WO2020003675A1 - Total reflection x-ray fluorescence analysis device and measuring method - Google Patents

Total reflection x-ray fluorescence analysis device and measuring method Download PDF

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WO2020003675A1
WO2020003675A1 PCT/JP2019/014524 JP2019014524W WO2020003675A1 WO 2020003675 A1 WO2020003675 A1 WO 2020003675A1 JP 2019014524 W JP2019014524 W JP 2019014524W WO 2020003675 A1 WO2020003675 A1 WO 2020003675A1
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total reflection
measurement sample
ray
fluorescent
differential curve
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French (fr)
Japanese (ja)
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浩 河野
智 村上
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株式会社リガク
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B15/00Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
    • G01B15/02Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons for measuring thickness
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/20Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/22Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
    • G01N23/223Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence

Definitions

  • the present invention relates to a total reflection X-ray fluorescence spectrometer and a measuring method.
  • a parameter called a film thickness is mainly managed.
  • the film thickness has been measured using a fluorescent X-ray analysis method or an X-ray reflectivity method (XRR: X-Ray Reflectometry).
  • XRR X-Ray Reflectometry
  • the fluorescent X-ray analysis method is based on the adhesion amount (mass per unit area) obtained from the measured intensity of the fluorescent X-ray, and the density obtained from the literature value or another method (for example, X-ray reflectivity method). (See Patent Document 1 below).
  • the X-ray reflectivity method is a method of irradiating a measurement sample with primary X-rays in the vicinity of a critical angle of total reflection and calculating surface roughness, density, film thickness, etc. based on attenuation due to interference of reflected X-rays. (See Patent Document 2 below).
  • the attached amount is divided by the density.
  • the density is information obtained by literature or other methods, and is not the density obtained from an actual measurement sample. Therefore, the calculated film thickness includes an error. Further, in the X-ray reflectivity method, there is a limitation on a range of a measured film thickness.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a method for measuring the density and thickness of a measurement sample and a total reflection X-ray fluorescence analyzer for measuring the density and thickness of the measurement sample. That is, it can be realized easily at low cost.
  • a detector that measures the intensity of the fluorescent X-rays generated from the measurement sample, and obtains a differential curve by differentiating the relationship between the intensity of the fluorescent X-rays and the incident angle with respect to the incident angle.
  • a calculating unit that obtains the critical angle for total reflection from a differential curve, and further calculates the density and / or film thickness of the measurement sample based on the critical angle for total reflection and the wavelength of the primary X-ray. It is characterized by.
  • the total reflection X-ray fluorescence spectrometer according to claim 2 is the total reflection X-ray fluorescence spectrometer according to claim 1, wherein the calculation unit acquires a peak angle of the differential curve as the critical angle for total reflection. It is characterized.
  • the total reflection X-ray fluorescence spectrometer according to claim 3 is the total reflection X-ray fluorescence spectrometer according to claim 1 or 2, wherein the calculation unit further includes: The method is characterized in that the amount of adhesion of the measurement sample is quantitatively analyzed, and the film thickness of the measurement sample is calculated based on the amount of adhesion and the density.
  • the total reflection X-ray fluorescence spectrometer according to claim 4 is the total reflection X-ray fluorescence spectrometer according to any one of claims 1 to 3, wherein the arithmetic unit is configured to perform the calculation based on a shape of the differential curve. It is characterized in that the surface roughness of the measurement sample is calculated.
  • the surface roughness of the measurement sample is calculated based on a relationship between a peak width of the curve and the surface roughness and a peak width of the differential curve acquired based on the measurement sample.
  • the density and the thickness of the measurement sample can be measured easily at low cost.
  • FIG. 1 is a diagram schematically illustrating a total reflection X-ray fluorescence spectrometer according to an embodiment of the present invention. It is a flowchart which shows the measuring method of a density. It is a figure showing an example showing the relation between incident angle and intensity of fluorescent X-rays. It is a figure showing an example of a differential curve. It is a figure showing another example of a differential curve. It is a figure showing another example of a differential curve. 5 is a flowchart illustrating a method for measuring a film thickness. It is a flowchart which shows the measuring method of surface roughness. 6 is a flowchart illustrating a method of measuring a correction value.
  • FIG. 1 is a view schematically showing a total reflection X-ray fluorescence spectrometer 100.
  • the total reflection X-ray fluorescence spectrometer 100 includes a sample stage 102, an X-ray source 104, a detector 106, a counter 108, and a calculation unit 110.
  • a measurement sample 112 is arranged on the sample stage 102.
  • the measurement sample 112 is, for example, a silicon substrate on which a thin film of silicon oxide (SiO2) is formed.
  • the X-ray source 104 irradiates monochromatic primary X-rays 114 while changing the incident angle with respect to the surface of the measurement sample 112 over the critical angle of total reflection of the measurement sample 112. Specifically, for example, the X-ray source 104 converts the X-rays emitted from an X-ray tube (not shown) into a single color using a monochromator (not shown) such as a spectral crystal and the like, and a slit (not shown). Squeeze thinly.
  • the X-ray source 104 irradiates the monochromatic primary X-ray 114 onto the surface of the measurement sample 112 within an angle range of 0.3 degrees before and after the critical angle for total reflection (for the sake of explanation, actual irradiation is performed). Angle greater than the angle).
  • the critical angle for total reflection is an angle unique to the measurement sample 112.
  • the angle range is set in a range in which a total reflection critical angle can be obtained from a differential curve described later.
  • the fluorescent X-ray 116 is generated from the measurement sample 112 irradiated with the primary X-ray 114.
  • the detector 106 measures the intensity of the fluorescent X-ray 116 generated from the measurement sample 112.
  • the detector 106 is a semiconductor detector such as an SDD detector.
  • the detector 106 measures the intensity of the fluorescent X-ray 116 and outputs a pulse signal having a peak value corresponding to the measured energy of the fluorescent X-ray 116.
  • the detector 106 measures the intensity of the fluorescent X-ray 116 each time the X-ray source 104 changes the incident angle of the fluorescent X-ray 116 on the measurement sample 112.
  • Counter 108 counts the pulse signal output as the measured intensity of detector 106 according to the peak value.
  • the counter 108 is a multi-channel analyzer, and counts the output pulse signal of the detector 106 for each channel corresponding to the energy of the fluorescent X-ray 116, and calculates the intensity of the fluorescent X-ray 116. Output to the arithmetic unit 110.
  • the calculation unit 110 calculates the density and / or the film thickness. A specific process performed by the arithmetic unit 110 will be described with reference to a flowchart (FIG. 2) illustrating a density measuring method according to the present invention.
  • the measurement sample 112 is placed on the sample table 102 (S202).
  • the measurement sample 112 is a silicon substrate (bare silicon) or a silicon substrate having a thin film of silicon carbide (SiC) or silicon oxide (SiO2) formed on the surface.
  • the measurement sample 112 is placed on the sample stage 102 and irradiated with primary X-rays 114 from the X-ray source 104.
  • the measurement sample 112 irradiated with the primary X-ray 114 generates a fluorescent X-ray 116.
  • the arithmetic unit 110 acquires the intensity of the fluorescent X-ray 116 counted by the counter 108 (S204). Specifically, the arithmetic unit 110 acquires the intensity of the fluorescent X-ray 116 counted by the counter 108 for each incident angle of the primary X-ray 114 on the measurement sample 112.
  • FIG. 3 is an example showing a relationship between the incident angle and the intensity of the fluorescent X-ray 116 (Si-k ⁇ ray) of Si which is a constituent element of the substrate. As shown in FIG. 3, as the incident angle increases, the intensity of the fluorescent X-ray 116 rapidly increases at a specific angle as a boundary. Further, the relationship between the incident angle and the intensity of the fluorescent X-ray 116 has an inflection point. The gradient of the intensity of the fluorescent X-ray 116 becomes gradually gentler at an angle larger than the inflection point.
  • the change in the intensity of the fluorescent X-rays 116 is caused by the following phenomenon.
  • the incident angle is smaller than the critical angle for total reflection, the primary X-ray 114 does not enter the inside of the measurement sample 112 due to the total reflection on the surface of the measurement sample 112. Therefore, the fluorescent X-ray 116 generated at the incident angle is very small.
  • the incident angle becomes larger than the critical angle for total reflection, the primary X-ray 114 enters the inside of the measurement sample 112.
  • the calculation unit 110 obtains a differential curve by differentiating the relationship between the intensity of the fluorescent X-rays 116 and the incident angle with respect to the incident angle (S206). Specifically, the arithmetic unit 110 differentiates the relationship between the intensity of the fluorescent X-rays 116 (Si-k ⁇ rays) acquired in S204 and the incident angle with respect to the incident angle, as shown in FIG. Get the curve. Since the relationship between the incident angle and the intensity of the fluorescent X-ray 116 shown in FIG. 3 has an inflection point, the differential curve shown in FIG. 4 has a peak. This inflection point, that is, the peak of the differential curve is the critical angle. The horizontal axis in FIG.
  • FIG. 4 is an incident angle based on a mechanical origin on design before performing correction described later.
  • FIG. 4 is a diagram showing a measurement result for correcting the incident angle and confirming the reproducibility, and showing a differential curve measured using a silicon substrate having a known total reflection critical angle as a standard sample.
  • FIG. 4 shows five measurement results for the same measurement sample 112.
  • the peak angle of the differential curve is acquired by performing, for example, smoothing by weighted moving average or function fitting.
  • Table 1 is a table showing each value included in FIG.
  • FIG. 5 is a diagram showing differential curves obtained based on the intensity of the fluorescent X-ray 116 (Si-k ⁇ ray) with respect to the three kinds of measurement samples 112.
  • the three kinds of measurement samples 112 are a silicon substrate, a silicon substrate having a silicon carbide (SiC) thin film formed on its surface, and a silicon substrate having a silicon oxide (SiO2) thin film formed on its surface.
  • SiC silicon carbide
  • SiO2 silicon oxide
  • FIG. 6 is a diagram showing differential curves obtained based on five types of measurement samples 112.
  • the five kinds of measurement samples 112 are a silicon substrate (Si in FIG. 6), a silicon substrate having a 10 nm thick titanium (Ti) thin film formed on the surface (FIG. 6, Ti (10 nm) in Table 2), and a surface.
  • FIG. 6 shows a silicon substrate (Co (6 nm), Co (8 nm), and Co (10 nm) in FIG. 6, Table 2) on which a cobalt (Co) thin film having a thickness of 6 nm, 8 nm, and 10 nm is formed.
  • the fluorescent X-rays 116 used for the intensity measurement include a Si-k ⁇ line of a silicon substrate, a Ti-k ⁇ line of a silicon substrate having a titanium thin film formed on its surface, and a Co-ka of a silicon substrate having a cobalt thin film formed on its surface. Line.
  • Table 2 shows the densities calculated by the later-described calculations for the five types of measurement samples 112 shown in FIG.
  • metals such as Ti and Co formed as an extremely thin film on a silicon substrate are considered to be silicided, and it is considered that a titanium silicide (TiSiX) thin film and a cobalt silicide (CoSiX) thin film are formed.
  • TiSiX titanium silicide
  • CoSiX cobalt silicide
  • the calculation unit 110 acquires a critical angle for total reflection from the differential curve (S208). Specifically, the calculation unit 110 acquires the angle at the peak of the differential curve acquired in S206 as the critical angle for total reflection. For example, the calculation unit 110 acquires a critical angle for total reflection of 0.184 degrees based on the differential curve shown in FIG. Here, the arithmetic unit 110 acquires the critical angle for total reflection by averaging the peak angles acquired from the five differential curves.
  • the peak of the differential curve shown in FIG. 4 is located at -0.066 degrees.
  • the acquired total reflection critical angle includes an error due to the inclination of the sample stage 102.
  • the critical angle for total reflection of 0.184 degrees is a value obtained by correcting an error with respect to the value of -0.066 degrees measured by an actual apparatus. The details of the error correction method will be described later.
  • the calculation unit 110 calculates the density of the measurement sample 112 based on the critical angle for total reflection and the wavelength of the primary X-ray 114 (S210). Specifically, the arithmetic unit 110 applies the critical angle of total reflection acquired in S208 and the wavelength of the primary X-ray 114 applied to the measurement sample 112 to Equation 1 representing the relationship between the critical angle of total reflection and the density. Thus, the density of the measurement sample 112 is calculated.
  • ⁇ c is the critical angle for total reflection.
  • is a constant.
  • is the wavelength of the primary X-ray 114 irradiated on the measurement sample 112.
  • Z is an atomic number.
  • A is the mass number.
  • the atomic number of Ti is 22, the mass number is 48, the atomic number of Co is 27, and the mass number is 59.
  • the unknowns included in the right side of Equation 1 are only the density ⁇ (g / cm 3) of the surface of the measurement sample 112 irradiated with the primary X-ray 114.
  • the critical angle of total reflection on the left side is calculated in S208. Therefore, according to the present invention, the density of the measurement sample 112 (the density of the film formed on the surface of the measurement sample 112) can be easily obtained.
  • FIG. 7 is a flowchart showing a method for measuring a film thickness according to the present invention. Note that if the density is obtained by the above method, the method shown in the flowchart of FIG. 7 uses the fluorescent X-ray analyzer that irradiates the measurement sample 112 with the primary X-ray 114 at an angle larger than the total reflection critical angle. May be performed.
  • the measurement sample 112 is placed on the sample table 102 (S702).
  • the measurement sample 112 is the measurement sample 112 used in S202, and is a silicon substrate having a silicon carbide (SiC) thin film, a silicon oxide (SiO2) thin film, etc. formed on the surface.
  • the measurement sample 112 is placed on the sample stage 102, and the X-ray source 104 irradiates the measurement sample 112 with primary X-rays 114 that have been made monochromatic.
  • the measurement sample 112 irradiated with the primary X-ray 114 generates a fluorescent X-ray 116.
  • the arithmetic unit 110 acquires the intensity of the fluorescent X-ray 116 counted by the counter 108 (S704). Specifically, the calculation unit 110 acquires the intensity of the fluorescent X-ray 116 generated from the analysis element included in the measurement sample 112 whose density has been obtained.
  • the arithmetic unit 110 quantitatively analyzes the amount of the measurement sample 112 attached based on the intensity of the fluorescent X-ray 116 (S706). Specifically, for example, using a conventional technique such as a fundamental parameter method or a calibration curve method, the calculation unit 110 determines the amount of the element attached (the mass per unit area) based on the intensity of the fluorescent X-ray 116 obtained in S704. ) Is calculated.
  • the calculation unit 110 calculates the film thickness of the analysis element based on the amount of adhesion and the density (S708). Specifically, the calculation unit 110 calculates the film thickness of the measurement sample 112 by applying the density acquired in S210 and the adhesion amount acquired in S706 to Equation 2.
  • t (cm) is the film thickness of the measurement sample 112.
  • c (g / cm2) is the amount of adhesion.
  • ⁇ (g / cm3) is the density.
  • the calculation unit 110 can calculate the film thickness from the information on the amount of adhesion and the density.
  • FIG. 8 is a flowchart showing a method for measuring surface roughness according to the present invention.
  • the calculation unit 110 acquires the relationship between the peak width of the differential curve acquired based on the sample whose surface roughness is known and the surface roughness (S802). Specifically, first, the computing unit 110 acquires a differential curve for a sample whose surface roughness is known by the same steps as S202 to S206. As the peak width of the differential curve, for example, the half width of the peak is used. The calculating unit 110 obtains the relationship between the known surface roughness and the half-value width by calculating the half-value width of the differential curve. A calibration curve for calculating surface roughness may be created using a plurality of samples whose surface roughness is known.
  • the peak width of the differential curve tends to increase as the surface roughness of the measurement sample 112 increases.
  • the intercept of each peak waveform on the vertical axis 0.5 is a half width.
  • the half widths of the silicon substrate, the titanium thin film, and the cobalt thin film (three types) are 0.090 °, 0.106 °, and 0.131 °, respectively. Accordingly, the results in FIG. 6 indicate that the surface roughness of the cobalt thin film is the same regardless of the thickness, is larger than the surface roughness of the titanium thin film, and has the smallest surface roughness of the silicon substrate.
  • a differential curve is obtained for the measurement sample 112 whose surface roughness is unknown by the same steps as S202 to S206 (S804 to S808).
  • the calculation unit 110 calculates the half width of the obtained differential curve (S810).
  • the calculation unit 110 calculates the surface roughness of the measurement sample 112 based on the relationship between the half-width obtained in S802 and the surface roughness, and the half-width obtained in S810 (S812).
  • a method of correcting the critical angle for total reflection will be described with reference to the flowchart shown in FIG.
  • a standard sample is placed on the sample table 102 (S902).
  • a silicon substrate having a known total reflection critical angle is arranged on the sample stage 102.
  • FIG. 4 is a differential curve obtained by measuring the intensity of a Si-k ⁇ ray as the fluorescent X-ray 116 using a silicon substrate that can be used as a standard sample. Although the silicon substrate has a known total reflection critical angle, the known value may be different from the peak angle of the differential curve. The reason for the difference is that the actual incident angle of the primary X-rays 114 on the measurement sample 112 and the incident angle recognized by the total reflection X-ray fluorescence spectrometer 100 depend on the accuracy of machining and assembly, changes over time, etc. This is because there is a case where a difference is made.
  • the arithmetic unit acquires the difference between the critical angle for total reflection acquired in S908 and the known critical angle for total reflection of the standard sample as a correction value (S910).
  • the correction value is used in step S210, which is a process of calculating the density.
  • the total reflection X-ray fluorescence spectrometer 100 may adjust the inclination of the sample table 102 based on the correction value acquired in S910. By adjusting the inclination of the sample stage 102, the incident angle of the actual primary X-ray 114 on the measurement sample 112 and the incident angle recognized by the total reflection X-ray fluorescence analyzer 100 can be matched. it can.
  • the density, film thickness, and surface roughness of the measurement sample 112 can be easily measured at low cost by the total reflection X-ray fluorescence spectrometer 100.
  • the present invention is not limited to the above embodiment, and various modifications are possible.
  • the configuration of the total reflection X-ray fluorescence analyzer 100 is an example, and the present invention is not limited to this. It may be replaced with a configuration substantially the same as the configuration shown in the above embodiment, a configuration having the same operation and effect, or a configuration achieving the same object.
  • the total reflection X-ray fluorescence spectrometer 100 adjusts the density measurement mode for measuring the density, the film thickness measurement mode for measuring the film thickness, the surface roughness measurement mode for measuring the surface roughness, and the inclination of the sample table 102.
  • Each of the maintenance modes may be configured as a device that can be individually executed according to a user's instruction.

Abstract

The present invention enables realizing, at low costs and in a simplified manner: a method for measuring the density and the thickness of a measurement sample; and a total reflection X-ray fluorescence analysis device for measuring the density and the thickness of a measurement sample. This total reflection X-ray fluorescence analysis device comprises: an X-ray source which emits a monochromatic primary X-ray while changing the incident angle with respect to the surface of a measurement sample in a range covering the total reflection critical angle of the measurement sample; a detector for measuring the intensity of a resultant fluorescent X-ray generated from the measurement sample; and a computation unit that acquires a differential curve by differentiating, with respect to the incident angle, the relation between the fluorescent X-ray intensity and the incident angle, that acquires the total reflection critical angle from the differential curve, and that, on the basis of the total reflection critical angle and the wavelength of the primary X-ray, computes the density and/or the thickness of the measurement sample.

Description

全反射蛍光X線分析装置及び測定方法Total reflection X-ray fluorescence analyzer and measuring method
 本発明は、全反射蛍光X線分析装置及び測定方法に関する。 The present invention relates to a total reflection X-ray fluorescence spectrometer and a measuring method.
 近年、電子デバイスの性能と歩留りを向上させるために、薄膜の製造プロセスの管理基準が厳格化されている。例えば、薄膜の製造プロセスにおいて、主に膜厚というパラメータが管理されている。従来、膜厚は、蛍光X線分析法やX線反射率法(XRR:X-Ray Reflectometry)を用いて測定されていた。具体的には、蛍光X線分析法は、蛍光X線の測定強度から求めた付着量(単位面積あたりの質量)と、文献値または他の方法(例えばX線反射率法)で求めた密度と、に基づいて膜厚を算出する方法である(下記特許文献1参照)。また、X線反射率法は、1次X線を全反射臨界角度近傍で測定試料に照射し、反射X線の干渉による減衰等に基づいて、表面ラフネス、密度及び膜厚等を算出する方法である(下記特許文献2参照)。 In recent years, in order to improve the performance and yield of electronic devices, management standards for thin film manufacturing processes have become strict. For example, in a thin film manufacturing process, a parameter called a film thickness is mainly managed. Conventionally, the film thickness has been measured using a fluorescent X-ray analysis method or an X-ray reflectivity method (XRR: X-Ray Reflectometry). Specifically, the fluorescent X-ray analysis method is based on the adhesion amount (mass per unit area) obtained from the measured intensity of the fluorescent X-ray, and the density obtained from the literature value or another method (for example, X-ray reflectivity method). (See Patent Document 1 below). The X-ray reflectivity method is a method of irradiating a measurement sample with primary X-rays in the vicinity of a critical angle of total reflection and calculating surface roughness, density, film thickness, etc. based on attenuation due to interference of reflected X-rays. (See Patent Document 2 below).
特開2000-131248号公報JP 2000-131248 A 特開平10-318737号公報JP-A-10-318737
 従来、蛍光X線分析法を用いて膜厚を算出する場合、付着量を密度で除算している。密度は、文献又は他の方法で得られた情報であり、実際の測定試料から求めた密度でない。そのため、計算された膜厚は誤差を含む。また、X線反射率法は、測定膜厚範囲には制限がある。 Conventionally, when calculating the film thickness using the fluorescent X-ray analysis method, the attached amount is divided by the density. The density is information obtained by literature or other methods, and is not the density obtained from an actual measurement sample. Therefore, the calculated film thickness includes an error. Further, in the X-ray reflectivity method, there is a limitation on a range of a measured film thickness.
 また、蛍光X線分析法とX線反射率法を組み合わせて実施できる複合装置も知られている。しかし、複合装置は、機械的構造が複雑でありコストが高い。 複合 Also, there is known a composite apparatus which can be implemented by combining the X-ray fluorescence analysis method and the X-ray reflectivity method. However, the complex device has a complicated mechanical structure and is expensive.
 本発明は上記課題に鑑みてなされたものであって、その目的は、測定試料の密度や膜厚の測定方法及び測定試料の密度や膜厚を測定する全反射蛍光X線分析装置を、低コストかつ簡便に実現できるようにすることである。 The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for measuring the density and thickness of a measurement sample and a total reflection X-ray fluorescence analyzer for measuring the density and thickness of the measurement sample. That is, it can be realized easily at low cost.
 請求項1に記載の全反射蛍光X線分析装置は、測定試料の全反射臨界角度を跨いで、前記測定試料の表面に対する入射角度を変えながら単色化した1次X線を照射するX線源と、前記測定試料から発生した蛍光X線の強度を測定する検出器と、前記蛍光X線の強度と前記入射角度との関係を、前記入射角度について微分することによって微分曲線を取得し、該微分曲線から前記全反射臨界角度を取得し、さらに、前記全反射臨界角度と前記1次X線の波長とに基づいて前記測定試料の密度及びまたは膜厚を算出する演算部と、を有することを特徴とする。 The X-ray source for irradiating a monochromatic primary X-ray while changing an incident angle with respect to the surface of the measurement sample over a critical angle of total reflection of the measurement sample, the total reflection X-ray fluorescence analyzer according to claim 1. And a detector that measures the intensity of the fluorescent X-rays generated from the measurement sample, and obtains a differential curve by differentiating the relationship between the intensity of the fluorescent X-rays and the incident angle with respect to the incident angle. A calculating unit that obtains the critical angle for total reflection from a differential curve, and further calculates the density and / or film thickness of the measurement sample based on the critical angle for total reflection and the wavelength of the primary X-ray. It is characterized by.
 請求項2に記載の全反射蛍光X線分析装置は、請求項1に記載の全反射蛍光X線分析装置において、前記演算部は、前記微分曲線のピーク角度を前記全反射臨界角度として取得すること特徴とする。 The total reflection X-ray fluorescence spectrometer according to claim 2 is the total reflection X-ray fluorescence spectrometer according to claim 1, wherein the calculation unit acquires a peak angle of the differential curve as the critical angle for total reflection. It is characterized.
 請求項3に記載の全反射蛍光X線分析装置は、請求項1または2に記載の全反射蛍光X線分析装置において、前記演算部は、さらに、前記蛍光X線の強度に基づいて、前記測定試料の付着量を定量分析し、前記付着量と、前記密度と、に基づいて前記測定試料の膜厚を算出する、こと特徴とする。 The total reflection X-ray fluorescence spectrometer according to claim 3 is the total reflection X-ray fluorescence spectrometer according to claim 1 or 2, wherein the calculation unit further includes: The method is characterized in that the amount of adhesion of the measurement sample is quantitatively analyzed, and the film thickness of the measurement sample is calculated based on the amount of adhesion and the density.
 請求項4に記載の全反射蛍光X線分析装置は、請求項1乃至3のいずれかに記載の全反射蛍光X線分析装置において、前記演算部は、前記微分曲線の形状に基づいて、前記測定試料の表面ラフネスを算出することを特徴とする。 The total reflection X-ray fluorescence spectrometer according to claim 4 is the total reflection X-ray fluorescence spectrometer according to any one of claims 1 to 3, wherein the arithmetic unit is configured to perform the calculation based on a shape of the differential curve. It is characterized in that the surface roughness of the measurement sample is calculated.
 請求項5に記載の全反射蛍光X線分析装置は、請求項4に記載の全反射蛍光X線分析装置において、前記演算部は、前記表面ラフネスが既知である試料に基づいて取得した前記微分曲線のピーク幅と前記表面ラフネスとの関係と、前記測定試料に基づいて取得した前記微分曲線のピーク幅と、に基づいて前記測定試料の表面ラフネスを算出することを特徴とする。 The total reflection X-ray fluorescence spectrometer according to claim 5, wherein in the total reflection X-ray fluorescence spectrometer according to claim 4, the calculation unit is configured to obtain the differential obtained based on a sample whose surface roughness is known. The surface roughness of the measurement sample is calculated based on a relationship between a peak width of the curve and the surface roughness and a peak width of the differential curve acquired based on the measurement sample.
 請求項6に記載の測定方法は、測定試料の全反射臨界角度を跨いで、前記測定試料の表面に対する入射角度を変えながら単色化した1次X線を照射する工程と、前記測定試料から発生した蛍光X線の強度を測定する工程と、前記蛍光X線の強度と前記入射角度との関係を、前記入射角度について微分することによって微分曲線を取得する工程と、前記微分曲線から前記全反射臨界角度を取得する工程と、前記全反射臨界角度と前記1次X線の波長とに基づいて前記測定試料の密度及びまたは膜厚を算出する工程と、を有することを特徴とする。 7. The measuring method according to claim 6, wherein a step of irradiating monochromatic primary X-rays while changing an incident angle with respect to the surface of the measurement sample over a critical angle of total reflection of the measurement sample, and generating from the measurement sample Measuring the intensity of the obtained fluorescent X-rays, obtaining a differential curve by differentiating the relationship between the intensity of the fluorescent X-rays and the incident angle with respect to the incident angle, and obtaining the total reflection from the differential curve. Obtaining a critical angle; and calculating a density and / or a film thickness of the measurement sample based on the total reflection critical angle and the wavelength of the primary X-ray.
 請求項1乃至3及び6に記載の発明によれば、低コストかつ簡便に測定試料の密度や膜厚を測定することができる。 According to the first to third and sixth aspects of the present invention, the density and the thickness of the measurement sample can be measured easily at low cost.
 請求項4及び5に記載の発明によれば、密度や膜厚のみならず、測定試料の表面ラフネスの情報を得ることができる。 According to the fourth and fifth aspects of the present invention, it is possible to obtain information on not only the density and the film thickness but also the surface roughness of the measurement sample.
本発明の実施形態に係る全反射蛍光X線分析装置を概略的に示す図である。FIG. 1 is a diagram schematically illustrating a total reflection X-ray fluorescence spectrometer according to an embodiment of the present invention. 密度の測定方法を示すフローチャートである。It is a flowchart which shows the measuring method of a density. 入射角度と蛍光X線の強度との関係を表す一例を示す図である。It is a figure showing an example showing the relation between incident angle and intensity of fluorescent X-rays. 微分曲線の一例を示す図である。It is a figure showing an example of a differential curve. 微分曲線の他の一例を示す図である。It is a figure showing another example of a differential curve. 微分曲線の他の一例を示す図である。It is a figure showing another example of a differential curve. 膜厚の測定方法を示すフローチャートである。5 is a flowchart illustrating a method for measuring a film thickness. 表面ラフネスの測定方法を示すフローチャートである。It is a flowchart which shows the measuring method of surface roughness. 補正値の測定方法を示すフローチャートである。6 is a flowchart illustrating a method of measuring a correction value.
 以下、本発明を実施するための好適な実施の形態(以下、実施形態という)を説明する。図1は、全反射蛍光X線分析装置100の概略を示す図である。 Hereinafter, preferred embodiments for implementing the present invention (hereinafter, referred to as embodiments) will be described. FIG. 1 is a view schematically showing a total reflection X-ray fluorescence spectrometer 100.
 図1に示すように、全反射蛍光X線分析装置100は、試料台102と、X線源104と、検出器106と、計数器108と、演算部110と、を有する。試料台102は、測定試料112が配置される。測定試料112は、例えば、酸化ケイ素(SiO2)の薄膜が表面に形成されたシリコン基板である。 As shown in FIG. 1, the total reflection X-ray fluorescence spectrometer 100 includes a sample stage 102, an X-ray source 104, a detector 106, a counter 108, and a calculation unit 110. On the sample stage 102, a measurement sample 112 is arranged. The measurement sample 112 is, for example, a silicon substrate on which a thin film of silicon oxide (SiO2) is formed.
 X線源104は、測定試料112の全反射臨界角度を跨いで、測定試料112の表面に対する入射角度を変えながら単色化した1次X線114を照射する。具体的には、例えば、X線源104は、X線管(図示せず)から出射されたX線を分光結晶等のモノクロメーター(図示せず)で単色化し、スリット(図示せず)で薄く絞る。また、X線源104は、当該単色化した1次X線114を測定試料112の表面に対して、全反射臨界角度の前後0.3度の角度範囲で照射する(説明上、実際の照射角度より大きい角度で図示している)。ここで、全反射臨界角度は、測定試料112に固有の角度である。角度範囲は、後述する微分曲線から全反射臨界角度を取得できる範囲で設定される。1次X線114が照射された測定試料112から、蛍光X線116が発生する。 The X-ray source 104 irradiates monochromatic primary X-rays 114 while changing the incident angle with respect to the surface of the measurement sample 112 over the critical angle of total reflection of the measurement sample 112. Specifically, for example, the X-ray source 104 converts the X-rays emitted from an X-ray tube (not shown) into a single color using a monochromator (not shown) such as a spectral crystal and the like, and a slit (not shown). Squeeze thinly. The X-ray source 104 irradiates the monochromatic primary X-ray 114 onto the surface of the measurement sample 112 within an angle range of 0.3 degrees before and after the critical angle for total reflection (for the sake of explanation, actual irradiation is performed). Angle greater than the angle). Here, the critical angle for total reflection is an angle unique to the measurement sample 112. The angle range is set in a range in which a total reflection critical angle can be obtained from a differential curve described later. The fluorescent X-ray 116 is generated from the measurement sample 112 irradiated with the primary X-ray 114.
 検出器106は、測定試料112から発生した蛍光X線116の強度を測定する。具体的には、例えば、検出器106は、SDD検出器等の半導体検出器である。検出器106は、蛍光X線116の強度を測定し、測定した蛍光X線116のエネルギーに応じた波高値を有するパルス信号を出力する。検出器106は、X線源104が測定試料112に対する蛍光X線116の入射角度を変えるごとに蛍光X線116の強度を測定する。 The detector 106 measures the intensity of the fluorescent X-ray 116 generated from the measurement sample 112. Specifically, for example, the detector 106 is a semiconductor detector such as an SDD detector. The detector 106 measures the intensity of the fluorescent X-ray 116 and outputs a pulse signal having a peak value corresponding to the measured energy of the fluorescent X-ray 116. The detector 106 measures the intensity of the fluorescent X-ray 116 each time the X-ray source 104 changes the incident angle of the fluorescent X-ray 116 on the measurement sample 112.
 計数器108は、検出器106の測定強度として出力されるパルス信号を、波高値に応じて計数する。具体的には、例えば、計数器108は、マルチチャンネルアナライザであって、検出器106の出力パルス信号を、蛍光X線116のエネルギーに対応したチャンネル毎に計数し、蛍光X線116の強度として演算部110に出力する。 Counter 108 counts the pulse signal output as the measured intensity of detector 106 according to the peak value. Specifically, for example, the counter 108 is a multi-channel analyzer, and counts the output pulse signal of the detector 106 for each channel corresponding to the energy of the fluorescent X-ray 116, and calculates the intensity of the fluorescent X-ray 116. Output to the arithmetic unit 110.
 演算部110は、密度及びまたは膜厚を算出する。具体的な、演算部110が行う処理は、本発明に係る密度の測定方法を示すフローチャート(図2)を用いて説明する。 The calculation unit 110 calculates the density and / or the film thickness. A specific process performed by the arithmetic unit 110 will be described with reference to a flowchart (FIG. 2) illustrating a density measuring method according to the present invention.
 まず、試料台102に測定試料112を配置する(S202)。具体的には、例えば、測定試料112は、シリコン基板(ベアシリコン)や、表面に炭化ケイ素(SiC)や酸化ケイ素(SiO2)の薄膜が形成されたシリコン基板である。測定試料112は、試料台102に配置されて、X線源104から1次X線114を照射される。1次X線114を照射された測定試料112は、蛍光X線116を発生する。 First, the measurement sample 112 is placed on the sample table 102 (S202). Specifically, for example, the measurement sample 112 is a silicon substrate (bare silicon) or a silicon substrate having a thin film of silicon carbide (SiC) or silicon oxide (SiO2) formed on the surface. The measurement sample 112 is placed on the sample stage 102 and irradiated with primary X-rays 114 from the X-ray source 104. The measurement sample 112 irradiated with the primary X-ray 114 generates a fluorescent X-ray 116.
 次に、演算部110は、計数器108が計数した蛍光X線116の強度を取得する(S204)。具体的には、演算部110は、1次X線114の測定試料112への入射角度ごとに、計数器108が計数した蛍光X線116の強度を取得する。図3は、入射角度と基板の構成元素であるSiの蛍光X線116(Si-kα線)の強度との関係を表す一例である。図3に示すように、入射角度が大きくなると、特定の角度を境界に蛍光X線116の強度が急激に増加する。また、入射角度と蛍光X線116の強度との関係は変曲点を有する。蛍光X線116の強度の傾きは、変曲点より大きい角度では、徐々に緩やかになる。 Next, the arithmetic unit 110 acquires the intensity of the fluorescent X-ray 116 counted by the counter 108 (S204). Specifically, the arithmetic unit 110 acquires the intensity of the fluorescent X-ray 116 counted by the counter 108 for each incident angle of the primary X-ray 114 on the measurement sample 112. FIG. 3 is an example showing a relationship between the incident angle and the intensity of the fluorescent X-ray 116 (Si-kα ray) of Si which is a constituent element of the substrate. As shown in FIG. 3, as the incident angle increases, the intensity of the fluorescent X-ray 116 rapidly increases at a specific angle as a boundary. Further, the relationship between the incident angle and the intensity of the fluorescent X-ray 116 has an inflection point. The gradient of the intensity of the fluorescent X-ray 116 becomes gradually gentler at an angle larger than the inflection point.
 蛍光X線116の強度の変化は、以下の現象により起こる。入射角度が全反射臨界角度より小さい場合、1次X線114は、測定試料112表面で全反射することにより測定試料112内部には侵入しない。そのため、当該入射角度において発生する蛍光X線116は非常に小さい。一方、入射角が全反射臨界角度より大きくなると、測定試料112内部に1次X線114が進入する。1次X線114が測定試料112内部に進入すると、内部に進入した1次X線114により励起された蛍光X線が発生し、その結果検出器106が検出する蛍光X線116が急激に増加する。 強度 The change in the intensity of the fluorescent X-rays 116 is caused by the following phenomenon. When the incident angle is smaller than the critical angle for total reflection, the primary X-ray 114 does not enter the inside of the measurement sample 112 due to the total reflection on the surface of the measurement sample 112. Therefore, the fluorescent X-ray 116 generated at the incident angle is very small. On the other hand, when the incident angle becomes larger than the critical angle for total reflection, the primary X-ray 114 enters the inside of the measurement sample 112. When the primary X-rays 114 enter the inside of the measurement sample 112, fluorescent X-rays excited by the primary X-rays 114 entering the inside are generated, and as a result, the fluorescent X-rays 116 detected by the detector 106 rapidly increase. I do.
 次に、演算部110は、蛍光X線116の強度と入射角度との関係を、入射角度について微分することによって微分曲線を取得する(S206)。具体的には、演算部110は、S204で取得した蛍光X線116(Si-kα線)の強度と入射角度との関係に対して、入射角度について微分することによって図4に示すような微分曲線を取得する。図3に示す入射角度と蛍光X線116の強度との関係が変曲点を有することから、図4に示す微分曲線はピークを有する。この変曲点、即ち微分曲線のピークが臨界角度である。図4の横軸は、後述する補正を行う前の設計上の機械的原点に基づく入射角度である。図4は、入射角度の補正と再現性の確認のための測定結果であって、全反射臨界角度が既知であるシリコン基板を標準試料として測定した微分曲線を示す図である。図4は、同一測定試料112に対する5回の測定結果を示している。微分曲線のピーク角度は、例えば重み付け移動平均によるスムージングや関数フィッティングを行い取得する。表1は、図4に含まれる各値を示す表である。 Next, the calculation unit 110 obtains a differential curve by differentiating the relationship between the intensity of the fluorescent X-rays 116 and the incident angle with respect to the incident angle (S206). Specifically, the arithmetic unit 110 differentiates the relationship between the intensity of the fluorescent X-rays 116 (Si-kα rays) acquired in S204 and the incident angle with respect to the incident angle, as shown in FIG. Get the curve. Since the relationship between the incident angle and the intensity of the fluorescent X-ray 116 shown in FIG. 3 has an inflection point, the differential curve shown in FIG. 4 has a peak. This inflection point, that is, the peak of the differential curve is the critical angle. The horizontal axis in FIG. 4 is an incident angle based on a mechanical origin on design before performing correction described later. FIG. 4 is a diagram showing a measurement result for correcting the incident angle and confirming the reproducibility, and showing a differential curve measured using a silicon substrate having a known total reflection critical angle as a standard sample. FIG. 4 shows five measurement results for the same measurement sample 112. The peak angle of the differential curve is acquired by performing, for example, smoothing by weighted moving average or function fitting. Table 1 is a table showing each value included in FIG.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
 図4及び表1に示すように、5回の測定結果はほぼ一致しており、後述する数1により算出する密度に対しても再現性があることが確認された。標準試料として測定に用いたシリコン基板の全反射臨界角度は既知(0.184°)である。そのため、5個の微分曲線から取得したピーク角度の平均値が全反射臨界角度となるよう補正(オフセット)を行う。ここで取得した補正値は、全反射臨界角度(密度)が未知の試料を測定するときに用いる。 (4) As shown in FIG. 4 and Table 1, the results of the five measurements were almost the same, and it was confirmed that the reproducibility was also obtained for the density calculated by Equation 1 described below. The critical angle of total reflection of the silicon substrate used for measurement as a standard sample is known (0.184 °). Therefore, the correction (offset) is performed so that the average value of the peak angles obtained from the five differential curves becomes the critical angle for total reflection. The correction value acquired here is used when measuring a sample whose critical angle for total reflection (density) is unknown.
 また、図5は、3種の測定試料112に対して、蛍光X線116(Si-kα線)の強度に基づいて取得した微分曲線を示す図である。3種の測定試料112は、シリコン基板、表面に炭化ケイ素(SiC)薄膜が形成されたシリコン基板、及び、表面に酸化ケイ素(SiO2)薄膜が形成されたシリコン基板である。図5に示すように、ピークの位置は測定試料112ごとに異なっている。すなわち、測定試料112の表面に形成された密度の異なる薄膜によって全反射臨界角度が異なることが確認された。 FIG. 5 is a diagram showing differential curves obtained based on the intensity of the fluorescent X-ray 116 (Si-kα ray) with respect to the three kinds of measurement samples 112. The three kinds of measurement samples 112 are a silicon substrate, a silicon substrate having a silicon carbide (SiC) thin film formed on its surface, and a silicon substrate having a silicon oxide (SiO2) thin film formed on its surface. As shown in FIG. 5, the position of the peak differs for each measurement sample 112. That is, it was confirmed that the critical angles of total reflection differ depending on the thin films having different densities formed on the surface of the measurement sample 112.
 また、図6は、5種の測定試料112に基づいて取得した微分曲線を示す図である。5種の測定試料112は、シリコン基板(図6のSi)、表面に10nmの膜厚でチタン(Ti)薄膜が形成されたシリコン基板(図6、表2のTi (10nm))及び、表面に6nm、8nm及び10nmの膜厚でコバルト(Co)薄膜が形成されたシリコン基板(図6、表2のCo (6nm)、Co (8nm)及びCo (10nm))である。強度測定の対象とした蛍光X線116は、シリコン基板のSi-kα線、表面にチタン薄膜が形成されたシリコン基板のTi-kα線、表面にコバルト薄膜が形成されたシリコン基板のCo-kα線である。 FIG. 6 is a diagram showing differential curves obtained based on five types of measurement samples 112. The five kinds of measurement samples 112 are a silicon substrate (Si in FIG. 6), a silicon substrate having a 10 nm thick titanium (Ti) thin film formed on the surface (FIG. 6, Ti (10 nm) in Table 2), and a surface. FIG. 6 shows a silicon substrate (Co (6 nm), Co (8 nm), and Co (10 nm) in FIG. 6, Table 2) on which a cobalt (Co) thin film having a thickness of 6 nm, 8 nm, and 10 nm is formed. The fluorescent X-rays 116 used for the intensity measurement include a Si-kα line of a silicon substrate, a Ti-kα line of a silicon substrate having a titanium thin film formed on its surface, and a Co-ka of a silicon substrate having a cobalt thin film formed on its surface. Line.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
 表2に、図6で示した5種の測定試料112に対して、後述する計算により算出した密度を示す。一般的に、シリコン基板上に極薄膜として形成されたTi、Co等の金属は、シリサイド化するとされ、チタンシリサイド(TiSiX)薄膜、コバルトシリサイド(CoSiX)薄膜が形成されたと考えられる。また、形成された薄膜は、成膜条件により、化合形態(例えばTi2Si、TiSi、TiSi2等)や付着形態が異なり、密度に違いがでることが知られている。 Table 2 shows the densities calculated by the later-described calculations for the five types of measurement samples 112 shown in FIG. Generally, metals such as Ti and Co formed as an extremely thin film on a silicon substrate are considered to be silicided, and it is considered that a titanium silicide (TiSiX) thin film and a cobalt silicide (CoSiX) thin film are formed. In addition, it is known that the formed thin film has a different compound form (for example, Ti2Si, TiSi, TiSi2, etc.) and an attached form depending on the film forming conditions, resulting in a difference in density.
 次に、演算部110は、微分曲線から全反射臨界角度を取得する(S208)。具体的には、演算部110は、S206で取得した微分曲線のピークにおける角度を全反射臨界角度として取得する。例えば、演算部110は、図4に示す微分曲線に基づいて、0.184度という全反射臨界角度を取得する。ここでは、5個の微分曲線から取得したピーク角度を平均することによって、演算部110は、全反射臨界角度を取得している。 Next, the calculation unit 110 acquires a critical angle for total reflection from the differential curve (S208). Specifically, the calculation unit 110 acquires the angle at the peak of the differential curve acquired in S206 as the critical angle for total reflection. For example, the calculation unit 110 acquires a critical angle for total reflection of 0.184 degrees based on the differential curve shown in FIG. Here, the arithmetic unit 110 acquires the critical angle for total reflection by averaging the peak angles acquired from the five differential curves.
 なお、図4に示す微分曲線のピークは、-0.066度に位置している。実際の装置を作製するにあたって、試料台102を、1次X線を照射する光学的原点角度に対して厳密に水平に設定することは困難である。そのため、取得した全反射臨界角度には、試料台102の傾きによる誤差が含まれている。上記0.184度という全反射臨界角度は、実際の装置により測定された-0.066度という値に対して、誤差を補正して得られた値である。誤差の補正方法の詳細は後述する。 The peak of the differential curve shown in FIG. 4 is located at -0.066 degrees. In manufacturing an actual apparatus, it is difficult to set the sample stage 102 strictly horizontally with respect to the optical origin angle at which primary X-rays are irradiated. Therefore, the acquired total reflection critical angle includes an error due to the inclination of the sample stage 102. The critical angle for total reflection of 0.184 degrees is a value obtained by correcting an error with respect to the value of -0.066 degrees measured by an actual apparatus. The details of the error correction method will be described later.
 次に、演算部110は、全反射臨界角度と1次X線114の波長とに基づいて、測定試料112の密度を算出する(S210)。具体的には、演算部110は、S208で取得した全反射臨界角度及び測定試料112に照射した1次X線114の波長を、全反射臨界角度と密度との関係を表す数1に適用することで測定試料112の密度を算出する。 Next, the calculation unit 110 calculates the density of the measurement sample 112 based on the critical angle for total reflection and the wavelength of the primary X-ray 114 (S210). Specifically, the arithmetic unit 110 applies the critical angle of total reflection acquired in S208 and the wavelength of the primary X-ray 114 applied to the measurement sample 112 to Equation 1 representing the relationship between the critical angle of total reflection and the density. Thus, the density of the measurement sample 112 is calculated.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
 ここで、φcは全反射臨界角度である。αは、定数である。λは、測定試料112に照射した1次X線114の波長である。Zは、原子番号である。Aは、質量数である。例えば、Tiの原子番号は22、質量数は48、Coの原子番号は27、質量数は59とする。1次X線114としてW-Lβ線を用いる場合、λ=0.1282nmとする。これらの数値が用いられる単位系ではα=1.33を用いる。数1の右辺に含まれる未知数は、1次X線114が照射された測定試料112の表面の密度ρ(g/cm3)のみである。また、左辺の全反射臨界角度は、S208において算出されている。従って、本発明によれば、簡便に測定試料112の密度(測定試料112の表面に形成された膜の密度)を得ることができる。 Φ Here, φc is the critical angle for total reflection. α is a constant. λ is the wavelength of the primary X-ray 114 irradiated on the measurement sample 112. Z is an atomic number. A is the mass number. For example, the atomic number of Ti is 22, the mass number is 48, the atomic number of Co is 27, and the mass number is 59. In the case where a WL-β line is used as the primary X-ray 114, λ is set to 0.1282 nm. In a unit system in which these numerical values are used, α = 1.33 is used. The unknowns included in the right side of Equation 1 are only the density ρ (g / cm 3) of the surface of the measurement sample 112 irradiated with the primary X-ray 114. The critical angle of total reflection on the left side is calculated in S208. Therefore, according to the present invention, the density of the measurement sample 112 (the density of the film formed on the surface of the measurement sample 112) can be easily obtained.
 続いて、膜厚を算出する方法について説明する。図7は、本発明に係る膜厚の測定方法を示すフローチャートである。なお、上記方法により密度が得られていれば、図7に示すフローチャートに示す方法は、測定試料112に対して全反射臨界角度より大きい角度で1次X線114を照射する蛍光X線分析装置を用いて行われてもよい。 Next, a method for calculating the film thickness will be described. FIG. 7 is a flowchart showing a method for measuring a film thickness according to the present invention. Note that if the density is obtained by the above method, the method shown in the flowchart of FIG. 7 uses the fluorescent X-ray analyzer that irradiates the measurement sample 112 with the primary X-ray 114 at an angle larger than the total reflection critical angle. May be performed.
 まず、試料台102に測定試料112が配置される(S702)。具体的には、例えば、測定試料112は、S202で用いた測定試料112であって、表面に炭化ケイ素(SiC)薄膜や酸化ケイ素(SiO2)薄膜等が形成されたシリコン基板である。測定試料112は、試料台102に配置されて、X線源104は、測定試料112に単色化した1次X線114を照射する。1次X線114を照射された測定試料112は、蛍光X線116を発生する。 First, the measurement sample 112 is placed on the sample table 102 (S702). Specifically, for example, the measurement sample 112 is the measurement sample 112 used in S202, and is a silicon substrate having a silicon carbide (SiC) thin film, a silicon oxide (SiO2) thin film, etc. formed on the surface. The measurement sample 112 is placed on the sample stage 102, and the X-ray source 104 irradiates the measurement sample 112 with primary X-rays 114 that have been made monochromatic. The measurement sample 112 irradiated with the primary X-ray 114 generates a fluorescent X-ray 116.
 次に、演算部110は、計数器108が計数した蛍光X線116の強度を取得する(S704)。具体的には、演算部110は、密度を求めた測定試料112に含まれる分析元素から発生する蛍光X線116の強度を取得する。 Next, the arithmetic unit 110 acquires the intensity of the fluorescent X-ray 116 counted by the counter 108 (S704). Specifically, the calculation unit 110 acquires the intensity of the fluorescent X-ray 116 generated from the analysis element included in the measurement sample 112 whose density has been obtained.
 次に、演算部110は、蛍光X線116の強度に基づいて、測定試料112の付着量を定量分析する(S706)。具体的には、例えば、演算部110は、ファンダメンタルパラメータ法や検量線法等の従来技術を用いて、S704で取得した蛍光X線116の強度から付着した元素の付着量(単位面積あたりの質量)を算出する。 Next, the arithmetic unit 110 quantitatively analyzes the amount of the measurement sample 112 attached based on the intensity of the fluorescent X-ray 116 (S706). Specifically, for example, using a conventional technique such as a fundamental parameter method or a calibration curve method, the calculation unit 110 determines the amount of the element attached (the mass per unit area) based on the intensity of the fluorescent X-ray 116 obtained in S704. ) Is calculated.
 次に、演算部110は、付着量と密度とに基づいて分析元素の膜厚を算出する(S708)。具体的には、演算部110は、S210で取得した密度とS706で取得した付着量とを、数2に適用することで測定試料112の膜厚を算出する。 Next, the calculation unit 110 calculates the film thickness of the analysis element based on the amount of adhesion and the density (S708). Specifically, the calculation unit 110 calculates the film thickness of the measurement sample 112 by applying the density acquired in S210 and the adhesion amount acquired in S706 to Equation 2.
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
 ここで、t(cm)は、測定試料112の膜厚である。c(g/cm2)は、付着量である。ρ(g/cm3)は、密度である。数1に示すように、演算部110は、付着量と密度の情報から膜厚を算出することができる。 Here, t (cm) is the film thickness of the measurement sample 112. c (g / cm2) is the amount of adhesion. ρ (g / cm3) is the density. As shown in Expression 1, the calculation unit 110 can calculate the film thickness from the information on the amount of adhesion and the density.
 続いて、微分曲線の形状に基づいて、測定試料112の表面ラフネスを算出する方法について説明する。図8は、本発明に係る表面ラフネスの測定方法を示すフローチャートである。 Next, a method of calculating the surface roughness of the measurement sample 112 based on the shape of the differential curve will be described. FIG. 8 is a flowchart showing a method for measuring surface roughness according to the present invention.
 まず、演算部110は、表面ラフネスが既知である試料に基づいて取得した微分曲線のピーク幅と表面ラフネスとの関係を取得する(S802)。具体的には、まず、演算部110は、表面ラフネスが既知である試料に対して、S202乃至S206と同様の工程により微分曲線を取得する。微分曲線のピーク幅としては、例えばピークの半値幅を用いる。演算部110は、当該微分曲線の半値幅を算出することで、既知の表面ラフネスと半値幅の関係を取得する。表面ラフネスが既知である複数の試料を用いて、表面ラフネスを算出する検量線を作成してもよい。 First, the calculation unit 110 acquires the relationship between the peak width of the differential curve acquired based on the sample whose surface roughness is known and the surface roughness (S802). Specifically, first, the computing unit 110 acquires a differential curve for a sample whose surface roughness is known by the same steps as S202 to S206. As the peak width of the differential curve, for example, the half width of the peak is used. The calculating unit 110 obtains the relationship between the known surface roughness and the half-value width by calculating the half-value width of the differential curve. A calibration curve for calculating surface roughness may be created using a plurality of samples whose surface roughness is known.
 ここで、図3に示すように、入射角度が全反射臨界角度より大きくなると、蛍光X線116の強度は急激に増加する。当該増加の程度は、測定試料112の表面ラフネスが大きい程緩やかになる。従って、微分曲線のピーク幅は、測定試料112の表面ラフネスが大きい程大きくなる傾向にある。例えば、図6に示す微分曲線は、ピーク値を1に規格化しているので、縦軸0.5での各ピーク波形の切片が半値幅である。シリコン基板、チタン薄膜及びコバルト薄膜(3種)の半値幅は、それぞれ、0.090°、0.106°、0.131°である。従って、図6の結果は、コバルト薄膜の表面ラフネスは、厚さによらず同等で、チタン薄膜の表面ラフネスよりも大きく、シリコン基板の表面ラフネスが最も小さいことを示している。 Here, as shown in FIG. 3, when the incident angle becomes larger than the critical angle for total reflection, the intensity of the fluorescent X-ray 116 rapidly increases. The degree of the increase becomes gentler as the surface roughness of the measurement sample 112 increases. Therefore, the peak width of the differential curve tends to increase as the surface roughness of the measurement sample 112 increases. For example, in the differential curve shown in FIG. 6, since the peak value is normalized to 1, the intercept of each peak waveform on the vertical axis 0.5 is a half width. The half widths of the silicon substrate, the titanium thin film, and the cobalt thin film (three types) are 0.090 °, 0.106 °, and 0.131 °, respectively. Accordingly, the results in FIG. 6 indicate that the surface roughness of the cobalt thin film is the same regardless of the thickness, is larger than the surface roughness of the titanium thin film, and has the smallest surface roughness of the silicon substrate.
 次に、S202乃至S206と同様の工程により、表面ラフネスが未知である測定試料112に対して、微分曲線を取得する(S804乃至S808)。次に、演算部110は、取得した微分曲線の半値幅を算出する(S810)。そして、演算部110は、S802で取得した半値幅と表面ラフネスとの関係と、S810で取得した半値幅と、に基づいて測定試料112の表面ラフネスを算出する(S812)。 Next, a differential curve is obtained for the measurement sample 112 whose surface roughness is unknown by the same steps as S202 to S206 (S804 to S808). Next, the calculation unit 110 calculates the half width of the obtained differential curve (S810). Then, the calculation unit 110 calculates the surface roughness of the measurement sample 112 based on the relationship between the half-width obtained in S802 and the surface roughness, and the half-width obtained in S810 (S812).
 続いて、図9に示すフローチャートを用いて、全反射臨界角度の補正方法について説明する。まず、試料台102に標準試料が配置される(S902)。具体的には、例えば、全反射臨界角度が既知であるシリコン基板が試料台102に配置される。 Next, a method of correcting the critical angle for total reflection will be described with reference to the flowchart shown in FIG. First, a standard sample is placed on the sample table 102 (S902). Specifically, for example, a silicon substrate having a known total reflection critical angle is arranged on the sample stage 102.
 次に、S202乃至S206と同様の工程により、標準試料に対して、微分曲線を取得する(S904乃至S908)。例えば、図4は、標準試料として用いることができるシリコン基板用い、蛍光X線116としてSi-kα線の強度を測定することによって取得した微分曲線である。シリコン基板は、全反射臨界角度が既知であるが、当該既知の値と微分曲線のピーク角度とは相違する場合がある。相違する理由は、実際の1次X線114の測定試料112への入射角度と、全反射蛍光X線分析装置100が認識している入射角度と、が機械加工や組み立ての精度、経時変化等により相違することがあるためである。 Next, a differential curve is obtained for the standard sample through the same steps as S202 to S206 (S904 to S908). For example, FIG. 4 is a differential curve obtained by measuring the intensity of a Si-kα ray as the fluorescent X-ray 116 using a silicon substrate that can be used as a standard sample. Although the silicon substrate has a known total reflection critical angle, the known value may be different from the peak angle of the differential curve. The reason for the difference is that the actual incident angle of the primary X-rays 114 on the measurement sample 112 and the incident angle recognized by the total reflection X-ray fluorescence spectrometer 100 depend on the accuracy of machining and assembly, changes over time, etc. This is because there is a case where a difference is made.
 次に、演算装置は、S908で取得した全反射臨界角度と、標準試料の既知の全反射臨界角度との差分を、補正値として取得する(S910)。当該補正値は、上述の密度を算出する過程であるS210工程で用いられる。 Next, the arithmetic unit acquires the difference between the critical angle for total reflection acquired in S908 and the known critical angle for total reflection of the standard sample as a correction value (S910). The correction value is used in step S210, which is a process of calculating the density.
 なお、全反射蛍光X線分析装置100は、S910で取得した補正値に基づいて、試料台102の傾きを調整してもよい。試料台102の傾きを調整することにより、実際の1次X線114の測定試料112への入射角度と、全反射蛍光X線分析装置100が認識している入射角度と、を一致させることができる。 Note that the total reflection X-ray fluorescence spectrometer 100 may adjust the inclination of the sample table 102 based on the correction value acquired in S910. By adjusting the inclination of the sample stage 102, the incident angle of the actual primary X-ray 114 on the measurement sample 112 and the incident angle recognized by the total reflection X-ray fluorescence analyzer 100 can be matched. it can.
 以上のように、本発明によれば、全反射蛍光X線分析装置100により、測定試料112の密度、膜厚及び表面ラフネスを低コストかつ簡便に測定することができる。 As described above, according to the present invention, the density, film thickness, and surface roughness of the measurement sample 112 can be easily measured at low cost by the total reflection X-ray fluorescence spectrometer 100.
 本発明は、上記の実施例に限定されるものではなく、種々の変形が可能である。上記全反射蛍光X線分析装置100の構成は一例であって、これに限定されるものではない。上記の実施例で示した構成と実質的に同一の構成、同一の作用効果を奏する構成または同一の目的を達成する構成で置き換えてもよい。 The present invention is not limited to the above embodiment, and various modifications are possible. The configuration of the total reflection X-ray fluorescence analyzer 100 is an example, and the present invention is not limited to this. It may be replaced with a configuration substantially the same as the configuration shown in the above embodiment, a configuration having the same operation and effect, or a configuration achieving the same object.
 例えば、全反射蛍光X線分析装置100は、密度を測定する密度測定モード、膜厚を測定する膜厚測定モード、表面ラフネスを測定する表面ラフネス測定モード、及び、試料台102の傾きを調整するメンテナンスモードの各モードを、ユーザの指示に応じて個別に実行できる装置として構成してもよい。 For example, the total reflection X-ray fluorescence spectrometer 100 adjusts the density measurement mode for measuring the density, the film thickness measurement mode for measuring the film thickness, the surface roughness measurement mode for measuring the surface roughness, and the inclination of the sample table 102. Each of the maintenance modes may be configured as a device that can be individually executed according to a user's instruction.
 100 全反射蛍光X線分析装置、102 試料台、104 X線源、106 検出器、108 計数器、110 演算部、112 測定試料、114 1次X線、116 蛍光X線。 {100} total reflection X-ray fluorescence spectrometer, 102 sample stand, 104 X-ray source, 106 detector, 108 counter, 110 operation unit, 112 measurement sample, 114 primary X-ray, 116 fluorescence X-ray.

Claims (6)

  1.  測定試料の全反射臨界角度を跨いで、前記測定試料の表面に対する入射角度を変えながら単色化した1次X線を照射するX線源と、
     前記測定試料から発生した蛍光X線の強度を測定する検出器と、
     前記蛍光X線の強度と前記入射角度との関係を、前記入射角度について微分することによって微分曲線を取得し、該微分曲線から前記全反射臨界角度を取得し、さらに、前記全反射臨界角度と前記1次X線の波長とに基づいて前記測定試料の密度及びまたは膜厚を算出する演算部と、
     を有することを特徴とする全反射蛍光X線分析装置。
    An X-ray source that irradiates monochromatic primary X-rays while changing the incident angle with respect to the surface of the measurement sample over the critical angle of total reflection of the measurement sample;
    A detector for measuring the intensity of the fluorescent X-rays generated from the measurement sample;
    The relationship between the intensity of the fluorescent X-rays and the incident angle is obtained by differentiating the incident angle to obtain a differential curve, and the total reflection critical angle is obtained from the differential curve. An arithmetic unit that calculates the density and / or thickness of the measurement sample based on the wavelength of the primary X-ray;
    A total reflection X-ray fluorescence spectrometer comprising:
  2.  前記演算部は、前記微分曲線のピーク角度を前記全反射臨界角度として取得すること特徴とする請求項1に記載の全反射蛍光X線分析装置。 The total reflection X-ray fluorescence spectrometer according to claim 1, wherein the calculation unit acquires a peak angle of the differential curve as the total reflection critical angle.
  3.  前記演算部は、さらに、
     前記蛍光X線の強度に基づいて、前記測定試料の付着量を定量分析し、
     前記付着量と、前記密度と、に基づいて前記測定試料の膜厚を算出する、
     こと特徴とする請求項1または2に記載の全反射蛍光X線分析装置。
    The arithmetic unit further includes:
    Based on the intensity of the fluorescent X-rays, quantitatively analyze the adhesion amount of the measurement sample,
    Calculating the film thickness of the measurement sample based on the adhesion amount and the density,
    The total reflection X-ray fluorescence spectrometer according to claim 1 or 2, wherein:
  4.  前記演算部は、前記微分曲線の形状に基づいて、前記測定試料の表面ラフネスを算出することを特徴とする請求項1乃至3のいずれかに記載の全反射蛍光X線分析装置。 The total reflection X-ray fluorescence analyzer according to any one of claims 1 to 3, wherein the calculation unit calculates the surface roughness of the measurement sample based on the shape of the differential curve.
  5.  前記演算部は、前記表面ラフネスが既知である試料に基づいて取得した前記微分曲線のピーク幅と前記表面ラフネスとの関係と、前記測定試料に基づいて取得した前記微分曲線のピーク幅と、に基づいて前記測定試料の表面ラフネスを算出することを特徴とする請求項4に記載の全反射蛍光X線分析装置。 The calculation unit, the relationship between the peak width of the differential curve and the surface roughness obtained based on the sample whose surface roughness is known, and the peak width of the differential curve obtained based on the measurement sample, The total reflection X-ray fluorescence spectrometer according to claim 4, wherein the surface roughness of the measurement sample is calculated based on the measurement.
  6.  測定試料の全反射臨界角度を跨いで、前記測定試料の表面に対する入射角度を変えながら単色化した1次X線を照射する工程と、
     前記測定試料から発生した蛍光X線の強度を測定する工程と、
     前記蛍光X線の強度と前記入射角度との関係を、前記入射角度について微分することによって微分曲線を取得する工程と、
     前記微分曲線から前記全反射臨界角度を取得する工程と、
     前記全反射臨界角度と前記1次X線の波長とに基づいて前記測定試料の密度及びまたは膜厚を算出する工程と、
     を有することを特徴とする測定方法。
    Irradiating a monochromatic primary X-ray while changing the incident angle with respect to the surface of the measurement sample over the critical angle of total reflection of the measurement sample;
    Measuring the intensity of the fluorescent X-rays generated from the measurement sample;
    Obtaining a differential curve by differentiating the relationship between the intensity of the fluorescent X-rays and the incident angle with respect to the incident angle;
    Obtaining the total reflection critical angle from the differential curve,
    Calculating the density and / or thickness of the measurement sample based on the total reflection critical angle and the wavelength of the primary X-ray,
    A measurement method comprising:
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