Method for measuring thickness of nanoscale anti-oxidation film

Abstract

The invention discloses a nanoscale anti-oxidation film thickness measuring method, and relates to the technical field of nanoscale film thickness measurement, and the nanoscale anti-oxidation film thickness measuring method comprises the following operation steps: soaking a metal foil containing a nanoscale anti-oxidation film in a hydrochloric acid solution, recording the residual liquid as an extraction liquid, and recording the volume of the extraction liquid as V1; diluting the extract, and recording the dilution rate as a; carrying out ultrasonic treatment on the diluted extraction liquid, taking the liquid, titrating the liquid on a polished silicon wafer, and recording the volume of the taken liquid as V2; carrying out heating treatment under a protective atmosphere, measuring the wetting and spreading area, and recording the wetting area as S2; performing multi-point measurement on the film thickness of the obtained sample through an atomic force microscope, and calculating the average film thickness which is the minimum fragment film thickness h2; analyzing the proportion of black spots in the measured picture through pixel points, and recording the proportion of the black spots as b; and substituting into a formula h1 = a * S2 * V1 * b * h2 / (V2 * S1) to calculate the film thickness h1 of the nanoscale anti-oxidation film.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-scale film thickness measurement, and specifically to a method for measuring the thickness of a nano-scale anti-oxidation film. Background Art

[0002] The anti-oxidation film is a surface treatment technology used to protect the metal surface from oxidation and corrosion; an organic film formed on the metal surface by a chemical method, which is usually composed of organic compounds, forms a dense and stable protective layer on the metal surface, aiming to prevent the metal from oxidizing and discoloring due to exposure to air; this film also has the effects of anti-oxidation and moisture resistance, and in the subsequent high-temperature welding, this protective film is easily removed, enabling the copper surface to immediately combine with the molten solder to form a firm solder joint; however, if the film thickness is too small, the required anti-oxidation effect cannot be achieved.

[0003] For conventional micron-scale anti-oxidation films, the surface of the anti-oxidation-treated product can be extracted with hydrochloric acid, and the film thickness can be calculated by measuring the absorbance; however, this method is not applicable to nano-scale anti-oxidation films because there are certain deviations in the measurement method itself, and due to the relatively thin nano-scale anti-oxidation film, the extraction amount is small and the measurement error is large. When measuring the film thickness of nano-scale anti-oxidation films, the measurement results are not credible; the accuracy of the film thickness measuring instrument cannot meet the measurement requirements of nano-scale film thickness; if a higher-precision (optical) method is used for measurement, there will be diffuse reflection caused by the too large roughness of the underlying metal (Ra≈1000nm), and the measurement results are also not credible.

[0004] This article proposes a method for measuring the thickness of a nano-scale anti-oxidation film, which can accurately measure the thickness of the nano-scale anti-oxidation film. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for measuring the thickness of a nano-scale anti-oxidation film to solve the problems raised in the above background art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] Step 1: Prepare a sample: Use a metal foil containing a nano-scale anti-oxidation film (metal foil with OSP film) as the sample;

[0008] Step 2: Immerse the sample in a hydrochloric acid solution for treatment; take out the sample, and record the remaining liquid as the extraction solution, and record the volume of the extraction solution as V1;

[0009] Step 3: Dilute the extraction solution and record the dilution ratio as a;

[0010] Step 4: Ultrasonically treat the diluted extraction solution obtained in Step 3, take the solution, titrate it on a polished silicon wafer, and let it freely wet and spread, and record the volume of the taken solution as V2;

[0011] Step 5: Heat-treat the sample obtained in Step 4 under a protective atmosphere, measure the wetting and spreading area, and record the wetting area as S2;

[0012] Step 6: Perform multi-point measurement on the film thickness of the sample obtained in Step 5 by atomic force microscopy and calculate the average film thickness, which is the minimum fragment film thickness, and record the minimum fragment thickness as h2;

[0013] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0014] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0015] In the solution, the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1) is transformed from S1 × h1 / V1 = a × S2 × b × h2 / V2; h2 is obtained by performing multi-point measurement on the sample obtained in Step 5 using atomic force microscopy.

[0016] In the solution, the sample is immersed in hydrochloric acid solution for treatment to completely dissolve the OSP film. The OSP film will become pieces during immersion; subsequent dilution is used to prevent the lamination of the pieces, and then it is dropped on a silicon wafer, dried, and multi-point measurement is performed; therefore, the average value measured at multiple points is recorded as the minimum fragment thickness h2; the thermal decomposition temperature of the OSP film is about 150 °C, and heating at 40 - 60 °C has no effect on the OSP film.

[0017] Preferably, the dilution factor is a = 5 - 50; the liquid taking volume is V2 = 0.1 μL - 10 μL.

[0018] Preferably, the concentration of the hydrochloric acid solution is 3wt% - 7wt%; the ratio of the sample in Step 1 to the hydrochloric acid solution is (30 mm × 50 mm) : (25 - 100 mL).

[0019] Preferably, the conditions for heat treatment are: under vacuum / nitrogen conditions, the temperature is 40 - 60 °C, and the time is 30 - 60 minutes.

[0020] Preferably, the vibration frequency of the ultrasonic treatment is ≥28 KHz, and the ultrasonic time is ≥5 minutes.

[0021] Preferably, the roughness of the polished silicon wafer is ≤1 nm; the immersion treatment time is 1 - 5 minutes.

[0022] Preferably, the metal foil includes one of copper foil, aluminum foil, and nickel foil.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. It can achieve the measurement of the nano-scale antioxidant film (OSP film); 2. The measurement error is small. Description of the Drawings

[0025] Figure 1 The copper foil with a nano-scale antioxidant film prepared in Step 1 of Example 1;

[0026] Figure 2 Placing the sample in a hydrochloric acid solution for soaking in Step 2 of Example 1;

[0027] Figure 3 The wetting and spreading of the diluted extract on the polished silicon wafer in Step 4 of Example 1;

[0028] Figure 4 Performing multi-point measurement on the thickness of the sample obtained in Step 5 in Step 6 of Example 1;

[0029] Figure 5 The measurement picture in Step 7 of Example 1 which is the picture in Step 6. Detailed Embodiments

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Example 1: A method for measuring the thickness of a nano-scale antioxidant film, comprising the following operating steps;

[0032] Step 1: Prepare a sample: As Figure 1 shown, use a copper foil with a nano-scale antioxidant film (S1 = 30×50 mm 2 ) as the sample;

[0033] Step 2: As Figure 2 shown, place the sample in a 3 wt% hydrochloric acid solution (V1 = 50 mL) and soak it for 1 minute (extraction time); take out the sample, and record the remaining liquid as the extract, and record the volume of the extract as V1;

[0034] Step 3: Dilute the extract by 10 times, and record the dilution factor as a;

[0035] Step 4: Ultrasonically treat the diluted extract obtained in Step 3 for 5 minutes at a vibration frequency of 28 KHz, take 0.1 μL of the liquid, titrate it on the polished silicon wafer, and let it freely wet and spread, as Figure 3as shown; record the liquid-taking volume as V2;

[0036] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting and spreading area, and record the wetting area as S2;

[0037] Step 6: Perform multi-point measurement (detect 5 points) on the film thickness of the sample obtained in Step 5 by atomic force microscope, and calculate the average film thickness of the 5 points. As Figure 4 shown, it is the minimum fragment film thickness, record the minimum fragment thickness h2, see Table 2;

[0038] Step 7: Synchronously, for the measurement pictures in Step 6, as Figure 5 shown, analyze the proportion of black dots in the picture through pixel point analysis, and record the black dot proportion as b, as shown in Table 2;

[0039] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a×S2×V1×b×h2 / (V2×S1).

[0040] Example 2 is based on Example 1, the difference is that the extraction time of the sample in the hydrochloric acid solution is 3 minutes, and the liquid-taking volume V2 = 0.5 μL;

[0041] Step 1: Prepare the sample: Use a copper foil with a nano-scale anti-oxidation film (S1 = 30×50 mm 2 ) as the sample;

[0042] Step 2: Immerse the sample in a 3 wt% hydrochloric acid solution (V1 = 50 mL) for 3 minutes (extraction time); take out the sample, and record the remaining liquid as the extraction solution, and record the extraction solution volume as V1;

[0043] Step 3: Dilute the extraction solution by 10 times, and record the dilution factor as a;

[0044] Step 4: Ultrasonically treat the diluted extraction solution obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 0.5 μL of the liquid, titrate it on the polished silicon wafer, and let it freely wet and spread; record the liquid-taking volume as V2;

[0045] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting and spreading area, and record the wetting area as S2;

[0046] Step 6: Perform multi-point measurement (detect 5 points) on the film thickness of the sample obtained in Step 5 by atomic force microscope, and calculate the average film thickness of the 5 points. It is the minimum fragment film thickness, record the minimum fragment thickness h2;

[0047] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel points, and record the proportion of black dots as b;

[0048] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0049] Example 3 is based on Example 1, the difference is that the extraction time of the sample in the hydrochloric acid solution is 5 minutes, and the liquid-taking volume V2 = 1.0 μL;

[0050] Step 1: Prepare a sample: Use a copper foil (S1 = 30 × 50 mm 2 ) with a nano-scale anti-oxidation film as the sample;

[0051] Step 2: Immerse the sample in a 3wt% hydrochloric acid solution (V1 = 50 mL) for 5 minutes (extraction time); take out the sample, and record the remaining liquid as the extraction solution, and record the volume of the extraction solution as V1;

[0052] Step 3: Dilute the extraction solution by 10 times, and record the dilution factor as a;

[0053] Step 4: Ultrasonically treat the diluted extraction solution obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 1.0 μL of the liquid, titrate it on the polished silicon wafer, and spread it freely by wetting; record the liquid-taking volume as V2;

[0054] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting spreading area, and record the wetting area as S2;

[0055] Step 6: Measure the film thickness of the sample obtained in Step 5 at multiple points (detect 5 points) by atomic force microscopy, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0056] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel points, and record the proportion of black dots as b;

[0057] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0058] Example 4 is based on Example 1, the difference is that the hydrochloric acid solution is 5wt%;

[0059] Step 1: Prepare a sample: Use a copper foil (S1 = 30 × 50 mm 2 ) with a nano-scale anti-oxidation film as the sample;

[0060] Step 2: Immerse the sample in a 5 wt% hydrochloric acid solution (V1 = 50 mL) for 1 minute (extraction time); take out the sample, and record the remaining liquid as the extractant, and record the volume of the extractant as V1;

[0061] Step 3: Dilute the extractant by 10 times, and record the dilution factor as a;

[0062] Step 4: Ultrasonically treat the diluted extractant obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 0.1 μL of the liquid, titrate it on a polished silicon wafer, and freely wet and spread; record the volume of the taken liquid as V2;

[0063] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting and spreading area, and record the wetting area as S2;

[0064] Step 6: Perform multi-point measurement (detect 5 points) on the film thickness of the sample obtained in Step 5 through an atomic force microscope, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0065] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0066] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0067] Example 5 is based on Example 4, the difference is that the extraction time of the sample in the hydrochloric acid solution is 3 minutes; the volume of the taken liquid V2 = 0.5 μL;

[0068] Step 1: Prepare the sample: Use a copper foil (S1 = 30 × 50 mm 2 ) with a nano-scale anti-oxidation film as the sample;

[0069] Step 2: Immerse the sample in a 5 wt% hydrochloric acid solution (V1 = 50 mL) for 3 minutes (extraction time); take out the sample, and record the remaining liquid as the extractant, and record the volume of the extractant as V1;

[0070] Step 3: Dilute the extractant by 10 times, and record the dilution factor as a;

[0071] Step 4: Ultrasonically treat the diluted extractant obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 0.5 μL of the liquid, titrate it on a polished silicon wafer, and freely wet and spread; record the volume of the taken liquid as V2;

[0072] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetted spreading area, and record the wetted area as S2;

[0073] Step 6: Perform multi-point measurements (detect 5 points) on the film thickness of the sample obtained in Step 5 by atomic force microscopy, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0074] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0075] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0076] Example 6 is based on Example 5, the difference is that the extraction time of the sample in the hydrochloric acid solution is 5 minutes; the liquid-taking volume V2 = 1.0 μL;

[0077] Step 1: Prepare a sample: Use a copper foil (S1 = 30 × 50 mm 2 ) with a nano-scale anti-oxidation film as the sample;

[0078] Step 2: Immerse the sample in a 5 wt% hydrochloric acid solution (V1 = 50 mL) for 5 minutes (extraction time); take out the sample, and record the remaining liquid as the extract, and record the extract volume as V1;

[0079] Step 3: Dilute the extract by 10 times, and record the dilution factor as a;

[0080] Step 4: Ultrasonically treat the diluted extract obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 1.0 μL of the liquid, titrate it on a polished silicon wafer, and freely wet and spread; record the liquid-taking volume as V2;

[0081] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetted spreading area, and record the wetted area as S2;

[0082] Step 6: Perform multi-point measurements (detect 5 points) on the film thickness of the sample obtained in Step 5 by atomic force microscopy, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0083] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0084] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula: h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0085] Example 7 is based on Example 1, with the difference that the concentration of the hydrochloric acid solution is 7 wt%;

[0086] Step 1: Prepare the sample: Use a copper foil with a nano-scale anti-oxidation film (S1 = 30 × 50 mm 2 ) as the sample;

[0087] Step 2: Immerse the sample in a 7 wt% hydrochloric acid solution (V1 = 50 mL) for 1 minute (extraction time); Take out the sample, and record the remaining liquid as the extract, and record the volume of the extract as V1;

[0088] Step 3: Dilute the extract by 10 times, and record the dilution factor as a;

[0089] Step 4: Ultrasonically treat the diluted extract obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 0.1 μL of the liquid, titrate it on a polished silicon wafer, and let it freely wet and spread; Record the volume of the taken liquid as V2;

[0090] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting and spreading area, and record the wetting area as S2;

[0091] Step 6: Perform multi-point measurement (detect 5 points) on the film thickness of the sample obtained in Step 5 through an atomic force microscope, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0092] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0093] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula: h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0094] Example 8 is based on Example 7, with the difference that the extraction time of the sample in the hydrochloric acid solution is 3 minutes; The volume of the taken liquid V2 = 0.5 μL;

[0095] Step 1: Prepare the sample: Use a copper foil with a nano-scale anti-oxidation film (S1 = 30 × 50 mm 2 ) as the sample;

[0096] Step 2: Immerse the sample in a 7 wt% hydrochloric acid solution (V1 = 50 mL) for 3 minutes (extraction time); take out the sample, and record the remaining liquid as the extract, and record the volume of the extract as V1;

[0097] Step 3: Dilute the extract 10 times, and record the dilution factor as a;

[0098] Step 4: Ultrasonically treat the diluted extract obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 0.5 μL of the liquid, titrate it on a polished silicon wafer, and freely wet and spread; record the volume of the taken liquid as V2;

[0099] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting and spreading area, and record the wetting area as S2;

[0100] Step 6: Multiply-point measure the film thickness of the sample obtained in Step 5 (detect 5 points) by an atomic force microscope, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0101] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0102] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0103] Example 9 is based on Example 7, the difference is that the extraction time of the sample in the hydrochloric acid solution is 5 minutes; the volume of the taken liquid V2 = 1.0 μL;

[0104] Step 1: Prepare a sample: Use a copper foil with a nano-scale anti-oxidation film (S1 = 30 × 50 mm 2 ) as the sample;

[0105] Step 2: Immerse the sample in a 7 wt% hydrochloric acid solution (V1 = 50 mL) for 5 minutes (extraction time); take out the sample, and record the remaining liquid as the extract, and record the volume of the extract as V1;

[0106] Step 3: Dilute the extract 10 times, and record the dilution factor as a;

[0107] Step 4: Ultrasonically treat the diluted extract obtained in Step 3 at a vibration frequency of 28 KHz for 5 minutes, take 1.0 μL of the liquid, titrate it on a polished silicon wafer, and freely wet and spread; record the volume of the taken liquid as V2;

[0108] Step 5: Heat-treat the sample obtained in Step 4 in a protective atmosphere at 50 °C for 45 minutes, measure the wetting and spreading area, and record the wetting area as S2;

[0109] Step 6: Perform multi-point measurements (detect 5 points) on the film thickness of the sample obtained in Step 5 using an atomic force microscope, and calculate the average film thickness of the 5 points, which is the minimum fragment film thickness, and record the minimum fragment thickness h2;

[0110] Step 7: Synchronously analyze the proportion of black dots in the measurement picture in Step 6 through pixel point analysis, and record the proportion of black dots as b;

[0111] Step 8: Calculate the film thickness h1 of the nano-scale anti-oxidation film of the sample in Step 1 through the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1).

[0112] Calculate the film thickness h1 of the nano-scale OSP film;

[0113] According to the extraction liquid concentration and the diluted extraction liquid concentration in the present invention, it can be obtained that S1 × h1 / V1 = a × S2 × b × h2 / V2, and the film thickness calculation formula h1 = a × S2 × V1 × b × h2 / (V2 × S1) is obtained;

[0114] Take the liquid volume V2 in Table 1, the corresponding minimum fragment thickness h2, wetting area S2 and black dot proportion b in Table 2, S1 = 1500 mm 2 , a = 10, V1 = 50 mL, substitute them into the formula h1 = a × S2 × V1 × b × h2 / (V2 × S1), and calculate the film thickness h1 of the nano-scale OSP film, as shown in Table 2.

[0115]

[0116]

[0117] Table 1

[0118]

[0119] Table 2

[0120] Conclusion: It can be seen from the data in Table 2 that the error of the calculated film thickness of the OSP film is small.

[0121] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in all respects, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Thus, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A method for measuring the thickness of a nano-scale anti-oxidation film, characterized in that: The steps include: Step 1: Prepare the sample: Use copper foil containing nano-scale anti-oxidation film as the sample; Step 2: Soak the sample in a hydrochloric acid solution; Take out the sample, and record the remaining liquid as the extract, and record the volume of the extract as V1; Step 3: dilute the extract and record the dilution factor as a; Step 4: subject the diluted extract obtained in step 3 to ultrasonic treatment, take the extract, and drip it on a polished silicon wafer, allowing it to spread freely by wetting, and record the volume of the extract as V2; Step 5: Heat the sample obtained in step 4 under a protective atmosphere, measure the wetted and spread area, and record the wetted area as S2; Step 6: Use an atomic force microscope to measure the film thickness of the sample obtained in step 5 at multiple points and calculate the average film thickness, which is the minimum fragment film thickness. The minimum fragment thickness is recorded as h2; Step 7: Synchronously analyze the proportion of black dots in the measured image in step 6 by pixel points, and record the proportion of black dots as b; Step 8: Calculate the thickness h1 of the nanoscale anti-oxidation film of the sample in step 1 by the formula: h1 = a×S2×V1×b×h2 / (V2×S1).

2. The method for measuring the thickness of a nano-scale anti-oxidation film according to claim 1, characterized in that: The dilution multiple is a=5-50; the liquid volume is V2=0.1 μL-10 μL.

3. The method for measuring the thickness of a nano-scale anti-oxidation film according to claim 1, characterized in that: The concentration of the hydrochloric acid solution is 3wt% to 7wt%; the ratio of the sample to the hydrochloric acid solution in step 1 is (30mm×50mm):(25 to 100mL).

4. The method for measuring the thickness of a nano-scale anti-oxidation film according to claim 1, characterized in that: The conditions for the heat treatment are: under vacuum / nitrogen conditions, a temperature of 40 to 60° C., and a time of 30 to 60 minutes.

5. The method for measuring the thickness of a nano-scale anti-oxidation film according to claim 1, characterized in that: The vibration frequency of the ultrasonic treatment is ≥28KHz, and the ultrasonic time is ≥5 minutes.

6. The method for measuring the thickness of a nano-scale anti-oxidation film according to claim 1, characterized in that: The roughness of the polished silicon wafer is ≤1nm; and the immersion treatment time is 1 to 5 minutes.

Images