JPH0843330A - Ion beam analyzer - Google Patents

Abstract

(57) [Summary] [Objective] To provide an ion beam analyzer capable of accurately measuring the dose of an ion beam applied to a sample. [Configuration] A specific gas that does not affect the analysis of elements contained in the sample TP, for example, a neon (Ne) gas I, is supplied from the specific gas supply means 6 into the hood 2, and then the sample TP is supplied from the ion beam generator 1. Irradiate with an ion beam,
Energy distribution data is obtained by processing the signal of the X-ray detected by the X-ray detector 3 by the calculation means 4.
Then, it is obtained in advance using a Faraday cup,
The ion beam irradiation amount at the time of analysis is calculated from the correspondence relationship between the characteristic X-ray intensity and the ion beam irradiation amount for this specific gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a sample with ions such as protons (H) and helium (He) accelerated to high energy, and analyzes the qualitative and quantitative properties of the sample from the electromagnetic waves specific to the sample. The present invention relates to an ion beam analyzer for performing.

[0002]

2. Description of the Related Art In general, ions are superior in controllability to energy, current, etc. as compared with X-rays and the like, and have a large interaction (scattering, recoil, atomic excitation, nuclear reaction, etc.) with substances. . Therefore, in analysis, it becomes a very effective excitation source and detection amount, and the use of ions is one of the indispensable in the technique of analysis and evaluation.

Then, the sample is irradiated with ions accelerated to high energy, and the generated electromagnetic wave (light, X
As a typical analysis method for qualitative / quantitative analysis of a sample from X-rays, γ-rays, etc., a particle beam excitation X-ray analysis method (hereinafter referred to as “PI
XE (Particle Induced X-ray Emission) analysis method "). FIG. 16 is a schematic diagram of an ion beam analyzer for performing PIXE analysis. The ion beam generated by the ion beam generator 11 is applied to the sample TP through the thin film 15, and the X-ray generated from the sample TP is detected by the X-ray detector. Detected at 13. Then, the calculation means 14 performs the energy analysis and the like, and analyzes the characteristic X-rays peculiar to the element to perform the qualitative / quantitative analysis of the sample TP. Normal,
The sample TP is covered with a hood 12 and a gas such as He is allowed to flow inside to prevent adverse effects on the analysis result so that X-rays from argon (Ar) in the atmosphere do not interfere with the analysis. ing.

Here, in order to measure the absolute concentration of the element contained in the sample TP, it is indispensable to measure the irradiation dose of the ion beam with which the sample TP is irradiated. Keep it insulated and attach an ammeter 1
The irradiation amount of the ion beam was obtained by connecting 6 and measuring the current flowing from the sample TP.

[0005]

However, in such a configuration in which the ammeter 16 is directly connected to the sample TP in this manner, secondary electrons generated by the irradiation of the ion beam, and the effect that the current flows to the outside due to the plasma, etc. However, there is a problem that the dose of the ion beam cannot be accurately measured, and as a result, the absolute concentration of the element contained in the sample TP cannot be accurately measured.

Therefore, the present invention was devised in order to solve these problems, and an object thereof is to provide an ion beam analyzer capable of accurately measuring the dose of the ion beam with which the sample is irradiated. To do.

[0007]

The first invention of the present application qualitatively / quantitatively quantifies a sample by irradiating the sample with an ion beam and analyzing the electromagnetic waves specific to the elements constituting the sample generated by the irradiation of the ion beam. In an ion beam analyzer for performing analysis such as the above, a specific gas supply means for supplying a specific gas that does not affect the analysis of elements contained in the sample to the periphery of the sample, and the specific gas supply means generated by the interaction with the ion beam. An electromagnetic wave specific to the specific gas detected by the electromagnetic wave detection means, using an electromagnetic wave detection means for detecting an electromagnetic wave specific to the specific gas, and the relationship between the intensity of the electromagnetic wave specific to the specific gas and the ion beam irradiation amount measured in advance. Calculating means for calculating the ion beam irradiation amount from the intensity of the.

The second invention of the present application irradiates a sample with an ion beam and analyzes the electromagnetic waves peculiar to the elements constituting the sample generated by the irradiation of the ion beam to analyze the sample qualitatively and quantitatively. In an ion beam analyzer for performing, a specific gas supply means for supplying a specific gas that does not affect the analysis of elements contained in the sample to the periphery of the sample, and a specific element generated by the interaction with the ion beam or a compound thereof By using the relationship between the detection signal value of the element / compound detection means for detecting the specific element or its compound measured in advance and the ion beam irradiation amount, or the specific element detected by the element / compound detection means or And a calculation unit that calculates the ion beam irradiation dose from the detection signal of the compound.

[0009]

The operation of the first invention of the present application will be described with reference to FIG. An ion beam from the ion beam generator 1 to the sample TP in a state where a specific gas that does not affect the analysis of elements contained in the sample TP, for example, a neon (Ne) gas I is supplied from the specific gas supply means 6 into the hood 2. Is irradiated, and the signal of the X-ray detected by the X-ray detector 3 (electromagnetic wave detecting means) is processed by the calculating means 4 to obtain the spectrum data shown in FIG. Then, from the correspondence relationship between the characteristic X-ray intensity and the ion beam irradiation amount for the specific gas I shown in FIG. 5, which is obtained in advance using the Faraday cup 7a shown in FIG. 3, the ion beam irradiation amount at the time of analysis is obtained. Is calculated.

Next, the operation of the second invention of the present application will be described with reference to FIG. From the ion beam generator 1 in the state where the specific gas I which does not affect the analysis of the elements contained in the sample TP, for example, the specific gas I such as carbon dioxide (CO2) is supplied into the hood 2 from the specific gas supply means 6 '. The sample TP is irradiated with an ion beam, and is calculated in advance by the calculation means 4 ′ using the Faraday cup 7a shown in FIG. 3 from the detection signal of the specific element or its compound detected by the element / compound detector 3 ′. Further, the ion beam irradiation amount at the time of analysis is calculated using the correspondence relationship between the detected amount of the specific element or its compound and the ion beam irradiation amount shown in FIG.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the first invention of the present application will be described below with reference to FIGS.

FIG. 1 is an overall schematic view of an ion beam analyzer according to the first invention of the present application.
It is an ion beam generator that irradiates P. Reference numeral 2 denotes a hood, to which He gas is supplied in order to remove an X-ray detection error due to the atmosphere. An X-ray detector 3 detects X-rays generated from the sample TP irradiated with the ion beam. Reference numeral 4 denotes a calculation means, which is the X detected by the X-ray detector 3.
The qualitative / quantitative analysis of the sample TP is performed by obtaining the energy distribution of the rays and analyzing the characteristic X-rays. Reference numeral 5 denotes a thin film, which shields the hood 2 side and the ion beam generator 1 side and keeps the ion beam passage 1a in vacuum.

Reference numeral 6 is a specific gas supply means for supplying a specific gas which does not affect the analysis of elements contained in the sample TP into the hood 2. This specific gas needs to be selected according to the type of the sample TP, but basically any gas that can be gasified and has no characteristic X-ray overlapping with the elements constituting the sample TP, such as neon ( Ne), sulfur (S),
Chlorine (Cl), selenium (Se), bromine (Br), krypton (Kr), xenon (Xe), radon (Rn), etc. are considered.

Next, the operation of the calculating means 4 will be described with reference to the procedure for obtaining the correspondence function showing the correspondence between the intensity of the characteristic X-ray obtained by irradiating the specific gas with the ion beam and the ion beam irradiation amount. A description will be given based on the flowchart.

First, prior to the calculation of the correspondence function, the sample TP shown in FIG. 1 is replaced with the Faraday cup 7a shown in FIG.
And ammeter 7b. Here, the ion beam with which the Faraday cup 7a is irradiated flows as a current to the ground, and the irradiation amount of the ion beam is measured as a current value by the ammeter 7b disposed in the middle thereof. And
A specific amount of the specific gas I is supplied from the specific gas supply means 6 to the hood 2.
In this state, the Faraday cup 7a is sequentially irradiated with different irradiation doses of the ion beam, and the characteristic X-ray intensities X1, X2 ,. .. is measured (S1). Here, the intensity of the characteristic X-ray is obtained by detecting the X-ray generated from the specific gas I via the X-ray detector 3, and measuring the characteristic X-ray shown in FIG.
It can be determined by measuring the peak value of the line.

Next, the current values y1, y2, ... Measured by the ammeter 7b are input for each ion beam irradiation amount (S2).

Then, from the characteristic X-ray intensities X1, X2, ... Measured for ion beams of different irradiation doses and the current values y1, y2 ,. By calculating the coefficient aj (j = 0 to n) of the following equation using the multiplication method, the corresponding function showing the relationship between the characteristic X-ray intensity and the ion beam irradiation dose shown in FIG. 5 is obtained (S
3).

[0018]

[Equation 1] In Equation 1, the value of n may normally be 1. However, if it is desired to increase the measurement accuracy of the dose of the ion beam, the order of n may be increased.

Next, using the corresponding function, PIXE
The operation in the case of analysis will be described based on the flowchart of FIG. 6 showing the operation of the calculating means 4 according to the present invention.

First, as shown in FIG. 1, the sample TP to be analyzed is placed in the hood 2, and the same amount and same kind of the specific gas I as when the corresponding function is obtained from the specific gas supply means 6 is hooded. The ion beam generating means 1 in the state of being supplied to the inside 2
Irradiates the sample TP with the ion beam. Then, the X-ray signal detected by the X-ray detector 3 is input (S
11) By processing the signal, the energy distribution of the detected X-ray is obtained as shown in FIG. 7 (S12).

Next, the peak value X of the characteristic X-ray of the specific gas I is calculated from the calculated energy distribution (S13), and the ion beam is calculated from the peak value X using the corresponding function shown in FIG. The current value y indicating the irradiation amount of is calculated (S14).

Then, the absolute concentration S of the element to be analyzed, for example, the peak value XC of the element C to be measured in FIG. 7 is calculated by the following formula (S15).

[0023]

[Equation 2] Thus, according to the first invention of the present application, as in the conventional case,
It is generated by ion beam irradiation because it is configured not to directly measure the current flowing out of the sample but to calculate the ion beam irradiation amount from the value of the characteristic X-ray of the specific gas that does not affect the analysis of the target element. Secondary electrons,
The ion beam irradiation dose can be accurately measured without being affected by plasma, and as a result, the absolute concentration of the element to be analyzed can be accurately measured.

Next, an embodiment of the second invention of the present application will be described with reference to FIGS. FIG. 8 is an overall schematic view of the ion beam analyzer according to the second invention of the present application. The difference from the first invention of the present application shown in FIG. 1 is that in addition to the X-ray detector 3, an element / compound detector 3 ′ is provided. Is used, the type of the specific gas to be supplied into the hood 2 is different, and the function of the calculation unit 4 is different, so that the description of the other components will be omitted here.

3'is an element / compound detector for detecting the amount of a specific element or its compound generated in the hood 2.
Reference numeral 4'is a calculating means, which calculates the ion beam irradiation dose from the detection signal of the specific element or its compound in the element / compound detector 3 ', and obtains the absolute concentration of the element to be analyzed.
Reference numeral 6'denotes a specific gas supply means. The specific gas supplied here is a gas in which a new element generated by the interaction with the ion beam does not affect the analysis of the element contained in the sample TP.

FIG. 9 showing the operation of the calculating means 4'for the procedure for obtaining the correspondence function showing the correspondence between the amount of the specific element or its compound obtained by irradiating the specific gas with the ion beam and the irradiation amount of the ion beam. A description will be given based on the flowchart.

First, prior to the calculation of the correspondence function, the sample TP shown in FIG. 8 is replaced with the Faraday cup 7a and the ammeter 7b shown in FIG. 3, as in the case of the first invention of the present application. Then, a predetermined amount of the specific gas I, for example, carbon dioxide (CO2), is supplied from the specific gas supply means 6'to the Faraday cup 7a while the ion beam, for example, the H ⁺ beam, having a different irradiation amount is supplied to the hood 2. Irradiate sequentially, for each dose, the following chemical formula, As shown in, the compound amount M of carbon monoxide (CO), which is a compound obtained by the interaction with carbon dioxide (CO2),
1, M2, ... And (S21), the current amounts y1, y2 ,.

Next, the current values y1, y2, ... Measured by the ammeter 7b are input for each ion beam irradiation amount (S22).

The amount of carbon monoxide (CO) compound M1, M2, ...
From the current values y1, y2, ... Indicating the irradiation dose of the ion beam, the coefficient aj (j = 0 to n) of the above-mentioned formula 1 is calculated by using the least squares method as in the case of the first invention. By calculating, a corresponding function showing the relationship between the detected amount of the compound shown in FIG. 10 and the irradiation amount of the ion beam is obtained (S2
3).

Next, using the corresponding function, PIXE
The operation in the case of performing the analysis will be described with reference to the flowchart of FIG. 11 showing the operation of the calculating means 4'according to the second invention of the present application.

First, as shown in FIG. 8, the sample TP to be analyzed is installed in the hood 2 and the same amount and same kind of carbon dioxide CO2 as those obtained when the corresponding function is obtained from the specific gas supply means 6'is obtained. The sample TP is irradiated with the ion beam from the ion beam generating means 1 while being supplied into the hood 2. Then, the signal of the X-ray detected by the X-ray detector 3 is input (S31), and the signal is processed to obtain the energy distribution of the detected X-ray as in the case of FIG. 7 (S).
32).

Next, a detection signal of carbon monoxide (CO) is input from the element / compound detector 3 '(S33), and a corresponding function shown in FIG.
A current value y indicating the irradiation amount of the ion beam is calculated (S3
4).

Then, as in the first aspect of the present invention, the absolute concentration S of the element to be measured is calculated from the above equation 1 from the peak value Xc of the element to be analyzed, eg, the element C to be measured in FIG. (S35).

As described above, according to the second invention of the present application, as in the first invention of the present application, the specific gas which does not affect the elemental analysis to be analyzed is not directly measured, but the current flowing out from the sample is directly measured. Since the dose of the ion beam is calculated from the value of the characteristic X-ray of, the ion beam dose can be accurately measured without being affected by the secondary electrons generated by the ion beam irradiation and plasma. Therefore, it is possible to accurately measure the absolute concentration of the element to be analyzed.

In the above-mentioned embodiment, the ion beam irradiation dose was calculated by detecting the characteristic X-rays generated from the specific gas or the specific element or its compound generated by the chemical reaction of the specific gas. Modifications are also possible.

<First Modification> In the first modification, the sample is irradiated with an ion beam, and electromagnetic waves peculiar to the elements constituting the sample are analyzed to perform qualitative / quantitative analysis of the sample. In the ion beam analysis device, a specific gas supply unit that supplies a specific gas that does not affect the analysis of elements contained in the sample to the periphery of the sample, and detects γ-rays generated by a nuclear reaction between the ion beam and the specific gas Gamma
Γ generated by the radiation detection means and the previously measured nuclear reaction
Arithmetic means for calculating the ion beam irradiation amount from the intensity of the γ-ray detected by the γ-ray detecting means by using the relationship between the intensity of the rays and the irradiation amount of the ion beam. Then, the ion beam irradiation dose is calculated by following the procedure substantially similar to the above-described first and second inventions of the present application.

The ion beam used here is, for example, a proton (H ⁺ ) beam of about 1.25 MeV. If ¹⁹ F is supplied as the specific gas, γ-rays are generated by the following nuclear reaction formula. To do.

H + ¹⁹ F → α + ¹⁶ O + γ <Second Modification> In the second modification, the sample is irradiated with an ion beam and electromagnetic waves peculiar to the elements constituting the sample are analyzed to determine the qualitative property of the sample. In an ion beam analyzer that performs quantitative analysis, etc., the optical transmittance of the thin film 5 shown in FIG. 1 etc. that separates the ion beam passage on the ion beam generator side from the sample side The feature is that the change is measured, and the amount of ion beam irradiation at the time of analysis is calculated from the amount of change in transmittance, using a corresponding function that shows the amount of change in optical transmittance and the amount of ion beam irradiation that was obtained in advance. And

That is, the second modified example utilizes the property that the optical transmittance of the thin film 5 shown in FIG. 1 and the like changes according to the irradiation amount of the ion beam. Before and after irradiation with the beam, the transmittance of the thin film 5 changes as shown in FIG. 12 according to the wavelength of light. Therefore, if the amount of change in optical transmittance at a specific wavelength λ of the thin film 5 is measured using the Faraday cup or the like in FIG. 3 while changing the irradiation amount of the ion beam, it is shown in the first invention of the present application. As described above, by using the method of least squares,
It is possible to obtain the correspondence function between the variation Δσ in transmittance and the ion beam irradiation amount y shown in FIG.

In the actual elemental analysis of the sample TP, the optical transmittance of the thin film 5 before and after the analysis is measured, and the corresponding function shown in FIG.
The irradiation amount of the ion beam with which the sample TP is irradiated can be calculated.

<Third Modification> In the third modification, the sample is irradiated with an ion beam and electromagnetic waves peculiar to the elements constituting the sample are analyzed to analyze the sample qualitatively and quantitatively. In the ion beam analyzer, a phosphor is formed on the surface of the thin film 5 that separates the ion beam passage on the side of the ion beam generator from the sample TP side, and the amount of light generated from this phosphor is detected by irradiation of the ion beam. It is characterized in that the calculation unit calculates the ion beam irradiation amount at the time of analysis from the detected light amount detected by the sensor, using a correspondence function between the light amount and the ion beam irradiation amount which are obtained in advance. .

FIG. 14 is a schematic view of a characteristic portion of the third modification, in which the thin film 5 is coated with a fluorescent substance 5a, and the fluorescent substance 5a emitted by the ion beam transmitted through the thin film 5 is emitted. The amount of light is detected by the light detection sensor 3 ″ and processed by a calculation unit (not shown). The light detection sensor 3 ″ is composed of a filter 3 ″ a and a photodiode 3 ″ b. Then, using the Faraday cup etc. of FIG.
If the light emission amount of the phosphor 5a and the ion beam irradiation amount are measured while changing the ion beam irradiation amount, the light emission amount of the phosphor 5a and the ion beam shown in FIG. 15 can be obtained by the same procedure as the first invention of the present application. It is possible to obtain the correspondence function with the irradiation dose.

In the actual elemental analysis of the sample TP, the X-rays generated from the sample TP are detected by the X-ray detector, and at the same time, the phosphor 5 is detected by the light detection sensor 3 ".
The amount of light emitted by a is measured, and the ion beam irradiation dose is calculated from the correspondence function shown in FIG.

[0044]

According to the ion beam analyzer of the present invention, the current flowing out from the sample is not directly measured, but the characteristic X-ray value of the specific gas which does not affect the elemental analysis to be analyzed is used. Since it is configured to calculate the dose of the ion beam, it is possible to measure the dose of the ion beam accurately without being affected by secondary electrons or plasma generated by the irradiation of the ion beam, and as a result, the element to be analyzed. Accurate measurement of the absolute concentration of

[Brief description of drawings]

FIG. 1 is a schematic view of an ion beam analyzer according to the first invention of the present application.

FIG. 2 is a flow chart showing an operation for obtaining a correspondence function between X-ray intensity and ion beam irradiation dose by the calculating means according to the first invention of the present application.

FIG. 3 is a diagram showing a case where an ion beam irradiation amount is measured using a Faraday cup.

FIG. 4 is a diagram showing an energy distribution of X-rays detected when calculating a correspondence function.

FIG. 5 is a diagram showing a correspondence function between a specific X-ray intensity and an ion beam irradiation dose.

FIG. 6 is a flowchart showing the operation of the calculating means during analysis of the first invention of the present application.

FIG. 7 is a diagram showing an X-ray energy distribution detected at the time of analysis.

FIG. 8 is a schematic view of an ion beam analyzer according to the second invention of the present application.

FIG. 9 is a flowchart showing an operation for obtaining a correspondence function between X-ray intensity and ion beam irradiation dose by the calculating means according to the second invention of the present application.

FIG. 10 is a diagram showing a correspondence function between a detected amount of a specific element or a compound thereof and an ion beam irradiation amount.

FIG. 11 is a flow chart showing the operation of the calculation means at the time of analysis of the second invention of the present application.

FIG. 12 is a diagram showing a change in light transmittance of a thin film before and after irradiation with an ion beam.

FIG. 13 is a diagram showing a correspondence function between a change amount of optical transmittance of a thin film and an ion beam irradiation amount.

FIG. 14 is a diagram showing a configuration for detecting the light emission amount of a phosphor formed on the surface of a thin film.

FIG. 15 is a diagram showing a correspondence function between a light emission amount of a phosphor formed on a thin film surface and an ion beam irradiation amount.

FIG. 16 is a schematic view of a conventional ion beam analyzer.

[Explanation of symbols]

 TP ... sample 1 ... ion beam generator 2 ... hood 3 ... X-ray detector 4 ... calculation means 5 ... thin film 6 ... specific gas supply means

Claims (2)

[Claims] 1. An ion beam analyzer for performing qualitative / quantitative analysis of a sample by irradiating the sample with an ion beam and analyzing electromagnetic waves specific to the elements constituting the sample generated by the irradiation of the ion beam, A specific gas supply unit that supplies a specific gas that does not affect the analysis of elements contained in the sample to the periphery of the sample, and an electromagnetic wave detection unit that detects an electromagnetic wave specific to the specific gas generated by the interaction with the ion beam. And an operation for calculating the ion beam irradiation amount from the intensity of the electromagnetic wave peculiar to the specific gas detected by the electromagnetic wave detection means, using the relationship between the intensity of the electromagnetic wave peculiar to the specific gas and the ion beam irradiation amount which is measured in advance. An ion beam analysis apparatus comprising: 2. An ion beam analyzer for performing qualitative / quantitative analysis of a sample by irradiating the sample with an ion beam and analyzing electromagnetic waves specific to the elements constituting the sample generated by the irradiation of the ion beam, A specific gas supply unit that supplies a specific gas that does not affect the analysis of elements contained in the sample to the periphery of the sample, and an element / compound detection that detects a specific element or a compound thereof generated by the interaction with the ion beam. Means and the relationship between the ion beam irradiation dose and the detection signal value of the specific element or its compound measured in advance,
An ion beam analysis apparatus comprising: an arithmetic unit that calculates an ion beam irradiation amount from a detection signal of a specific element or its compound detected by the compound detection unit.