JPH1123499A - Electron spectroscopy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To find the chemical bonding state or the existing ratio of elements in the surface layer of a sample accurately by finding the electronic spectrum of the sample through a time-of-flight method and then performing signal processing using the photoelectron spectrum of the sample as a reference spectrum. SOLUTION: A micro-region of a sample 111 on a moving stage 112 is irradiated with X-rays 108 from a plasma 107. Discharged photoelectrons 113 are passed through a flight tube 114 and detected by means of a micro-channel plate 116. Since the energy distribution of photoelectron is analyzed from the flight time distribution during that interval, the photoelectron distribution can be obtained at once over the entire energy range. A detected waveform of photoelectron is quantized and delivered to a processing section 118 and subjected to data processing. More specifically, a single electronic spectrum, an existing ratio, and the like, corresponding to an interesting chemical bonding state or an element are found through processing using a photoelectron spectrum, obtained from a region containing a plurality of chemical bonding states or elements purely or from another standard element, as a reference electronic spectrum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to electron spectroscopy.

[0002]

2. Description of the Related Art In a conventional X-ray photoelectron analysis method using X-rays from an X-ray tube, which is a continuous light source, in one count, an energy slit is provided to narrow the energy range of photoelectrons to be detected. The number of photoelectrons therein is counted. The photoelectron spectrum waveform distribution in the entire energy region was obtained by performing a large number of scans by scanning the value of the central energy of the energy slit.

[0003]

In the above-described electron analysis method according to the prior art, the change in the output intensity of the X-ray emitted from the X-ray tube and the change in the charged state of the sample due to the measurement are considered.
There is a problem that the number of photoelectrons detected during the energy scan fluctuates due to a change in the measurement environment.

When a sample contains a plurality of chemical bonding states or elements, if the measurement environment fluctuates during an energy scan, the existence ratio of each chemical bonding state or element obtained from the obtained spectrum waveform is incorrect. Become something. Also,
When scanning the irradiation position of the excitation light on the sample to measure the state of each chemical bond or the spatial distribution of elements on the sample, each chemical bond at each irradiation position determined from the obtained spectral waveform The state or the abundance of the elements becomes incorrect.

[0005] As described above, in the conventional electron analysis method, there is a problem that the chemical bonding state or the abundance ratio of the elements contained in the sample cannot be escaped from the fear of occurrence of errors due to fluctuations in the measurement environment and the like. was there.

[0006] The present invention has been made in view of the above problems, and has as its object to provide an electron analysis method capable of accurately determining the state of each chemical bond or the abundance of elements contained in a sample surface layer. And

[0007]

Means for Solving the Problems The present invention first provides a method of "irradiating a sample with pulsed light such as X-rays, extreme ultraviolet light, ultraviolet light, etc.
In electron spectroscopy that measures the surface state of a sample from the energy spectrum of electrons emitted from the sample, N types (N ≧ 2) of chemical bonding states or a sample containing elements
Irradiating the pulsed light to obtain an electronic spectrum using a time-of-flight method; and at least (N-1) chemical bonding states or elements of the N types of chemical bonding states or elements, respectively. By performing signal processing using a photoelectron spectrum obtained in each region on the sample containing pure (or high purity) alone or another standard sample as a reference electron spectrum, thereby obtaining the N kinds of chemical bonding states. Or, of the elements, a single electron spectrum, abundance,
Electron spectroscopy (claim 1), comprising: obtaining an abundance ratio, a mixing ratio, or a photoelectron number.

Further, the present invention provides a second method of “N kinds (N ≧ 2)
Was obtained by superimposing an electronic spectrum obtained from a region containing the chemical bonding state or element of the above and the reference electron spectrum of at least (N-1) kinds of chemical bonding states or elements contained in the region. The contribution of each reference electron spectrum is determined by minimizing the sum of squares of the difference between the reconstructed spectrum and the entire spectrum in the entire energy range or the energy range of the specific range, and one or more types of interest or Electron spectroscopy (Claim 2) according to claim 1, wherein a single electron spectrum, abundance, abundance ratio, mixing ratio or number of photoelectrons of a plurality of chemical bonding states or elements are obtained.

Further, the present invention relates to a third aspect of the present invention in which "the peak intensity or the number of electrons of the electronic signal is a ratio Ri (i = 1,2,2) between the electronic spectrum and the reference electron spectrum.
3,. . . . . , N−1, or i = 1, 2, 2,
3,. . . . . , N), and the signal processing is performed by subtracting each reference electron spectrum multiplied by each Ri from the electronic speckle, and performing the signal processing, wherein the electron spectroscopy (claim 3) is provided. I do.

Further, the present invention fourthly provides a method for calculating a reference electron spectrum which is predicted to be obtained under the measurement conditions of the electronic spectrum when the measurement conditions of the reference electron spectrum are different from the measurement conditions of the electronic spectrum. Photoelectron spectroscopy according to claims 1 to 3 (claim 4) ".

Further, the present invention provides a fifth aspect of the present invention, wherein "the irradiation area and / or the irradiation position of the pulse light on the sample can be changed so that one kind of chemical bonding state or element can be pure (or high purity). 5. The electron spectroscopy according to claim 1, wherein a single electron spectrum from a micro-region included in (1) and an electron spectrum from a region including two or more kinds of chemical bonding states or elements are obtained. (Claim 5) is provided.

Also, the present invention provides a sixth aspect of the present invention wherein "the irradiation position of the pulse light on the sample can be changed so that the electronic spectrum can be obtained in the entire region or an arbitrary region on the sample. Electron spectroscopy according to claims 1 to 5 (claim 6) ".

The present invention also provides a seventh aspect of the present invention, in which a stopping electric field is applied to electrons inside the flight tube used in the time-of-flight method to reduce the speed of the electrons, so that the time required to reach the electron detector is increased. To increase the energy resolution by the electron spectroscopy according to claims 1 to 6 (claim 7).

An eighth aspect of the present invention is an electron spectroscopy method of irradiating a sample with pulsed light such as X-rays, extreme ultraviolet rays, and ultraviolet rays, and measuring the surface state of the sample from the energy spectrum of electrons emitted from the sample. In the process of irradiating the sample with pulsed light emitted from a pulsed light source to obtain an electronic spectrum using the time-of-flight method, and the time-of-flight spectrum data points obtained at equal time intervals are converted into equal energy intervals at arbitrary energy intervals. Converting the data points into data points to obtain a photoelectron spectrum waveform.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, photoelectron energy analysis is carried out by the time-of-flight method in order to perform spectrum intensity measurement under exactly the same conditions over a wide energy range. In the time-of-flight method, a sample is irradiated with pulsed excitation light, electrons emitted from the sample surface are caused to fly for a certain distance, and the time waveform of the electron flow is measured using an electron detector. This is a method of analyzing the energy distribution of photoelectrons from the time-of-flight distribution, and the photoelectron number distribution in the entire energy range can be obtained at once.

That is, in the electron spectroscopy according to the present invention, a spectrum measurement over a wide energy range can be performed once without performing a large number of scans of the center energy value of the energy slit performed by the conventional electron spectroscopy. Measurement.

Therefore, the spectrum obtained by the electron spectroscopy according to the present invention is not affected at all by changes in the measurement environment such as fluctuations in the output of the excitation source and fluctuations in the sample environment.

Therefore, according to the electron spectroscopy according to the present invention, the state of each chemical bond or the abundance of elements contained in the sample surface layer can be accurately obtained.

For a pulsed excitation X-ray or the like necessary for the time-of-flight method, it is optimal to use a plasma X-ray source generated by a pulsed laser. If X-rays are condensed and radiated onto a minute area using an X-ray optical element, a spatial change in the distribution of the chemical bonding state on the sample can be measured.

In order to obtain a high-accuracy spectral waveform having a large signal-to-shot noise ratio, a large number of measured electrons are required, and therefore, a large number of X-ray irradiations are required. In the time-of-flight method, the number of electrons of all energies is measured for each shot. Therefore, even if the X-ray intensity fluctuates during this many irradiations, the effect is not And the resulting spectral waveform distribution is completely unaffected by fluctuations in X-ray intensity.

Incidentally, an electronic spectrum obtained from a region on a sample containing a plurality of chemical bonding states or elements includes a chemical bonding state to be measured or an electronic spectrum from an element, and an electronic spectrum from another chemical bonding state or an element. Have overlapping electron spectra.

Therefore, in the present invention, an electronic spectrum from a chemical bonding state or an element to be measured is obtained by a method having the following steps.

[Method according to claim 1] "First step: A sample containing N kinds (N ≧ 2) of chemically bonded states or elements is irradiated with pulsed excitation light, and the corresponding electron spectrum is obtained. Obtained using the time-of-flight method.

Second step: at least N-1 on the sample
By performing signal processing using a photoelectron spectrum obtained in a region containing pure (or highly pure) kinds of chemical bonds or elements or another standard sample as a reference electron spectrum, the N kinds of elements or chemicals can be obtained. A single electron spectrum, abundance, abundance ratio, mixing ratio, or number of photoelectrons corresponding to a chemical bonding state or an element of interest in a specific bonding state is obtained. Here, the reference electron spectrum is used when measuring the sample.
Pure (or high purity) chemical bond or element
It may be obtained from the area on the sample containing the sample or another standard sample, or the electronic spectrum measured in advance in the standard sample containing the chemical bonding state or the element pure (or high purity) is stored in the storage device. This may be used as a reference electron spectrum.

In the above method, for example, the sum of squares of the difference between the obtained electronic spectrum and the reconstructed spectrum obtained by superimposing the reference spectrum in the entire energy region or the energy region in a specific range is minimized. In this way, the contribution of each reference spectrum can be determined to obtain the single electron spectrum, the single electron spectrum, the abundance, the abundance ratio, the mixing ratio, or the number of photoelectrons of one or more kinds of chemical bonding states or elements of interest. (Claim 2).

Alternatively, regarding the peak intensity or the number of electrons of the electronic signal, the ratio Ri (i = 1, 2, 3,...
1, or i = 1, 2, 3,. . . . . , N), and the signal processing can be performed by subtracting each reference electron spectrum multiplied by each Ri from the obtained electronic speckles (claim 3).

When the measurement conditions of the reference electron spectrum are different from the measurement conditions of the electronic spectrum, the reference electron spectrum predicted to be obtained under the measurement conditions of the electronic spectrum may be obtained by calculation.

In the electron spectroscopy of the present invention, the irradiation area and / or the irradiation position of the pulsed excitation light on the sample can be changed, so that one kind of chemical bonding state or element can be purified (or highly purified). It is preferable to obtain an electron spectrum from a micro-region included in (1) and an electron spectrum from a region including two or more kinds of chemical bonding states or elements (claim 5).

With this configuration, both the reference electron spectrum and the electronic spectrum in the mixed region can be obtained by actual measurement.

In the electron spectroscopy of the present invention, the irradiation position of the pulsed excitation light on the sample can be changed so that the electron spectrum can be obtained in the entire region or an arbitrary region on the sample. (Claim 6).

With this configuration, a required electronic spectrum in an arbitrary region on the sample can be obtained.

In the electron spectroscopy of the present invention, the arrival time at the electron detector is reduced by applying a blocking electric field to the electrons inside the flight tube used in the time-of-flight method to reduce the speed of the electrons. It is preferable to increase the energy resolution to increase the energy resolution (claim 7).

Hereinafter, as an example of the present invention, a case where X-rays are used as excitation light will be described. However, the excitation light is not limited to X-rays, but may be extreme ultraviolet light or ultraviolet light.

As described above, when a sample contains a plurality of chemical bonding states or elements, the photoelectron signal spectrum from the chemical bonding state or element to be measured may be converted to a value obtained from another chemical bonding state or element. Photoelectron signal spectra overlap.

Therefore, in the case of photoelectron microspectroscopy in which X-rays are focused on a minute area on a sample using an X-ray optical element and a two-dimensional distribution is obtained by scanning the sample or the focused X-rays. Information such as a photoelectron signal spectrum to be measured may be obtained as follows.

First, a region R1 (for example, the region B in FIG. 2) on the sample to be measured containing the element A in a pure (or high-purity) state.
FIG. 5 (a) shows a reference photoelectron spectrum obtained from a sample containing pure gold (or gold) or a standard sample. Then, it can be obtained from a region R2 (for example, the region A in FIG. 2 containing pure SiO ₂ ) or a standard sample on the sample to be measured which contains the chemical bonding state B in a pure (or high purity) state. The reference photoelectron spectrum is shown in FIG.
It is assumed that the focused X-ray diameter is sufficiently smaller than the regions R1 and R2.

Next, a region to be measured R3 containing the element A and the chemical bonding state B (for example, a region where SiO ₂ and gold are mixed in the region C in FIG. 2) is irradiated with X-rays, and a photoelectron spectrum is obtained. measure. The photoelectron spectrum at this time is shown in FIG.
Shown in

If it is known that there are only two types of elements and chemical bonding states A and B included in the region R3, the spectrum of FIG. 5C becomes the spectrum of FIGS. 5A and 5B. This is a superposition of spectra. Therefore, the reconstructed spectrum obtained by amplifying the spectrum of the element A (FIG. 5A) and the spectrum of the chemical bonding state B (FIG. 5B) by α times and β times, respectively, and the reconstructed spectrum of FIG. The sum of squares of the difference between each data point and the spectrum is calculated, and the magnifications α and β are determined so as to minimize this value. The obtained α and β indicate the abundance ratios of the elements A and B, and by using these values, the abundance, the abundance ratios of the element A and the chemical bonding state B,
A two-dimensional distribution such as a mixing ratio and the number of photoelectrons can be obtained.

Here, two spectra (FIG. 5C)
And the reconstructed spectrum) were compared in the entire measured energy range, but this may be performed only in a specific energy range. For example, when only the element A is known in the reference spectrum, the comparison is performed only in the region of δEa in FIG. 5C, and when the sum of squares of the difference is minimized, FIG. By taking the difference from the spectrum of ()), the spectrum of the chemical bonding state B can be obtained.

Alternatively, information such as a photoelectron signal spectrum to be measured may be obtained as follows.

First, a region R1 containing pure (or high purity) element A (for example, a region containing pure gold in region B in FIG. 2) is irradiated with X-rays, and a photoelectron spectrum is measured. It is assumed that the focused X-ray diameter is sufficiently smaller than the region R1. The photoelectron spectrum at this time is shown in FIG.
(A).

Next, a region R2 containing the element A and the chemical bonding state B (for example, a region where SiO ₂ and gold are mixed in the region C in FIG. 2) is irradiated with X-rays to measure a photoelectron spectrum. . FIG. 7A shows the photoelectron spectrum at this time.

The number of photoelectrons contained in the photoelectron energy region δEa in FIG. 7A is integrated, and the number of photoelectrons from the element A is obtained by subtracting the background component. If you go, element A
(Two-dimensional distribution) is obtained.

However, since the photoelectron signal resulting from the spectrum of the element A overlaps the spectrum of the chemical bonding state B, the mapping is simply performed by integrating the number of photoelectrons contained in the photoelectron energy region δEb. Then
The two-dimensional distribution of element B cannot be obtained accurately.

Therefore, the unnecessary element A is prepared as follows.
, Only the photoelectrons in the chemically bonded state B need to be obtained.

First, the background component is subtracted from the photoelectron spectrum of the sample region containing only the element A (FIG. 6).
(B)). This spectrum includes a peak a of a photoelectron signal emitted from the inner shell of the element A and a signal a ′ caused by the photoelectron.

Next, the background component is subtracted from the spectrum of the region R2 (FIG. 7B). This spectrum includes a peak a of the photoelectron signal emitted from the inner shell of the element A, a signal a ′ caused by this photoelectron, and a peak b of the photoelectron signal emitted from the inner shell of the chemical bonding state B. ing.

The shape of the signal a 'resulting from the photoelectron signal (peak a) of the element A is proportional to the intensity of the peak signal a irrespective of the X-ray intensity or the abundance of the element A.

Therefore, for the element A, the ratio between the peak value P2a of the photoelectron signal in FIG. 7B and the peak value P1a of the photoelectron signal in FIG. 6B is obtained, and the ratio is shown in FIG. FIG. 7 shows the result obtained by multiplying the entire spectral region.
It is subtracted from the spectrum of (b) (FIG. 7 (c)).

As a result, in the obtained spectrum of FIG. 7C, the signal due to the element A disappears and only the spectrum of the photoelectron signal in the chemical bonding state B remains. The number of photoelectrons can be determined accurately.

In this description, unnecessary photoelectron signals are removed by using the ratio of the peak intensities of the photoelectron signals serving as indices. However, the ratio of the number of photoelectrons contained in the photoelectron signals serving as the indices may be used.

In the above example, the element A and the chemical bonding state B
Was used as a reference electron spectrum from a region on the sample that contained pure (or high purity). As described above, when an electron spectrum from a pure (or high-purity) region existing on a measurement sample is used as a reference spectrum, the reference spectrum and the electron spectrum of the measurement region of the sample have the same measurement conditions (vacuum degree, irradiation X-rays). (Spectral width, pulse width, surface state, etc.), it is possible to measure a very small amount of chemical bonding state or element with high accuracy.

When there is no region containing the element or the chemical bonding state in a pure (or high-purity) state on the measurement sample,
Another standard sample containing only these elements and the state of chemical bonding in a pure (or high-purity) state may be measured, and the obtained electron spectrum may be used as a reference electron spectrum. Alternatively, an electronic spectrum from the standard sample may be measured in advance, and the one stored on the storage device may be used as the reference electronic spectrum.

In the above description, it is assumed that the sample contains one kind of element and one kind of chemical bond. However, the same operation is used for a sample containing more elements and one kind of chemical bond. It is possible to accurately perform two-dimensional mapping on a power element.

In the above example, the mapping of the element and the chemical bonding state has been described. However, the mapping of the plurality of different chemical bonding states of the same element, the plural elements, or both the plural elements and the plural chemical bonding states can be performed. Mapping may be included.

The procedure for removing an unnecessary signal spectrum from an electronic spectrum obtained from a region containing a plurality of chemical bonding states or elements is not limited to the procedure described above. By referring to a purely (or highly pure) chemical bond state or a spectrum from an element alone, it is possible to separate contributions of a plurality of contained chemical states or elements from the electronic spectrum or to remove unnecessary spectral components. Any procedure may be used as long as it is removed.

In order to accurately determine the abundance or the like by performing the above-described data processing, it is important to reduce shot noise contained in the obtained photoelectron spectrum.

However, when trying to obtain a spectrum using the time-of-flight method, when sampling a signal from a photoelectron detector, sampling is performed at equal time intervals.
When converting this into an electronic spectrum, E = (m /
2) (L / T) ² (where m is the mass of the electron, L is the flight distance, and T is the arrival time of the electron), so that the data points of the electron spectrum are equally spaced in terms of energy. Not be. In the low energy region (for example, several eV), the interval between each data point becomes (for example) several tens meV. Since the number of electrons existing in a narrow energy width becomes small, shot noise becomes extremely large.

In order to solve this problem, the present invention provides a method of analyzing time-of-flight spectral data not at equal time intervals but at equal energy intervals (claim 8).

This will be specifically described with reference to FIG. FIG.
In (a), a sample is irradiated with pulsed X-rays, and a photoelectron flow measured by a detector (in this case, a microchannel plate (MCP) is measured by a time-of-flight method using a measuring device (in this case, an oscilloscope)). It is a photoelectron spectrum obtained based on a waveform obtained by sampling at equal time intervals.

This photoelectron spectrum is given by the following equation:
This is converted from the photoelectron current waveform.

N = Vt^ThreeδE (mL^TwoZGη)^-1  N is the number of detected photoelectrons per δE (eV), and V is the detector
(In this case, MCP) output voltage (V), t is during flight
Interval (sec), m is the mass of the electron (kg), L is the flight length
(M), Z is the input of the measuring instrument (in this case, oscilloscope)
G is a detector (in this case, MCP)
, Η is the detection efficiency (opening) of the detector (in this case, MCP).
Percentage).

As can be seen from FIG. 8A and the above equation, the interval between data points becomes narrower toward the lower energy side.
Therefore, the shot noise is very large. FIG. 8B shows a case where a new data point is created with a width of 0.5 eV, the value of the original data included in the width of 0.5 eV is integrated around the data point, divided by 0.5 eV, and the unit energy is calculated. This is a plot obtained by converting the number of photoelectrons per unit (claim 9).

That is, in FIG.
7, 6.2 eV. . . And new data points are created at intervals of 0.5 eV. The value obtained by integrating the number of photoelectrons included between 4.95 to 5.45 eV of the raw data and dividing by 0.5 eV is
The value of the newly created 5.2 eV data point is used. (The same applies hereinafter.) It can be seen that this method significantly reduces the apparent shot noise shown in FIG.

In the above description, the integral of the data value included in the energy width is simply obtained, but the integral may be obtained by arbitrarily weighting them.

In FIG. 8, the original data is converted into the number of photoelectrons per unit energy, but the data values are the output voltage of the detector (for example, a microchannel plate) or the current value of the photoelectron current. 0.5 eV in case
It may be the sum of the data values within the width.

In the above description, the energy width is 0.5
Although it is calculated as eV, the present invention is not limited to this, and an arbitrary energy width may be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0069]

Embodiment 1 FIG. 1 shows a schematic configuration of a photoelectron spectroscopy apparatus used for photoelectron spectroscopy of this embodiment.

A laser beam 103 emitted from a pulsed laser light source is condensed and irradiated by a lens 104 onto a target 106 made of boron nitride (BN, an example of a target material) disposed in a vacuum vessel 101, and is irradiated with the target material. Is turned into plasma and X-rays are radiated (they become a laser plasma X-ray source which is an example of a pulse excitation source).

The inside of the vacuum vessel 101 is previously exhausted by an exhaust system to a pressure at which generated X-rays are sufficiently transmitted.

X-rays 108 emitted from plasma 107
Is transmitted through a carbon film 109 as an X-ray transmission filter, and is then condensed and radiated onto a small area on a sample 111 by a Schwarzschild mirror 110 (an example of an X-ray optical element). The X-rays radiated onto the sample by the filters and the multilayer mirror used in the Schwarzschild mirror are 6.03 nm in wavelength due to the 1s2-1s2p transition of helium-like boron (photon energy = 206 eV).
Is monochromatic.

The sample 111 has a planar structure as shown in FIG. That is, in the sample, different concentrations of gold are distributed on the SiO ₂ thin film (A). In order to obtain a gold reference electron spectrum, a rectangular region (B) of pure gold is formed on a portion of the SiO ₂ thin film.

The focused diameter of the X-ray is sufficiently smaller than the rectangular area B, and the sample is mounted on the moving stage 112 and can be moved in axial directions orthogonal to each other.

Photoelectrons 113 emitted from sample 112
After passing through the flight tube 114, is detected by the microchannel plate MCP116 (an example of an electronic detector). While flying in the flight tube 114, the photoelectrons 113 are applied with a blocking electric field from the electrodes 115 and decelerated so as to have an appropriate energy resolution.

The detected photoelectron signal waveform is quantized by the high-speed oscilloscope 117 and taken in. The fetched photoelectric signal waveform is sent to an arithmetic processing unit (for example, a personal computer) 118 via a line, where it is subjected to data processing and stored in a hard disk or an external storage device 120.

By measuring the photoelectron spectrum at each point on the sample while the sample is two-dimensionally scanned by the stage 112, a mapping (two-dimensional distribution) of the element to be measured or the chemical bonding state on the sample is obtained. Then, the obtained mapping (two-dimensional distribution) is stored in the external storage device 120.

Here, as an example, FIG. 3A shows a photoelectron spectrum from a SiO ₂ region (region A in FIG. 2) obtained when a sample as shown in FIG. 2 was used as a sample. The photoelectron spectrum from the region (region B in FIG. 2) is shown in FIG.
(B). FIG. 3C shows a photoelectron spectrum from a region containing both SiO ₂ and gold (region C in FIG. 2).

Since X-rays having a photon energy of 206 eV are used, the spectrum from SiO ₂ (FIG. 3A)
Does not show a photoelectron spectrum from the inner shell of oxygen, but shows only a photoelectron spectrum of chemically shifted Si. In addition, the spectrum from gold (FIG. 3B) shows 4
A spectrum from the f orbital and a spectrum (peak near 10 eV) resulting from the spectrum appear.

A reconstructed spectrum obtained by superposing the spectrum of SiO ₂ (FIG. 3A) and the spectrum of gold (FIG. 3B) by α times and β times, respectively, and obtained at an arbitrary position on the sample. The sum of the squares of the difference at each data point from the obtained spectrum (for example, FIG. 3C) is calculated, and the magnifications α and β are determined so that this value is minimized. This scanning is performed for each point on the sample, and by plotting the magnifications α and β determined at each point, a two-dimensional distribution of SiO ₂ and gold can be obtained. Since the time-of-flight method is employed, spectra of a plurality of chemical bonding states or elements can be collectively captured under the same conditions.

That is, according to the method of the present embodiment, in one count, the energy range of photoelectrons to be detected is narrowed by providing an energy slit, and the number of photoelectrons in the photoelectrons is counted. The waveform distribution is
Unlike the conventional method, which was obtained by performing a large number of scans by scanning the value of the central energy of the energy slit, fluctuations in the X-ray intensity, changes in the charged state of the sample, etc.
Data that is not affected by changes in the measurement environment can be obtained.

Therefore, according to this embodiment, it is possible to measure a trace amount of a chemical bond or an element with higher sensitivity than the conventional photoelectron analysis.

Further, according to this embodiment, since unnecessary spectrum signals can be removed and the necessary spectrum signals can be obtained clearly, mapping of a plurality of elements (or chemical bonding states) can be performed by a conventional photoelectron. Faster than spectroscopy,
Moreover, it can be performed with high accuracy.

[0084]

Embodiment 2 FIG. 4 shows a schematic configuration of a photoelectron spectroscopy apparatus used in the photoelectron spectroscopy of this embodiment. As in the first embodiment, boron nitride is used as the target material.

X-ray 408 emitted from plasma 407
Is transmitted onto the sample 410 after passing through the X-ray filter 409. The sample is the same as in Example 1.

The X-ray irradiation region is larger than the gold region (B), and includes the gold region (B) and the region of the SiO ₂ thin film A in the irradiation region. Therefore, unlike the first embodiment, only the SiO ₂ region (A) and the gold region (B) on the sample are irradiated with X-rays, and the pure (or high-purity) photoelectron spectrum of SiO ₂ and gold is changed. You can't get it.

Therefore, a single pure (or high-purity) gold photoelectron spectrum previously obtained by measurement of another sample is stored in the external storage device 418 as a reference spectrum, and the sample is stored based on the reference spectrum. By removing the spectral component caused by gold from the photoelectron spectrum (composite photoelectron spectrum) obtained by the measurement at 410, the photoelectron signal spectrum of SiO ₂ can be accurately obtained.

Here, as the external storage device 418, one externally connected to an arithmetic processing unit (for example, a personal computer) 416, one connected to a network, one connected to a host connected to the Internet,
Etc. are available.

Note that the measurement conditions of the another sample relating to the reference spectrum stored in the external storage device and the sample 41
When the measurement condition of 0 (for example, the applied voltage of the blocking electric field) is different, a spectrum obtained by calculation, which is predicted to be obtained under the measurement condition of the sample 410, may be used.

For example, when a reference spectrum stored in the external storage device 418 is obtained,
When the applied voltage of the blocking electric field when the sample 410 is measured is different, a reference spectrum shifted by the difference between the applied voltages may be used as the reference spectrum.

Here, a magnetic lens (P. Kruit and F. H. Read,
J. Phys. E, 16, 1983, p313), the shape of the electron spectrum changes when the stopping electric field is changed, but the change may be corrected by calculation to obtain the reference electron spectrum.

Although this embodiment does not use a light-collecting optical element, the above-described method can be similarly used when a light-collecting optical element is used.

In this embodiment, since the time-of-flight method is used for the photoelectron energy analysis, a plurality of chemical bonding states or spectra of elements can be collectively captured under the same conditions.

That is, according to the method of this embodiment, in one count, the energy slit is provided to narrow the energy range of photoelectrons to be detected and the number of photoelectrons in the photoelectrons is counted. The spectrum waveform distribution differs from the conventional method, which is obtained by performing a large number of counts by scanning the value of the center energy of the energy slit, and measures the fluctuations in the output intensity of X-rays and changes in the charged state of the sample due to measurement. Data that is not affected by environmental changes can be obtained.

Therefore, according to the present embodiment, it is possible to analyze a very small amount of a chemical bond or an element with higher sensitivity than the conventional photoelectron analysis.

Further, according to the present embodiment, since unnecessary spectrum signals can be removed and necessary spectrum signals can be clearly obtained, mapping of a plurality of chemical bonding states or elements can be performed by the conventional photoelectron spectroscopy. This can be performed more quickly and accurately.

In the first embodiment, a Schwarzschild mirror is used as an X-ray focusing optical element. In addition, a total reflection mirror such as a multilayer elliptical mirror and a Walter mirror, and an optical device utilizing diffraction such as a zone plate are used. An element may be used.

In the above embodiment, one kind of element and one
Although the types of chemical bonding states (gold and SiO ₂ ) have been described, multi-element analysis can be performed by a similar method even if the types of elements and chemical bonding states are further increased.

In the above embodiment, the analysis of the chemical bonding state with the element was performed. However, the analysis of the plural different chemical bonding states of the same element, the plural elements, or the plural different elements and the chemical bonding state were performed. The analysis of a sample containing is also possible by a similar technique.

[0100]

As described above, according to the present invention,
It is possible to accurately determine the absolute number of each chemical bond or element contained in the sample surface layer and the relative abundance ratio.

In the present invention, since the time-of-flight method is employed for the electron energy analysis, a plurality of chemical bonding states or spectrums of elements can be collectively captured under the same conditions.

That is, according to the method of the present invention, data which is not affected by fluctuations due to output fluctuations of the excitation source, which is a problem in the conventional method of obtaining the entire spectrum by scanning a limited energy region, is obtained. Is obtained.

Therefore, according to the present invention, it is possible to analyze a trace amount of a chemical bond state or element with higher sensitivity than the conventional electron analysis method.

Further, according to the present invention, since unnecessary spectrum signals can be removed and a necessary spectrum signal can be clearly obtained, mapping of a plurality of chemical bonding states or elements can be performed more easily than in the conventional electron spectroscopy. It can be performed quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a photoelectron spectroscopy apparatus used for photoelectron spectroscopy in Example 1.

FIG. 2 is a schematic plan view of a sample used for photoelectron spectroscopy of an example.

FIG. 3 is a photoelectron spectrum obtained by the photoelectron spectroscopy of the example, and shows a photoelectron spectrum from a gold region and a photoelectron spectrum from a SiO2 region.

FIG. 4 is a schematic configuration diagram of a photoelectron spectroscopy device used for photoelectron spectroscopy in Example 2.

FIG. 5 is a schematic diagram of a spectrum for explaining a data processing method according to the present invention. Fig. 5 (a): Photoelectron spectrum from the region of element A Fig. 5 (b): Photoelectron spectrum from the region of element B Fig. 5 (c): Photoelectron spectrum obtained from the region containing elements A and B

FIG. 6 is a schematic diagram of a spectrum for explaining a data processing method according to the present invention. FIG. 6 (a): Photoelectron spectrum from the region of element A FIG. 6 (b): Photoelectron spectrum after subtracting the background component from the spectrum of FIG. 6 (a)

FIG. 7 is a schematic diagram of another spectrum for explaining the data processing method according to the present invention. FIG. 7 (a): Photoelectron spectrum from a region containing elements A and B FIG. 7 (b): Photoelectron spectrum after subtracting the background component from the spectrum of FIG. 7 (a) FIG. 7 (c): FIG. Referring to the spectrum of FIG. 6B from the spectrum of FIG. 6B, the spectrum after removing the spectrum component of the element A.

FIG. 8 is another photoelectron spectrum for explaining the data processing according to the present invention. FIG. 8A: Raw data of the photoelectron spectrum obtained by the time-of-flight method. FIG. 8B: A new data point is created with a width of 0.5 eV, the number of photoelectrons of the raw data included in the width of 0.5 eV is integrated with the data point as a center, and converted to a unit energy width. Photoelectron spectrum.

[Description of Signs of Main Parts]

101: vacuum container, 102: vacuum container, 103: laser light, 104: lens 105: laser light introduction window, 106: target material (boron nitride), 107: plasma 108: X-ray, 109: X-ray transmission filter, 110 …
Schwarzschild mirror 111: sample, 112: sample moving stage, 113: photoelectron, 114: flight tube 115: blocking electric field application electrode 116: microchannel plate (MCP) 117: high-speed digital storage oscilloscope 118: arithmetic processing unit, 119 ... CRT, 120 ... External storage device 401, 402 ... Vacuum container, 403 ... Laser light, 40
4 Lens 405 Laser light introduction window 406 Target material (boron nitride) 407 Plasma 408 X-ray 409 X-ray transmission filter 410
Sample 411, photoelectron 412, flight tube, 413, electrode for applying a blocking electric field 414, microchannel plate (MCP) 415, high-speed digital storage oscilloscope 416, arithmetic processing unit, 417, CRT, 418, external storage device

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Noriaki Kamitaka 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (72) Inventor Toshihisa Tomie 1-4-1 Umezono, Tsukuba, Ibaraki Industrial Technology (72) Inventor: Hideaki Shimizu, 1-4-1 Umezono, Tsukuba, Ibaraki Pref.

Claims (8)

[Claims] 1. An electron spectroscopy method for irradiating a sample with pulsed light such as X-rays, extreme ultraviolet rays, or ultraviolet rays and measuring a surface state of the sample from an energy spectrum of electrons emitted from the sample. 2) a step of irradiating the sample containing a chemical bond state or an element with the pulsed light to obtain an electronic spectrum using a time-of-flight method, and at least (N) N-1) a signal using a photoelectron spectrum obtained in each region on the sample or another standard sample containing each of the chemical bonding states or elements in a pure (or high purity) state alone as a reference electron spectrum. By performing the processing, of the N types of chemical bonding states or elements, a single electron spectrum corresponding to the chemical bonding state or element of interest, abundance, Standing ratio, electron spectroscopy and having the steps, the obtained mixing ratio, or a number of photoelectrons. 2. An electronic spectrum obtained from a region containing N kinds (N ≧ 2) of chemical bonding states or elements, and at least (N−1) kinds of chemical bonding states or elements contained in the region. With the reconstructed spectrum obtained by superimposing the reference electron spectra of the elements, the sum of the squares of the difference between the two spectra in the entire energy region or a specific range of energy regions is minimized, and each reference electron spectrum is 2. The electron spectroscopy according to claim 1, wherein a contribution is obtained to obtain a single electron spectrum, an abundance, an abundance ratio, a mixing ratio, or a photoelectron number of one or more kinds of chemical bonding states or elements of interest. Law. 3. A method according to claim 1, wherein a ratio Ri (i = 1, 2, 3,..., N−1, or i = 1) between the electron spectrum and the reference electron spectrum is determined with respect to the peak intensity or the number of electrons of the electronic signal. , 2, 3,..., N), and performing the signal processing by subtracting each reference electron spectrum multiplied by each Ri from the electronic speckles. Spectroscopy. 4. When a measurement condition of the reference electron spectrum is different from a measurement condition of the electronic spectrum, a reference electron spectrum predicted to be obtained under the measurement condition of the electronic spectrum is obtained by calculation. Item 1. Photoelectron spectroscopy according to items 1 to 3. 5. The irradiation area and / or irradiation position of the pulse light on the sample can be changed,
A single electron spectrum from a fine region containing one kind of chemical bonding state or element in a pure (or high purity) state and an electronic spectrum from a region containing two or more kinds of chemical bonding state or element can be obtained. 5. The electron spectroscopy according to claim 1, wherein: 6. An electron spectrum in an entire region or an arbitrary region on a sample is obtained by changing an irradiation position of the pulse light on the sample. 5. Electron spectroscopy according to 5. 7. In a flight tube used in the time-of-flight method, a stopping electric field is applied to the electrons to reduce the speed of the electrons, thereby increasing the time to reach the electron detector and increasing the energy resolution. The electron spectroscopy according to claim 1, wherein: 8. An electron spectroscopy for irradiating a sample with pulsed light such as X-rays, extreme ultraviolet rays, ultraviolet rays, etc., and measuring a surface state of the sample from an energy spectrum of electrons emitted from the sample. The process of irradiating the emitted pulse light to obtain an electron spectrum using the time-of-flight method, and converting the time-of-flight spectrum data points obtained at equal time intervals into equal energy interval data points with an arbitrary energy interval Photoelectron spectroscopy, comprising: obtaining a spectral waveform.