Quantitative analysis method of elements

Abstract

The present invention provides a method for quantitative analysis of elements in a sample gas, such as LA-ICP-MS, without using a solid standard sample. The present invention is characterized in that, in a method for quantitative analysis of elements in a solid sample by introducing a sample gas into an inductively coupled plasma mass spectrometer, the concentration of each element contained in the sample gas generated from the solid sample is measured by using the signal intensity obtained by introducing the standard solution from a solution introduction means to a torch part, by directly supplying (standard addition) a standard solution containing a specific element at a known concentration at a flow rate of 3 μL / min or less.

Description

Technology Field

[0001] The present invention relates to a method for quantitative analysis of elements, and more particularly to a method for quantitatively analyzing an element of a target from a sample gas containing the target using an inductively coupled plasma mass spectrometer. Background Technology

[0002] Recently, it has become known that inductively coupled plasma mass spectrometry (hereinafter abbreviated as ICP-MS) is used for the analysis of metals, organic substances, etc., incorporated into substrates such as semiconductor wafers, and for the analysis of metals, etc., among particles suspended in the gas phase. In this inductively coupled plasma mass spectrometry, an analysis method called laser ablation ICP-MS (hereinafter abbreviated as LA-ICP-MS) is known, in which a solid sample is irradiated with laser light to evaporate and atomize the sample, and the atomized sample is analyzed directly.

[0003] In the case of LA-ICP-MS, a general quantitative analysis method is known to semi-quantify each element of a solid sample by using multi-element glass or solid standard samples with compositions similar to those of the sample being measured, and calculating concentration conversion factors for each element. However, since these solid standard samples are commercially available only for glass of specific compositions or compositions containing specific metals, there are few elements guaranteed to be present in solid standard samples. Furthermore, if the components of the sample being measured and the solid standard samples are not identical, the amount of particles emitted by laser irradiation differs, which can make accurate quantification difficult in some cases.

[0004] Furthermore, regarding elements contained in a solid sample that are not guaranteed as solid standard samples, a method for quantifying them using relative sensitivity coefficients is known. In this case, the detection sensitivity obtained using a standard solution in the general solution introduction method of ICP-MS is used for correction. Specifically, a relative sensitivity coefficient (A / A') is calculated from the sensitivity of the guaranteed element (A) by laser irradiation and the sensitivity of the same element obtained from the standard solution introduced by solution introduction (A'), and this is applied to the sensitivity B' of the non-guaranteed element to determine the sensitivity B when laser irradiated. By this method, the weight of all elements detected when the solid sample is laser irradiated is calculated, and the concentration of each element is calculated from the sum of the absolute amounts. However, in the case of this method of quantification using relative sensitivity coefficients, since the introduction of the sample gas generated by laser irradiation and the introduction of the standard solution by solution introduction are performed as separate operations, the plasma conditions are different, and a problem arises in that not all elements are given the same coefficient.

[0005] Based on this, a method for quantitative analysis using LA-ICP-MS has been proposed for quantitative analysis using a standard solution without using a solid standard sample (e.g., Patent Document 1). In this prior art, a standard solution containing a known amount of an element contained in a solid sample is heated and vaporized, then introduced into an ICP-MS. The weight of each element per count of the total element's detection signal intensity is determined from the detection signal intensity, and this is used to perform quantitative analysis of the element contained in the solid sample. Specifically, 3 to 10 μL of the standard solution is introduced into an electric furnace, water is evaporated in advance at approximately 100°C, and then the temperature of the furnace is rapidly increased to several thousand degrees (°C) to evaporate the element. The evaporated element is transported by argon gas introduced into the furnace and introduced into the ICP-MS. As a result, the entire amount of the element contained in the standard solution introduced into the electric heating furnace is introduced into the plasma of the ICP-MS, and from the amount of the standard solution introduced and the detection signal intensity, the weight of the element per count of the detection signal intensity can be determined for the element contained in the standard solution.

[0006] In the prior art described in this patent document 1, simultaneous analysis of multiple elements is performed using TOF (TIME OF FLIGHT)-ICP-MS. Since this TOF-ICP-MS has lower sensitivity compared to the ICP-MS of a quadrupole mass spectrometer, it is difficult to analyze fine particles. Furthermore, if the temperature of the electric furnace is raised to thousands of degrees, the argon gas expands, and the detection sensitivity of the ICP-MS tends to change. In addition, the element introduced into the ICP-MS by heating the furnace is for a few seconds, and in the case of a quadrupole ICP-MS that does not use TOF-ICP-MS, the analysis is limited to a single element. As a result, it is impossible to analyze all elements in the sample gas, and in the case of the method using the electric furnace, the analysis is performed based on relative sensitivity with respect to the sensitivity obtained from the electric furnace. In that case, the detection sensitivity when introducing the sample gas generated by laser irradiation is not the same as the detection sensitivity when introducing the element that has evaporated by heating the standard solution in the electric furnace. From these facts, the prior art of Patent Document 1 is not considered sufficient in terms of practicality for quantitative analysis, and the current situation is that it is not being used.

[0007] Furthermore, regarding the quantitative analysis of sample gases containing the measurement target, it is difficult to perform the analysis because there are almost no gaseous metal standard samples available. Prior art literature

[0008] Japanese Patent Publication No. 2018-136190 The problem to be solved

[0009] Against the backdrop of the above circumstances, the present invention aims to provide an analytical technique that enables the quantitative analysis of elements in a sample gas without using a solid standard sample when quantitatively analyzing a sample gas, such as with LA-ICP-MS. means of solving the problem

[0010] The inventors have developed a technology (see Patent Document; International Publication No. WO2020 / 027345) that allows almost 100% (the entire amount) of the standard solution introduced from the spray chamber to the torch section to be introduced into the plasma when a standard solution of a specific element at a known concentration is directly supplied to the nebulizer at a very low flow rate. By utilizing this technology, it was discovered that quantitative analysis of the element in the sample gas is possible without using a solid standard sample, and thus the present invention was described.

[0011] The present invention relates to an inductively coupled plasma mass spectrometer comprising: a standard solution introduction unit comprising a standard solution introduction unit comprising a standard solution spray chamber combined with a syringe pump for aspirating and discharging the standard solution and a standard solution nebulizer for supplying the standard solution, wherein a standard solution introduction path for introducing the standard solution flowing out from the standard solution spray chamber is connected to a path connecting the gasification sample introduction unit and the torch unit, wherein the standard solution introduction path for introducing the standard solution is connected to a path connecting the gasification sample introduction unit and the torch unit, wherein the standard solution introduction path for introducing the standard solution is connected to a path connecting the gasification sample introduction unit and the torch unit. As a quantitative analysis method, the standard solution contains all elements possessed by the solid sample to be measured or the gas containing the target to be measured as specific elements at a known concentration, and after detecting the device background signal intensity with only argon gas introduced, the standard solution is directly supplied to a standard solution nebulizer at a flow rate of 3 μL / min or less with argon gas introduced, thereby introducing the standard solution from the solution introduction means to the torch part, and the standard solution signal intensity obtained from the detector is detected for all elements contained in the standard solution, and the specific element standard solution signal intensity is calculated by subtracting the device background signal intensity of each element from the detected standard solution signal intensity of each element, and based on the specific element standard solution signal intensity and the amount of specific element introduced in the introduced standard solution, a standard solution sensitivity value, which is the weight of the specific element per count of the specific element standard solution signal intensity, andThe method comprises a first process of calculating the absolute amount of device background standard solution, calculated from the device background signal intensity and the standard solution sensitivity value, for all elements contained in the standard solution; and a second process of detecting the sample gas signal intensity in a state where only the sample gas is introduced, and then, while the sample gas is introduced, directly supplying the standard solution to a standard solution nebulizer at a flow rate of 3 μL / min or less to introduce the standard solution from a solution introduction means to the torch part, detecting the mixed signal intensity obtained from the detector for all elements contained in the sample gas, and calculating the signal intensity of the mixed standard solution for each specific element by subtracting the sample gas signal intensity of each element from the mixed signal intensity of each detected element, and based on the signal intensity of the mixed standard solution for the specific element and the amount of the specific element introduced in the introduced standard solution, calculating the mixed standard solution sensitivity value, which is the weight of the specific element per count of the specific element mixed standard solution signal intensity, and the absolute amount of the specific element in the sample gas calculated from the sample gas signal intensity and the mixed standard solution sensitivity value for all elements contained in the sample gas. The method is characterized by calculating the absolute amount of a specific element contained in the sample gas for all elements contained in the sample gas by subtracting the absolute amount of the device background standard solution of each element obtained in the first process from the absolute amount of the specific element contained in the sample gas of each element contained in the second process, and measuring the concentration of each element contained in the sample gas from the sum of the absolute amounts of the specific elements contained in the sample gas of all elements contained in the sample gas and the absolute amount of the specific element contained in the sample gas of each element.

[0012] In the present invention, the standard solution is introduced from the solution introduction means to the torch portion by directly supplying the standard solution to a standard solution nebulizer at a flow rate of 3 μL / min or less. In this case, 100% (the entire amount) of the introduced standard solution is introduced into the plasma. This has been demonstrated by the following four verifications (refer to International Publication No. WO2020 / 027345). Verification 1: Even when the temperature was changed by heating the spray chamber for the standard solution, there was no change in the standard solution sensitivity value, which is the weight of a specific element per count of the standard solution signal intensity. Verification 2: The sensitivity value obtained by metal fine particles of Au of a known particle size was almost identical to the standard solution sensitivity value. Verification 3: When the amount of standard solution introduced was changed, the signal intensity changed linearly at a flow rate up to 3 μL / min. When the flow rate exceeded 3 μL / min, the signal intensity tended to decrease, and it was confirmed that the standard solution began to get trapped within the spray chamber for the standard solution. Verification 4: When three identical types of nebulizers were used as nebulizers for the standard solution and the sensitivity values ​​of the standard solution were compared, the relative standard deviation was within 1%.

[0013] The present invention uses a standard solution that contains all elements of a solid sample or a gas containing the subject of measurement as specific elements at known concentrations. Such a standard solution can be used by mixing commercially available standard solutions. Examples of elements included in the standard solution obtained by mixing are Al, As, Sb, Ba, B, Bi, Cd, Ca, Cs, Cr, Co, Cu, Ga, Ge, Fe, Pb, Li, Mg, Mn, Mo, Ni, P, K, Rb, Se, Si, Ag, Na, Sr, Sn, Ti, W, U, V, Zn, Zr, Au, Ir, Pd, Pt, Rh, Ru, Te, Hf, Sb, Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Sc, Tb, Tm, Yb, Y, etc.

[0014] In the present invention, first, in the first process, the device background noise of the ICP-MS used is determined. That is, the absolute amount of the device background standard solution in the state where only argon gas is introduced is calculated for all elements contained in the standard solution. Next, in the present invention, in the second process, the absolute amount of the specific element in the sample gas is calculated for all elements contained in the sample gas. Then, the absolute amount of the specific element contained in the sample gas is calculated for all elements contained in the sample gas by subtracting the absolute amount of the device background standard solution of each element obtained in the first process from the absolute amount of the specific element contained in the sample gas of each element obtained in the second process. The total sum of the absolute amounts of the specific elements contained in the sample gas is, for example, the total amount of particulates detected by the ICP-MS that evaporated from the solid sample by laser irradiation, and the concentration of each element in the sample gas can be calculated from this total sum of the absolute amounts of the specific elements contained in the sample gas and the absolute amounts of the specific elements contained in the sample gas of each element. In other words, the concentration of each element is the concentration of each element contained in the fine particles evaporated from the solid sample by laser irradiation, and is the concentration of each element of the solid sample.

[0015] In the present invention, when a sample gas consisting of a solid sample or a gas containing the sample to be measured contains an unmeasurable element that cannot be analyzed by an inductively coupled plasma mass spectrometer at a specific ratio a, and a measurable element and a major known component element at a ratio (1-a), a standard solution is used to contain all elements of the sample gas consisting of the solid sample or a gas containing the sample to be measured, excluding the unmeasurable element, as specific elements of known concentration. After calculating the absolute amount of specific elements contained in the sample gas for all measurable elements contained in the sample gas, the sum of the absolute amounts of specific elements contained in the major known component sample gas for the major known component elements is calculated, and the sum of the absolute amounts of specific elements contained in the major known component sample gas is divided by (1-a) to calculate the sum of the absolute amounts of specific elements contained in the major known component sample gas for 100% of sample gas for 100% of the sample gas for 100% of the major known component sample gas for 100% of the sample gas for 100% of the sample gas for 100% of the sample gas for 100% of the sample gas for 100% of the sample gas for 100

[0016] For example, when SiC or GaN is adopted as a solid sample, the sample gas contains unmeasurable elements, such as C (carbon) or N (nitrogen), which cannot be analyzed by an inductively coupled plasma mass spectrometer, in a specific ratio a, and has a composition in which measurable major known component elements, such as Si or Ga, are contained in a ratio (1-a). In such a case, the standard solution is used to contain all elements of the sample gas, which consists of the solid sample to be measured or the gas containing the target to be measured, excluding the unmeasurable elements, as specific elements at a known concentration, and the first and second processes described above are performed. Then, since the absolute amount of specific elements contained in the sample gas for measurable elements is obtained, the absolute amount of specific elements contained in the sample gas for major known component elements is extracted from among them and summed to obtain the total absolute amount of specific elements contained in the sample gas for major known component elements. Then, by dividing this total absolute amount of specific elements contained in the sample gas for major known component elements by (1-a), the total absolute amount of specific elements contained in the sample gas for 100% of major known component elements is calculated. The concentration of each element contained in the sample gas can be measured from the total absolute amount of specific elements contained in the 100% main base component sample gas and the absolute amount of specific elements contained in the sample gas of each element other than the main base component.

[0017] In the present invention, since the first process detects signal intensity in the state of introducing argon gas and the second process detects signal intensity in the state of introducing sample gas, the detection sensitivity in each process becomes the same. Therefore, even if a change in sensitivity occurs, it can be corrected, and the concentration of each element in the sample gas can be accurately measured. Effects of the invention

[0018] According to the present invention, quantitative analysis of elements in a sample gas, such as LA-ICP-MS, is possible without using a solid standard sample. Brief explanation of the drawing

[0019] Figure 1 is a schematic diagram of an inductively coupled plasma mass spectrometer for sample gas analysis. Specific details for implementing the invention

[0020] FIG. 1 shows a schematic diagram of an inductively coupled plasma mass spectrometer of the present embodiment. The ICP-MS shown in FIG. 1 (Model 8900 manufactured by Agilent Technologies, Inc.) is equipped with a gasified sample introduction unit (101), a torch unit (102) that forms plasma to ionize the sample, an interface unit (103) for introducing ions from the plasma, a mass spectrometer (104) for separating ions, and a detector unit (105) for detecting the separated ions. In addition, a standard solution introduction device (2) is connected to this ICP-MS. This standard solution introduction device (2) is composed of a standard solution storage container (201) for storing the standard solution, a syringe pump (202) for sucking and discharging the standard solution, a standard solution nebulizer (203) for supplying the standard solution, and a standard solution spray chamber (204). In addition, a waste container (205) for disposal is also provided. A standard solution introduction path (206) for introducing the standard solution flowing out into the torch section (102) is connected to the spray chamber (204) for the standard solution. In addition, a syringe pump (202) capable of controlling a flow rate of 0.1 to 99.0 μL / min is used. The control flow rate of this syringe pump is determined by calculating from the physical operating amount of the ball screw used in the syringe constituting the syringe pump. In addition, a gas substituter (301) is provided. This gas substituter (301) replaces the gas component of the sample gas containing the measurement target with argon gas. In addition, this gas substituter (301) is connected to the gasification sample introduction section (101) via a flow path (110). In addition, a laser ablation device (302) is connected to the gas substituter (301). This gas substituent (301) is configured to replace the air component containing fine particles emitted from the laser ablation device (302) with argon gas, and to supply the sample gas to the gasification sample introduction part (101) by passing through the flow path (110).When a small amount of solution is introduced from the standard solution introduction device (2) under dry plasma conditions such as LA-ICP-MS, the plasma conditions may change and the sensitivity of the ICP-MS may fluctuate. In this case, it is effective to combine two standard solution introduction devices (2), fix the output amount of the two devices at 3 μL / min, and create a calibration curve by changing the ratio of the two syringes.

[0021] Next, the quantitative analysis of elements in solid samples will be explained. The standard solution used for analysis can be commercially available standard solutions. For example, by mixing three types of ICP-MS general-purpose mixed standard solutions (manufactured by SPEX, USA) XSTC-622, XSTC-7, and XSTC-1, a standard solution containing 59 elements can be prepared.

[0022] In this embodiment, the quantitative analysis of elements is explained by taking the case where 26 elements are included as measurement targets in a solid sample as an example. The 26 elements as measurement targets are denoted by the alphabet A, B, C, D, ..., Z. The amount of standard solution introduced when introduced at 3 μL / min or less is denoted as N (ag / sec). Since the amount of standard solution introduced at this amount N is 3 μL / min or less, it is supplied directly to the standard solution nebulizer, so that it passes through the standard solution introduction path (206) from the standard solution spray chamber (204) and is introduced into the torch part (102), and 100% (the entire amount) of the introduced standard solution is introduced into the plasma.

[0023] First, in the first process, the device background signal intensity (Count / sec) with only argon gas introduced is detected. For elements A, B, C, D...Z, the detected device background signal intensity (Count / sec) is indicated by the following notation.

[0024] Element A: A_Ar_BL

[0025] Element B: B_Ar_BL

[0026] Element C: C_Ar_BL

[0027] Element D: D_Ar_BL

[0028] ·

[0029] ·

[0030] ·

[0031] Element Z: Z_Ar_BL

[0032] Subsequently, with argon gas introduced, the standard solution is supplied directly to a standard solution nebulizer at a flow rate where the amount of standard solution introduced is N (ag / sec), and the standard solution signal intensity (Count / sec) obtained from the detector is detected. For elements A, B, C, D...Z, the detected standard solution signal intensity (Count / sec) is indicated by the following notation.

[0033] Element A: A_Ar_STD

[0034] Element B: B_Ar_STD

[0035] Element C: C_Ar_STD

[0036] Element D: D_Ar_STD

[0037] ·

[0038] ·

[0039] ·

[0040] Element Z: Z_Ar_STD

[0041] The signal intensity of a specific element standard solution is calculated by subtracting the device background signal intensity of each element from the signal intensity of the standard solution of each detected element, and based on this specific element standard solution signal intensity and the amount of standard solution introduced, the standard solution sensitivity value, which is the weight of the specific element per count of the specific element standard solution signal intensity, is calculated. The standard solution sensitivity values ​​(ag / count) for elements A, B, C, D...Z are indicated by the following notation.

[0042] Element A: A_Ar_S=N / (A_Ar_STD - A_Ar_BL)

[0043] Element B: B_Ar_S=N / (B_Ar_STD - B_Ar_BL)

[0044] Element C:C_Ar_S=N / (C_Ar_STD – C_Ar_BL)

[0045] Element D:D_Ar_S=N / (D_Ar_STD - D_Ar_BL)

[0046] ·

[0047] ·

[0048] ·

[0049] Element Z:Z_Ar_S=N / (Z_Ar_STD - Z_Ar_BL)

[0050] The absolute amount of device background standard solution (ag) is calculated from the device background signal intensity of each element and the standard solution sensitivity value obtained above. The absolute amount of device background standard solution (ag) for elements A, B, C, D...Z is indicated by the following notation.

[0051] Element A:A_Ar=A_Ar_BL × A_Ar_S

[0052] Element B: B_Ar = B_Ar_BL × B_Ar_S

[0053] Element C:C_Ar=C_Ar_BL × C_Ar_S

[0054] Element D:D_Ar=D_Ar_BL × D_Ar_S

[0055] ·

[0056] ·

[0057] ·

[0058] Element Z:Z_Ar=Z_Ar_BL × Z_Ar_S

[0059] Next, in the second process, the sample gas signal intensity (Count / sec) is detected in a state where only the sample gas, in which the gas component of the gas containing fine particles emitted from the laser ablation device (302) has been replaced with argon gas, is introduced. For elements A, B, C, D...Z, the detected sample gas signal intensity (Count / sec) is indicated by the following notation.

[0060] Element A: A_SAM_BL

[0061] Element B: B_SAM_BL

[0062] Element C: C_SAM_BL

[0063] Element D: D_SAM_BL

[0064] ·

[0065] ·

[0066] ·

[0067] Element Z: Z_SAM_BL

[0068] Subsequently, with the sample gas introduced, the standard solution is supplied directly to the standard solution nebulizer at a flow rate where the standard solution introduction amount is N (ag / sec), and the mixed signal intensity (Count / sec) obtained from the detector is detected. For elements A, B, C, D...Z, the detected mixed signal intensity (Count / sec) is indicated by the following notation.

[0069] Element A: A_SAM_STD

[0070] Element B: B_SAM_STD

[0071] Element C: C_SAM_STD

[0072] Element D: D_SAM_STD

[0073] ·

[0074] ·

[0075] ·

[0076] Element Z: Z_SAM_STD

[0077] The signal intensity of the mixed standard solution of a specific element is calculated by subtracting the sample gas signal intensity of each element from the mixed signal intensity of each detected element, and based on this signal intensity of the mixed standard solution of the specific element and the amount of standard solution introduced, the sensitivity value of the mixed standard solution, which is the weight of the specific element per count of the signal intensity of the mixed standard solution of the specific element, is calculated. The sensitivity values ​​(ag / count) of the mixed standard solution for elements A, B, C, D...Z are expressed in the following notation.

[0078] Element A: A_SAM_S = N / (A_SAM_STD - A_SAM_BL)

[0079] Element B: B_SAM_S = N / (B_SAM_STD - B_SAM_BL)

[0080] Element C:C_SAM_S=N / (C_SAM_STD-C_SAM_BL)

[0081] Element D:D_SAM_S=N / (D_SAM_STD-D_SAM_BL)

[0082] ·

[0083] ·

[0084] ·

[0085] Element Z:Z_SAM_S=N / (Z_SAM_STD-Z_SAM_BL)

[0086] The absolute amount (ag) of a specific element in the sample gas is calculated from the signal intensity of the sample gas for each element and the sensitivity value of the mixed standard solution obtained above. The absolute amount (ag) of the specific element in the sample gas for elements A, B, C, D...Z is expressed in the following notation.

[0087] Element A: A_SAM = A_SAM_BL × A_SAM_S

[0088] Element B:B_SAM=B_SAM_BL × B_SAM_S

[0089] Element C:C_SAM=C_SAM_BL × C_SAM_S

[0090] Element D:D_SAM=D_SAM_BL × D_SAM_S

[0091] ·

[0092] ·

[0093] ·

[0094] Element Z:Z_SAM=Z_SAM_BL × Z_SAM_S

[0095] The absolute amount of a specific element contained in the sample gas (A”, B”, C”, D”····Z”) is calculated for each element contained in the sample gas by subtracting the absolute amount of the device background standard solution of each element obtained in the first process from the absolute amount of the specific element contained in the sample gas of each element contained in the sample gas obtained in the second process. The absolute amount of the specific element contained in the sample gas (ag) for elements A, B, C, D···Z is indicated by the following notation.

[0096] Element A: A” = A_SAM - A_Ar

[0097] Element B: B”=B_SAM - B_Ar

[0098] Element C: C”=C_SAM - C_Ar

[0099] Element D: D”=D_SAM - D_Ar

[0100] ·

[0101] ·

[0102] ·

[0103] Element Z:Z”=Z_SAM - Z_Ar

[0104] The total amount of the element of the target element contained in the sample gas is determined by summing the absolute amounts of the specific element contained in the sample gas for all elements included in the sample gas obtained from the above. Then, the concentration of each element in the sample gas can be determined using this sum of the absolute amounts of the specific element contained in the sample gas and the absolute amounts of the specific element contained in the sample gas for each element. The element concentrations in the sample gas for elements A, B, C, D...Z are as follows.

[0105] Concentration of element A: A” / (A”+B”+C”+D”····Z”)

[0106] Concentration of element B: B” / (A”+B”+C”+D”····Z”)

[0107] Concentration of element C: C” / (A”+B”+C”+D”····Z”)

[0108] Concentration of element D: D” / (A”+B”+C”+D”····Z”)

[0109] ·

[0110] ·

[0111] ·

[0112] Concentration of element Z: Z” / (A”+B”+C”+D”····Z”)

[0113] Next, we will explain the case where the sample gas contains an unmeasurable element, such as C (carbon) or N (nitrogen), which cannot be analyzed by an inductively coupled plasma mass spectrometer, at a specific ratio a. Let the unmeasurable element be Z and its specific ratio be a, and let the measurable and major known constituent elements be X and Y, with their content ratios be (1 - a). In this case, elements A, B, C through W other than elements X, Y, and Z become measurable trace impurities. Furthermore, as the standard solution, one containing measurable elements A, B, C, ..., Y other than element Z at known concentrations is used.

[0114] When the above-described first and second processes are performed, data for each of elements A, B, C...Y, excluding the unmeasurable element Z, are obtained. Then, the absolute amount of a specific element contained in the sample gas is determined for the measurable elements A to Y, and among them, the absolute amount of the specific element contained in the sample gas with respect to the major known component elements (X, Y) is extracted and summed to obtain the total absolute amount of the specific element contained in the sample gas of the major known component.

[0115] Element X: X”=X_SAM-X_BL

[0116] Element Y:Y”=Y_SAM-Y_BL

[0117] Element (X, Y): (X + Y)” =

[0118] Then, by dividing the sum of the absolute amounts of specific elements contained in the main known component sample gas (X+Y) by (1-a), the sum of the absolute amounts of specific elements contained in the main known component sample gas is calculated. From this sum of the absolute amounts of specific elements contained in the main known component sample gas and the absolute amounts of specific elements contained in the sample gas of each element (A to W) other than the main known component elements, the concentration of each element contained in the sample gas can be determined. The element concentrations of elements A to W are the impurity concentrations contained in the sample gas, and if the sample gas is generated from a solid sample, they are the impurity concentrations in the solid sample.

[0119] Concentration of element A: A” / ((X+Y)” / (1-a))

[0120] Concentration of element B: B” / ((X+Y)” / (1-a))

[0121] Concentration of element C: C” / ((X+Y)” / (1-a))

[0122] Concentration of element D: D” / ((X+Y)” / (1-a))

[0123] ·

[0124] ·

[0125] ·

[0126] Element W concentration: W” / ((X+Y)” / (1-a))

[0127] Next, the test results of quantitative analysis of impurities by LA-ICP-MS on solid samples in which the impurity elements are known will be explained based on the examples. The ICP-MS used is a Model 8900 manufactured by Agilent Technologies, Inc.

[0128] Example 1

[0129] In Example 1, a Si wafer was used as the solid sample. The constituent elements of this solid sample consist of Si as the base material and four types of impurities: Na, Al, Mg, and Fe. In addition, the standard solution used in the quantitative analysis of Example 1 had a Si concentration of 1 ppm and concentrations of each element (Na, Al, Mg, and Fe) of 10 ppb. Furthermore, the device conditions of the ICP-MS were set to an Ar gas flow rate of 1 L / min and a high-frequency output of 1300 W.

[0130] First, as a first process, the device background signal intensity (Count / sec) with only argon gas introduced, and the standard solution signal intensity (Count / sec) was detected by directly supplying the standard solution to a standard solution nebulizer at a flow rate of 1 μL / min with argon gas introduced, and the standard solution sensitivity value, which is the weight of a specific element per count of the specific element standard solution signal intensity, was calculated to measure the absolute amount of the device background standard solution (ag). When introducing the standard solution, the gas flow rate of the standard solution nebulizer was set to 0.3 L / min. When the standard solution was introduced at a flow rate of 1 μL / min, the amount of Si introduced was 166,666,667 ag / sec because the Si concentration of the standard solution was 1 ppm, and the amount of each element introduced was 166,667 ag / sec because the concentrations of Na, Al, Mg, and Fe in the standard solution were 10 ppb. With this amount, 100% (the entire amount) of the standard solution introduced is introduced into the plasma. The measurement results of the first process are shown in Table 1.

[0131]

[0132] Next, a second process was performed using a sample gas in which the gas component of the gas containing fine particles emitted from the Si wafer of the solid sample was replaced with argon gas by a laser ablation device. The conditions of the laser ablation device were set to a laser wavelength of 257 nm, a laser irradiation frequency of 10,000 Hz, and a laser beam diameter of 13 μm.

[0133] In this second process, the sample gas signal intensity (Count / sec) in a state where only the sample gas, in which the gas component of the gas containing fine particles emitted from the laser ablation device has been replaced with argon gas, is introduced, and the mixed signal intensity (Count / sec) obtained by directly supplying the standard solution to a standard solution nebulizer at a flow rate of 1 μL / min while the sample gas is introduced are detected, and the mixed standard solution sensitivity value, which is the weight of the specific element per count of the specific element mixed standard solution signal intensity, is calculated to measure the absolute amount (ag) of the specific element in the sample gas. The results are shown in Table 2.

[0134]

[0135] Table 3 shows the results of calculating the impurity concentration in the solid sample Si wafer from the absolute amount of the device background standard solution obtained in the first process (Table 1) and the absolute amount of the sample gas specific element obtained in the second process (Table 2).

[0136]

[0137] Example 2

[0138] In this Example 2, the results of analysis using a Si-C wafer as a solid sample are described. In this Si-C wafer of the solid sample, 50% of the solid sample is Si (major base element) and 50% is C (unmeasurable element), and the impurities are of four types: Na, Al, Mg, and Fe.

[0139] In the quantitative analysis of Example 2, the standard solution composition, ICP-MS apparatus conditions, and laser ablation device conditions were the same as in Example 1. In addition, the first process in Example 2 is the same as the first process in Example 1. Furthermore, C (carbon) is excluded as an element to be analyzed because it is included as an impurity in the argon gas that generates the ICP-MS plasma, resulting in a high background, and because carbon has a high ionization potential and poor ionization efficiency in the plasma.

[0140] As the second process of Example 2, the sample gas signal intensity (Count / sec) in a state where only the sample gas, in which the gas component of the gas containing fine particles emitted from the laser ablation device has been replaced with argon gas, was introduced, and the mixed signal intensity (Count / sec) obtained by directly supplying the standard solution to a standard solution nebulizer at a flow rate of 1 μL / min while the sample gas is introduced was detected, and the mixed standard solution sensitivity value, which is the weight of the specific element per count of the specific element mixed standard solution signal intensity, was calculated to measure the absolute amount (ag) of the specific element in the sample gas. The results are shown in Table 4.

[0141]

[0142] Table 5 shows the results of calculating the impurity concentration in the solid sample Si-C wafer from the absolute amount of the device background standard solution obtained in the first process (see Table 1 of Example 1) and the absolute amount of the sample gas specific element obtained in the second process (Table 4).

[0143]

[0144] Since the solid sample of Example 2 is 50% Si, the absolute amount of Si in Table 5 (175,456,887 ag) corresponds to the 50% Si concentration of the solid sample, so the absolute amount in 100% of the Si-C wafer is 175,456,887 ag / 0.5 = 350,913,773 ag. The impurity concentration in the Si-C wafer shown in Table 5 is the result calculated by dividing the absolute amount of each impurity element by the absolute amount in 100% of the Si-C wafer (350,913,773 ag).

[0145] As shown in Tables 3 and 5, it was found that high-precision quantitative analysis of impurity concentration in solid samples is possible without using solid standard samples. Explanation of the symbols

[0146] 1 ICP-MS (Main Unit) 101 Gasification Sample Inlet 102 Torch 103 Interface 104 Mass Spectrometer 105 Detector 110 Flow Path 2 Standard Solution Inlet 201 Standard Solution Storage Container 202 Syringe Pump 203 Standard Solution Nebulizer 204 Standard Solution Spray Chamber 205 Disposal Container 206 Standard Solution Inlet Path 301 Gas Displacer 302 Laser Ablation Unit

Claims

Claim 1 A standard solution introduction device comprising a standard solution introduction unit comprising a standard solution spray chamber combined with a syringe pump for aspirating and discharging the standard solution and a standard solution nebulizer for supplying the standard solution, wherein a standard solution introduction path for introducing the standard solution flowing out from the standard solution spray chamber is connected to a path connecting the gasification sample introduction unit and the torch unit, wherein the standard solution introduction path for introducing the standard solution is connected to a path connecting the gasification sample introduction unit and the torch unit, and wherein the standard solution introduction path for introducing the standard solution is connected to a path connecting the gasification sample introduction unit and the torch unit, and wherein the standard solution introduction path for introducing the standard solution is connected to a path connecting the standard sample introduction unit and the torch unit, and wherein the standard solution introduction path for introducing the standard solution is connected to a path connecting the standard sample introduction unit and the torch unit. As a quantitative analysis method, the standard solution contains all elements possessed by the solid sample to be measured or the gas containing the target to be measured as specific elements at a known concentration; after detecting the device background signal intensity with only argon gas introduced, the standard solution is directly supplied to a standard solution nebulizer at a flow rate of 3 μL / min or less with argon gas introduced, thereby introducing the standard solution from the solution introduction means to the torch part, and the standard solution signal intensity obtained from the detector is detected for all elements contained in the standard solution, and the specific element standard solution signal intensity is calculated by subtracting the device background signal intensity of each element from the standard solution signal intensity of each detected element, and based on the specific element standard solution signal intensity and the amount of specific element introduced in the introduced standard solution, the standard solution sensitivity value, which is the weight of the specific element per count of the specific element standard solution signal intensity, and the absolute amount of the device background standard solution calculated from the device background signal intensity and the standard solution sensitivity value areThe method comprises a first process for calculating all elements contained in a standard solution, and a second process for detecting the sample gas signal intensity with only the sample gas introduced, and then introducing the standard solution from a solution introduction means to a torch part by directly supplying the standard solution to a standard solution nebulizer at a flow rate of 3 μL / min or less with the sample gas introduced, thereby detecting the mixed signal intensity obtained from a detector for all elements contained in the sample gas, calculating the signal intensity of a mixed standard solution for specific elements by subtracting the sample gas signal intensity of each element from the detected mixed signal intensity of each element, and calculating the mixed standard solution sensitivity value, which is the weight of the specific element per count of the mixed standard solution signal intensity, and the absolute amount of the specific element in the sample gas calculated from the sample gas signal intensity and the mixed standard solution sensitivity value for all elements contained in the sample gas based on the signal intensity of the mixed standard solution for specific elements and the amount of the specific element introduced in the introduced standard solution, in the first process A method for quantitative analysis of elements, characterized by calculating the absolute amount of a specific element contained in the sample gas for all elements contained in the sample gas by subtracting the absolute amount of the device background standard solution of each obtained element, and measuring the concentration of each element contained in the sample gas from the sum of the absolute amounts of the specific element contained in the sample gas for all elements contained in the sample gas and the absolute amount of the specific element contained in the sample gas for each element. Claim 2 In claim 1, if the sample gas comprising a solid sample of the object to be measured or a gas containing the object to be measured has a composition in which an unmeasurable element that cannot be analyzed by an inductively coupled plasma mass spectrometer is contained in a specific ratio a, and a measurable element is also contained in a ratio (1-a), the standard solution contains all elements possessed by the sample gas comprising the solid sample of the object to be measured or a gas containing the object to be measured, excluding the unmeasurable element, as specific elements of known concentration, and after calculating the absolute amount of specific elements contained in the sample gas for all measurable elements contained in the sample gas, the sum of the absolute amounts of specific elements contained in the sample gas for the major known component elements is calculated, and the sum of the absolute amounts of specific elements contained in the sample gas for the major known component elements is calculated, and the sum of the absolute amounts of specific elements contained in the sample gas for the major known component elements is divided by (1-a) to calculate the sum of the absolute amounts of specific elements contained in the sample gas for the 100% major known component elements is calculated, and the concentration of each element contained in the sample gas is measured from the sum of the absolute amounts of specific elements contained in the sample gas for the 100% major known component elements and the absolute amount of specific elements contained in the sample gas for each element other than the major known component elements. Quantitative analysis method.

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