cleaning agents, drug synthesis, and the preparation of photosensitive materials. However, hydroxylamine solutions typically contain Fe. 3+ Cu 2+ Impurities such as these metal ions can form deep-level traps in silicon, becoming carrier recombination centers. This leads to increased reverse leakage current in the PN junction, decreased breakdown voltage, and increased risk of premature component failure. Furthermore, polyvalent metal ions catalyze the decomposition of hydroxylamine and its salt solutions, causing their concentration to decrease too rapidly. Organic impurities introduced during hydroxylamine salt synthesis adsorb onto the silicon wafer surface, hindering the uniform deposition of subsequent thin films (such as high-k dielectrics and metal gates), resulting in film voids or abnormal stress. As the linewidth of integrated circuits continues to decrease, particulate impurities can cause patterning defects and embed themselves in metal interconnect layers or dielectric layers, causing short circuits or open circuits between adjacent conductors, reducing product yield.

[0003] Publication patents CN 1233551C / CN 1271331A disclose a method for preparing a high-concentration hydroxylamine solution from hydroxylamine salts. This method uses a plate column or stripping column to achieve concentration through distillation. Related document US1998 / 010445 discloses a method for purifying hydroxylamine, which involves passing the hydroxylamine stock solution to be purified through a bed of ion exchange resins with strong acid and strong base properties.

[0004] Traditional purification methods, such as simple distillation or ion exchange, suffer from high risks, low efficiency, high energy consumption, and difficulty in meeting metal residue standards. Therefore, there is an urgent need to develop a low-cost, high-purity, low-risk method for the preparation and purification of hydroxylamine solutions suitable for industrial scale-up. Summary of the Invention

[0005] This invention provides a low-cost, high-purity, low-risk method for the preparation and purification of hydroxylamine solution suitable for industrial scale-up. Through multi-stage feeding synthesis and concentration reaction, followed by pre-filtration, two-stage adsorption and precision filtration, the content of metal ions, organic impurities and particle size is significantly reduced, finally obtaining an electronic grade hydroxylamine solution with a concentration of 35-45%, metal ion content <5 ppb, and particle number ≤50 pcs / mL.

[0006] To address the above problems, the present invention provides a technical solution: A method for preparing and purifying an electronic-grade hydroxylamine solution includes the following steps: Step 1: Synthesis and Concentration of Hydroxylamine. Under low temperature and stirring, ammonia gas is bubbled into the hydroxylamine salt solution to carry out the reaction until the concentration of the product hydroxylamine solution is >45%. Step 2: Addition of chelating agent and pre-filtration. Add 0.01-0.1% (by mass) of hydroxylamine salt as a chelating agent to the generated hydroxylamine solution, stir, cool, allow to settle, and then filter using a ceramic membrane; Step 3: Adsorption of chelating resin and mixed-bed resin in series. Two stages of chromatography columns are connected in series, with the first stage packed with chelating resin and the second stage packed with mixed-bed resin; Step 4: Terminal ultrafiltration. Use an ultrafiltration membrane to remove residual nanoparticles.

[0007] The hydroxylamine salt mentioned in step one is one or more of hydroxylamine phosphate, hydroxylamine sulfate, and hydroxylamine hydrochloride, and the content of metal impurities is <10 ppm.

[0008] In step one, the flow rate of ammonia gas is 100-500 mL / min, the purity of ammonia gas is >99.99%, and the total metal content is <1 ppb.

[0009] Ammonia not only acts as a reactant, but also reduces the rate at which hydroxylamine is oxidized by oxygen.

[0010] The low-temperature reaction temperature is 5-10℃, the pH is controlled at 5.5-10.5, and the stirring speed is 50-100 rpm.

[0011] Preferably, the pH is monitored to 6.5-9.5.

[0012] The hydroxylamine concentration was measured using a potentiometric titrator.

[0013] An increased alkalinity improves the solubility of strong acid-weak base salts, but excessive alkalinity promotes the decomposition of hydroxylamine. Hydroxylamine salts continuously react with ionized OH- ions. - The reaction produces the target product, hydroxylamine free base. Repeated addition of reactants can promote the dispersion of hydroxylamine salt and the formation rate of the target product, while avoiding excessive local heat accumulation.

[0014] In step one, the reaction is carried out by adding hydroxylamine salt multiple times while continuously introducing ammonia gas. Each time, the amount of hydroxylamine hydrochloride added is 0.2-1.0 times the amount prepared in the first step. The number of times the hydroxylamine salt is added repeatedly is 3-10 times. Preferably, the number of times is 3-6.

[0015] The chelating agent mentioned in step two is one or more of MPPA (2-(4-methylphenoxy)-6-tris(hydroxymethyl)phenyl) tripolyphosphate, diethylenetriaminepentaacetic acid, hexamethylenediaminetetra(methylene phosphate), and hexamethylenediaminetetra(methylenephosphonic acid).

[0016] The chelating agent used has a number of teeth in its multidentate ligands, which can form multi-chelate ring complexes with metal ions. This stable monomolecular encapsulation state makes it difficult for the ligand molecule to be released, thereby preventing hydroxylamine from directly contacting metal ions and effectively inhibiting the catalytic decomposition of hydroxylamine by metal ions.

[0017] The settling temperature in step two is 0-5℃, and the settling time is 2-5 h.

[0018] As the number of ligands increases, the complex product gradually grows larger. Cooling accelerates the aggregation and precipitation of such complexes, thereby rapidly and significantly removing metal impurities from the hydroxylamine solution.

[0019] The chelating resin mentioned in step three is a cross-linked polystyrene resin containing iminodiacetic acid groups (such as Lewatit TP 207, MTS9300, ZGS930), and the flow rate is controlled at 2-5 BV / h.

[0020] Further selective adsorption of Fe in the solution that was not removed by sedimentation 3+ Cu 2+ Metal ions, etc.

[0021] The mixed resin mentioned in step three is selected from one or more of MR-450 UPW, UP6150, UP8150, 001×7 / 201×7 (1:1 filling), with a flow rate of 3-6 BV / h.

[0022] Further removal of Na + NH4 + PO4 3- Cl - and SO4 2- Plasma.

[0023] The ultrafiltration membrane described in step four has a pore size of 0.005-0.02 μm.

[0024] Advantages and benefits of the present invention (1) The reaction rate of the present invention is mild and controllable, avoiding direct reaction of strong acids and strong bases and the corresponding waste liquid discharge; (2) The hydroxylamine solution is concentrated by multi-stage feeding rather than distillation, which has a high safety factor; (3) The addition of chelating agents not only removes metal impurities quickly and in large quantities, but the unprecipitated chelating agents can also act as hydroxylamine stabilizers to inhibit the decomposition of the target product. (4) The target product was purified by tandem adsorption of chelating resin and mixed bed resin in a specific ratio.

[0025] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Detailed Implementation

[0026] Examples 1-13 The present invention provides a method for preparing and purifying an electronic-grade hydroxylamine solution, comprising the following steps: Step 1: Multi-stage synthesis and concentration reaction of hydroxylamine salt. Prepare a near-saturated aqueous solution of hydroxylamine salt with metal impurity content <10 ppm. Circulate the solution in a low-temperature constant-temperature water bath at 5-10℃ with a stirring rate of 50-100 rpm. Introduce ammonia gas at a flow rate of 100-500 mL / min, with an ammonia purity >99.99% and a total metal content <1 ppb. Monitor the pH to 5.5-10.5, then add hydroxylamine salt again, at a mass of 0.2-1.0 times the initial amount. Stir and disperse evenly, then continue introducing ammonia gas. Repeat this process 3-6 times until the hydroxylamine concentration at the effluent outlet is >45%. Step 2: Addition of chelating agent and pre-filtration. Add 0.01-0.1% (by mass) of MPPA (one or more of the following: 2-(4-methylphenoxy)-6-tris(hydroxymethyl)phenyl tripolyphosphate, diethylenetriaminepentaacetic acid, hexamethylenediaminetetra(methylene phosphate), hexamethylenediaminetetra(methylenephosphonic acid), hexamethylenediaminetetra(methylenephosphonic acid), methylenephosphonic acid) to the generated hydroxylamine solution. After stirring, cool to 0-5℃ and allow to stand for 2-5 hours to settle. Then filter using a ceramic membrane. Step 3: Adsorption of chelating resin and mixed bed resin in series. Two stages of chromatography columns are connected in series. The first stage is filled with cross-linked polystyrene resin containing iminodiacetic acid groups, with a flow rate controlled at 2-5 BV / h. The second stage is filled with mixed resin, with a flow rate of 3-6 BV / h. Step 4: Terminal ultrafiltration. Use an ultrafiltration membrane with a pore size of 0.005-0.02 μm to remove residual nanoscale particles.

[0027] Under the above conditions, the metal content of electronic-grade hydroxylamine prepared was reduced to below 5 ppb, the concentration of the finished hydroxylamine was 35-45%, and the particle size of 0.2 ppm was <50 pcs / mL. Specific data are shown in Table 2.

[0028] Table 1 shows the different conditions in Examples 1-13, including ammonia gas flow rate, pH, secondary hydroxylamine salt dosage, number of reciprocating cycles, type of chelating agent, chelating / mixed bed resin, and ultrafiltration membrane pore size.

[0029] Table 2 shows the product concentration (%), particle size of 0.2 μm particles (pcs / mL), and metal ion content (ppb) for Examples 1-13 and Comparative Examples 1-7.

[0030] Table 1 Process Conditions

[0031] Comparative Example 1: Based on Example 1, the ammonia flow rate was adjusted to 2000 mL / min, while other conditions remained unchanged. The hydroxylamine concentration in step 1 was <40%, and the finished product concentration was <35%, which did not meet the preparation requirements.

[0032] In gas-liquid reactions, increasing the gas flow rate can enhance the turbulence at the gas-liquid interface, reduce the thickness of the mass transfer boundary layer, and thus increase the mass transfer rate from the gas phase to the liquid phase (i.e., increase the mass transfer coefficient k). L However, excessively high ammonia gas flow rates can cause bubbles to merge and the local pH to become too high, prompting the generated hydroxylamine to undergo a disproportionation reaction and decompose and overflow, resulting in the concentration of the generated hydroxylamine product not meeting the standard.

[0033] Comparative Example 2: Based on Example 1, the pH was monitored to 4, hydroxylamine salt was added again, and other conditions remained unchanged. The concentration of hydroxylamine in the output of step 1 was <20%, and the concentration of the finished product was <15%, which did not meet the preparation requirements.

[0034] Under alkaline conditions, the standard electrode potential for the decomposition of hydroxylamine is 3.04 eV, while under acidic conditions it is 1.87 eV, indicating that hydroxylamine has stronger reducing properties in alkaline solutions. However, the reaction is incomplete in alkaline solutions, and most of it still exists in the form of hydroxylamine salt.

[0035] Comparative Example 3: Based on Example 1, the mass ratio of the secondary hydroxylamine salt addition was 3, the number of repetitions was 2, and other conditions remained unchanged. The concentration of hydroxylamine output in step 1 was <30%, and the concentration of the finished product was <20%, which did not meet the preparation requirements.

[0036] Adding too much hydroxylamine salt at once will prolong its dissolution time and reduce the reaction rate.

[0037] Comparative Example 4: Based on Example 1, without adding the chelating agent in step 2, and with other conditions unchanged, the prepared hydroxylamine solution had a metal content >5 ppb, which does not meet the requirements for electronic-grade hydroxylamine. Specific data are shown in Table 2.

[0038] Comparative Example 5: Based on Example 1, chelating agent citric acid was added, and other conditions remained unchanged. The prepared hydroxylamine solution had a metal content >1 ppm, which did not meet the requirements for electronic-grade hydroxylamine. Specific data are shown in Table 2.

[0039] These chelating agents have high solubility; although they can complex metal ions, they prevent hydroxylamine from reacting with Fe. 3+ (Fe) 2+ The formation of complexes weakens the NO and NH bonds, leading to decomposition. However, this system cannot rapidly and massively cause the complexes to settle and be removed.

[0040] Comparative Example 6: Based on Example 1, using a strong acid type cation exchange resin D001 and a resin with sulfonic acid groups, with other conditions unchanged, the prepared hydroxylamine solution had a metal content >5 ppb, which does not meet the requirements for electronic grade hydroxylamine. Specific data are shown in Table 2.

[0041] Comparative Example 7: Based on Example 1, the second-stage filling mixed resin used was a strong acid and strong base type NM60SG. The prepared hydroxylamine solution had a metal content >5 ppb, which did not meet the requirements for electronic grade hydroxylamine. Specific data are shown in Table 2.

[0042] Table 2 shows the product concentration (%), particle size (pcs / mL), and metal ion content (ppb).

Claims

1. A method for preparing an electronic-grade hydroxylamine solution, characterized in that... Includes the following steps: Step 1: Synthesis and concentration of hydroxylamine. Under low temperature and stirring, ammonia gas is introduced into the hydroxylamine salt solution to carry out the reaction until the concentration of the product hydroxylamine solution is >45%. Step 2: Addition of chelating agent and pre-filtration. Add chelating agent to the generated hydroxylamine solution, stir, cool, let stand and settle, and then filter with a ceramic membrane. Step 3: The hydroxylamine solution, after being filtered through a ceramic membrane, is adsorbed by a series of chelating resin and mixed bed resin. The hydroxylamine solution is then passed through two chromatographic columns in series. The first stage is filled with chelating resin and the second stage is filled with mixed bed resin to obtain a purified hydroxylamine solution. Step 4: Terminal ultrafiltration, using an ultrafiltration membrane to remove residual nanoscale particles in the hydroxylamine solution to obtain an electronic grade hydroxylamine solution.

2. The method according to claim 1, characterized in that, The hydroxylamine salt mentioned in step one is one or more of hydroxylamine phosphate, hydroxylamine sulfate, and hydroxylamine hydrochloride, and the content of metal impurities is <10 ppm.

3. The method according to claim 1, characterized in that, In step one, the flow rate of ammonia gas is 100-500 mL / min, the purity of ammonia gas is >99.99%, and the total metal content is <1 ppb.

4. The method according to claim 1, characterized in that, The low-temperature reaction temperature is 5-10℃, the pH is controlled at 5.5-10.5, and the stirring speed is 50-100 rpm.

5. The method according to claim 1, characterized in that, In step one, the reaction is carried out by adding hydroxylamine salt multiple times and continuously passing ammonia gas through it. Each time, the amount of hydroxylamine hydrochloride added is 0.2-1.0 times that of the first preparation.

6. The method according to claim 1, characterized in that, The chelating agent mentioned in step two is one or more of MPPA (2-(4-methylphenoxy)-6-tris(hydroxymethyl)phenyl) tripolyphosphate, diethylenetriaminepentaacetic acid, hexamethylenediaminetetra(methylene phosphate), and hexamethylenediaminetetra(methylenephosphonic acid).

7. The method according to claim 1, characterized in that, The settling temperature in step two is 0-5℃, and the settling time is 2-5h.

8. The method according to claim 1, characterized in that, The chelating resin mentioned in step three is one or more of Lewatit TP207, MTS9300, and ZG S930, and the flow rate is controlled at 2-5 BV / h.

9. The method according to claim 1, characterized in that, The mixed resin mentioned in step three is selected from one or more of MR-450 UPW, UP6150, UP8150, 001×7 / 201×7, with a flow rate of 3-6 BV / h.

10. The method according to claim 1, characterized in that, The ultrafiltration membrane described in step four has a pore size of 0.005-0.02 μm.

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