Method for preparing standard sample for calibration of time-of-flight secondary ion mass spectrometer and method for calibrating time-of-flight secondary ion mass spectrometer

Abstract

To provide a calibration standard sample for use in mass calibration of a time-of-flight secondary ion mass spectrometer, which has a wide range of mass numbers and enables the creation of a more accurate mass calibration curve.SOLUTION: A method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer includes the steps of: charging a hindered phenol-based antioxidant into a container; charging hexane into the container; stirring the solution in the container to dissolve the hindered phenol-based antioxidant in the hexane to prepare a solution; dripping the solution onto a surface of a silicon wafer to form droplets; and drying the droplets to prepare the standard sample for calibration of the time-of-flight secondary ion mass spectrometer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer and a method for calibrating a time-of-flight secondary ion mass spectrometer. [Background technology]

[0002] Time-of-flight secondary ion mass spectrometry (hereinafter sometimes abbreviated as TOF-SIMS) is used to obtain chemical information on the microscopic regions on the outermost surface of a sample. To identify surface chemical species, it is important to be able to measure mass accurately. To accurately measure molecular weights and ion masses using mass spectrometry, a mass calibration method is used in which attributable fragment ions are used and a calibration curve is created based on the actual measured and theoretical values ​​of the fragment ions. A common negative secondary ion mass calibration method is to use low-mass C n The mass calibration curve using +H fragment ions (n=1-4) is extrapolated to calibrate the mass up to the high mass region.

[0003] Another mass calibration method for performing mass calibration over a wide mass range is the mass calibration method using a standard sample made of a mixture of glucose and its polysaccharides, as described in Patent Document 1. This method uses fragment ions originating from sugars to create a mass calibration curve in the high mass range with a mass number of 600 or more.

[0004] Furthermore, there is a method described in Patent Document 2. In this method, a mass axis calibration material is placed on the surface of a sample, and during measurement, signals originating from the sample surface and signals originating from the mass axis calibration material are simultaneously detected, and the mass axis of the obtained mass spectrum is calibrated using the mass axis calibration material. Specifically, when identifying organic compounds with a mass number exceeding 1000, ionic substances such as alkyl sulfonates, alkyl amino acids, alkyl betaines, and alkyl amine oxides are dissolved in an acetonitrile solvent as mass calibration materials, and the solvent is sprayed onto the surface of a silicon wafer using a nebulizer, and this is used for mass calibration. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-292093 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-51934 Summary of the Invention [Problem to be solved by the invention]

[0006] When analyzing contamination on silicon wafer surfaces using TOF-SIMS, chemical species with mass numbers ranging from 12 to 250 are often identified. For this reason, the general mass calibration method uses low-mass C n The mass calibration curve using +H fragment ions is extrapolated to calibrate the mass up to the high mass region, which results in a large discrepancy between the measured mass and the theoretical mass at the high mass end, making it difficult to identify chemical species due to poor mass accuracy.

[0007] Furthermore, in the mass calibration method using a standard sample made of a mixture of glucose and its polysaccharides as described in Patent Document 1, fragment ions originating from sugars are used to create a mass calibration curve in the high mass region where the mass number is 600 or more. This results in a large discrepancy between the measured mass value and the theoretical value in the low mass region, and the mass accuracy is poor, making it difficult to identify chemical species.

[0008] The mass calibration method disclosed in Patent Document 2 aims to determine the exact mass of unknown peaks with mass numbers exceeding 500 with high accuracy. The mass error between the measured mass number and the theoretical mass number is small for mass numbers near the fragment ions used for mass calibration, but there is a problem in that the mass error increases as the mass number gets farther away from the mass number of the fragment ions used for mass calibration.

[0009] To identify surface chemical species in TOF-SIMS, it is necessary to use known substances with masses that cover the mass range of interest for mass calibration, or their fragment ions, to create a more accurate mass calibration curve in order to perform measurements with high mass accuracy.

[0010] The present invention has been made to solve the above problems, and has as its object to provide a calibration standard sample for use in mass calibration of a time-of-flight secondary ion mass spectrometer, which has a wide range of mass numbers and can generate a more accurate mass calibration curve. [Means for solving the problem]

[0011] The present invention has been made to achieve the above-mentioned object, and provides a method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer, comprising the steps of: adding a hindered phenol-based antioxidant to a container; adding hexane to the container; stirring the solution in the container to dissolve the hindered phenol-based antioxidant in the hexane to prepare a solution; dropping the solution onto the surface of a silicon wafer to form droplets; and drying the droplets to prepare a standard sample for calibration of the time-of-flight secondary ion mass spectrometer.

[0012] This method for preparing calibration standards for time-of-flight secondary ion mass spectrometers allows hindered phenol-based antioxidants to be dispersed and immobilized on a solid surface, such as a silicon wafer. This makes it possible to prepare calibration standards that cover a wide range of mass numbers and that can generate more accurate mass calibration curves for use in mass calibration of time-of-flight secondary ion mass spectrometers.

[0013] In this case, it is preferable that the container into which the hindered phenol-based antioxidant and hexane are placed is made of polypropylene.

[0014] Such polypropylene containers can be used to appropriately prepare the dissolving solution for preparing the calibration standard samples of the present invention.

[0015] Furthermore, it is preferable that the silicon wafer onto which the dissolving solution is dropped is a mirror-finished silicon wafer.

[0016] By using such a mirror-finished silicon wafer, it can be made more suitable as a calibration standard sample.

[0017] It is also preferable that the droplets are dried by spin drying.

[0018] Drying by such spin drying makes it possible to produce calibration standard samples for time-of-flight secondary ion mass spectrometers with good productivity.

[0019] The present invention also provides a calibration method for a secondary ion mass spectrometer using a standard calibration sample prepared by any of the above methods for preparing a standard calibration sample for a time-of-flight secondary ion mass spectrometer, wherein the calibration target is negative secondary ions.

[0020] When a calibration standard sample is prepared using a hindered phenol-based antioxidant as in the present invention, negative secondary ions are likely to be emitted, resulting in a high detection intensity of the negative secondary ions. Therefore, in the present invention, it is preferable to perform mass calibration of the negative secondary ions using a time-of-flight secondary ion mass spectrometer.

[0021] In this case, it is preferable to calibrate the time-of-flight secondary ion mass spectrometer using a mass calibration curve created from fragment ions with mass numbers of 12 to 515.

[0022] The calibration standard sample of the present invention provides high mass accuracy, particularly for fragment ions with mass numbers of 12 to 515. Therefore, in the method for calibrating a time-of-flight secondary ion mass spectrometer, it is preferable to use a mass calibration curve created from fragment ions with such mass numbers. [Effects of the Invention]

[0023] The method for preparing calibration standards for a time-of-flight secondary ion mass spectrometer of the present invention makes it possible to prepare calibration standards for use in mass calibration of a time-of-flight secondary ion mass spectrometer, which have a wide range of mass numbers and can produce more accurate mass calibration curves. In particular, accurate mass calibration curves can be provided for negative secondary ion mass numbers from 12 to 515. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a flow chart showing an example of a method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer according to the present invention. [Figure 2] 1 is a graph showing a mass spectrum for mass calibration in an example. [Figure 3] 1 is a graph showing a mass calibration curve obtained from a mass calibration mass spectrum in an example. [Figure 4] 1 is a graph showing a mass calibration curve calculated by extrapolation from the mass calibration points in Comparative Example 1. [Figure 5] 10 is a graph showing a mass spectrum for mass calibration in Comparative Example 2. [Figure 6] 10 is a graph showing a mass calibration curve obtained from a mass spectrum for mass calibration in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below, but the present invention is not limited thereto.

[0026] In order to solve the above-mentioned problems, the present inventors have discovered a method for preparing a mass calibration standard sample using a hindered phenol-based antioxidant, and have discovered that it is possible to provide an accurate mass calibration curve using the mass calibration standard sample, thereby completing the present invention.

[0027] The present invention is a method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer, comprising the steps of: adding a hindered phenol-based antioxidant to a container; adding hexane to the container; stirring the solution in the container to dissolve the hindered phenol-based antioxidant in the hexane to prepare a solution; dropping the solution onto a surface of a silicon wafer to form droplets; and drying the droplets to prepare a standard sample for calibration of a time-of-flight secondary ion mass spectrometer.

[0028] Each step will be described in more detail below with reference to the drawings.

[0029] FIG. 1 is a flow diagram showing an example of a method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer according to the present invention.

[0030] [Step S11: Adding a hindered phenol-based antioxidant to a container] 1 is a step of adding a hindered phenol-based antioxidant to a container. In this step S11, for example, 1 mL of a solution of Irganox 259 (product name) (manufactured by BASF Japan Ltd.) as a hindered phenol-based antioxidant is added to a polypropylene container.

[0031] Here, the container into which the hindered phenol-based antioxidant is placed is preferably made of polypropylene, but the material of the container is not limited to polypropylene and may be made of a resin material such as polyethylene, polycarbonate, polytetrafluoroethylene, or a perfluoroalkyl ether copolymer, or a glass bottle.

[0032] Hindered phenol antioxidants are generally supplied as powders, so they can be dissolved in an aromatic organic solvent such as toluene or xylene, or in a straight-chain alkane such as hexane, or they can be used in a state where they are pre-dissolved in a solvent.In addition to Irganox 259, Irganox 245, Irganox 1035, and Irganox 1098, which have similar molecular structures, can also be used as hindered phenol antioxidants.

[0033] Furthermore, for use as a mass calibration standard for TOF-SIMS, a solution concentration of 1 to 100 μg / mL of hindered phenolic antioxidants is suitable. When a sufficient amount of antioxidant is added and the solution concentration is 1 μg / mL, the detection intensity by TOF-SIMS is sufficient, ensuring sufficient mass calibration accuracy and preventing erroneous detection of target ions. When the antioxidant is not added in excessive amounts and the solution concentration is 100 μg / mL or less, the detection intensity by TOF-SIMS is sufficient, while the effects of antioxidant-induced contamination in the TOF-SIMS analysis chamber are suppressed, reducing erroneous detection of ions caused by the antioxidant when measuring unknown samples.

[0034] [Step S12: Add hexane to the container] Step S12 in FIG. 1 is a step of adding hexane to the container. In step S12, for example, 9 mL of hexane is added to the container to adjust the concentration of the hindered phenol-based antioxidant to a desired concentration. The amount of hexane added varies depending on the concentration of the hindered phenol-based antioxidant solution before preparation and the amount required to drip onto the wafer. For example, if the concentration of the hindered phenol-based antioxidant solution before preparation is 1000 μg / mL and the amount to be dripped onto the wafer is 10 mL, then 9 mL of hexane is added to adjust the concentration of the hindered phenol-based antioxidant solution after preparation to 100 μg / mL.

[0035] The introduction of hexane into the vessel may be carried out before the introduction of the hindered phenol-based antioxidant. That is, the order of steps S11 and S12 may be reversed. Furthermore, the introduction of the hindered phenol-based antioxidant and the introduction of hexane into the vessel may be carried out simultaneously. That is, steps S11 and S12 may be carried out simultaneously.

[0036] [Step S13: Stirring] Step S13 in Fig. 1 is a step of dissolving the hindered phenol-based antioxidant in hexane by stirring the solution in the container prepared in steps S12 to prepare a solution. In this step S13, for example, the container is sealed with a lid and shaken for 10 to 20 seconds at an amplitude of 20 to 50 mm and a frequency of 1 to 3 Hz to homogenize the solution. In this step, the amplitude, frequency, and time are not limited as long as a solution can be prepared.

[0037] [Step S21: Preparation of silicon wafer] The solution prepared in steps S11 to S13 is dropped onto the surface of a silicon wafer in step S14, as described below. In step S21 of Figure 1, a silicon wafer is prepared. Of course, steps S11 to S13 and step S21 can be performed independently, and either can be performed first. The silicon wafer prepared and used here refers to a silicon wafer that has undergone final cleaning in its manufacturing process and has no metal or organic contamination on its surface. The silicon wafer used here is preferably a p-type or n-type mirror-finished silicon wafer with a resistivity of 0.1 Ωcm or higher. Furthermore, to prepare a mass calibration standard, it is preferable to clean the silicon wafer to remove metal impurities and organic matter from its surface. This is because if a mass calibration standard is prepared using a wafer with metal or organic contamination on its surface, if the ions have similar masses to those used for mass calibration, the wrong ions may be selected for mass calibration, resulting in reduced accuracy. Furthermore, when the resistivity of the wafer falls below 0.1 Ωcm, the concentration of dopants such as boron and phosphorus increases, and if the mass of ions containing these dopants is close to that of ions used for mass calibration, the wrong ions may be selected for mass calibration, thereby reducing the accuracy of mass calibration.In this way, to clean the silicon wafer, it is preferable to remove the native oxide film on the wafer surface with, for example, a 1% hydrofluoric acid aqueous solution.

[0038] [Step S14: Dropping the solution onto the silicon wafer] Step S14 in Fig. 1 is a step of dripping the solution onto the surface of a silicon wafer to form droplets. In this step S14, an appropriate amount of the prepared hindered phenol-based antioxidant solution is extracted with a syringe and dripped onto the center of a clean, mirror-finished silicon wafer. The amount of solution to be dripped is preferably 10 to 30 mL for a silicon wafer with a diameter of 200 mm, and the area to which the solution is dripped is preferably within 40 mm from the center of the silicon wafer.

[0039] [Step S15: Drying] Step S15 in Fig. 1 is a step of drying the droplets dropped in step S14 to prepare a standard sample for calibration of the time-of-flight secondary ion mass spectrometer. Natural drying may be used as the drying method, but spin drying is more preferable. The spin drying conditions are a rotation speed of 2000 to 3500 rpm and a rotation time of 25 to 60 seconds, and it is preferable that the dropped solution is completely dried.

[0040] In this manner, a calibration standard sample for a time-of-flight secondary ion mass spectrometer can be prepared. The present invention also provides a calibration method for a secondary ion mass spectrometer using a calibration standard sample prepared by the above-mentioned method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer, characterized in that the calibration target is negative secondary ions.

[0041] [TOF-SIMS secondary ion mass calibration] As in the present invention, the dried wafer is used as a standard sample for mass calibration. In this case, in the present invention, it is preferable to perform mass calibration of negative secondary ions using TOF-SIMS. Samples using hindered phenol-based antioxidants tend to emit negative secondary ions, resulting in a higher detection intensity of negative secondary ions. Furthermore, a higher secondary ion intensity results in a higher ratio to background signal intensity (S / N ratio), and a mass spectrum with high mass accuracy can be obtained. For this reason, it is preferable to perform mass calibration of negative secondary ions using TOF-SIMS.

[0042] In addition, in order to identify the chemical species measured by TOF-SIMS, it is considered preferable that the mass error be ±1 ppm or less, which is expressed by the following formula. (Measured mass number - theoretical mass number) ÷ theoretical mass number × 1,000,000 (ppm)

[0043] In TOF-SIMS, hydrogen, carbon, and oxygen tend to become negative secondary ions, so negative secondary ions are easily detected from these elements adhering to the sample surface and from components of lower alcohols. Furthermore, Irganox 259 is synthesized by an ester reaction between the basic raw material 4-hydroxy-3,5-di-butyl phenyl propionic acid (mass number 277) and propylene glycol, generating secondary ions with the mass numbers of the constituent substances, as well as related fragment ions and their molecular ions. For this reason, those with mass numbers greater than 163 generate fragment ions and molecular ions that reflect the molecular structure. Furthermore, those with mass numbers less than 100 also generate ions with CH2 attached to the benzene ring and fragment ions of the benzene ring. Therefore, the mass spectrum shows the following: mass number 12 (C), mass number 16 (O), mass number 31 (CHO), mass number 41 (COH), mass number 45 (CHO), mass number 57 (CHO), mass number 65 (COH), mass number 73 (CHO), mass number 81 (COH), mass number 93 (CHO), mass number 163 (C 11 H 15 O), mass number 175 (C 12 H 15 O), mass number 205 (C 14 H 21 O), mass number 219 (C 15 H 23 O), mass number 231 (C 16 H 23 O), mass number 259 (C 17 H 23 O2), mass number 277 (C 17 H 25 O3), mass number 317 (C 20 H 29 O3), mass number 346 (C 22 H 34 O3), mass number 388 (C 25 H 40 O3), mass number 416 (C 27 H 44 O3), mass number 443 (C 29 H 47 O3), mass number 459 (C 30 H 51 O3), mass number 474 (C 31 H54 O3), mass number 499 (C 33 H 55 O3), mass number 515 (C 34 H 59 O3) is detected.

[0044] Furthermore, in the present invention, it is particularly preferable to calibrate the time-of-flight secondary ion mass spectrometer using a mass calibration curve created from fragment ions with mass numbers of 12 to 515. This is because, although the detected fragment ion intensity decreases as the mass number increases, when the mass number is 520 or less, the difference between the fragment ion intensity associated with hindered phenol antioxidants such as Irganox 259 and the ion intensity associated with other deposits becomes large, making it easy to identify the fragment ions required for mass calibration.

[0045] In TOF-SIMS, the theoretical mass numbers of fragment ions related to hindered phenolic antioxidants such as Irganox 259 are known, and by measuring these as mass calibration points, the mass deviation can be determined by comparing the measured mass number with the theoretical mass number. A calibration curve showing the relationship between mass number and mass deviation is created from the mass deviation obtained for each fragment ion. The measured mass number when measuring any ion can be calibrated based on the created calibration curve. [Example]

[0046] EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0047] [Example] The hindered phenol antioxidant solution (dissolution solution) for the mass calibration standard sample was prepared as follows. First, 1000 μg / mL Irganox 259 (Fujifilm Wako Pure Chemical Industries, Ltd.) (hexane solvent) was used. 1 mL of Irganox 259 and 9 mL of hexane (special grade) (Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 50 mL polypropylene bottle (AS ONE Corporation) and sealed (steps S11 and S12). Next, the solution was stirred using an AS ONE Corporation shaker at an amplitude of 30 mm and a frequency of 3 Hz for 20 seconds to prepare a 100 μg / mL Irganox 259 solution (step S13). A 200 mm diameter, p-type (100) mirror-polished silicon wafer with a resistivity of 10 Ωcm was prepared and used as the mass calibration standard sample (step S21). The mass calibration standard sample was prepared by immersing the wafer in a 1 wt% hydrofluoric acid solution for 3 minutes to remove the native oxide film from the wafer surface, followed by rinsing with ultrapure water for 10 minutes. Next, 10 mL of a 100 μg / mL Irganox 259 solution was dropped onto the center of the silicon wafer using a 30 mL disposable syringe (step S14), and then drying the wafer in a spin dryer at 3000 rpm for 30 seconds (step S15).

[0048] The mass calibration standard sample thus prepared was cut into 15 mm squares from the center of the silicon wafer and placed on a sample holder for measurement by TOF-SIMS. The TOF-SIMS was performed using an ULVAC-PHI nano-TOFII with a Bi3 ion source as the primary ion source. ++ Measurement was performed for approximately 5 minutes under the following measurement conditions: acceleration voltage 30 kV, primary ion current 10 nA, raster size 200 μm square, with a beam buncher, and negative secondary ion measurement.

[0049] In TOF-SIMS, the relationship between the mass number and the time of flight of secondary ions emitted from the sample to the detector is determined by the following equation: T=L·(M / 2eU) 1 / 2 (formula) T: flight time, L: flight distance, M: mass, e: charge, U: extraction potential Since L, e, and U are constant, T ∝ M1 / 2 is. Therefore, if the time of flight is known, the mass number can be calculated.

[0050] Generally, mass calibration in TOF-SIMS uses a mass calibration curve (theoretical mass calibration curve) for the time of flight at a mass number based on this relationship. Therefore, if the time of flight at a certain mass number deviates from the theoretical mass calibration curve, and the ion composition at that mass number can be determined to be accurate, that point can be used as a calibration point to correct the theoretical mass calibration curve.

[0051] Of the mass spectra measured for mass calibration, those with mass numbers from 0 to 515 are shown in Figure 2, and the mass calibration curve obtained from the mass calibration mass spectra is shown in Figure 3. With the mass calibration standard sample prepared using a hindered phenol antioxidant, the negative secondary ions shown on the labels in Table 1 are detected, so it is possible to correct the theoretical mass calibration curve by correcting for the flight times at the measured mass values ​​of these secondary ions and calculating an approximate mass calibration curve.

[0052] By appropriately correcting the mass calibration curve within the mass range required for measurement, it is possible to obtain measured mass values ​​that are extremely close to the theoretical values. Table 2 shows the measured mass values ​​of ions obtained in this way, the theoretical mass values, and the errors between the theoretical mass values.

[0053] [Table 1] [Table 2]

[0054] As can be seen from Figure 2, Tables 1 and 2, the nuclei from O (mass number ≒ 16) to C 11 H 29 The mass error is within ±1 ppm up to O2Si3 (mass number ≒ 277), making it possible to identify chemical species.

[0055] Next, as comparative examples, the mass calibration methods of Comparative Examples 1 and 2 below were carried out, and measurements were carried out by TOF-SIMS under the same conditions as in the examples.

[0056] [Comparative Example 1] As Comparative Example 1, the results of a general mass calibration method are shown.

[0057] Table 3 lists the ions (mass numbers 13 to 49) used for mass calibration, and Figure 4 shows the mass calibration curve calculated based on this by extrapolating from the mass calibration points. Table 4 shows the actual mass values ​​of the measured ions and the theoretical mass values, as well as the error between the theoretical mass values. It can be seen that the mass error increases with increasing mass numbers.

[0058] [Table 3] [Table 4]

[0059] Comparative Example 2 As Comparative Example 2, the results of the mass calibration method of Patent Document 1 are shown.

[0060] The measured mass calibration mass spectrum (mass numbers 645 to 2600) is shown in Figure 5, and the mass calibration curve obtained from the mass calibration mass spectrum is shown in Figure 6. Table 5 shows the actual mass values ​​and theoretical mass values ​​of the measured ions, as well as the error between the theoretical mass values. It can be seen that the mass error increases as the mass number decreases.

[0061] [Table 5]

[0062] The present specification includes the following aspects. [1]: A method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer, comprising: adding a hindered phenol-based antioxidant to a container; charging hexane into the vessel; a step of dissolving the hindered phenol-based antioxidant in the hexane by stirring the solution in the container to prepare a solution; a step of dropping the solution onto a surface of a silicon wafer to form droplets; drying the droplets to prepare a calibration standard for a time-of-flight secondary ion mass spectrometer; A method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer, comprising: [2]: The method for preparing a standard sample for calibration of the time-of-flight secondary ion mass spectrometer according to [1] above, wherein the container into which the hindered phenol-based antioxidant and hexane are placed is made of polypropylene. [3]: The method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer according to [1] or [2] above, wherein the silicon wafer onto which the dissolving solution is dropped is a mirror-finished silicon wafer. [4]: A method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer according to any one of [1] to [3] above, wherein the droplets are dried by spin drying. [5]: A calibration method for a secondary ion mass spectrometer using a calibration standard sample prepared by the method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer according to any one of [1] to [3] above, wherein the calibration target is a negative secondary ion. [6]: A method for calibrating a time-of-flight secondary ion mass spectrometer according to [5] above, wherein the time-of-flight secondary ion mass spectrometer is calibrated using a mass calibration curve created from fragment ions with mass numbers of 12 to 515.

[0063] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer, comprising: adding a hindered phenol-based antioxidant to a container; charging hexane into the vessel; a step of dissolving the hindered phenol-based antioxidant in the hexane by stirring the solution in the container to prepare a solution; a step of dropping the solution onto a surface of a silicon wafer to form droplets; drying the droplets to prepare a calibration standard for a time-of-flight secondary ion mass spectrometer; 1. A method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer, comprising:

2. 2. The method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer according to claim 1, wherein the container into which the hindered phenol-based antioxidant and hexane are placed is made of polypropylene.

3. 2. The method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer according to claim 1, wherein the silicon wafer onto which the dissolving solution is dropped is a mirror-finished silicon wafer.

4. 2. The method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer according to claim 1, wherein the droplets are dried by spin drying.

5. 5. A method for calibrating a secondary ion mass spectrometer using a calibration standard sample prepared by the method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer according to claim 1, wherein the calibration target is negative secondary ions.

6. 6. The method for calibrating a time-of-flight secondary ion mass spectrometer according to claim 5, wherein the calibration of the time-of-flight secondary ion mass spectrometer is performed using a mass calibration curve created from fragment ions with mass numbers of 12 to 515.

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