JP2001281180A - Measuring method using photoelectron spectroscope and pre-treating method for sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of photoelectron spectroscopic analysis capable of realizing more accurate and efficient measurement of insulating material, and equipped with a charge relaxing function with a wide relaxation margin by relaxing uneven charge-up. SOLUTION: This method of photoelectron spectroscopic analysis for an insulating material has, at least, a conductive-film forming process for forming a conductive thin film near a measured position of a sample prior to measurement, and a measurement process for performing measurement while irradiating the measured position with electron rays and applying a voltage on the thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectron spectroscopic analysis method and a sample pretreatment method for analyzing elements contained in the surface of semiconductors and insulators and the bonding state thereof, and more particularly to a method for preventing charging of an insulating sample. Spectroscopic analysis method and a sample pretreatment method for the same.

[0002]

2. Description of the Related Art Surface analysis usually gives the elements contained in a sample, their chemical bonding state, or the electronic structure of the sample by examining the energy and intensity distribution of electrons and X-rays emitted from the sample. is there. Electron beams, X-rays, and ionizing radiation such as ions are used as excitation rays to emit electrons and ions from the sample surface.For example, when irradiating soft X-rays and observing photoelectrons emitted from the surface Is called X-ray photoelectron spectroscopy (XPS or ESCA),
It is well known as a technique for elemental analysis of a sample's extreme surface and for giving its chemical bond state. In addition, an ultraviolet electron spectroscopy (UPS) method using vacuum ultraviolet light and an Auger electron spectroscopy (AES) method using a focused electron beam are well known.

However, when the sample is insulative, electrons lost due to emission cannot be quickly compensated, so that the sample is charged up (in most cases, has a positive charge). For this reason, the electrons emitted from the sample change in the kinetic energy of the electrons due to the potential difference generated between the sample and the detector, and the obtained spectrum is shifted with respect to the binding energy (kinetic energy of the electron) axis. If the shift is large, the target peak will protrude from the measurement range. Therefore, it is necessary to perform re-measurement or set a wide measurement range in advance, which increases the measurement time. In addition, when the degree of charging is not uniform in the plane or in the depth direction due to unevenness of the intensity of the excitation light on the sample or the layer structure of the sample, the spectrum is deformed by superposition of spectra having different shift amounts. , Peak width broadening and so-called tailing become problems. The effect of these charge-ups is particularly remarkable when an electron beam or an X-ray is used as the excitation beam.

[0004] FIG. 10 shows a conventional technique in which an X-ray photoelectron spectroscopy (XPS) is used to form a Si oxide film (film thickness: 50) on a Si substrate.
0 nm) in the depth direction. Sputter etching was performed using argon ions (acceleration voltage: 3 kV, etching rate: 10 nm / min), and the O1s electron peak was measured every 10 minutes of etching. The spectrum obtained by setting the measurement range with reference to the peak position shifted by charge-up at the start of measurement.However, as the measurement progresses and the oxide film thickness decreases, the shift due to charge-up decreases. It is shown that the peak has protruded from the measurement range.

In order to prevent the influence of the charge-up on the sample surface, a method of correcting the spectrum shift due to the charge-up after the measurement or actively neutralizing the charge-up itself is used. For example, in the case of X-ray photoelectron spectroscopy, as a method of correcting the shift, electrons emitted from carbon that is naturally adsorbed on the sample surface whose binding energy is known, so-called hydrocarbon contamination, or gold that is thinly deposited on the surface are emitted. A well-known method such as a method based on electrons emitted from Ar when sputtering is performed using Ar ions or the like is well known. However, this method cannot correct the above-mentioned non-uniform charge-up spectrum deformation, and cannot be applied to a sample having no adsorbed hydrocarbon on a clean surface or a sample on which gold cannot be deposited.

In such a case, it is effective to supply a charge from the outside to the sample to neutralize the charge-up. In addition, even when a metal such as gold can be deposited, the deposition process is troublesome and time-consuming, and it is particularly difficult to control the thickness of the film to be thin so that the detection efficiency and sensitivity cannot be reduced. It is a problem that cannot be solved.

On the other hand, various methods of supplying electrons to neutralize the charge-up have been considered, and a method of introducing a small amount of a rare gas into a vacuum in a photoelectron spectrometer and utilizing the electrons emitted therefrom ( JP-A-3-26948)
Or a method of irradiating a metal portion close to a sample with an excitation beam and using electrons emitted therefrom (JP-A-3-1133)
No. 54 gazette).

However, the most widespread and effective method is the neutralization method using a neutralizing electron gun for irradiating a sample with an electron beam because of the advantage that neutralization conditions such as the amount of supplied electrons and the irradiation range are easily controlled. is there.

In the conventional neutralization using a neutralizing electron gun, although there are some differences depending on the apparatus, the amount of electrons to be irradiated, the kinetic energy of the electrons to be irradiated, and the position (range) to which the electrons are irradiated can be controlled. The operator measures and uses the neutralization condition so as to eliminate the shift or deformation due to charge-up while watching the measured spectrum or the spectrum displayed immediately.

However, in this case, when unattended measurement is performed by automatically aligning a plurality of samples, even if the likelihood of charge-up varies depending on the sample, neutralization conditions cannot be adjusted accordingly. In addition, even if there is a measurer, if the charge-up state changes over time during measurement due to sample damage due to excitation radiation, or if the charge-up state differs depending on the depth in depth direction analysis using sputtering, It is difficult to adjust the neutralization conditions, and there are problems such as limitations on the measurement conditions and an increase in the measurement time. In addition, this method does not completely eliminate charge-up even when irradiating an electron beam with a neutralizing electron gun. In fact, by irradiating excess electrons, only an electron balance is created. It is.

[0011] Therefore, in XPS or the like, it is necessary to correct the energy shift due to charge-up by the peak of the reference substance on the sample surface, and distribution unevenness may occur due to the charge-up sample position. It can happen. In the case of an insulating thin film sample, the degree of charge-up also differs in the film thickness direction.
A difference in energy shift also occurs in the depth direction.

Therefore, the emission electron peak from the reference element embedded on the surface of the sample or inside the surface is measured, and the signal information is fed back to automatically adjust the amount of irradiated electrons and the kinetic energy of the electrons. (Japanese Patent Application Laid-Open No. 9-243579). This method sets a neutralization condition for a change in the charge-up state at each measurement or during the measurement, and enables accurate surface analysis in a relatively short time.

This method is effective in that a point for neutralization can be appropriately set according to the charge-up amount. On the other hand, the fact that it is necessary to cope with a change in the charge-up state at each measurement or during the measurement indicates that the range of the charge-up state that can be relaxed by one neutralization condition is narrow.

A method has also been proposed in which a conductive mesh of earth potential is covered on a sample surface and used in combination with an electron beam for neutralization (CE Bryson: Surf. Sci., 189 / 190.50 (1)
987), G. Barth, et al. Surf. Interface Anal, 11,
307 (1988)). This method is effective for charge-up when a monochromatic X-ray source is used. That is, it is difficult to mitigate charge-up when using a monochromatic X-ray source because the X-rays are focused on the sample surface. If the irradiation area of the neutralizing electron is wider than the irradiation area of the X-ray, the area irradiated with only the electron beam is negatively charged. Therefore, the free movement of electrons in the negatively charged region is hindered, and it becomes difficult for the electrons to reach the central region irradiated with X-rays. Therefore, if a metal mesh is placed on the surface of the sample, the influence of the electric field in the region not irradiated with the X-ray can be reduced. In this method, a conductive substance is placed in the vicinity of a charged portion to release an excessive charge, thereby mitigating the charge-up and stabilizing the potential on the sample surface. Compared with the method of only irradiating electrons, the charge relaxation margin is large, and a stable surface potential can be always maintained. On the other hand, the signal from the metal mesh is mixed into the spectrum from the sample,
There is a problem that the analysis accuracy is reduced. When a metal mesh is used, such contamination can be reduced by slightly separating the mesh from the sample surface, but the analysis accuracy is still reduced.

As described above, the insulator analysis by XPS or UPS requires a means for eliminating or neutralizing the charge on the sample surface.

[0016]

As described above, the mitigation of the charge-up by the neutralizing gun requires time and effort to find a condition in which the charge-up and the neutralization are balanced.
In addition, there are problems such as a decrease in measurement accuracy and measurement efficiency. In particular, the non-uniform charge-up in the plane and in the depth direction may not be alleviated only by the neutralizing gun, and the tail may be drawn to the low binding energy side.

This phenomenon is caused by the fact that the charge relaxation by the neutralizing gun is balanced on average for the entire sample, but the balance margin is narrow, and the components that deviate even slightly from the equilibrium can be alleviated. It is not shown.
That is, charge relaxation by electron beam irradiation is the most serious problem in that the relaxation margin is narrow. This problem is particularly likely to occur when a monochromatic X-ray source is used.

The present invention has been made in view of the above-mentioned problems of the prior art, and has been developed to provide a more accurate and efficient insulator measurement having a charge mitigation function which alleviates uneven charge-up and has a wide mitigation margin. It is an object of the present invention to provide a photoelectron spectroscopic analysis method that can be realized.

Further, the present invention proposes a droplet applying means and a droplet applying method for forming a conductive thin film on an insulator sample.

[0020]

That is, the present invention provides an X-ray photoelectron spectroscopy method for an insulating sample, comprising the steps of: forming a conductive thin film in the vicinity of a measurement site of the sample prior to measurement; While irradiating the measurement location with an electron beam,
And a measuring step of performing a measurement while applying a voltage to the conductive thin film.

Here. The “near the measurement location” is a region where an excitation beam (X-ray or ultraviolet ray) is irradiated and an electron beam for charge-up correction is simultaneously irradiated when performing XPS or UPS measurement.

It is desirable that the conductive thin film is formed so as not to excessively cover the measurement site of XPS or UPS and to maintain conductivity so that a voltage can be supplied from outside the sample. For example, as shown in FIGS. 4, 5, and 9, it is very effective to form a conductive thin film in a mesh shape near the measurement region.

In the present invention, the photoelectrons from the atoms forming the insulator sample and the photoelectrons from the atoms forming the conductive thin film may be adjusted by adjusting a voltage applied to the conductive thin film in the measuring step. X-ray photoelectron spectroscopy analysis method for identifying

In an XPS or UPS detector, photoelectrons from atoms constituting a sample and photoelectrons from a conductive thin film are simultaneously detected. In a usual method, the detected photoelectrons could not be separated by the place where they were generated. However, in the present invention, by applying a voltage to the conductive thin film, the photoelectrons generated from the conductive thin film are forcibly shifted in energy, so that the two can be distinguished.

Further, in the present invention, in the conductive thin film forming step, a droplet of a raw material solution of a conductive thin film containing at least a conductive substance is applied to a predetermined portion of a sample surface using a droplet applying means. The present invention provides an X-ray photoelectron spectroscopy method characterized by forming a conductive thin film composed of fine particles in an arbitrary shape by post-drying.

It is desirable to use a dispersion in which at least conductive fine particles are dispersed in the solution as a raw material solution for the conductive thin film formed near the sample measurement site.

It is desirable to use metal fine particles as the conductive fine particles dispersed in the raw material solution.

The metal fine particles are composed of Cu, Pt, Au, Mo, W, T
any one selected from a, Ag, Pd, Ni, Co, Cr or In
Preferably, it is of the type.

In the method of forming a conductive thin film according to the present invention, a droplet of a dispersion liquid containing conductive fine particles is applied to a desired portion of a sample surface by using a droplet applying means, and then dried. The conductive thin film is formed in an arbitrary shape.

The present invention uses the following several means to alleviate the charge-up that occurs during the XPS and UPS measurements of an insulator. A conductive thin film was formed in the vicinity of the measurement location so that the charge accumulated at the charge-up occurrence site could be moved quickly, thereby increasing the passive charge-up mitigation margin. At the time of measurement, the conductive thin film is irradiated with excitation rays (ultraviolet rays, X-rays) as well as the measurement region, and photoelectrons generated from the conductive thin film are supplied to the charge-up region, thereby positively mitigating charge-up.

By these two methods, the charge-up mitigation margin during the analysis of the insulator is greatly improved.

Further, the separation between the atoms constituting the mesh and the atoms constituting the sample, which has conventionally been a problem in the measurement using a metal mesh, was achieved at a very high level by the following method. By applying a voltage to the conductive thin film, the photoelectrons of the constituent atoms of the conductive thin film were forcibly shifted in energy. The voltage applied to the conductive thin film was appropriately adjusted so that the backup ground strength of the photoelectron peak of the element of interest did not increase.

Accordingly, the present invention provides an X
It is possible to increase a charge-up mitigation margin when performing PS and UPS measurements, and to provide an easier insulator analysis method.

In addition, by applying a voltage to the conductive thin film formed near the measurement site and artificially shifting the kinetic energy of photoelectrons emitted from the conductive thin film sample, the electrons emitted from the atoms constituting the sample are changed. Photoelectrons can be distinguished from photoelectrons emitted from the atoms that make up the conductive thin film, making it possible to analyze insulators with the same quantitative accuracy as conventional methods.

The present invention also relates to a conductive thin film forming apparatus for forming a conductive thin film on the surface of a sample for measurement by X-ray photoelectron spectroscopy, wherein (1) a droplet containing a conductive substance on the surface of the sample. (2) an optical microscope for observing the application position of the droplet and the surface of the sample, and (3)
A conductive thin film comprising at least moving means for displacing the relative position between the sample surface and the droplet applying means, wherein the observation of the applying position and the application of the droplet by the optical microscope are performed simultaneously. A forming device is provided.

The droplet applying means of the conductive film forming apparatus is preferably of an ink jet type.

With the apparatus for forming a conductive thin film of the present invention, a measurer can form a conductive thin film at an arbitrary place while observing a measurement place with an optical microscope. Although it depends on the composition of the raw material solution and the discharge amount of the droplets, a single discharge of the raw material solution can form a conductive thin film having a diameter of about 100 μm. By discharging the raw material solution while moving the sample under the microscope visual field, a conductive thin film of an arbitrary shape can be formed.

A conductive thin film formed by using the above-mentioned conductive film forming apparatus is also one of the constitutions of the present invention.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 1 shows a typical XPS apparatus used in the present invention. In the insulator sample 1, the conductive thin film 2 of the present invention is formed near the measurement location. Measurement area of conductive thin film and sample (area marked with “+” on the surface of insulator sample)
Irradiated X-rays 4 ′ are emitted from the X-ray source so as to irradiate both regions. The region irradiated with the irradiation X-rays 4 ′ is further irradiated with the neutralizing electron beam 5 ′ from the neutralizing electron gun 5. This neutralizing electron beam is also irradiated so as to hit both the measurement area of the sample and the conductive thin film.

Photoelectrons 6 are emitted from the conductive thin film 2 irradiated with X-rays and electron beams. A part of the photoelectrons is used for neutralizing the sample surface, but a part is detected by the energy analyzer 8 together with the photoelectrons emitted from the sample surface.

The neutralizing electron gun 5, X-ray source 4, energy analyzer 8, insulator sample 1, etc. are all set in a vacuum chamber 7, and are maintained at a high vacuum by a vacuum pump 9. I have.

The signal of the photoelectron detected by the energy analyzer is transmitted to the control device 10 and displayed on a display means 11 such as a CRT.
Will be displayed. The conductive thin film 2 input to the control device 10
The instruction to change the voltage to be applied to is supplied from the DC power supply 3 through the power supply 12.

In general, the charge-up of a photoelectron spectroscopy apparatus, particularly X-ray photoelectron spectroscopy, is more remarkable when a monochrome X-ray source is used, but in the apparatus of the present invention, the X-ray source 4 is monochromatic. And non-monochrome (characteristic X-ray). The photoelectron spectroscopy device using X-ray and ultraviolet photoelectron spectroscopy is equipped with an electron gun for alleviating the charge. In the present invention, however, the neutralizing gun 5 must be installed in order to sufficiently exert the effect of the conductive thin film. desirable.

The application of a voltage to the conductive thin film 2 only needs to be able to separate the signal from the sample and the signal from the thin film. The absolute value of the applied voltage depends on the width of the peak of interest. Usually, separation can be achieved by applying a voltage of several tens of volts or less. Applying more voltage than necessary may rather distort the spectrum or lower the yield, so a voltage as low as possible within a separable range is desirable.

The polarity of the applied voltage may be any as long as the signal from the sample and the signal from the conductive thin film can be separated. However, in the case where the background (BG) of the peak of interest significantly increases due to the application of a voltage, it is desirable to make the polarity opposite to that.
For example, in FIG. 1, it is assumed that the same element exists on both the sample surface and the conductive thin film surface. If X-rays are irradiated on both the sample surface and the conductive thin film in the state where the electron beam for neutralization is irradiated, photoelectrons of the element are generated from both.
To detect only the same element from the sample surface, when a positive potential is applied to the conductive thin film, the signal from the thin film apparently shifts to a higher binding energy side, and the background of the same element peak from the sample is It remains low (FIG. 2). If a negative potential is applied to the thin film, the BG of the peak of the same element from the thin film is superimposed on the peak of the same element in the sample, and the spectral accuracy is reduced. In such a case, the polarity of the voltage applied to the thin film is preferably a positive potential.

The polarity and magnitude of the voltage to be applied are determined by a measurer sending an appropriate control signal to the control device 10 while observing the shape of the photoelectron spectrum displayed on the display device 11.

Next, a method for forming the conductive thin film 2 on the surface of the insulating sample 1 will be described.

FIG. 3 is a view showing a configuration of a thin film forming apparatus according to the present invention.

A sample 14 for measurement is fixed to a sample stage 13 of the thin film forming apparatus.
The optical axis center of the microscope for sample observation (in this case, concave mirror 2
Droplet 1 ejected from nozzle 23 installed at (1 center)
5 is discharged on the measurement sample. The amount of liquid droplets ejected from the nozzle 23 is formed by the liquid droplet applying means 16, and the liquid droplet applying means 16 further passes through the control device 19 according to a user's instruction or according to an automatic ejection program. Controlled.

The present thin film forming apparatus is integrated with an optical microscope, so that a user can spray a droplet to an arbitrary position while observing the sample surface. To match the optical axis of the optical microscope with the droplet ejection axis of the nozzle,
A concave mirror having an injection nozzle at the center of the optical axis was used.

The image on the sample surface is turned at a right angle by a concave mirror, passes through a magnifying lens system (not shown), and then enters a 1 / 4λ plate. Further, an image which is incident on a beam splitter installed at a direction of 45 ° with respect to the incident direction of the image and whose path is bent at a right angle is applied to a light receiving system 22 including an eyepiece and the like, and the other image which proceeds straight is CCD The light enters a light emitting unit such as a camera and is output to a CRT or the like.

A moving means 18 is provided for moving the sample placed on the stage within the visual field of the microscope. The moving means 18 is provided with two orthogonal members in the plane where the stage exists.
It has a motor for moving in the axial direction and a motor for moving up and down in the vertical direction. These motors can move according to instructions from the user.

In this apparatus, the optical axis of the optical microscope and the trajectory of the droplet applied by the droplet applying means coincide with each other. Droplets can be applied to the site without moving the optical microscope as it is. After positioning with the optical microscope, the droplet applying means 16
A droplet 15 containing a conductive substance is applied from a discharge nozzle 25. The control of the discharge amount and the discharge timing is performed by the control device 19. The applied droplets become a conductive thin film by drying the solvent, and the process ends.

Incidentally, In addition to repeatedly performing positioning and droplet application each time, a plurality of application locations are input in advance to the control device, and then the moving unit and the droplet application unit are driven based on the input result to perform processing automatically. Can also. This makes it possible to easily form a conductive thin film at an arbitrary position on the sample in an arbitrary pattern.

In the present invention, it is preferable that the means for applying droplets is of an ink jet type capable of easily forming droplets in a minute amount (about ten to several ng to several tens of ng).
Examples of the ink jet method include a piezo jet method using a piezoelectric element and a bubble jet method in which bubbles are generated in a liquid by thermal energy and the liquid is discharged as droplets.

In the present invention, a dispersion liquid of conductive fine particles is used as the application liquid. Mainly as conductive fine particle material
Cu, Pt, Au, Mo, W, Ta, Ag, Al, Pd, Ni, Co, Cr, In
Metal particles such as are preferably used. The photoionization cross section of these metals and the kinetic energy of the photoelectron peak also affect the relaxation effect. A material having a large photoionization cross section or a material having a photoelectron peak having a large kinetic energy may provide a larger charge-up mitigation effect (eg, Pt, Au, etc.). What is necessary is just to have electroconductivity.

The particle size of the fine particles is 1 from the viewpoint of dispersion stability.
The thickness may be less than μm, but is preferably less than 0.5 μm in order to prevent nozzle clogging of the ink jet device. The addition amount of these fine particles is 3 to 2 of the entire dispersion.
It is preferably in the range of 0 wt%.

As the conductive fine particles used in the present invention, commercially available fine particles can be used as they are, but in the case of metal fine particles, a method known in the art, for example, a method of chemically reducing the above metal salt, can be used. It is possible.

As a solvent for dispersing the conductive fine particles, an aqueous solvent containing water as a main component is preferably used. In addition, a water-soluble organic solvent, a surfactant and the like can be added. The purpose of adding the additive is to improve the dispersibility of the fine particles,
These include adjusting the viscosity of the liquid, improving discharge stability, and improving wettability. As the water-soluble organic solvent used by mixing with water,
For example, alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol and n-butyl alcohol; amides such as dimethylformamide; ketones such as acetone; polyalkylenes such as polyethylene glycol Examples thereof include ethers such as glycols and dioxane, and alkylene glycols such as ethylene glycol, propylene glycol, and triethylene glycol. The content of the water-soluble organic solvent in the dispersion of the present invention is preferably in the range of 3 to 30% by weight based on the total weight of the dispersion.

Examples of the surfactant include anionic surfactants such as fatty acid salts and higher alcohol sulfates, and nonionic surfactants such as esters of polyhydric alcohols and fatty acids.

When preparing a dispersion, it is important to uniformly disperse the conductive fine particles in a solvent. For this purpose, various dispersion methods such as a ball mill, a roll mill, a sand mill, a homomixer, and an ultrasonic dispersion are used. Can be used.

The dispersion containing the conductive fine particles, water, water-soluble organic solvent and other additives shown above has a viscosity of 30 cp.
It is preferably adjusted to s or less.

When droplets are applied onto a sample using the above-described droplet applying apparatus and the dispersion liquid, depending on the wetting property of the sample surface, a single droplet application results in a diameter of about 100 μm.
Can be formed. In addition, since the applied liquid amount is small, no special treatment is required for drying the droplets. However, in the case of a sample having excellent heat resistance, drying can be promoted by heating. .

By such a method, a fine conductive thin film composed of conductive fine particles can be formed at an arbitrary position on the sample surface in an arbitrary shape. By continuously performing this process, a fine line having a width of about 100 μm can be drawn in an arbitrary pattern. Therefore, for example, a conductive thin film can be effectively formed in accordance with the shape of a sample, even for a sample having large irregularities or a sample having a limited measurement location.

[0066]

EXAMPLES The present invention will be described in more detail with reference to Examples.

Example 1 A sample having 3 nm of SiO ₂ formed on Si was measured. Prior to the measurement, first, a fine particle thin film made of Mo was formed on the sample surface.

The composition of the dispersion containing Mo used in this example is as follows, and was dispersed uniformly using a ball mill. The average particle size of the obtained Mo fine particles was 0.3 μm.

Composition of Dispersion Mo Fine Particles 10 wt% Isopropyl Alcohol 20 Surfactant 0.5 (Glycerin Fatty Acid Ester) Distilled Water 69.5 Total 100 wt% The dispersion prepared in this manner is mounted on a droplet applying means. While observing the sample surface with an optical microscope, the droplet applying means was driven to drop the dispersion liquid onto the sample. This operation was performed continuously, and as shown in FIG.
A thin film made of 0 μm of Mo was formed.

The sample was converted to a monochrome Al-k α ray (1
486.6 eV, a beam size diameter of about 1 mmφ), and a photoelectron spectrum was measured while irradiating with an electron beam for neutralization. A power supply was connected to the Mo thin film so that a voltage could be applied. The obtained Si-2p spectrum had a peak of about 103 eV, and was observed on the side of the binding energy slightly lower than the original binding energy according to the standard data. The peak shape showed a continuous change, and it was suggested that there was no distortion of the spectrum on the low energy side as in the following comparative example, and that the charge-up was uniformly alleviated. Then,
By applying +10 eV to the Mo thin film, the C and O photoelectron peaks of the sample and the Mo thin film were separated. When the composition ratio of Si and O was calculated from the area of Si-1p and O-1s (lower binding energy) from quartz, Si: O ≒ 1: 2 was obtained. The signal of the sample and the Mo thin film were obtained. From the signal.

(Comparative Example 1) A photoelectron spectrum was measured on the same sample as in Example 1 without forming the conductive thin film. The measurement conditions and neutralization conditions are the same as described above. The peak of Si-2p was observed to be slightly shifted to a low binding energy side of 102.5 eV. At this time, a slight shoulder was observed on the low binding energy side of the peak. This component is probably due to non-uniform charge (in-plane and depth)
This is considered to be caused by the occurrence of, but when analyzing the state of a suboxide or the like, it becomes a factor that lowers the accuracy of the determination. The component on the low binding energy side can be reduced by further optimizing the electron beam irradiation conditions. However, there is an inefficient aspect that requires much labor and time.

(Example 2) When quartz glass is measured by X-ray photoelectron spectroscopy, the kinetic energy of the peak of photoelectrons decreases due to charge-up of the sample surface unless neutralizing means such as electron beam irradiation is used. Apparently, it appears shifted to the higher binding energy side. Using a 1 cm square 2 mm quartz glass, Mg characteristic X-ray (1253.6 e
When measured by irradiation with V), the peak from quartz glass shifted to a higher binding energy side by about 2 eV.

Next, a fine particle thin film made of Cu was formed on the surface of the sample. The composition of the dispersion containing Cu used in this example is as follows, and was uniformly dispersed using a ball mill.
The average particle size of the obtained Cu fine particles was 0.3 μm.

Composition of Dispersion Cu Fine Particles 10 wt% Ethanol 15 Nonionic Surfactant 1 (Polyoxyethylene Alkyl Ether) Distilled Water 74 Total 100 wt% The dispersion prepared in this manner is mounted on a droplet applying means. While observing the sample surface with an optical microscope, the droplet applying means was driven to drop the dispersion liquid on the sample. This operation was performed continuously, and as shown in FIG.
A thin film made of Cu of 0 μm was formed.

The surface of the quartz glass on which the Cu thin film was formed was irradiated with Mg characteristic X-rays (1253.6 eV). In addition,
A power supply was connected to the Cu thin film so that a voltage could be applied. The X-ray output is 8kV-30mA, and the irradiation area is about 4mmφ. Further, electron beam irradiation by an electron gun was also used for neutralization mitigation. In the obtained electron spectrum, photoelectron peaks and Auger electrons from Si, C, O, and Cu were observed. The binding energy of Si-2p was about 104 eV, and charge-up was almost alleviated. In this state, when the irradiation amount of the electron beam was changed from 0.5 to 1.0 mA, the kinetic energy of the photoelectrons did not change significantly. This indicates that the potential in the analysis region is stable due to the presence of the conductor in the vicinity of the insulator, which indicates that the relaxation margin of the charge-up is widened.

Here, in order to separate the signal from the sample from the signal from the Cu thin film, +10 V was applied to the thin film and the photoelectron spectrum was measured. Although the peak of Si hardly changed, the photoelectron peaks of C and O were separated into two, and the peak of Cu shifted to the high binding energy side (low kinetic energy side) of 10 eV. The composition ratio of Si and O was calculated from the area of O-1s (lower binding energy) between Si-2p and quartz.
i: O ≒ 1: 2 was obtained, and it was confirmed that the signal of the sample and the signal from the mask could be separated. Also, even at a voltage of -10 V, the C and O signals were separated, and almost the same quantitative results were obtained.

Example 3 A similar conductive thin film was formed on a sample similar to that in Example 2, and the sample was irradiated with Al-kα radiation in monochrome, and the photoelectron spectrum was measured. The irradiation conditions of the electron beam for neutralization and the voltage application to the mesh are the same as in the first embodiment. In the obtained photoelectron spectrum, photoelectron peaks and Auger electrons from Si, C, O, and Cu were observed. The binding energy of Si-2p is about 104e
V and the charge-up was almost alleviated. Here, in order to separate the signal from the sample from the signal from the mask, +10 V was applied to the mask, and the photoelectron spectrum was measured. Almost no shift was observed in the Si peak, but the C and O peaks were separated into two peaks, and the Cu peak was 10 eV.
It shifted to the higher binding energy side (lower kinetic energy side). The composition ratio of Si and O was calculated from the area of Si-1p and O-1s (lower binding energy) from quartz.
≒ 1: 2 was obtained, and it was confirmed that the signal of the sample and the signal from the mask could be separated.

Example 4 A bulk blue plate glass (5 mm × 5 mm × 1 mm) was used as a sample. Prior to the measurement, first, a fine particle thin film made of Al was formed on the sample surface.

The composition of the dispersion liquid containing Al used in this example is as follows, and was uniformly dispersed using a ball mill. The half diameter of the obtained gold fine particles was 0.3 μm.

Composition of Dispersion Al Fine Particles 10 wt% Isopropyl Alcohol 20 Surfactant 0.5 (Glycerin Fatty Acid Ester) Distilled Water 69.5 Total 100 wt% The dispersion prepared in this manner is mounted on a droplet applying means. While observing the sample surface with an optical microscope, the droplet applying means was driven to drop the dispersion liquid onto the sample. This operation was performed continuously, and as shown in FIG.
A thin film made of 0 μm Al was formed.

The monochromatic X-ray (Al-kα) was irradiated on the surface of the blue plate glass on which the Al thin film was formed, and the photoelectron spectrum was measured while irradiating an electron beam for neutralization. The Al
Applying -25V to the thin film, O-1s and
C-1s was separated. Si-2p had a 103.3 eV peak, indicating that charge-up was almost alleviated. The situation is shown in FIGS. From the area of O-1s (higher binding energy) from Si-2p and quartz,
When the composition ratio of O and O was determined, Si: O ≒ 1: 2 was obtained.
It was confirmed that the signal of the sample and the signal from the mask could be separated.

(Embodiment 5) As shown in FIG.
Measurement was performed on a sample insulating film in which a 500 μm square SiO ₂ insulating film was patterned on a glass substrate. Prior to the measurement, first, a fine particle thin film made of Mo was formed on the sample surface. In this example, the same dispersion liquid as in Example 1 was used. The dispersion liquid was attached to the droplet applying means, and the dispersion liquid was dropped on the sample by driving the droplet applying means while observing the sample surface with an optical microscope. At this time, the dispersion was dropped so as to cover the exposed glass portion where the SiO ₂ film was not formed, and a conductive thin film was formed on this portion. Thus, FIG. 9 (b)
As shown in (1), a thin film made of Mo was formed.

The photoelectron spectrum of this sample was measured in the same manner as in Example 1. The obtained spectrum of Si-2p had a peak of about 103 eV, and was observed on the side of the binding energy slightly lower than the original binding energy according to the standard data. The peak shape showed a continuous change, no spectral distortion on the low energy side, and it was suggested that the charge-up was uniformly alleviated. Next, +1 is added to the Mo thin film.
By applying 0 eV, the C and O photoelectron peaks of the sample and the Mo thin film were separated. When the composition ratio of Si and O was determined from the area of O-1s (lower binding energy) from Si-2p and quartz, Si: O ≒
1: 2 was obtained, and it was confirmed that the signal of the sample and the signal from the Mo thin film could be separated.

[0084]

According to the present invention, a conductive thin film is formed in the vicinity of a charge-up portion to increase a passive charge-up mitigation margin. In addition, the conductive thin film is irradiated with ionizing radiation. By positively mitigating charge-up by photoelectron generation from the conductive thin film, the overall charge-up mitigation margin is greatly improved,
The signal between the sample and the conductive thin film is separated by applying a voltage to the conductive thin film.

Also, by appropriately adjusting the voltage applied to the conductive thin film so that the background intensity of the photoelectron peak of the element of interest does not increase, the signal from the sample and the signal from the conductive thin film can be separated. In addition, the charge-up can be eased without impairing the quantitative accuracy.

Further, in the present invention, a fine conductive thin film made of conductive fine particles can be formed at an arbitrary position on the sample surface in an arbitrary shape. By performing this process continuously, a fine line having a width of about 100 μm can be drawn in an arbitrary pattern. Therefore, for example, a conductive thin film can be formed in accordance with the shape of the sample, even for a sample having large irregularities or a sample having a limited number of measurement points.

[Brief description of the drawings]

FIG. 1 is a diagram showing a photoelectron spectroscopy device according to the present invention.

FIG. 2 is a diagram showing a state in which a positive voltage is applied to a conductive mask to separate O-1s between the sample and the conductive mask.

FIG. 3 is a view showing an apparatus for forming a conductive thin film according to the present invention.

FIG. 4 is a diagram illustrating a method for forming a conductive thin film described in Examples 1 and 4 of the present invention.

FIG. 5 is a diagram showing a method for forming a conductive thin film described in Examples 2 and 3 of the present invention.

FIG. 6 is a diagram showing a measurement result according to the present invention.

FIG. 7 is a diagram showing a measurement result according to the present invention.

FIG. 8 is a diagram showing a measurement result according to the present invention.

FIG. 9 is a diagram illustrating a method for forming a conductive thin film described in Embodiment 5 of the present invention.

FIG. 10 is a diagram showing an example of an X-ray photoelectron spectroscopy spectrum according to a conventional method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulator sample 2 Conductive thin film 3 DC power supply 4 X-ray source 4 'Irradiation X-ray 5 Neutralizing electron gun 5' Irradiation neutralizing electron beam 6 Photoelectrons emitted from a conductive thin film 7 Vacuum chamber 8 Energy analyzer 9 Vacuum Pump 10 Controller 11 Display 12 Power supply for applying voltage to conductive thin film 13 Stage 14 Sample 15 Droplet 16 Droplet applying unit 17 Optical microscope 18 Means for moving optical microscope and droplet applying unit 19 Control device 20 1 / 4λ plate 21 concave mirror 22 light receiving means 23 nozzle 24 light emitting means 25 beam splitter 26 optical path of optical microscope 27, 29, 35 conductive fine particle film 28, 30 sample 31 substrate 32 insulating thin film 33 O-1s photoelectrons from insulator Peak 34 O-1s photoelectric peak from the conductive thin film shifted by applying positive voltage

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2G001 AA01 AA03 AA07 AA09 AA10 BA08 BA09 CA03 EA09 GA01 GA09 HA09 HA13 KA01 KA13 NA03 NA07 NA13 NA17 NA21 PA07 RA08 RA20 SA10

Claims (9)

[Claims] In an X-ray photoelectron spectroscopy of an insulating sample, prior to measurement, a conductive thin film forming step of forming a conductive thin film in the vicinity of a measurement location of the sample, and irradiating the measurement location with an electron beam. And performing a measurement while applying a voltage to the conductive thin film. 2. A photoelectron from an atom constituting the insulator sample and a photoelectron from an atom constituting the conductive thin film are distinguished by adjusting a voltage applied to the conductive thin film in the measuring step. The X-ray photoelectron spectroscopy analysis method according to claim 1. 3. In the conductive thin film forming step, a droplet of a raw material solution of a conductive thin film containing at least a conductive substance is applied to a predetermined portion of a sample surface using a droplet applying means, and then dried. 2. The X-ray photoelectron spectroscopic analysis method according to claim 1, wherein the conductive thin film made of fine particles is formed in an arbitrary shape. 4. The X-ray photoelectron spectroscopy according to claim 3, wherein a dispersion in which at least conductive fine particles are dispersed in the solution is used as a raw material solution for the conductive thin film. 5. The X-ray photoelectron spectroscopy according to claim 4, wherein metal fine particles are used as said conductive fine particles. 6. The method according to claim 1, wherein the metal fine particles are Cu, Pt, Au, Mo,
The X-ray photoelectron spectroscopy according to claim 5, wherein the X-ray photoelectron spectroscopy is any one selected from W, Ta, Ag, Pd, Ni, Co, Cr and In. 7. A conductive thin film forming apparatus for forming a conductive thin film on the surface of a measurement sample for X-ray photoelectron spectroscopy analysis, wherein (1) a liquid for applying a droplet containing a conductive substance to the sample surface A droplet applying means, (2) an optical microscope for observing the application position of the droplet and the sample surface, and (3) a moving means for displacing the relative position between the sample surface and the droplet applying means, An apparatus for forming a conductive thin film, comprising at least observing an application position by the optical microscope and applying a droplet simultaneously. 8. The conductive thin film forming apparatus according to claim 7, wherein said droplet applying means is of an ink jet type. 9. The conductive thin film according to claim 7, formed using the conductive film forming apparatus.