JP5209930B2 - X-ray photoelectron spectroscopy analysis method - Google Patents

Description

  The present invention relates to an X-ray photoelectron spectroscopic analysis method using a photoelectron spectrometer.

  In the photoelectron spectrometer, the sample to be analyzed is irradiated with X-rays, and the photoelectrons emitted from the sample are decelerated and focused by the input lens and made incident on the analyzer. An energy spectrum is obtained, and quantitative analysis of elements contained in the sample is performed from the energy spectrum.

  As one of the modes of such an analysis method, there is a CAE (Constant Analyzer Energy) mode in which the energy (path energy) of the photoelectrons passing through the analyzer is constant regardless of the kinetic energy of the photoelectrons emitted from the sample. is there.

  FIG. 1 shows a schematic example of a photoelectron spectrometer to which such a CAE mode is applied.

  In the figure, 1 is an X-ray source, 2 is a sample irradiated with X-rays 3 from the X-ray source, and 4 is photoelectrons emitted from the sample 2 by irradiation with the X-rays.

  Reference numeral 20 denotes a photoelectron spectrometer, which is selected by the input lens 5, an analyzer 6 comprising an inner hemispherical electrode 6 a and an outer hemispherical electrode 6 b for analyzing the energy of photoelectrons incident through the input lens, and the analyzer. And a detector 7 for detecting photoelectrons having a certain energy.

  A certain set voltage is applied to the inner hemisphere electrode 6a and the outer hemisphere electrode 6b, and the pass energy of photoelectrons is determined by the set voltage.

  On the other hand, the input lens 5 includes an electrostatic lens 5a, an electrostatic lens 5b, and a deceleration lens 5c. The electrostatic lenses 5a and 5b focus the photoelectrons on a slit 5S provided at the entrance of the analyzer 6. There is work. By sweeping the applied voltage supplied to the decelerating lens 5c together with the set voltage, photoelectrons having various energies emitted from the sample 2 and introduced into the analyzer 6 have a constant energy (corresponding to the set energy). ) To decelerate the photoelectrons. 8 is an amplifier for amplifying the output signal of the detector 7, and 9 is an AD converter.

  Reference numeral 10 denotes a control device that controls various means constituting the photoelectron spectrometer and performs various arithmetic processes.

  Reference numeral 11 denotes a power source for sending a control signal for generating X-rays 3 from the X-ray source 1 based on a command from the control device. Reference numeral 12 denotes the input lens 5 and the analyzer based on a command from the control device 10. 6 is a power supply unit that sends an appropriate control voltage to 6.

  Reference numeral 13 denotes a storage device that stores the output signal (photoelectron energy spectrum signal) of the detector 7, and reference numeral 14 denotes the photoelectron energy spectrum signal read from the storage device 13 based on a command from the control device 10. A display device 15 is an input device such as a mouse and a keyboard.

  In the photoelectron spectrometer having such a configuration, first, the path energy is set by the input device 15. Then, the control device 10 applies a voltage (set voltage) based on the set path energy to the electrodes 6a and 6b of the analyzer 6 and the electrostatic lens (not shown) of the input lens 5; A command to apply a sweep voltage for decelerating the photoelectrons to the decelerating lens 5c so that the energy of the photoelectrons emitted from the sample 2 and introduced into the analyzer 6 becomes constant energy (corresponding to the set path energy). The power supply unit 12 is sent.

  At the same time, the control device 10 also sends an X-ray irradiation command for performing X-ray irradiation to the sample 2 to the power supply 11.

  In accordance with such a command, X-rays are generated from the X-ray source 1 and irradiated onto the sample 2. Then, photoelectrons of various energies emitted from the sample and incident on the input lens 5 are decelerated so as to become the set path energy by the decelerating lens 5c and converged on the slit 5S by the electrostatic lenses 5a and 5b. And enters the analyzer 6. Actually, when a light beam slightly deviated from the set path energy is incident on the analyzer 6, the photoelectrons are subjected to energy spectroscopy in the analyzer, and the photoelectrons having the set path energy are detected by the detector 7.

  The output signal of the detector is sent to the control device 10 via the amplifier 8 and the AD converter 9, and is related to the sweep voltage and stored in the storage device 13 as a photoelectron energy spectrum signal.

  Next, the control device 10 reads out the photoelectron energy spectrum signal from the storage device 13 and sends it to the display device 14 to display the photoelectron energy spectrum on the display screen of the display device.

JP-A-9-219174

  The photoelectron spectrometer performs quantitative analysis of elements present in the sample based on the energy spectrum measured in this way.

  By the way, the measured energy spectrum differs depending on the resolution and sensitivity of the apparatus. If the resolution is poor, it is difficult to separate the chemical bond state peaks of the measured energy spectrum, and it is difficult to analyze the chemical bond state. If it is bad, the entire measured energy spectrum, or the peak of each chemical bond state, is lowered, and detection becomes difficult.

  Generally, the resolution is sacrificed to some extent if the sensitivity is increased, and the sensitivity is sacrificed to some extent if the resolution is increased.

  Therefore, analysis of chemical bonding states of elements contained in large amounts in a sample seems to be possible without problems with the set resolution and sensitivity, but analysis of chemical bonding states that are contained only in trace amounts in the sample. Is often difficult with the set resolution and sensitivity.

  Therefore, when performing chemical bonding state analysis of elements contained only in trace amounts in the sample, the setting value of the path energy related to resolution and sensitivity is changed many times, and the energy spectrum is measured each time, While observing the measured energy spectrum, an appropriate energy spectrum is obtained and a chemical bonding state analysis or the like is performed. Therefore, the entire analysis was extremely time consuming.

  The same can be said for the case where the chemical bond state analysis of the known chemical bond state is performed on the contained chemical bond state.

  It is an object of the present invention to provide a novel X-ray photoelectron spectroscopic analysis method that solves such problems.

The X-ray photoelectron spectroscopic analysis method of the present invention irradiates a sample with X-rays, introduces photoelectrons emitted from the sample by irradiation of the X-rays into an energy analyzer via an introduction electron optical system, and uses the energy analyzer. An X-ray photoelectron spectroscopic analysis method for obtaining an energy spectrum of the sample by performing energy spectroscopy of the photoelectrons,
The peak position of the intrinsic energy spectrum of the chemical bond state of the element contained in the sample to be analyzed is E _c1 , the half width of the peak is W ₁ , and the intrinsic energy spectrum of the chemical bond state of the other element closest to the energy spectrum. E _c2 peak position, the half-value width of the peak W _2, the half-value width of the peak of the energy spectrum of the X-ray Wx, and the pass energy to be set as E _p, the energy analyzer which is proportional with the pass energy E _p the half width based as _{W a,} the pass energy _{E p,
E c2 -E c1> 1/2} × {(W 1 2 + Wx 2 + W A 2) 1/2 + (W 2 2 + Wx 2 + W A 2) 1/2}
It is characterized by calculating by.

  According to the present invention, since an appropriate path energy can be set by calculation, only one pass energy setting is required, and even analysis of chemical bonding states contained in a trace amount in a sample is short. I can do it on time.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 2 shows a schematic example of a photoelectron spectrometer which is an example of an apparatus for carrying out the spectroscopic analysis method of the present invention. In FIG. 2, the same reference numerals as those used in FIG. Indicates the component.

  In the figure, 17 is the peak position of the energy spectrum of each element, the peak position of the energy spectrum of each chemical bond state, the half-value width of the peak intensity at the peak position, and the peak intensity of the X-ray irradiated on the surface of the sample 2 An analysis information storage device 18 that stores analysis information with a half-value width, 18 is a measurement condition calculation device that calculates a value of path energy from a chemical bond state name or the like designated by the input device 15.

  By the way, the X-ray source is composed of, for example, an electron gun and a metal target, and the electron from the electron gun collides with the target and emits X-rays from the target. As shown in FIG. 3, the energy spectrum of emitted X-rays includes the energy spectrum Sbr of the braking X-ray BR generated when electrons pass through the vicinity of the nucleus of the element constituting the target, and the energy spectrum of the element constituting the target. The energy spectrum Scr of the characteristic X-ray CR unique to the element generated by the incidence of X, and the X-ray having these spectra represents the peak of the X-ray irradiated on the sample surface.

Incidentally, FIG. 4 is obtained by displaying the peak portion extracted monochromatic light of a specific wavelength by the energy spectrum shown in FIG. 3 generated from the X-ray source, for example monochromator, P1max the maximum intensity value, W ₁ is The full width at half maximum, which is the energy width (P1max / 2) at half of the maximum intensity value, is shown.

  In the photoelectron spectrometer having such a configuration, when chemical bond state analysis is performed on a sample having a known chemical bond state, the amount of chemical bond state to be analyzed as shown in the flow of FIG. Regardless, first, an appropriate path energy value capable of appropriately analyzing the chemical bonding state of the chemical bonding state is set, and the energy spectrum of the sample is measured under the set path energy.

  In this analysis, for example, the sample 2 contains, for example, trace amounts of Pd and Pd oxide PdO, and the X-ray source 1 is a non-monochromatic X-ray that uses magnesium Kα ray as an excitation source. Assume that MgKα radiation is used.

  As shown in FIG. 5, the chemical bond state names are displayed in the analysis information table on the display screen of the display device 14, and the operator selects Pd and PdO from the analysis information table by the input device 15, respectively. Specify (S301).

  Then, the control device 10 sends a designation completion command to the measurement condition calculation device 18, and the peak positions 335.5 eV and 337.1 eV of the designated chemical bonding states Pd and PdO from the analysis information storage device 17 to the measurement condition calculation device, respectively. Then, the peak half-value widths 1.05 eV and 0.97 eV and the half-value width 0.7 eV of the MgKα line corresponding to each peak position are read (S302).

  The measurement condition calculation device 18 calculates the path energy of photoelectrons passing through the analyzer 6 based on the read values as follows (S303).

The half width of the peak of the energy spectrum of the sample is W, the half width of the peak of the intrinsic energy spectrum of the element or chemical bonding state contained in the sample is W _Ec , and the peak of the energy spectrum of the X-ray irradiated to the sample surface Half width is W _X
If the energy resolution of the analyzer is W _A (the energy resolution W _{A of the} analyzer is proportional to the path energy E _p ), the following relational expression (1) holds.

If the sample contains at least two chemical bond states, the peak position of one of the two energy spectrum peaks where the energy spectra of the chemical bond states are close to each other is _Ec1 . half-width W ₁ of the full width at half maximum _of the peak in the other energy spectrum peaks of peak positions E _c2 is W _2, both binding energy difference is to Delta] E, is to calculate the path energies E _p, the following (2 ) It is necessary to satisfy the condition of the expression.

Now, the half-width of the peak of the intrinsic energy spectrum of one chemical bond state is W _Ec1 , the half-width of the peak of the intrinsic energy spectrum of the other chemical bond state is W _Ec2 , and the energy spectrum of X-rays irradiated to the sample surface When the half width of a peak and Wx, the measurement condition calculating device 18, from the equation (1) and (2), and calculates the pass energy E _p so as to satisfy the following equation (3).

  According to such a path energy calculation method, the appropriate path energy in the case of performing the chemical bond state analysis of the chemical bond states Pd and PdO contained in the sample 2 is as follows.

For example, the half-value width of the peak of specific energy spectrum of Pd W _ECPD, the half width of W _EcPdO peak specific energy spectrum of PdO, the half width of the peak of MgKα rays to be irradiated to the sample surface and Wx _Mg, the measurement condition calculating device 18 calculates the path energy E _p so as to satisfy the equation (4).

  Next, the measurement condition calculation device 18 sends the calculated path energy value to the power supply unit 12 (S304).

  The power supply unit 12 supplies a voltage based on the calculated path energy to the electrodes 6 a and 6 b of the analyzer 6 and the electrostatic lens (not shown) of the input lens 5. The power supply unit 12 also supplies a sweep voltage to the electrostatic lens (not shown) as described above.

  When the operator designates the start of measurement using the input device 15, the control device 10 sends an X-ray irradiation command to the X-ray source 1, and the measurement of the energy spectrum of the sample 2 is started (S305).

  Then, the X-ray 3 generated from the X-ray source 1 is irradiated onto the sample 2. Then, photoelectrons 4 ′ having various energies emitted from the surface of the sample and incident on the input lens 5 are decelerated by the electrostatic lens (not shown) to the set path energy and focused on the slit 5 </ b> S. And enters the analyzer 6. The incident photoelectrons are subjected to energy spectroscopy in the analyzer, and most photoelectrons having a path energy corresponding to the calculated path energy are detected by the detector 7.

  The output signal of the detector is sent to the control device 10 via the amplifier 8 and the AD converter 9, and is related to the sweep voltage and stored in the storage device 13 as a photoelectron energy spectrum signal.

  Next, the control device 10 reads out the photoelectron energy spectrum signal from the storage device 13 and sends it to the display device 14 to display the photoelectron energy spectrum on the display screen of the display device.

  The photoelectron energy spectrum obtained in this way is an appropriate path energy value (appropriately the chemical bond state) obtained and set in one operation regardless of the amount of the chemical bond state to be analyzed. Therefore, even if it is an analysis of a very small amount of chemical bond state, an appropriate chemical bond state analysis can be performed in a short time.

  In the above example, the non-monochromatic X-ray source is used as the X-ray source 1, but a monochromatic X-ray source may be used.

1 shows a schematic example of a conventional photoelectron spectrometer. 1 shows an example of a schematic position of a photoelectron spectrometer that is an example of an apparatus that carries out the spectroscopic analysis method of the present invention. The energy spectrum of the X-rays emitted from the X-ray source is shown. The peak part of the energy spectrum is shown. An example of the analysis information table displayed on the display screen is shown. It is an example of the flow of the spectroscopic analysis method of the present invention. It is the figure used for description of the spectroscopic analysis method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... X-ray source 2 ... Sample 3 ... X-ray 4, 4 '... Photoelectron 5 ... Input lens 5a, 5b ... Electrostatic lens 5c ... Deceleration lens 5S ... Slit 6 ... Analyzer 6a ... Inner hemisphere electrode 6b ... Outer hemisphere electrode 7 ... Detector 8 ... Amplifier 9 ... AD converter 10 ... Control device 11 ... Power supply 12 ... Power supply unit 13 ... Storage device 14 ... Display device 15 ... Input device 17 ... Analysis information storage device 18 ... Measurement condition calculation device 20 ... Electron spectroscopy vessel

Claims (1)

A sample is irradiated with X-rays, photoelectrons emitted from the sample by irradiation with the X-rays are introduced into an energy analyzer through an introduction electron optical system, and the photoelectrons are subjected to energy spectroscopy with the energy analyzer, and the energy of the sample is measured. An X-ray photoelectron spectroscopic analysis method for obtaining a spectrum, wherein the energy spectrum is obtained by sweeping the energy of a photoelectron introduced into the energy analyzer while keeping the path energy of the photoelectron passing through the energy analyzer constant. In the X-ray photoelectron spectroscopic analysis method obtained,
The peak position of the intrinsic energy spectrum of the chemical bond state of the element contained in the sample to be analyzed is E _c1 , the half width of the peak is W ₁ , and the intrinsic energy spectrum of the chemical bond state of the other element closest to the energy spectrum. E _c2 peak position, the half-value width of the peak W _2, the half-value width of the peak of the energy spectrum of the X-ray Wx, and the pass energy to be set as E _p, the energy analyzer which is proportional with the pass energy E _p the half width based as _{W a,} the pass energy _{E p,
E c2 -E c1> 1/2} × {(W 1 2 + Wx 2 + W A 2) 1/2 + (W 2 2 + Wx 2 + W A 2) 1/2}
An X-ray photoelectron spectroscopic analysis method, characterized by:

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