Method for determining contents of fluosilicic acid, hydrofluoric acid and nitric acid in etching acid

A technology of nitric acid content and determination method, which is applied to electrochemical variables of materials, material analysis by observing the influence on chemical indicators, and analysis by chemical reaction of materials, etc., can solve the problem of low analysis cost, complicated pretreatment, The problem of high detection cost can achieve the effect of good result accuracy and repeatability, simple method operation and good method selectivity.

Inactive Publication Date: 2020-10-30
QINGDAO UNIV OF SCI & TECH
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Problems solved by technology

[0008] The purpose of the present invention is to overcome the problems of complex pretreatment, high detection cost, long analysis period and large detection error in the above-mentioned prior art, adopt acid-base titration and complexometric titration to measure three kinds of acid content, compared with instrument analysis The cost is low, and does not require complicated pretreatment, and can quickly complete the determination of the content of the three acids, providing an analysis method for etching acid raw materials and recycling

Method used

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  • Method for determining contents of fluosilicic acid, hydrofluoric acid and nitric acid in etching acid
  • Method for determining contents of fluosilicic acid, hydrofluoric acid and nitric acid in etching acid
  • Method for determining contents of fluosilicic acid, hydrofluoric acid and nitric acid in etching acid

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Experimental program
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Effect test

Embodiment 1

[0064] (1) Preparation of sample solution: Weigh about 2.4543g of the sample, put it in a 100mL plastic volumetric flask, add 10mL of saturated potassium nitrate solution, precipitate fluosilicic acid, add absolute ethanol and shake, and wait for the solution to cool to room temperature , use absolute ethanol to set the volume to the mark, let it stand until the precipitation layers, take the supernatant for the determination of total acidity, hydrofluoric acid and fluorosilicic acid, this is the sample solution A.

[0065] (2) Determination of total acidity: Add 30mL of water to a 250mL plastic beaker, pipette 25mL of solution A into the plastic beaker, add 3 drops of phenolphthalein indicator solution dropwise, and titrate with 0.5013mol / L sodium hydroxide standard titration solution until the solution is slightly The end point is pink and does not fade for 30s. The titration volume of the sample is 11.68mL, and the titration volume of the blank is 0.02mL. The total acidity ...

Embodiment 2

[0075] (1) Preparation of the sample solution: Weigh about 1.0065g of the sample, put it in a 100mL plastic volumetric flask, add 10mL of saturated potassium chloride solution, precipitate the fluorosilicic acid, add anhydrous methanol and shake, and wait for the solution to cool to room temperature Finally, use anhydrous methanol to make the volume up to the mark, let it stand until the precipitation layers, and take the supernatant for the determination of total acidity, hydrofluoric acid and fluorosilicic acid, which is sample solution A.

[0076] (2) Determination of total acidity: Add 30mL of water to a 250mL plastic beaker, pipette 25mL of solution A into the plastic beaker, add 3 drops of phenolphthalein indicator solution dropwise, and titrate with 0.5013mol / L sodium hydroxide standard titration solution until the solution is slightly The end point is pink and does not fade for 30s. The titration volume of the sample is 6.34mL, and the titration volume of the blank is 0...

Embodiment 3

[0080] Embodiment 3 accuracy verification

[0081] Weigh 99.66g of 34.82% hydrofluoric acid solution, 115.39g of 31.74% fluosilicic acid solution, 200.13g of 60.18% nitric acid and 50.09g of water to prepare a simulated sample. The theoretical values ​​of the content of the three mixed acids in the simulated sample are: 7.46% hydrofluoric acid, 7.87% fluosilicic acid, and 25.89% nitric acid. Weigh 1.0522g, 1.3738g, 1.5660g, 1.9009g, 2.2177g, and 2.4990g to simulate sample, prepare 6 samples of solution A in parallel, measure the total acidity and hydrofluoric acid content; weigh 0.2737g, 0.3003g, 0.3760g, 0.4082g, 0.4661g, 0.5003g to determine the total fluorine content, and measure the solution hydrofluoric acid according to the determination steps acid, fluosilicic acid and nitric acid concentrations. The measurement results are as follows:

[0082]

[0083] The repeatability RSD of the determination results of the three acid contents is less than 2%, and the deviation fr...

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Abstract

The invention discloses a method for determining the contents of hydrofluoric acid, fluosilicic acid and nitric acid in etching acid through acid-base titration and complexometric titration. The method comprises the following steps: (1) adding potassium salt into a sample to precipitate fluosilicic acid, titrating supernatant by using a sodium hydroxide standard titration solution by taking phenolphthalein as an indicator, and calculating the total acidity of the sample solution; (2) adding potassium salt into the sample to precipitate fluosilicic acid, titrating fluorine ions in the solutionby using a lanthanum nitrate standard titration solution by taking a fluorine ion selective electrode as an indicating electrode, determining a reaction endpoint by using a secondary micro-commerce method, and calculating the content of hydrofluoric acid; (3) heating and hydrolyzing fluosilicic acid, titrating total fluorine in the solution by using a lanthanum nitrate standard titration solutionby taking a fluorine ion selective electrode as an indicating electrode, determining a reaction endpoint by using a secondary micro-commerce method, and calculating the content of fluosilicic acid byusing a subtraction method; and (4) obtaining the nitric acid content by subtracting the sum of the hydrofluoric acid content and the fluosilicic acid content from the total acidity.

Description

technical field [0001] The invention relates to a detection of mixed inorganic acid content, in particular to the detection of hydrofluoric acid, fluosilicic acid and nitric acid. Background technique [0002] Wet chemical etching is a major process in the semiconductor chip industry. The purpose of etching is achieved by corroding the surface of the substrate with acidic substances. Among them, the mixture of hydrofluoric acid, fluosilicic acid and nitric acid is a common etching solution. The concentration of the etching solution affects the etching speed and quality. During the recycling process, it is also necessary to add acid solution according to the content of each component. There are many testing methods for nitric acid, hydrofluoric acid and fluosilicic acid alone and binary mixed acid, but the content test of mixed acid composed of three acids has not been reported. [0003] At present, the determination methods of nitric acid, hydrofluoric acid and fluorosilici...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/78G01N27/44
CPCG01N21/78G01N27/44
Inventor 张晓霞杨松王艳邢伶王瑞菲岳涛
Owner QINGDAO UNIV OF SCI & TECH
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