Method for measuring concentration of each component in mixed acid solution

Abstract

The invention relates to the technical field of solution concentration analysis, in particular to a method for measuring the concentration of each component of a mixed acid etching solution, which comprises the following steps: step 1, taking alkali liquor as a titrant, determining the volume # imgabs0 # of alkali liquor accumulated and consumed by a first jump point and the volume # imgabs1 # of alkali liquor accumulated and consumed by a second jump point of the mixed acid solution through potentiometric titration; step 2, weighing a certain amount of the mixed acid solution, dispersing the mixed acid solution in a solvent, taking alkali liquor as a titrant, and measuring the volume # imgabs2 # of the alkali liquor accumulatively consumed by a third jump point and the volume # imgabs3 # of the alkali liquor accumulatively consumed by a fourth jump point of the mixed acid solution through a potentiometric titration method; and step 3, according to the mass of the weighed mixed acid, the mass fraction of the # imgabs 8 #, the mass fraction of the # imgabs 9 # and the mass fraction of the # imgabs 10 #, the mass fraction of the # imgabs 5 #, the mass fraction of the # imgabs 6 # and the mass fraction of the # imgabs 7 #, the mass fraction of the # imgabs 8 #, the mass fraction of the # imgabs 9 # and the mass fraction of the # imgabs 10 # are calculated. According to the method, the mass fraction of each component of nitric acid, hydrofluoric acid and fluosilicic acid can be precisely measured by using a potentiometric titrator.

Description

Technical Field

[0001] The present invention relates to the technical field of solution concentration analysis, and more particularly to a method for measuring the concentration of each component of a mixed acid etching solution. Background Art

[0002] Wet etching is a common etching method in the semiconductor field. During the over-etching process, the semiconductor material reacts with the etching solution to obtain a certain pattern on the semiconductor surface, or the semiconductor material is cleaned by etching.

[0003] Silicon and its oxides are common semiconductor materials. The etchant commonly used for wet etching of silicon and silicon dioxide is typically a mixture of hydrofluoric acid and nitric acid. When the etchant reacts with silicon, fluorosilicic acid is produced, forming a ternary system. To precisely control the etching process, the industry has strict requirements for the concentration ratio of hydrofluoric acid to nitric acid, making accurate acid concentration detection crucial.

[0004] Publication number CN108493295A discloses a method for recycling solar silicon wafer texturing solutions. The method uses a potentiometric titrator to determine the concentrations of various components in a mixed solution of nitric acid, hydrofluoric acid, and fluorosilicic acid. This method uses a reverse osmosis membrane to remove fluorosilicic acid impurities from the etching solution, and then uses a nitrate ion-selective electrode to titrate in a non-aqueous solvent to measure the concentration changes of hydrofluoric acid and nitric acid. However, the following technical issues were encountered during the experiment: 1. Fluorosilicic acid contained in the acid solution after etching cannot be distinguished from nitric acid / hydrofluoric acid in the existing titration method and cannot be measured; 2. To determine the content of other acid components, the existing technology requires pre-treatment (such as reverse osmosis membrane filtration) to remove fluorosilicic acid, and then determine the remaining components in the solution system. The process is relatively complicated and tedious, and the filtration operation will interfere with the determination of the content of other components. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for measuring the concentration of each component of a mixed acid solution to solve the technical problems mentioned in the background technology.

[0006] The present invention proposes a method for determining the concentration of each component of a mixed acid solution, wherein the mixed acid solution comprises 、 、 ; wherein the method comprises the following steps: Step 1: Weigh a certain amount of mixed acid solution and disperse it in a solvent. Use alkali solution as titrant and measure the cumulative volume of alkali solution consumed at the first jump point of the mixed acid solution by potentiometric titration. The cumulative volume of alkali consumed at the second jump point ,in, The first jump point corresponds to and middle Neutralization reaction; The second hop point corresponds to middle Neutralization reaction; Step 2: Weigh a certain amount of mixed acid solution and disperse it in a solvent. Use alkali solution as titrant to determine the cumulative volume of alkali solution consumed at the third jump point of the mixed acid solution by potentiometric titration. The cumulative volume of alkali solution consumed at the fourth jump point ,in, The third hop point corresponds to all Neutralization reaction; The fourth jump point corresponds to and reaction; Step 3: According to the mass of the mixed acid and 、 、 、 , titrant concentration, calculate 、 and quality score.

[0007] In the above technical solution, further, the alkali solution in step 1 and step 2 is or solution.

[0008] In any of the above technical solutions, further, the solvent in step 1 and step 2 is a non-aqueous solvent or an aqueous solvent.

[0009] In any of the above technical solutions, further, when the solvent is a non-aqueous solvent, the alkali solution is solution.

[0010] In any of the above technical solutions, further, the non-aqueous solvent is methanol or ethanol.

[0011] In any of the above technical solutions, further, the concentration of the alkali solution is 0.5-2 mol / L.

[0012] In any of the above technical solutions, further, 、 and The quality score is calculated as follows: in, is the alkali concentration, for Molar mass, for Molar mass, for Molar mass, is the mass of the mixed acid solution in step 1, in g; is the mass of the mixed acid solution in step 2, in g, 、 、 、 The unit is ml.

[0013] Beneficial effects: Compared with the existing technology, this method can accurately measure the mass fraction of each component of nitric acid, hydrofluoric acid, and fluosilicic acid by using a potentiometric titrator.

[0014] The method is simple to operate and does not require pretreatment of the liquid to be tested. The concentration of each component of the ternary system mixed solution can be determined through a maximum of two titration steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 It is the titration curve figure of the first titration of Example; Figure 2 It is the titration curve diagram of the second titration of Example. DETAILED DESCRIPTION

[0017] Below, example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. It should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] It should be noted that, as shown in this application and the claims, unless the context clearly indicates an exception, the words "a," "an," "an," and / or "the" do not refer to the singular and may include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0019] If the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative positional relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0021] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] Silicon and its oxides are common semiconductor materials. The etchant commonly used for wet etching of silicon and silicon dioxide is typically a mixture of hydrofluoric acid and nitric acid. When the etchant reacts with silicon, it produces fluorosilicic acid, forming a ternary system. Accurate detection of the acid concentration is crucial for precise control of the etching process. To this end, this application proposes a method for precisely measuring the concentration of each component of this ternary system.

[0023] The present application proposes a method for determining the concentration of each component of a mixed acid solution, wherein the mixed acid solution contains hydrofluoric acid ( ), nitric acid ( ), Fluorosilicic acid ( ); wherein the method comprises the following steps: Step 1: Weigh a certain amount of mixed acid solution and disperse it in a solvent. Use alkali solution as titrant and measure the cumulative volume of alkali solution consumed at the first jump point of the mixed acid solution by potentiometric titration. The cumulative volume of alkali consumed at the second jump point ,in, The first jump point corresponds to and middle Neutralization reaction; The second hop point corresponds to middle Neutralization reaction; Step 2: Weigh a certain amount of mixed acid solution and disperse it in a solvent. Use alkali solution as titrant to determine the cumulative volume of alkali solution consumed at the third jump point of the mixed acid solution by potentiometric titration. The cumulative volume of alkali solution consumed at the fourth jump point ,in, The third hop point corresponds to all Neutralization reaction; The fourth jump point corresponds to and reaction; Step 3: According to the mass of the mixed acid and 、 、 、 , titrant concentration, calculate 、 and quality score.

[0024] In step 1, due to the different components in the mixed acid solution The ionization constants in the solvent are different, so there will be two obvious jump points, corresponding to the first jump point and the second jump point; the first jump point (i.e. the first jump point) is at and middle As the alkali solution continues to titrate, the alkali solution will reaction, and middle Neutralization is carried out, and after neutralization, the second jump point (i.e., the second jump point) appears.

[0025] In step 2, there will still be two obvious jump points, corresponding to the third jump point and the fourth jump point; when all the When the solution is neutralized, the third jump point (i.e. the first jump point) appears. As the alkali solution continues to be titrated, the solution system Gradually overdose, it will middle The reaction occurs, 1 mol Will consume 4 mol ( ), the fourth hop point (i.e. the second hop point) is formed here.

[0026] It should be noted that step 1 and step 2 are two separate titrations. In order to distinguish the jump points of the titration, they are distinguished by “first”, “second”, “third” and “fourth”.

[0027] Optimized, the alkali solution in step 1 and step 2 is or solution.

[0028] Optimally, the solvent in step 1 and step 2 is a non-aqueous solvent or an aqueous solvent.

[0029] It should be noted that when the solvent is a non-aqueous solvent, the alkali solution is solution; when the solvent is aqueous, the alkali solution is or Any solution is acceptable. The solubility of the product produced by titration of the solution in non-aqueous solvents is low, which leads to the formation of precipitation that interferes with the test accuracy. The solution is best used for titration of aqueous solvents.

[0030] Optimized, non-aqueous solvents are methanol or ethanol.

[0031] Optimally, the concentration of the alkali solution is 0.5-2 mol / L.

[0032] This method enables precise measurement of the mass fractions of each component in a mixed acid solution. Furthermore, it is simple to operate, requires no pretreatment of the liquid being tested, and can determine the concentrations of each component in a ternary mixed solution in a maximum of two titration steps.

[0033] about 、 and The quality score is calculated as follows: in, is the alkali concentration, for Molar mass, for Molar mass, for Molar mass, is the mass of the mixed acid solution in step 1, in g; is the mass of the mixed acid solution in step 2, in g, 、 、 、 The unit is ml.

[0034] The method of the present application is tested by the following examples.

[0035] Example 1: The concentration is 19±1% , 23±1% , 5±0.5% Titrate with mixed acid solution.

[0036] 1. Take 0.496g of mixed acid solution and disperse it in ethanol solvent. electrode, and then 1 mol / L It is titrated as a titrant, and the titration curve is as follows Figure 1 As shown, at this time ml, ml, then from formula (1) we can get Formula (1) 2. Take 1.006g of mixed acid solution and disperse it in water solvent. Electrode, 1 mol / L It is titrated as a titrant, and the titration curve is as follows Figure 2 As shown, at this time ml, ml, then from formula (2) and formula (3) we can get: Formula (2) Formula (3) It should be noted that the use of mol / L, mol / L, Calculations are performed using mol / L.

[0037] about 、 The concentration of 1 mol / L was used.

[0038] In non-aqueous titrations (e.g., ethanol solvents), 、 、 of The difference in ionization ability is significant. High concentration titrant can quickly neutralize , so that the potential jump point (such as 、 ) is steeper, making it easier to accurately identify the endpoint. If the concentration is too low (such as 0.1 mol / L), the sudden jump point is gentle, which can easily lead to misjudgment of the endpoint (especially and separation).

[0039] In aqueous titration, and The reaction ( ) requires a large amount of alkali, 1 mol / L NaOH can ensure the complete reaction and avoid the problem of insufficient concentration. The jump point is not obvious.

[0040] Of course, titration can also be performed using alkali solutions of other concentrations, and is not limited to this concentration.

[0041] The mass fractions of the various components of the acid solution measured by the above data and formula are The mass fraction is 18.59%, The mass fraction is 23.67%, The mass fraction of hydrofluoric acid is 5.18%, and the measured result is within the error range of the solution preparation. Therefore, this method can achieve the ), nitric acid ( ), Fluorosilicic acid ( ) Measurement of ternary system mixed solution.

[0042] While various embodiments of the present disclosure have been described above, the above descriptions are illustrative, non-exhaustive, and not intended to be limiting of the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for determining the concentration of each component of a mixed acid solution, wherein the mixed acid solution comprises 、 、 ; It is characterized in that, The method comprises the following steps: Step 1: Weigh a certain amount of mixed acid solution and disperse it in a solvent. Use alkali solution as titrant and measure the cumulative volume of alkali solution consumed at the first jump point of the mixed acid solution by potentiometric titration. The cumulative volume of alkali consumed at the second jump point ,in, The first hop point corresponds to and middle Neutralization reaction; The second hop point corresponds to middle Neutralization reaction; Step 2: Weigh a certain amount of mixed acid solution and disperse it in a solvent. Use alkali solution as titrant to determine the cumulative volume of alkali solution consumed at the third jump point of the mixed acid solution by potentiometric titration. The cumulative volume of alkali solution consumed at the fourth jump point ,in, The third hop point corresponds to all Neutralization reaction; The fourth hop point corresponds to and reaction; Step 3: According to the mass of the mixed acid and 、 、 、 , titrant concentration, calculate 、 and quality score.

2. The method for determining the concentration of each component of a mixed acid solution according to claim 1, wherein: The alkali solution in step 1 and step 2 is or solution.

3. The method for determining the concentration of each component of a mixed acid solution according to claim 2, wherein: The solvent in step 1 and step 2 is a non-aqueous solvent or an aqueous solvent.

4. The method for determining the concentration of each component of a mixed acid solution according to claim 3, wherein: When the solvent is non-aqueous solvent, the alkali solution is solution.

5. The method for determining the concentration of each component of a mixed acid solution according to claim 3, wherein: The non-aqueous solvent is methanol or ethanol.

6. The method for determining the concentration of each component of a mixed acid solution according to claim 1, wherein: The concentration of the alkali solution is 0.5-2 mol / L.

7. The method for determining the concentration of each component of a mixed acid solution according to any one of claims 1 to 6, wherein: 、 and The quality score is calculated as follows: in, is the alkali concentration, for Molar mass, for Molar mass, for Molar mass, is the mass of the mixed acid solution in step 1, in g; is the mass of the mixed acid solution in step 2, in g, 、 、 、 The unit is ml.

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