JP6311532B2 - Composition analysis method, composition analysis apparatus, and composition analysis program - Google Patents

Description

  The present invention relates to a composition analysis method, a composition analysis apparatus, and a composition analysis program.

  A technique for obtaining the composition and content of elements contained in a material using X-ray spectroscopy is known. For example, X-ray spectroscopy is used to measure the alloy element content of an alloy plating material and to evaluate the elemental composition of a semiconductor material.

JP-A-8-297106 JP 2004006545 A

  By the way, a stoichiometric compound is widely used as a functional material, and an impurity element may be added in order to modify its function. In such a compound, it is important to grasp the composition of the impurity element in order to control its function.

  However, in X-ray spectroscopy, the composition of the impurity element (additive element) in the compound is affected by the form of the sample used for measurement, the absorption of X-rays generated from the measurement target element into the sample (X-ray absorption), and the like. It may be difficult to accurately obtain

  According to a position aspect of the present invention, the first element and the second element of the compound in which a part of the first element among the first element and the second element of the stoichiometric compound is substituted with the third element. A step of determining the composition ratio of the element using X-ray spectroscopy, and a step of determining the composition of the first element in the compound using the composition ratio and the composition of the second element in the compound. And a step of determining the composition of the third element in the compound using the composition of the first element in the compound.

  In addition, according to one aspect of the present invention, a composition analysis apparatus and a composition analysis program used for composition analysis are provided.

  According to the disclosed technique, the composition of an element added to a compound can be obtained with high accuracy by using X-ray spectroscopy and suppressing the influence of sample form and X-ray absorption.

It is explanatory drawing of a TEM-EDS analysis. It is explanatory drawing of X-ray absorption. It is a figure which shows an example of a composition analysis method. It is a figure which shows an example of a composition analysis result. It is a figure which shows an example of a composition analyzer. It is a figure which shows an example of the hardware constitutions of a computer.

Stoichiometric compound represented by the formula A _x B _y is widely used as functional materials, there is a case where the addition of the impurity element is performed for further improvements. In controlling the function, it is important to grasp the composition (concentration) of the impurity element of the compound obtained by adding the impurity element to the stoichiometric compound.

  The composition of the impurity element in such a compound is determined using, for example, an energy dispersive x-ray spectroscopy (EDS) detector attached to a transmission electron microscope (TEM). Analyzed (TEM-EDS analysis).

FIG. 1 is an explanatory diagram of TEM-EDS analysis.
As shown in FIG. 1, a sample 20a of a compound set in a sample holder 10a of a TEM is irradiated with an electron beam 30a, and characteristic X-rays 40a emitted from the sample 20a irradiated with the electron beam 30a are detected by EDS. It is detected by the device 50a. From the intensity of the characteristic X-ray 40a of each element generated from the sample 20a by irradiation with the electron beam 30a, the composition of the sample 20a is obtained using a coefficient called k factor (k factor).

The elements contained in the compound of the sample are A, B, C,..., The characteristic X-ray intensities of the detected elements are I _A , I _B , I _C ,. When the factors are k _A , k _B , k _C ,..., The composition C _{A of the} element _A is expressed by the following formula (1).

C _A = k _A I _A / (k _A I _A + k _B I _B + k _C I _C ...) (1)
According Such equation (1), it is possible to obtain the composition C _A of the element A contained in the compound. The composition C _B , C _C ,... Of other elements B, C,.

There are two methods for obtaining the k factor used here.
One is a method for experimental determination using a standard sample having a known composition. For example, the characteristic X-ray of each element included in a standard sample having a composition close to the target sample whose composition is to be measured is measured, and the composition ratio of the standard sample and the relational expression (C _A / C _B = (k _A / k _B ) · (I _A / I _B ) etc.) to obtain the k factor. This is used as the k factor of the target sample. Alternatively, the relationship between the characteristic X-ray intensity of each element and the k factor (calibration curve) was obtained for a plurality of types of standard samples with known compositions, and the target sample for which the composition was determined based on the relationship was obtained. The k factor is obtained from the characteristic X-ray intensity of each element.

  In order to properly determine the composition of the target sample, it is important to use an appropriate k factor, but in order to determine such an appropriate k factor by the above method, the composition of the target sample as much as possible is used as a standard sample. It is desirable to use the one with close. However, it is not always easy to prepare such a standard sample.

Another method for obtaining the k factor is a method for obtaining it based on a theoretical formula. The k factor k _A of the element A contained in the compound of the sample is represented by the following theoretical formula (2).
k _A = M _A / (σ _A ω _A p _A ε _A ) (2)
In the formula (2), M _A is the atomic weight of the element A, σ _A is the ionization cross section of the element A, ω _A is the fluorescence yield of the element A, p _A is various characteristic X-rays (Kα ray, The ratio of characteristic X-rays of interest to Kβ rays, Lα rays, etc., ε _A is the detector efficiency of element A.

Note that k factors k _B , k _C ,... Of other elements B, C,.
By using a theoretical formula such as the above formula (2), the k factor of each element can be obtained. However, since the TEM sample thickness is approximated to zero in the theoretical formula such as the equation (2), in practice, a TEM sample having a finite thickness causes a problem of X-ray absorption.

FIG. 2 is an explanatory diagram of X-ray absorption.
As shown in FIG. 2, the characteristic X-ray 40b generated in the sample 20b irradiated with the electron beam 30b passes through the sample 20b and is detected by the detector 50b. Part of the characteristic X-ray 40b is absorbed into the sample 20b while passing through the sample 20b.

  When the sample 20b is a compound containing a light element and a heavy element, the characteristic X-ray of the light element has a smaller energy than the characteristic X-ray of the heavy element and is absorbed more in the sample 20b. For this reason, the light element composition is evaluated smaller than the actual one, and conversely the heavy element composition is evaluated larger than the actual one. This is a problem of X-ray absorption.

In order to solve this problem, the thickness t of the sample 20b may be made as thin as possible and close to zero, but this also has a limit.
As a method different from the method of reducing the thickness of the sample 20b, a method called absorption correction is known. Correction is performed by dividing the characteristic X-ray intensity I of each detected element by the absorption correction coefficient CF expressed by the following equation (3).

CF = [1-exp {− (μ / ρ) · cosec (α) · ρt}] / {(μ / ρ) · cosec (α) · ρ} (3)
In Expression (3), μ / ρ is the mass absorption coefficient of the characteristic X-ray of each element with respect to the sample 20b, α is the angle of the detector 50b, ρ is the density of the sample 20b, and t is the thickness of the sample 20b.

  In the absorption correction using the absorption correction coefficient CF represented by the equation (3), the characteristic X-ray mass absorption coefficient μ / ρ of each element, the angle α of the detector 50b, the density ρ of the sample 20b, and the thickness of the sample 20b It is important to use an accurate value for each parameter t.

  Among these parameters, for the angle α of the detector 50b, a value determined by the TEM to be used and its measurement conditions can be used. On the other hand, it is necessary to separately measure the density ρ and thickness t of the sample 20b using another apparatus and method, and it is not always easy to obtain accurate values by the measurement. As the mass absorption coefficient μ / ρ, a known value (for example, http://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html) can be used. In addition, if there is an error in the density ρ and thickness t of the sample 20b, an error occurs in the composition value of the sample 20b.

  As described above, in the method using the standard sample or the method for performing the absorption correction, the composition of the impurity element of the compound obtained by adding the impurity element to the stoichiometric compound may not be accurately analyzed.

  Therefore, a method that can accurately analyze the composition of impurity elements contained in a compound (a compound obtained by adding an impurity element to a stoichiometric compound) without using a standard sample or performing absorption correction is described below. Will be described as an embodiment.

FIG. 3 is a diagram showing an example of a composition analysis method.
In the present embodiment, first, a compound in which a part of the first element among the first element and the second element contained in the stoichiometric compound is replaced with a third element (impurity element) is prepared (step S1). .

  Here, the first element and the second element are, for example, a combination of elements having atomic numbers close to each other or a combination of elements having close characteristics X-ray energy. For example, the first element and the second element are combinations of elements of Group 13 to Group 15, Group 12 to Group 16, Group 2 to Group 4, Group 1 to Group 17, It is a combination of elements having an atomic number or characteristic X-ray energy close to each other.

  The impurity element is an element that occupies the same atomic site as the first element of the stoichiometric compound including the first element and the second element in such a combination. In step S1, a compound in which a part of the first element of the stoichiometric compound is replaced with such an impurity element is prepared.

  Subsequently, about the prepared compound, the composition ratio of a 1st element and a 2nd element (matrix) is calculated | required by X-ray spectroscopy using TEM (TEM-EDS) provided with an EDS detector, for example (step S2).

  When the atomic numbers of the first element and the second element in the compound are close, the energy difference between the characteristic X-rays is small, so the difference in mass absorption coefficient is small and the difference in absorption correction coefficient CF is also small. Even if the atomic numbers of the first element and the second element in the compound are separated, if the energy of the characteristic X-rays is close to each other, the difference in the mass absorption coefficient and the difference in the absorption correction coefficient CF are similarly small. Become.

  Therefore, in the composition analysis of the present embodiment, the difference in the degree of X-ray absorption absorbed by the compound between the characteristic X-ray generated from the first element and the characteristic X-ray generated from the second element is ignored. From the intensity of the characteristic X-ray of the first element obtained for the compound and the intensity of the characteristic X-ray of the second element, the characteristic X by the absorption correction coefficient CF is calculated using the above equation (1) and the theoretical formula (2) of the k factor. The composition ratio of the first element and the second element of the compound containing the impurity element is obtained without correcting the line absorption.

  The composition of the first element in the compound is determined using the composition ratio of the first element and the second element thus determined for the compound containing the impurity element and the composition of the second element in the compound ( Step S3).

  The impurity element replaces only the first element of the stoichiometric compound and does not replace the second element. Therefore, the composition of the second element in the compound containing the impurity element is the same as the composition of the second element in the stoichiometric compound not containing the impurity element. Using the composition of the second element and the composition ratio of the first element and the second element of the compound containing the impurity element obtained in step S2, the composition of the first element in the compound is obtained.

Using the composition of the first element obtained for the compound containing the impurity element in this way, the composition of the impurity element in the compound is obtained (step S4).
For example, the composition of the first element (atom%), the composition of the second element (atom%) in the stoichiometric compound not containing the impurity element, and the compound containing the impurity element obtained as described above The composition (atom%) of the impurity element is obtained using the composition (atom%) of the first element.

The composition analysis method will be described more specifically.
Here, the stoichiometric compound A _x B _y of atomic number close element A (first element) and an element B (second element), the impurity element Q (third element) is substituted to the element A The composition n of the impurity element Q of the added compound Q _n A _xn B _y (step S1) is determined.

Since the element A and the element B have similar atomic numbers, the difference in the degree of X-ray absorption between them is ignored. Using the compound Q _n A _xn B characteristic X-ray intensity of the resulting element A by X-ray spectroscopy _y, from the characteristic X-ray intensity of the element B, and no attenuation correction, the equation (1) and (2) Then, the composition ratio xn: y (or (xn) / y) of the element A and the element B is obtained (step S2).

That is, from the formula (1), the composition of the element A xn (= C _A), the composition y (= C _B) of the element B, Compound Q _n A _xn B _y element A obtained by the X-ray spectroscopy The characteristic X-ray intensity I _{A of} the above and the characteristic X-ray intensity I _B of the element B have the relationship of the following formula (4).

(X−n) / y = C _A / C _B = k _A I _A / k _B I _B (4)
The k-factor k _A of the element _A and the k-factor k _{B of the} element B obtained from the theoretical formula of the above formula (2), the characteristic X-ray intensity I _{A of the} element A obtained by X-ray spectroscopy, and the characteristic X of the element B using the line intensities I _B, from equation (4), the composition ratio of compound Q _n a _xn B _y of the element a and the element B (mother phase) xn: y is determined.

Impurity element Q is only allowed substitution sites of the elements A, does not replace the site element B, the composition y (atom%) of the element B does not contain an impurity element Q stoichiometric compound of A _x B _y It is a known value without changing from the composition y. Accordingly, the composition xn (atom%) of the element A is obtained from the value of the composition y and the composition ratio xn: y obtained as described above (step S3).

Then, the compound _{Q n A xn B y, n} + (xn) + y = 100atom% relationships, as well as the composition of the known element B y (atom%), and the composition x of the element A obtained in step S3 −n (atom%) is used to determine the composition n of the impurity element Q (step S4). That is, the composition n of the impurity element Q is obtained by subtracting the composition x−n obtained in step S3 and the known composition y from 100 which is the sum of the compositions.

Alternatively, not contain an impurity element Q stoichiometric compound A _x B _y composition known element A in x (atom%), the composition x-n of the element A obtained in the step S3 (atom%) is used Then, the composition n of the impurity element Q is obtained (step S4). That is, the composition n of the impurity element Q is obtained by subtracting the composition x-n obtained in step S3 from the known composition x.

Furthermore, a specific example is given and demonstrated.
As an example, an Al _x Ga _1-x As compound in which aluminum (Al) is added to gallium arsenide (GaAs) having a zinc blend structure will be described.

Since Ga and As have similar atomic numbers, the difference in the degree of X-ray absorption is ignored. From the characteristic X-ray intensity of Ga and the characteristic X-ray intensity of As obtained by X-ray spectroscopy, the composition ratio C _Ga : C _{As of Ga and As} is obtained without absorption correction. Since the Al atom replaces only the Ga site and not the As site, the composition C _As of _As is 50 atom%. The Ga composition C _Ga is determined from the Ga: As composition ratio C _Ga : C _As . Furthermore, the _{C Al + C Ga + C As} = 100atom% of relationships, including the composition C _Al of Al, composition C _Al of Al is determined.

Here, an example in which the Al composition of the Al _x Ga _1-x As compound is analyzed using TEM-EDS will be described.
FIG. 4 is a diagram showing an example of the composition analysis result.

In FIG. 4, a plurality of types (four types here) of TEM samples having different TEM sample thicknesses were prepared from an Al _x Ga _1-x As compound sample having an Al composition of 12.8 atom%, and TEM-EDS was used. The results of obtaining the Al composition from the characteristic X-ray intensity of each element detected in this manner are shown.

FIG. 4D shows the result of obtaining the Al composition according to the method of the present embodiment as described above.
For comparison, FIG. 4 also shows the result (E in FIG. 4) of obtaining the Al composition according to (1) above using the characteristic X-ray intensity of each element and the k factor obtained by the above equation (2). It shows. That is, E in FIG. 4 is a result of obtaining the Al composition by a conventional method without absorption correction.

  Further, in FIG. 4, for comparison, the characteristic X-ray intensity of each element is corrected using the absorption correction coefficient CF of the above equation (3), and this and the k factor obtained by the above equation (2) are used. The result (F of FIG. 4) which calculated | required Al composition by (1) is shown collectively. That is, F in FIG. 4 is a result of obtaining the Al composition by a conventional technique with absorption correction.

  4A to 4F, the Al composition value according to the method of the present embodiment shown in FIG. 4D (FIG. 3) is the most true Al composition value (12.8 atoms) at any TEM sample thickness. %).

  In the method without absorption correction shown in E of FIG. 4, the Al composition value deviates relatively greatly from the true Al composition value (12.8 atom%) at any TEM sample thickness, and the TEM sample thickness The greater the thickness, the greater the discrepancy. Since the absorption correction is not performed, it can be said that the X-ray absorption of the TEM sample affects the Al composition value, and that the influence of the X-ray absorption on the Al composition value increases as the TEM sample thickness increases.

  On the other hand, in the method with absorption correction shown in F of FIG. 4, the influence of the X-ray absorption of the TEM sample on the Al composition value is suppressed by the absorption correction, and the method without absorption correction shown in E of FIG. In comparison, the deviation of the Al composition value from the true Al composition value (12.8 atom%) is reduced. The dependency of the Al composition value on the TEM sample thickness is also improved as compared with the method without absorption correction. However, compared with the method of the present embodiment (D in FIG. 4), there is a deviation from the true Al composition value. It is considered that an error in the absorption correction coefficient CF (an error in the mass absorption coefficient, the density of the TEM sample, the thickness, etc.) affects the Al composition value.

  Thus, according to the method of the present embodiment, the composition of the impurity element of the compound obtained by adding the impurity element to the stoichiometric compound can be analyzed with high accuracy. In the method of this embodiment, since the influence of the TEM sample thickness on the composition of the impurity element can be suppressed, it is not necessary to make the TEM sample as thin as possible as in the prior art.

Here, the technique of the present embodiment is applied to a stoichiometric compound containing an element having an atomic number or characteristic X-ray energy that is close enough to ignore the difference in the degree of X-ray absorption.
The mass absorption coefficient of a compound is represented by the average of the weight ratio using the mass absorption coefficient of each element of the compound. The mass absorption coefficient changes rapidly with respect to the energy of X-rays. Therefore, in the elements having greatly different atomic numbers, the difference in energy of characteristic X-rays generated from them is large, so that the difference in mass absorption coefficient is also large. On the other hand, elements with similar atomic numbers have a small energy difference between characteristic X-rays generated from them, so that a difference in mass absorption coefficient is also small.

  The method of the present embodiment targets a stoichiometric compound containing an element having an atomic number or characteristic X-ray energy close enough to neglect X-ray absorption. An element having a close atomic number is, for example, an element having a difference in atomic number of 4 or less. If the atomic numbers are close, the difference in the characteristic X-ray energy is small, the difference in the mass absorption coefficient is small, the difference in the absorption correction coefficient CF is also small, and the difference in the degree of X-ray absorption can be ignored. The ratio of mass absorption coefficients when the difference in absorption correction coefficient CF between elements is 1% or less is 4 or less. If the ratio of the mass absorption coefficient between the elements exceeds 4, the composition of the impurity element is evaluated by deviating from the true value within a range of about 1% due to X-ray absorption. In order to ignore the difference in the degree of X-ray absorption and analyze the composition of the impurity element with high accuracy, the method of this embodiment includes a stoichiometrical element including a combination of elements whose mass absorption coefficient ratio is 4 or less. It is desirable to target compounds and compounds containing such combinations of elements in the parent phase.

  As the stoichiometric compound to which the technique of the present embodiment is applied, indium antimonide (InSb), cadmium telluride (CdTe), boron nitride (BN), zinc selenide (ZnSe) having the same zinc blend structure as GaAs. ), And aluminum phosphide (AlP). In addition, there are ordered nickel-iron alloys (FeNi) and cobalt-manganese alloys (CoMn). Further, there are sodium fluoride (NaF), potassium chloride (KCl), rubidium bromide (RbBr) having a sodium chloride (NaCl (rock salt)) structure, and cesium iodide (CsI) having a cesium chloride (CsCl) structure.

  Note that the stoichiometric compound to which the technique of the present embodiment is applied may be selected based on the analysis (evaluation) accuracy required for the composition of the impurity element. When the required compositional analysis accuracy of the impurity element is 1%, for example, a stoichiometric compound including a combination of elements having a mass absorption coefficient ratio of 4 or less as described above is targeted. To. When the composition analysis accuracy of the required impurity element exceeds 1%, such as 5% or 10%, the combination of the mass absorption coefficient ratio exceeds 4 according to the required composition analysis accuracy Stoichiometric compounds containing these elements can also be targeted.

  In the above description, a case where a binary stoichiometric compound containing two elements (a compound added with an impurity element) is exemplified, but a ternary system containing three elements is used. It is also possible to target a stoichiometric compound (compound with an impurity element added thereto).

Here, the compound Q _{n in} which the impurity element Q is added to the stoichiometric compound A _x B _y C _z containing the elements A and B having similar atomic numbers and the element C in place of the element A is added. a _xn B _y C _z of (step S1), the determine the composition n the impurity element Q.

Since the element A and the element B have similar atomic numbers, the difference in the degree of X-ray absorption between them is ignored. From the characteristic X-ray intensity of element A and the characteristic X-ray intensity of element B obtained by X-ray spectroscopy of compound Q _n A _xn B _y C _z , the above formulas (1) and (2) can be obtained without absorption correction. Is used to determine the composition ratio xn: y (or (xn) / y) between the element A and the element B (step S2).

That is, from the above formula (1), it is obtained by X-ray spectroscopy of element A composition xn (= C _A ), element B composition y (= C _B ), and compound Q _n A _xn B _y C _z. The characteristic X-ray intensity I _{A of} the element _A and the characteristic X-ray intensity I _B of the element B have the relationship of the above formula (4).

The k-factor k _A of the element _A and the k-factor k _{B of the} element B obtained from the theoretical formula of the above formula (2), the characteristic X-ray intensity I _{A of the} element A obtained by X-ray spectroscopy, and the characteristic X of the element B using the line intensities I _B, from the formula (4), compound Q _n a _xn B _y C composition ratio of the element a and element B of _z xn: y is determined.

Since the impurity element Q replaces only the site of the element A and does not replace the sites of the element B and the element C, the composition y of the element B and the composition z (atom%) of the element C are the impurity elements, respectively. stoichiometric compound contains no Q at a _x B _y C _z of composition y and composition z, it is known. Accordingly, the composition xn (atom%) of the element A is obtained from the value of the composition y and the composition ratio xn: y obtained as described above (step S3).

For the compound Q _n A _xn B _y C _z , the relationship of n + (x−n) + y + z = 100 atom%, the composition y of the element B (atom%), the composition z of the element C (atom%), and The obtained composition x-n (atom%) of the element A is used, and the composition n of the impurity element Q is obtained (step S4). That is, the composition n of the impurity element Q is obtained by subtracting the composition xn obtained in step S3, the known composition y, and the known composition z from 100 which is the sum of the compositions. The composition n of the impurity element Q may be obtained by subtracting the composition xn obtained in step S3 and the known composition y from 100-z obtained by subtracting the known composition z of the element C in advance.

Alternatively, the composition x (atom%) of the known element A in the stoichiometric compound A _x B _y C _z not including the impurity element Q and the composition xn (atom%) of the element A determined in step S3 are obtained. The composition n of the impurity element Q is obtained (step S4). That is, the composition n of the impurity element Q is obtained by subtracting the composition x-n obtained in step S3 from the known composition x.

Furthermore, a specific example is given and demonstrated.
As an example, a Q _n Ca _1-x TiO ₃ compound of calcium titanate (CaTiO ₃ ) having a perovskite structure, to which an impurity element Q that replaces the Ca site is added, will be described.

Since Ca and Ti have similar atomic numbers, the difference in the degree of X-ray absorption is ignored. From the characteristic X-ray intensity of Ca and the characteristic X-ray intensity of Ti obtained by X-ray spectroscopy, the composition ratio C _Ga : C _{As of} Ca and Ti is obtained without absorption correction. Since the Q atom replaces only the Ca site and does not replace the Ti site and the O site, the Ti composition C _Ti is 20 atom%, and the O composition _CO is 60 atom%. From the composition ratio C _Ca : C _{Ti of} Ca and Ti, the composition C _{Ca of Ca} is obtained. Further, the composition C _Q of _Q is obtained from the relationship of C _Q + C _Ca + C _Ti + C _O = 100 atom% including the composition C _{Q of Q.}

The method of this embodiment (FIG. 3) can also be applied to such a ternary stoichiometric compound, and the composition of the impurity element added thereto can be analyzed with high accuracy.
In the method of this embodiment, even in the case of targeting a ternary stoichiometric compound, as described above, an element having a combination of atomic numbers or characteristic X-ray energies that are close enough to neglect the difference in the degree of X-ray absorption. Applies to stoichiometric compounds containing In order to ignore the difference in the degree of X-ray absorption and analyze the composition of the impurity element with high accuracy, the stoichiometry includes a combination of elements in which the atomic number difference is 4 or less or the mass absorption coefficient ratio is 4 or less. It is desirable to target theoretical compounds.

Ternary stoichiometric compounds to which the method of this embodiment can be applied include CaTiO ₃ , barium cerate (BaCeO ₃ ) having the same perovskite structure, strontium zirconate (SrZrO ₃ ), and alumine having a spinel structure. There is magnesium acid (MgAl ₂ O ₄ ).

  The stoichiometric compounds that have been described so far have close atomic numbers of the two elements contained in the stoichiometric compound, and among these characteristic X-rays, the energy between the K-lines or between the L-lines is high. Get closer. For example, in the case of GaAs, the energy of Ga Kα ray is 9.241 keV, and the energy of As Kα ray is 10.530 keV. In the above description, the method of obtaining the composition of the impurity element to be added accurately by avoiding the influence of X-ray absorption by utilizing the fact that the energy of K lines or L lines is close as described above. .

In addition, the method of the present embodiment (FIG. 3) can also be applied to a stoichiometric compound containing a combination of elements having similar energy between the K line of one element and the L line of the other element. is there. Examples of such stoichiometric compounds include zinc blend structure aluminum arsenide (AlAs), rutile structure cobalt fluoride (CoF ₂ ), and perovskite structure barium titanate (BaTiO ₃ ). In AlAs, the energy of Al Kα ray is 1.486 keV, and the energy of As α α ray is 1.282 keV. In CoF ₂ , the energy of the Co Lα ray is 0.776 keV, and the energy of the F Kα ray is 0.677 keV. In BaTiO ₃ , the energy of Ba Lα ray is 4.465 keV, and the energy of Ti Kα ray is 4.508 keV. The technique of the present embodiment can also be applied to a stoichiometric compound containing a combination of elements having similar energy of K-line and L-line.

  In the above description, TEM-EDS is used as an example in which a sample compound is irradiated with an electron beam and characteristic X-rays emitted from the compound irradiated with the electron beam are detected. In addition to the EDS detector, a wavelength dispersive x-ray spectroscopy (WDS) detector can also be used for detecting characteristic X-rays. In addition to TEM, devices that emit characteristic X-rays from compounds include a scanning electron microscope (SEM), an X-ray fluorescence spectrometer (XRF), an electron microanalyzer ( Electron Probe MicroAnalyzer (EPMA) can also be used.

The method of the present embodiment described above can be implemented using, for example, the composition analyzer 100 having a configuration as shown in FIG.
FIG. 5 is a diagram illustrating an example of a composition analyzer.

5 includes an irradiation unit 110, a detection unit 120, and a composition analysis processing unit 130.
The irradiation unit 110 irradiates the sample 101 of the compound to be analyzed with an electron beam or X-ray 102. For the irradiation unit 110, a device such as a TEM or SEM is used. The sample 101, the stoichiometric compound atomic number or the characteristic X-ray energy includes close element A and the element B (including the structure of the A _x B _y at least in part), part of one of the elements A compounds substituted with an impurity element Q (including the structure of the Q _n a _xn B _y at least a portion) is used.

  The detection unit 120 detects the characteristic X-ray 103 of the element A and the element B emitted from the sample 101 irradiated with the electron beam or the X-ray 102 by the irradiation unit 110. As the detection unit 120, an EDS detector, a WDS detector, or the like is used.

  The composition analysis processing unit 130 includes a first processing unit 131, a second processing unit 132, and a third processing unit 133. The composition analysis processing unit 130 further includes an acquisition unit 134 and a database (DB) 135.

  The acquisition unit 134 includes information (structure information) indicating the structure of the stoichiometric compound not containing the impurity element Q (general formula of composition) and the structure of the compound of the sample 101 containing the impurity element Q (general formula of composition). To get. This structural information is input to the composition analysis processing unit 130 by an operator, for example, and the acquisition unit 134 acquires the input information.

The DB 135 stores information on various parameters used for calculating the k factors k _A and k _B of the element A and the element B using the theoretical formula of the above formula (2).
The first processing unit 131 uses the above formula (1) and formula (2) from the characteristic X-ray intensity I _A of the element _A and the characteristic X-ray intensity I _{B of} the element B detected by the detection unit 120, The composition ratio (xn) / y of the element A and the element B in the compound containing the impurity element Q is obtained without correcting the X-ray absorption. That is, the first processing unit 131 executes the process described in step S2 of FIG.

For the element A and the element B, the first processing unit 131 uses the various parameters stored in the DB 135 and the characteristic X-ray intensities I _A and I _B detected by the detection unit 120, and the above equation (2). From the above, k factors k _A and k _B are calculated. The first processing unit 131 further uses the characteristic X-ray intensities I _A and I _{B of} the element A and element B detected by the detection unit 120 and the calculated k factors k _A and k _B from the above equation (1). The composition ratio (xn) / y of the element A and the element B is calculated from the obtained relational expression of the above expression (4).

  The second processing unit 132 uses the composition ratio (xn) / y of the element A and the element B obtained by the first processing unit 131 and the composition y of the element B in the compound to determine the element in the compound. The composition x-n of A is obtained. That is, the second processing unit 132 performs the process described in step S3 of FIG.

  In the processing in the second processing unit 132, the impurity element Q occupies only the site of the element A of the stoichiometric compound, and the composition of the element B is the same as the stoichiometric compound before the addition of the impurity element Q. What is known is used. The second processing unit 132 extracts the composition y (atom%) of the element B from the structural information of the stoichiometric compound not including the impurity element Q or the compound including the impurity element Q acquired by the acquisition unit 134. . The second processing unit 132 uses the extracted composition B (element%) of the element B and the composition ratio (xn) / y of the element A and the element B calculated by the first processing unit 131 to form a compound. The composition xn (atom%) of the element A in the inside is calculated.

  The third processing unit 133 uses the composition y (atom%) of the known element B and the composition x-n (atom%) of the element A obtained by the second processing unit 132 to use the impurity element Q in the compound. The composition n is determined. That is, the third processing unit 133 executes the process described in step S4 of FIG.

  For example, the third processing unit 133 sets the sum of the compositions of the elements (including the impurity element Q) in the compound to 100 (atom%), and the composition xn (atom%) of the element A and the composition y of the element B ( atom%) is used to calculate the composition n (atom%) of the impurity element Q. Alternatively, the composition x (atom%) of the known element A in the stoichiometric compound not including the impurity element Q and the composition xn (atom%) of the element A calculated by the second processing unit 132 are used. Then, the composition n of the impurity element Q is calculated.

  Although not shown here, the composition analyzer 100 further includes a storage unit that stores information such as the calculated composition n of the impurity element Q, and an output unit such as a display device that outputs such information. Also good.

With the composition analyzer 100 as described above, the composition of the impurity element contained in the predetermined compound can be obtained with high accuracy.
The processing function of the composition analyzer 100 can be realized using a computer.

FIG. 6 is a diagram illustrating an example of a hardware configuration of a computer.
The computer 200 is entirely controlled by the processor 201. A RAM (Random Access Memory) 202 and a plurality of peripheral devices are connected to the processor 201 via a bus 209. The processor 201 may be a multiprocessor. The processor 201 is, for example, a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), or a programmable logic device (PLD). The processor 201 may be a combination of two or more elements among CPU, MPU, DSP, ASIC, and PLD.

  The RAM 202 is used as a main storage device of the computer 200. The RAM 202 temporarily stores at least part of an OS (Operating System) program and application programs to be executed by the processor 201. The RAM 202 stores various data necessary for processing by the processor 201.

  Peripheral devices connected to the bus 209 include an HDD (Hard Disk Drive) 203, a graphic processing device 204, an input interface 205, an optical drive device 206, a device connection interface 207, and a network interface 208.

  The HDD 203 magnetically writes data to and reads data from a built-in disk. The HDD 203 is used as an auxiliary storage device for the computer 200. The HDD 203 stores an OS program, application programs, and various data. A semiconductor storage device such as a flash memory can be used as the auxiliary storage device.

  A monitor 211 is connected to the graphic processing device 204. The graphic processing device 204 displays an image on the screen of the monitor 211 in accordance with an instruction from the processor 201. Examples of the monitor 211 include a display device using a CRT (Cathode Ray Tube) and a liquid crystal display device.

  A keyboard 212 and a mouse 213 are connected to the input interface 205. The input interface 205 transmits a signal transmitted from the keyboard 212 or the mouse 213 to the processor 201. The mouse 213 is an example of a pointing device, and other pointing devices can be used. Examples of other pointing devices include a touch panel, a tablet, a touch pad, and a trackball.

  The optical drive device 206 reads data recorded on the optical disc 214 using laser light or the like. The optical disk 214 is a portable recording medium on which data is recorded so that it can be read by reflection of light. The optical disk 214 includes a DVD (Digital Versatile Disc), a DVD-RAM, a CD-ROM (Compact Disc Read Only Memory), a CD-R (Recordable) / RW (ReWritable), and the like.

  The device connection interface 207 is a communication interface for connecting peripheral devices to the computer 200. For example, the device connection interface 207 can be connected to the memory device 215 or the memory reader / writer 216. The memory device 215 is a recording medium equipped with a communication function with the device connection interface 207. The memory reader / writer 216 is a device that writes data to the memory card 217 or reads data from the memory card 217. The memory card 217 is a card type recording medium.

  The network interface 208 is connected to the network 210. The network interface 208 transmits and receives data to and from other computers or communication devices via the network 210.

With the hardware configuration described above, the processing function of the composition analyzer 100 can be realized.
The computer 200 implements the processing function of the composition analyzer 100 by executing a program recorded on a computer-readable recording medium, for example. A program describing the processing contents to be executed by the computer 200 can be recorded in various recording media. For example, a program to be executed by the computer 200 can be stored in the HDD 203. The processor 201 loads at least a part of the program in the HDD 203 into the RAM 202 and executes the program. A program to be executed by the computer 200 can also be recorded on a portable recording medium such as the optical disc 214, the memory device 215, and the memory card 217. The program stored in the portable recording medium becomes executable after being installed in the HDD 203 under the control of the processor 201, for example. The processor 201 can also read and execute a program directly from a portable recording medium.

Regarding the embodiment described above, the following additional notes are further disclosed.
(Additional remark 1) The composition ratio of the said 1st element and the said 2nd element of the compound by which the part of the said 1st element was substituted by the 3rd element among the 1st element of the stoichiometric compound and the 2nd element A step of obtaining using X-ray spectroscopy;
Using the composition ratio and the composition of the second element in the compound to determine the composition of the first element in the compound;
Using the composition of the first element in the compound to determine the composition of the third element in the compound.

(Supplementary note 2) The composition analysis method according to supplementary note 1, wherein the characteristic X-ray energy of the first element is close to the characteristic X-ray energy of the second element.
(Supplementary note 3) The supplementary note 2, wherein the characteristic X-rays of the first element and the characteristic X-rays of the second element are K-lines, L-lines, or K-lines and L-lines. Composition analysis method.

  (Supplementary Note 4) The ratio between the characteristic X-ray mass absorption coefficient of the first element and the characteristic X-ray mass absorption coefficient of the second element is set based on the analysis accuracy of the composition of the third element. The composition analysis method according to Supplementary Note 2 or 3, wherein the composition analysis method is within a predetermined range.

(Supplementary note 5) The composition analysis method according to any one of supplementary notes 1 to 4, wherein the atomic number of the first element is close to the atomic number of the second element.
(Supplementary note 6) The composition analysis method according to supplementary note 5, wherein a difference between an atomic number of the first element and an atomic number of the second element is 4 or less.

  (Additional remark 7) The said 1st element and the said 2nd element are elements which can consider that X-ray absorption with respect to the said compound when obtaining a mutual characteristic X-ray | X_line by the said X-ray spectroscopy is comparable. The composition analysis method according to any one of appendices 1 to 6.

  (Supplementary Note 8) The step of obtaining the composition ratio includes the intensity of the characteristic X-ray of the first element obtained by the X-ray spectroscopy, the first k factor of the first element obtained by a theoretical formula, and the X-ray. Supplementary note 1 including a step of obtaining the composition ratio using the characteristic X-ray intensity of the second element obtained by spectroscopy and the second k factor of the second element obtained by a theoretical formula The composition analysis method according to any one of 1 to 7.

  (Supplementary Note 9) In the step of obtaining the composition of the first element in the compound, the composition of the second element in the stoichiometric compound is used as the composition of the second element in the compound. The composition analysis method according to any one of appendices 1 to 8.

  (Supplementary Note 10) The step of determining the composition of the third element in the compound includes determining the composition of the first element in the stoichiometric compound and the composition of the second element from the sum of the composition of the first element and the composition of the second element. 10. The composition analysis method according to any one of appendices 1 to 9, further comprising a step of subtracting a composition of one element and a composition of the second element to obtain a composition of the third element in the compound.

  (Supplementary Note 11) The step of determining the composition of the third element in the compound includes subtracting the composition of the first element in the compound from the composition of the first element in the stoichiometric compound. The composition analysis method according to any one of appendices 1 to 9, further comprising a step of obtaining a composition of the third element therein.

(Supplementary Note 12) Using information obtained by X-ray spectroscopy, a part of the first element and the second element of the stoichiometric compound, wherein a part of the first element is substituted with a third element, A first processing unit for determining a composition ratio between the first element and the second element;
A second processing unit for determining the composition of the first element in the compound using the composition ratio and the composition of the second element in the compound;
And a third processing unit that obtains the composition of the third element in the compound using the composition of the first element in the compound.

(Supplementary note 13)
Using the information obtained by X-ray spectroscopy, the first element of a compound in which a part of the first element of the first and second elements of the stoichiometric compound is replaced with a third element Determining the composition ratio of the second element;
Using the composition ratio and the composition of the second element in the compound, the composition of the first element in the compound is obtained,
A composition analysis program for executing a process for obtaining the composition of the third element in the compound using the composition of the first element in the compound.

10a Sample holder 20a, 20b Sample 30a, 30b Electron beam 40a, 40b Characteristic X-ray 50a EDS detector 50b Detector 100 Composition analyzer 101 Sample 102 Electron beam or X-ray 103 Characteristic X-ray 110 Irradiation unit 120 Detection unit 130 Composition analysis Processing unit 131 First processing unit 132 Second processing unit 133 Third processing unit 134 Acquisition unit 135 DB
200 Computer 201 Processor 202 RAM
203 HDD
204 Graphic Processing Device 205 Input Interface 206 Optical Drive Device 207 Device Connection Interface 208 Network Interface 209 Bus 210 Network 211 Monitor 212 Keyboard 213 Mouse 214 Optical Disk 215 Memory Device 216 Memory Reader / Writer 217 Memory Card

Claims (8)

X-ray spectroscopy of the composition ratio of the first element and the second element of a compound in which a part of the first element of the stoichiometric compound is substituted with a third element. The process of using the method
Using the composition ratio and the composition of the second element in the compound to determine the composition of the first element in the compound;
Using the composition of the first element in the compound to determine the composition of the third element in the compound.   The first element and the second element are elements that can be considered to have the same degree of X-ray absorption with respect to the compound when characteristic X-rays of each other are obtained by the X-ray spectroscopy. 2. The composition analysis method according to 1.   The step of obtaining the composition ratio is obtained by the characteristic X-ray intensity of the first element obtained by the X-ray spectroscopy, the first k factor of the first element obtained by a theoretical formula, and the X-ray spectroscopy. 3. The method according to claim 1, further comprising a step of obtaining the composition ratio using the characteristic X-ray intensity of the second element obtained and the second k factor of the second element obtained by a theoretical formula. The composition analysis method described.   The step of determining the composition of the first element in the compound uses the composition of the second element in the stoichiometric compound as the composition of the second element in the compound. The composition analysis method according to any one of 1 to 3.   The step of determining the composition of the third element in the compound includes the composition of the first element in the compound from the sum of the composition of the first element and the composition of the second element in the stoichiometric compound. 5. The composition analysis method according to claim 1, further comprising a step of subtracting the composition of the second element from the composition to obtain the composition of the third element in the compound.   The step of determining the composition of the third element in the compound includes subtracting the composition of the first element in the compound from the composition of the first element in the stoichiometric compound. The composition analysis method according to claim 1, further comprising a step of obtaining a composition of three elements. Using the information obtained by X-ray spectroscopy, the first element of a compound in which a part of the first element of the first and second elements of the stoichiometric compound is replaced with a third element A first processing unit for obtaining a composition ratio of the second element;
A second processing unit for determining the composition of the first element in the compound using the composition ratio and the composition of the second element in the compound;
And a third processing unit that obtains the composition of the third element in the compound using the composition of the first element in the compound. On the computer,
Using the information obtained by X-ray spectroscopy, the first element of a compound in which a part of the first element of the first and second elements of the stoichiometric compound is replaced with a third element Determining the composition ratio of the second element;
Using the composition ratio and the composition of the second element in the compound, the composition of the first element in the compound is obtained,
A composition analysis program for executing a process for obtaining the composition of the third element in the compound using the composition of the first element in the compound.

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