Method for determining concentration of each component in hydrofluoric acid and fluosilicic acid binary system

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 hydrofluoric acid and fluosilicic acid binary system, which comprises the following steps: step 1, weighing a certain amount of mixed acid solution, dispersing in a solvent, taking alkali liquor as a titrant, and measuring the concentration of each component of the hydrofluoric acid and fluosilicic acid binary system; the volume # imgabs0 # of alkali liquor consumed accumulatively at a first jump point of the mixed acid solution and the volume # imgabs1 # of alkali liquor consumed accumulatively at a second jump point of the mixed acid solution are measured through potentiometric titration, and the first jump point corresponds to a neutralization reaction of # imgabs3 # in # imgabs2 #; the second jump point corresponds to a neutralization reaction of # imgabs 5 # in # imgabs 4 #; 2, according to the mass of the weighed mixed acid, the mass fraction of the # imgabs8 # and the mass fraction of the # imgabs9 #, the mass fraction of the # imgabs8 # and the mass fraction of the # imgabs9 # are calculated;

Description

Technical Field

[0001] The present invention relates to the technical field of solution concentration analysis, and more specifically, to a method for measuring the concentration of each component of a binary system of hydrofluoric acid and fluosilicic acid. Background Art

[0002] In semiconductor manufacturing, wet chemical etching technology, as a key thin-film patterning process, is widely used in the fabrication of micro- and nanostructures and surface cleaning of silicon-based materials. Single-crystal silicon, polycrystalline silicon, and their silicon dioxide counterparts, which serve as core structural layers in integrated circuits and microelectromechanical systems (MEMS), are commonly etched using hydrofluoric acid (HF) solutions as the reaction medium.

[0003] During the etching process, hydrofluoric acid chemically reacts with the silicon substrate to produce fluorosilicic acid (H2SiF6), gradually transforming the etchant system from a single component to a binary hydrofluoric acid-fluorosilicic acid mixture. It is important to note that the dynamic changes in the hydrofluoric acid concentration in the etchant system directly affect the etching rate, surface morphology, and process repeatability of silicon-based materials. Therefore, the accuracy of HF solution concentration detection is of great significance.

[0004] Among existing technical solutions, the invention patent application with publication number CN108493295A, entitled "A Method for Recycling Solar Silicon Wafer Texturing Solution," describes a method for determining the concentrations of various components in a mixed acid of nitric acid, hydrofluoric acid, and fluorosilicic acid using a potentiometric titrator. The method first 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. This process requires filtration using a reverse osmosis membrane and cannot determine the concentration of fluorosilicic acid in the solution system.

[0005] There is also an invention patent application with publication number CN111751491A, entitled "A Method for Analyzing the Concentration of Mixed Acids in Silicon Etching Solutions." This patent describes a method for determining the concentrations of each component in a mixed acid of nitric acid, hydrofluoric acid, and acetic acid. The method involves first dissolving the sample in a mixture of an aprotic organic solvent (such as ethanol) and an anti-precipitation interfering agent (such as cyclohexanol) to avoid precipitation interference during the titration process. Potentiometric titration is then performed using a strong alkaline aqueous solution (such as sodium hydroxide). The concentrations of each acid are directly calculated from the three sudden jump points (corresponding to the neutralization endpoints of the three acids) in a single titration curve. However, this method is limited to measuring acid solutions that have not undergone an etching process and cannot titrate mixed acid solutions containing fluorosilicic acid after etching. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for measuring the concentration of each component of a binary system of hydrofluoric acid and fluorosilicic acid, so as to solve the technical problems mentioned in the background technology.

[0007] The present invention provides a method for determining the concentration of each component of a binary system of hydrofluoric acid and fluosilicic acid, 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 jump point corresponds to middle Neutralization reaction; The second hop point corresponds to middle Neutralization reaction; Step 2: According to the mass of the mixed acid and 、 , titrant concentration, calculate 、 Quality score.

[0008] In the above technical solution, further, the alkali solution in step 1 is or solution.

[0009] In any of the above technical solutions, further, the solvent in step 1 is a non-aqueous solvent or an aqueous solvent.

[0010] In any of the above technical solutions, further, when the solvent is a non-aqueous solvent, the alkali solution is solution.

[0011] In any of the above technical solutions, further, the non-aqueous solvent is methanol or ethanol.

[0012] In any of the above technical solutions, further, the concentration of the alkali solution is 0.5-2 mol / L.

[0013] In any of the above technical solutions, further, 、 The quality score is calculated as follows: in, is the alkali concentration, for Molar mass, for Molar mass, is the mass of the mixed acid solution in step 1, in g, 、 The unit is ml.

[0014] Beneficial effects: Compared with the existing technology, this method can accurately measure the mass fraction of hydrofluoric acid, fluosilicic acid and each component by using a potentiometric titrator. 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 a titration curve diagram of the titration of Example 1. 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] Single-crystal silicon, polycrystalline silicon, and their silicon dioxide materials, serving as core structural layers for integrated circuits and microelectromechanical systems (MEMS), are commonly etched using hydrofluoric acid (HF) solutions as the reaction medium during their wet etching process. During the etching process, hydrofluoric acid chemically reacts with the silicon substrate to produce fluorosilicic acid (H2SiF6), gradually transforming the etching solution from a single component to a binary hydrofluoric acid-fluorosilicic acid mixture. Because the dynamic changes in the hydrofluoric acid concentration in the etching solution directly affect the etching rate, surface morphology, and process repeatability of silicon-based materials, the accuracy of acid concentration detection is of great significance. Based on this, this application proposes a method for accurately measuring the concentrations of each component of this binary mixed solution.

[0023] The present application proposes a method for determining the concentration of each component of a binary system of hydrofluoric acid and fluosilicic acid, 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 jump point corresponds to middle Neutralization reaction; The second hop point corresponds to middle Neutralization reaction; Step 2: According to the mass of the mixed acid and 、 , titrant concentration, calculate 、 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 middle As the lye continues to titrate, the lye will reaction, and middle Neutralization is carried out, and after neutralization, the second jump point (i.e., the second jump point) appears.

[0025] Optimized, the alkali solution in step 1 is or solution.

[0026] Optimally, the solvent in step 1 is a non-aqueous solvent or an aqueous solvent.

[0027] 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.

[0028] Optimized, non-aqueous solvents are methanol or ethanol.

[0029] Optimally, the concentration of the alkali solution is 0.5-2 mol / L.

[0030] The above method enables precise measurement of the mass fractions of the various components of a mixed acid solution. Furthermore, the method is simple to operate and requires no pretreatment of the liquid being tested. The concentrations of each component in a binary mixed solution can be determined in a single titration step.

[0031] about 、 The quality score is calculated as follows: in, is the alkali concentration, for Molar mass, for Molar mass, is the mass of the mixed acid solution in step 1, in g, 、 The unit is ml.

[0032] The method of the present application is tested by the following examples.

[0033] Example 1: Configuration 4±0.1% , 1±0.5% Titrate with mixed acid solution.

[0034] Take 7.989g 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 according to formula (1) and formula (2), we can get: Formula (1) Formula (2) It should be noted that the use of mol / L, Calculations are performed using mol / L.

[0035] about A concentration of 1 mol / L was used.

[0036] It should be noted that and All are monobasic acids ( Dissociates in alcohol to and ),and The neutralization reaction molar ratio is 1:1. A 1 mol / L concentration ensures the appropriate titrant dosage, avoiding excessive sample dilution while ensuring a clear breakpoint. Furthermore, 1 mol / L KOH exhibits excellent solubility and stability in non-aqueous solvents such as ethanol and methanol, avoiding precipitation or demixing (higher concentrations may induce KOH precipitation).

[0037] Of course, titration can also be performed using alkali solutions of other concentrations, and is not limited to this concentration.

[0038] The mass fractions of the various components of the acid solution measured by the above data and formula are The mass fraction is 3.9%, The mass fraction of hydrofluoric acid is 1.2%, and the measured results are within the error range of the solution preparation. Therefore, this method can achieve the ), fluorosilicic acid ( ) Measurement of binary system mixed solutions.

[0039] 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 binary system of hydrofluoric acid and fluosilicic acid, 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 middle Neutralization reaction; The second hop point corresponds to middle Neutralization reaction; Step 2: According to the mass of the mixed acid and 、 , titrant concentration, calculate 、 Quality score.

2. The method for measuring the concentration of each component of the binary system of hydrofluoric acid and fluosilicic acid according to claim 1, wherein: The alkali solution in step 1 is or solution.

3. The method for measuring the concentration of each component of the binary system of hydrofluoric acid and fluosilicic acid as claimed in claim 2, characterized in that: The solvent in step 1 is a non-aqueous solvent or an aqueous solvent.

4. The method for measuring the concentration of each component of the binary system of hydrofluoric acid and fluosilicic acid as claimed in claim 3, characterized in that: When the solvent is non-aqueous solvent, the alkali solution is solution.

5. The method for measuring the concentration of each component of the binary system of hydrofluoric acid and fluosilicic acid as claimed in claim 3, characterized in that: The non-aqueous solvent is methanol or ethanol.

6. The method for measuring the concentration of each component of the binary system of hydrofluoric acid and fluosilicic acid 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 binary system of hydrofluoric acid and fluorosilicic acid according to any one of claims 1 to 6, wherein: 、 The quality score is calculated as follows: in, is the alkali concentration, for Molar mass, for Molar mass, is the mass of the mixed acid solution in step 1, in g, 、 The unit is ml.

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