JP2000097889A - Sample analyzing method and sample analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct elementary analysis in a sample electrode surface and in a site deeper than the surface without carrying out etching, in analysis using total reflection photoelectron spectroscopy. SOLUTION: An Alkα ray separated into its spectral components by an X-ray monochromater analyzing crystal 6 gets incident into a sample with a total reflection angle. A photoelectron emitted from the sample 7 is detected by an electron spectroscope 11, and a sample analyzing means 21 provides elementary information of a sample 7 electrode surface. A fluorescent X-ray emitted from the sample 7 is detected by a detector 16. An escape depth of the fluorescent X-ray is deeper than that of the photoelectron, the detected fluorescent X-ray has elementary information in a position of about several μm of depth from a sample surface, and the elementary information in a position deeper than that of the sample elctrode surface is provided based on an analyzed result of the second sample analyzing means 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample analysis method and a sample analysis apparatus for irradiating a sample with X-rays, detecting a signal emitted from the sample by the X-ray irradiation, and analyzing the sample.

[0002]

2. Description of the Related Art A photoelectron spectroscopy device is known as a surface analysis device. This photoelectron spectroscopy device irradiates an X-ray (characteristic X-ray such as MgKα ray or AlKα ray) onto a sample surface, and is emitted from the sample by the irradiation. This device measures the kinetic energy of photoelectrons and performs qualitative and quantitative analysis of surface elements from the measurement results, as well as analysis of the state of chemical bonding.

The kinetic energy of photoelectrons detected by a photoelectron spectrometer is as low as about 0 to 3 keV, and the escape depth of these electrons is at most several nm. For this reason, if a photoelectron spectroscopy device is used, information of several nm can be obtained from the sample surface.

[0004] Recently, researchers in the field of semiconductor-related materials have requested to know the distribution of elements several nanometers deeper than the surface of a sample in order to evaluate the characteristics of a material having a layered structure. There are many. In order to meet this demand, a recent photoelectron spectroscopy apparatus is provided with an ion gun, and after one analysis, the sample is subjected to ion etching and element analysis at a deeper place is performed.

Recently, in order to improve the detection sensitivity of a photoelectron spectrometer, X-rays are incident on a sample slightly below the surface of the sample, that is, the sample is irradiated with X-rays under the condition of total reflection, and the background of the detection spectrum is changed. Decrease P /
Total reflection photoelectron spectroscopy for increasing the B ratio is often used. The escape depth of electrons when using this total internal reflection photoelectron spectroscopy is several 0.1 nm, and when using total internal reflection photoelectron spectroscopy, information of only 0.1 nm from the sample surface can be obtained from the sample surface only. be able to.

Now, after analyzing the surface of the sample electrode using total reflection photoelectron spectroscopy, ion etching is performed on the sample surface, and the analysis of the sample surface that has appeared by ion etching is similarly performed. Reflection photoelectron spectroscopy seems to provide a detection spectrum with a small background component in elemental analysis at the surface of the sample and deeper than it, but in practice such analysis is very difficult. is there. The reason will be described below.

[0006] In order to make X-rays incident on a very small portion of the sample surface that has appeared by ion etching, the sample surface must be ion-etched over a wide range.
Then, it is not only necessary to perform the etching, but if the sample surface is roughened by the ion etching, the detection sensitivity is lowered. Therefore, the sample surface must be uniformly etched at the atomic level. However, such ion etching is very difficult.

Although the above is the reason described above, even if the sample is etched by a dedicated etching apparatus in a place different from the sample chamber of the photoelectron spectrometer in order to uniformly etch the sample surface at an atomic level, the analysis position is reproduced. I can not get the nature,
Analysis in the depth direction using total reflection photoelectron spectroscopy cannot be performed well.

Further, when performing sample etching, elemental analysis must be interrupted, and the total time of analysis using sample etching becomes longer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to perform analysis using total reflection photoelectron spectroscopy without performing etching, and to analyze a sample electrode surface and elements deeper than the sample electrode surface. An object of the present invention is to provide a sample analysis method and a sample analyzer capable of performing analysis.

[0010]

Means for Solving the Problems A sample analysis method of the present invention that achieves this object irradiates a sample with X-rays under total reflection conditions, detects photoelectrons emitted from the sample by the X-ray irradiation, Based on the detected photoelectrons, element information on the sample pole surface is obtained, and the fluorescence X emitted from the sample by the X-ray irradiation is obtained.
The method is characterized in that a line is detected and element information at a position deeper than the sample pole surface is obtained based on the detected fluorescent X-ray.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing an example of the sample analyzer of the present invention. First, the configuration of the apparatus shown in FIG. 1 will be described.

In FIG. 1, reference numeral 1 denotes a chamber. 2
Is an X-ray source arranged in the chamber 1;
Includes a filament 3, a focus adjustment electrode 4, and a target 5. The target 5 is made of Al, and in a photoelectron spectroscopy device that uses monochromatic excited X-rays, Al is generally used for the target.

Reference numeral 6 denotes an X-ray monochromator spectral crystal curved in a double focusing type.
Is disposed in the chamber so as to face the X-ray source 2. The X-ray monochromator spectral crystal 6 is formed of a crystal [α-SiO 2], and the semiconductor wafer 7 to be measured is a X-ray monochromator spectral crystal 6.
Irradiation of Alkα rays that have been spectroscopically performed. The sample 7 is placed on a sample stage 8, and the sample stage 8
An XY stage 9 and a tilt stage 10 are provided.

An electron spectroscope 11 for detecting photoelectrons emitted from the sample is disposed above the sample 7, and the electron spectroscope 11 has an input lens (deceleration lens) 12 composed of a plurality of electrostatic lenses. And hemispherical analyzer 1
3 and a detector 14. The input lens 12 is arranged so that its optical axis is substantially perpendicular to the sample surface.

An energy dispersive X-ray detector (EDS) 15 for detecting fluorescent X-rays emitted from the sample is arranged near the sample 7. In the photoelectron spectroscopy device, the inside of the chamber 1 is baked out at about 150 ° C. for 8 to 10 hours to evacuate the chamber 1 to an ultra-high vacuum. In order to prevent the N diode element from being damaged by the bakeout, a thermal measure shown in FIG. 2 is taken. FIG.
Shows the periphery of the detector 16;
A heat insulating material 18 is provided inside the cylindrical cover 17 in S15, and the surface of the heat conducting rod 19 supporting the detector 16 and connected to the liquid nitrogen tank has a mirror surface for improving heat radiation. Finished.

Reference numeral 20 denotes an exhaust device. Reference numeral 21 denotes first sample analysis means connected to the detector 14 of the electron spectrometer 11, and reference numeral 22 denotes a detector 16 of the EDS 15.
The second sample analysis means is connected to the second sample analysis means.

In such a configuration, the X-rays generated by the X-ray source 2 are dispersed by the X-ray monochromator spectral crystal 6, and
The sample 7 is irradiated with Alk α-rays separated by the X-ray monochromator crystal 6. At this time, the tilt stage 10 is set so that the Alkα ray is incident on the sample at a total reflection angle (2 to 3 degrees).
Is adjusted, the Alkα ray enters the sample 7 at a total reflection angle. When X-rays enter the sample at a total reflection angle in this way, the incident X-rays are totally reflected by surface atoms without entering the sample, and the background of the spectrum due to the interaction between the internal atoms and the X-rays is greatly reduced. I do.

Now, when X-rays irradiate the sample 7, the sample 7
Photoelectrons are emitted from the electron spectrometer 1
1 is detected. Then, the detected signal is sent to the first sample analyzing means 21. The sample analyzing means 21 performs a qualitative analysis or a quantitative analysis of the surface element and an analysis of the chemical bonding state based on the sent signal. . As a result, it is possible to obtain element information on the very surface of the sample 7.

When X-rays irradiate the sample 7, fluorescent X-rays are emitted from the sample 7 in addition to photoelectrons, and the fluorescent X-rays are detected by the detector 16 of the EDS 15. Then, the detected signal is sent to the second sample analysis means 22, and the sample analysis means 22 performs qualitative analysis or quantitative analysis of the sample element based on the sent signal. The escape depth of this fluorescent X-ray is deeper than the escape depth of photoelectrons, and the detected fluorescent X-ray has elemental information at a position of about several μm from the sample surface. For this reason, from the analysis result of the second sample analysis means 22, it is possible to obtain element information at a position deeper than the sample pole surface.

As described above, in the apparatus shown in FIG. 1, the element information on the sample electrode surface can be obtained very accurately by the analysis by the total reflection photoelectron spectroscopy, and the sample electrode surface can be obtained without etching the sample. It is possible to simultaneously obtain elemental information at a deep place.

In the apparatus shown in FIG.
Although the analysis of the points and the analysis in the line direction by moving the XY stage 9 are possible, when the analysis in the line direction is performed, the XY stage 9 is moved in a direction perpendicular to the X-ray incident axis. As described above, the reason why the XY stage 9 is moved is that when X-rays are incident on the sample surface, even if the X-rays are minute, a tail is drawn on the sample surface in the X-ray reflection direction. It is because it becomes bad.

Instead of moving the XY stage 9 to perform the line analysis, the line analysis may be performed by changing the irradiation position of the X-ray on the sample. This can be easily performed by scanning the electron beam on the target 5 in the X-ray source 2. Also at this time, the electron beam is scanned on the target so that the irradiation position of the X-ray on the sample moves in a direction orthogonal to the X-ray incident axis.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a sample analyzer of the present invention.

FIG. 2 is a diagram shown for explaining an EDS 15 in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... X-ray source, 3 ... Filament, 4 ... Focus adjustment electrode, 5 ... Target, 6 ... X-ray monochromator spectral crystal, 7 ... Sample to be measured, 8 ... Sample stage,
9 XY stage, 10 tilt stage, 11 electron spectrometer, 12 input lens, 13 hemispherical analyzer, 14 detector, 15 EDS, 16 detector
7 ... Cylindrical cover, 18 ... Insulation material, 19 ... Heat conductive rod, 20
... Exhaust device, 21 ... First sample analysis means, 22 ... Second sample analysis means

Claims (4)

[Claims] 1. A sample is irradiated with X-rays under total reflection conditions, and photoelectrons emitted from the sample by the X-ray irradiation are detected.
At the same time as obtaining elemental information on the sample pole surface based on the detected photoelectrons, detecting the fluorescent X-rays emitted from the sample by the X-ray irradiation, and detecting a portion deeper than the sample pole surface based on the detected fluorescent X-rays A sample analysis method characterized by obtaining element information of a sample. 2. An X-ray source and an X-ray incident angle adjusting device provided for irradiating the sample with X-rays generated from the X-ray source under the condition of total internal reflection, for adjusting an incident angle of the X-ray to the sample. Means, first detection means for detecting photoelectrons emitted from the sample by the X-ray irradiation, first sample analysis means for performing sample analysis based on the output of the first detection means, A second detecting means for detecting the fluorescent X-rays emitted from the sample by the irradiation of the radiation; and a second sample analyzing means for performing the sample analysis based on the output of the second detecting means. Sample analyzer. 3. The sample analyzer according to claim 2, wherein said X-ray incident angle adjusting means is a sample tilt stage, and adjusts an incident angle of X-rays on the sample by tilting the sample. 4. The photoelectron spectroscopy apparatus according to claim 2, further comprising an X-ray monochromator for monochromaticizing X-rays generated from the X-ray source.