Method for producing calibration standard sample of time-of-flight secondary ion mass spectroscope and method for calibrating time-of-flight secondary ion mass spectroscope

Abstract

To provide a calibration standard sample with a wide range of mass number and with high mass accuracy as a calibration standard sample to be used in mass calibration of TOF-SIMS (time-of-flight secondary ion mass spectroscope).SOLUTION: A method for producing a calibration standard sample of time-of-flight secondary ion mass spectroscope includes the steps for: inputting fine polytetrafluoroethylene particles to water, so as to produce a mixture of the fine polytetrafluoroethylene particles with water; adding a fluorine-based surface-active agent to the mixture of the fine polytetrafluoroethylene particles with water; stirring-up the mixture to allow the fine polytetrafluoroethylene particles to distribute in water, to thereby produce an aqueous dispersion where the fine polytetrafluoroethylene particles are distributed in water; forming droplets by dripping the aqueous dispersion onto a front surface of a silicon wafer; and drying the droplets so as to produce the calibration standard sample of the time-of-flight secondary ion mass spectroscope.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 and theoretical values ​​of the fragment ions. A common mass calibration method is to use low-mass C x H y The mass calibration curve using fragment ions 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. This method uses a mass calibration standard sample made of low-molecular-weight PTFE obtained by heating polytetrafluoroethylene (hereinafter sometimes abbreviated as PTFE) from above its melting point to 600°C, bringing it into contact with one or more selected from molecular fluorine, nitrogen trifluoride, halogen fluoride, or rare gas fluorides at an ambient temperature of 200 to 550°C, and cooling the generated gas, and is characterized by the ability to obtain stable mass spectra with a mass number (m / z) interval of 50, with CF2 as the basic structure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-292093 [Patent Document 2] Japanese Patent Application Publication No. 8-233781 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 x H y Because the mass calibration is performed up to the high mass region by extrapolating a mass calibration curve using fragment ions, there is a large discrepancy between the measured mass values ​​and the theoretical values ​​at the high mass end, and the mass accuracy is poor, making it difficult to identify chemical species.

[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] Patent Document 2 describes that PTFE fine powder dispersed in a fluorine-based solvent can be used as a standard material for mass calibration in SIMS, but does not describe dripping the dispersed solution onto a silicon wafer and drying it. SIMS measurements are performed in a high vacuum, so with a solution sample, there is a possibility that the inside of the measurement chamber will be contaminated due to the evaporation of solution components, or that the state of the sample will change due to the evaporation of the material being measured under high vacuum.

[0009] The present invention has been made to solve the above problems, and aims to provide a calibration standard sample that has a wide range of mass numbers and high mass accuracy as a calibration standard sample to be used for mass calibration of a time-of-flight secondary ion mass spectrometer. [Means for solving the problem]

[0010] 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 polytetrafluoroethylene microparticles to water to prepare a mixture of polytetrafluoroethylene microparticles and water; adding a fluorine-based surfactant to the mixture of polytetrafluoroethylene microparticles and water; stirring the mixture to disperse the polytetrafluoroethylene microparticles in water to prepare an aqueous dispersion of the polytetrafluoroethylene microparticles in water; dropping the aqueous dispersion onto the 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.

[0011] This method of preparing calibration standards for time-of-flight secondary ion mass spectrometers involves dispersing and fixing polytetrafluoroethylene microparticles onto a solid surface, such as a silicon wafer. This makes it possible to prepare calibration standards with a wide range of mass numbers and high mass accuracy for use in mass calibration of time-of-flight secondary ion mass spectrometers.

[0012] In this case, in the step of adding the fluorosurfactant to the mixture of polytetrafluoroethylene fine particles and water, the volume ratio of the fluorosurfactant to be added is preferably 0.1 to 5% relative to the mixture.

[0013] With such a volume ratio of the fluorochemical surfactant, the polytetrafluoroethylene fine particles can be easily dispersed in the liquid and can be easily dried.

[0014] Furthermore, it is preferable that the silicon wafer onto which the aqueous dispersion of polytetrafluoroethylene fine particles dispersed in water is dropped is a mirror-finished silicon wafer.

[0015] By using such a mirror-finished silicon wafer, it can be made more suitable as a calibration standard sample.

[0016] It is also preferable that the droplets are dried by spin drying.

[0017] Drying by such spin drying makes it possible to produce calibration standard samples for time-of-flight secondary ion mass spectrometers with good productivity.

[0018] 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 positive secondary ions.

[0019] In a sample using PTFE, positive secondary ions are easily emitted, and the detection intensity of the positive secondary ions is high. Therefore, in the present invention, it is preferable to perform mass calibration of the positive secondary ions using a time-of-flight secondary ion mass spectrometer.

[0020] 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 981.

[0021] The calibration standard sample of the present invention provides high mass accuracy, particularly for fragment ions with mass numbers of 12 to 981. 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]

[0022] The method for preparing calibration standards for a time-of-flight secondary ion mass spectrometer of the present invention enables the preparation of calibration standards with a wide range of mass numbers and high mass accuracy for use in mass calibration of a time-of-flight secondary ion mass spectrometer. In particular, it is possible to provide accurate mass calibration curves for positive secondary ion mass numbers from 12 to 981. [Brief explanation of the drawings]

[0023] [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

[0024] The present invention will be described in detail below, but the present invention is not limited thereto.

[0025] To solve the above problems, the present inventors discovered that by uniformly dispersing a high-molecular-weight PTFE powder sample in a liquid, dropping it onto a silicon wafer, and drying it, and analyzing the resulting standard sample by TOF-SIMS, it is possible to obtain a mass spectrum containing ions with a mass number (m / z) interval of 50, each having a CF2 basic structure, and their fragment ions, which are suitable for creating a mass calibration curve. Based on this finding, the present inventors have completed the present invention.

[0026] 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 polytetrafluoroethylene microparticles to water to prepare a mixture of polytetrafluoroethylene microparticles and water; adding a fluorine-based surfactant to the mixture of polytetrafluoroethylene microparticles and water; stirring the mixture to disperse the polytetrafluoroethylene microparticles in water to prepare an aqueous dispersion of the polytetrafluoroethylene microparticles in water; dropping the aqueous dispersion onto the 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.

[0027] Each step will be described in more detail below with reference to the drawings.

[0028] 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.

[0029] [Step S11: Adding PTFE microparticles to water] Step S11 in FIG. 1 is a step of adding polytetrafluoroethylene microparticles (PTFE microparticles) to water to prepare a mixture of polytetrafluoroethylene microparticles and water. The water used here is preferably ultrapure water. In this step, for example, 50 mL of ultrapure water is added to a container containing 0.1 g of PTFE microparticles. The size of the PTFE microparticles used here is preferably approximately 1 to 50 μm. If the size of the PTFE microparticles is 50 μm or less, they are less susceptible to the influence of static electricity during measurement, improving mass accuracy. Furthermore, if the size of the PTFE microparticles is 1 μm or more, they are less likely to aggregate in the liquid, improving mass accuracy.

[0030] [Step S12: Adding Fluorosurfactant] Step S12 in FIG. 1 is a step of adding a fluorosurfactant to the mixture of polytetrafluoroethylene microparticles and water prepared in step S11. In step S12, for example, 0.5 mL of fluorosurfactant can be added to achieve a volumetric ratio of 1%. Here, the volumetric ratio of the fluorosurfactant added is preferably 0.1 to 5% relative to the mixture. If the volumetric ratio of the fluorosurfactant is 0.1% or more, the PTFE microparticles are easily dispersed in the liquid, and aggregation can be suppressed. Furthermore, if the volumetric ratio of the fluorosurfactant is 5% or less, the viscosity of the liquid can be kept low and the vapor pressure can be kept in a high range, making drying easy.

[0031] [Step S13: Stirring] Step S13 in Fig. 1 is a step of stirring the mixture prepared in S12 to disperse the polytetrafluoroethylene microparticles in water, thereby preparing an aqueous dispersion of polytetrafluoroethylene microparticles dispersed in water. In this step S13, for example, the container is closed 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, thereby dispersing the PTFE microparticles in water. In this step, the amplitude, frequency, and time are not limited to those described above, as long as an aqueous dispersion can be prepared.

[0032] [Step S21: Preparation of silicon wafer] The aqueous dispersion 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 the silicon substrate 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 sample, it is preferable to clean the silicon wafer to remove any metal impurities or organic matter from its surface. To clean the silicon wafer, it is preferable to remove the native oxide film from the wafer surface using, for example, a 1% hydrofluoric acid solution.

[0033] [Step S14: Dropping the aqueous dispersion onto the silicon wafer] Step S14 in Fig. 1 is a step of dripping an aqueous dispersion onto the surface of a silicon wafer to form droplets. In this step S14, an appropriate amount of the aqueous dispersion containing dispersed PTFE microparticles is extracted with a syringe and dripped onto the center of a clean, mirror-finished silicon wafer. The amount of aqueous dispersion 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 aqueous dispersion is dripped is preferably within 40 mm from the center of the silicon wafer.

[0034] [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 aqueous dispersion is completely dried.

[0035] 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-described method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer, characterized in that the calibration target is positive secondary ions.

[0036] [TOF-SIMS secondary ion mass calibration] In the present invention, the dried wafer is used as a standard sample for mass calibration. Samples using PTFE tend to emit positive secondary ions, resulting in a higher detection intensity of the positive secondary ions. Furthermore, a higher secondary ion intensity results in a higher signal-to-noise ratio to the background signal intensity (S / N ratio), resulting in a mass spectrum with high mass accuracy. Therefore, it is preferable to perform mass calibration of the positive secondary ions using TOF-SIMS.

[0037] 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)

[0038] PTFE has a basic structure of CF2, which is a bond between carbon and fluorine, and exists in a polymer state. Therefore, when PTFE is irradiated with primary ions during TOF-SIMS measurement, the carbon atoms and carbon-fluorine bonds, C and C, are detected. x F y , in the mass range higher than C5F9 (CF2) n It has the property of emitting fragment ions with (n=1 to 15) added.

[0039] For this reason, the mass spectrum detects mass numbers 12 (C), 31 (CF), 50 (CF), 62 (C), 69 (CF), 74 (C), 93 (C), 100 (C), 112 (C), 119 (C), 124 (C), 131 (C), 143 (C), 155 (C), 162 (C), 169 (C), 181 (C), 193 (C), and 231 (C). CF is added and mass numbers are increased by 50.

[0040] 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 981. This is because, although the detected fragment ion intensity decreases as the mass number increases, if the mass number is 1000 or less, the difference between the fragment ion intensity associated with PTFE and the ion intensity due to other deposits becomes large, making it easy to identify the fragment ions.

[0041] In TOF-SIMS, the theoretical mass numbers of PTFE-related fragment ions are known, and by measuring these as mass calibration points, the mass deviation is 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. Based on the created calibration curve, the measured mass number when measuring any ion can be calibrated. [Example]

[0042] 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.

[0043] [Example] An aqueous dispersion of PTFE microparticles was prepared as follows. First, 0.1 g of PTFE powder manufactured by Maishidai Co., Ltd. (with an average particle size of 1.6 μm) was placed in a 50 mL polypropylene bottle manufactured by AS ONE Corporation, and 49.9 mL of ultrapure water was added thereto (step S11). Then, 0.5 mL of a fluorochemical surfactant (product name: Surflon) manufactured by AGC Seimi Chemical Co., Ltd. was added thereto and the bottle was sealed (step S12). Next, the bottle was shaken using an AS ONE shaker at an amplitude of 30 mm and a frequency of 3 Hz for 20 seconds to agitate the PTFE microparticles so that they were uniformly dispersed in the aqueous dispersion (step S13). A 200 mm diameter, p-type (100) mirror-finished silicon wafer with a resistivity of 10 Ωcm was prepared and used as a mass calibration standard sample (step S21). The mass calibration standard sample was prepared by immersing the wafer in a 1 wt% aqueous solution of hydrofluoric acid for 3 minutes to remove the native oxide film from the wafer surface, followed by rinsing with ultrapure water for 10 minutes. Next, 20 mL of an aqueous dispersion of PTFE microparticles was dropped onto the center of the silicon wafer using a 30 mL disposable syringe (step S14), and then drying was performed using a spin dryer at 3000 rpm for 30 seconds (step S15).

[0044] 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 positive secondary ion measurement.

[0045] 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 ∝ M 1 / 2 is. Therefore, if the time of flight is known, the mass number can be calculated.

[0046] 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.

[0047] Of the mass spectra measured for mass calibration, those for mass numbers 0 to 200 are shown in Figure 2, and the mass calibration curve obtained from the mass calibration mass spectra is shown in Figure 3. In the mass calibration standard sample prepared by dispersing PTFE microparticles, the positive 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.

[0048] 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.

[0049] [Table 1] [Table 2]

[0050] As can be seen from Figure 2, Tables 1 and 2, the mass number of Si (mass number ≒ 28) to C 15 H 22 The mass error is within ±1 ppm up to OSi (mass number ≈ 262), making it possible to identify chemical species. Furthermore, it can be used as a mass calibration sample for TOF-SIMS without using low-molecular-weight PTFE as in Patent Document 2.

[0051] 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.

[0052] [Comparative Example 1] As Comparative Example 1, the results of a general mass calibration method are shown.

[0053] Table 3 lists the ions (mass numbers 27 to 69) 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 as the mass number increases.

[0054] [Table 3] [Table 4]

[0055] Comparative Example 2 As Comparative Example 2, the results of the mass calibration method of Patent Document 1 are shown.

[0056] 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.

[0057] [Table 5]

[0058] The present specification includes the following aspects. [1]: A method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer, comprising the steps of: adding polytetrafluoroethylene microparticles to water to prepare a mixture of polytetrafluoroethylene microparticles and water; adding a fluorine-based surfactant to the mixture of polytetrafluoroethylene microparticles and water; stirring the mixture to disperse the polytetrafluoroethylene microparticles in water to prepare an aqueous dispersion of the polytetrafluoroethylene microparticles in water; dropping the aqueous dispersion onto the 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. [2]: The method for preparing a standard sample for calibration of a time-of-flight secondary ion mass spectrometer according to [1] above, wherein in the step of adding the fluorosurfactant to the mixture of polytetrafluoroethylene fine particles and water, the volume ratio of the fluorosurfactant to be added is 0.1 to 5% relative to the mixture. [3]: A 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 aqueous dispersion of polytetrafluoroethylene microparticles dispersed in water is dropped is a mirror-finished silicon wafer. [4]: The method for preparing a standard sample for calibration of 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 [4] above, wherein the calibration target is a positive 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 981.

[0059] 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: A step of adding polytetrafluoroethylene fine particles into water to prepare a mixture of polytetrafluoroethylene fine particles and water; adding a fluorosurfactant to the mixture of polytetrafluoroethylene fine particles and water; a step of stirring the mixture to disperse the polytetrafluoroethylene microparticles in water, thereby preparing an aqueous dispersion in which the polytetrafluoroethylene microparticles are dispersed in water; a step of dropping the aqueous dispersion 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 in the step of adding the fluorosurfactant to the mixture of polytetrafluoroethylene fine particles and water, the volume ratio of the fluorosurfactant to be added is 0.1 to 5% with respect to the mixture.

3. 2. The method for preparing a calibration standard sample for a time-of-flight secondary ion mass spectrometer according to claim 1, wherein the silicon wafer onto which the aqueous dispersion of polytetrafluoroethylene microparticles dispersed in water 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 positive 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 981.

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