JPH0462458A - Surface analyzing device for sample - Google Patents

Abstract

PURPOSE:To improve the reliability of position information on a photoelectron distribution by providing a hole electrode 8 where photoelectron flux can pass nearby an energy selection electrode. CONSTITUTION:The sample 2 is irradiated with synchrotron emitted light 1 and an emitted photoelectron 3 is converged by a converging and deflecting means 7 and then deflected vertically and horizontally to make a scan. In a figure 1, the hole electrode 8 is placed right behind the energy selection electrode 5 by insertion. In the beginning, the converging and deflecting means 7 is so adjusted that an enlarged image of the sample corresponding to the irradiation position of the sample 2 is positioned on the surface of the hole electrode 8. Consequently, when the enlarged image itself is deflected by the deflecting means 7, photoelectrons transmitted through the hole electrode 8 are detected by an electron multiplier detector 6.

Description

[Detailed Description of the Invention] [Summary] Regarding an apparatus for analyzing the surface condition over a wide range of a sample, the present invention provides an apparatus that can irradiate a sample with synchrotron radiation light and efficiently analyze the two-dimensional distribution state of emitted photoelectrons. We aim to provide an electron multiplication detector that irradiates a sample with synchrotron radiation light and focuses the emitted electron distribution through an electron optical system that focuses the photoelectrons and an energy selection electrode to form an image of the photoelectrons. An apparatus for analyzing the surface of a sample by measuring the energy distribution of photoelectrons using the electron multiplication detector, comprising: means for converging and electromagnetically deflecting the photoelectrons; It is equipped with a hole electrode through which the bundle passes, and is configured by determining positional information of the photoelectron distribution.

[Industrial application field]

The present invention relates to an apparatus for analyzing surface conditions over a wide range of samples.

It is well known to irradiate a sample with synchrotron radiation light, image the emitted photoelectrons on an electron multiplier detector, and analyze the surface state of the sample in terms of "points". In such technical fields, there has been an increasing demand for evaluating a wide range of samples in real time.

[Conventional technology]

Technological development of new materials that combine various elements is becoming more popular as a fundamental technology in the electronics industry. Efforts are also being made to modify materials using synchrotron radiation (SOR light) or ion or electron beams to create crystals and materials with new functions. In view of the demand for higher functionality and higher quality of semiconductor devices, means for evaluating the quality of the crystals that form the basis are becoming increasingly important. In particular, we use "in-situ observation" methods during crystal growth and crystal processing to observe changes in the material's crystal structure in real time, making it possible to evaluate at a glance what elements of the material's crystalline bond contribute to the essence of the process. If there is a method, it will become a valuable technology both from a practical perspective and from the physical property analysis perspective.

As a detailed means for evaluating the modification of these new materials and conventional materials, there is a need for an evaluation method that can easily be used to analyze not only valence electrons but also the core electrons of crystals. As one of them,
It is particularly important to know the inner-shell electronic state by performing energy analysis on photoelectrons emitted by high-energy light irradiation. This has conventionally been analyzed using an apparatus having the configuration shown in FIG. In FIG. 9, ■ indicates synchrotron radiation, 2 indicates a sample, 3 indicates a photoelectron flux emitted from the sample, 4 indicates an electron optical system, 5 indicates an energy selection electrode, and 6 indicates an electron multiplication detector. In order to analyze the surface condition of the sample 2, the sample 2 is obliquely irradiated with synchrotron radiation 1, which is a general term for radiated electromagnetic waves in the range of X-rays to ultraviolet rays. The surface condition of the sample 2 is analyzed by analyzing the photoelectrons emitted from the sample at that time.

This is because by analyzing the energy of photoelectrons emitted by irradiation with high-energy light such as synchrotron radiation, it is possible to determine the state of the ``inner shell electrons'' of the sample. The term "inner shell electron" as used herein refers to an electron in the so-called inner shell of an atom, such as the Ni shell or L shell. As a conventional technique, the photoelectron flux 3 emitted from the sample is converged by an electron optical system 4, and then the energy in the photoelectron flux 3 is controlled by changing the degree of negative voltage applied to the energy selection electrode 5. The electron multiplier detector 6 gradually disappears from the weaker ones (those that are repelled by the electrode 5 and cannot pass through even if the negative voltage of the energy selection electrode 5 is low). Then, by differentially processing the data captured by the electron multiplier detector 6 arranged two-dimensionally in a matrix with respect to the energy selection electrode, it is possible to analyze the surface condition of the sample 2 in particular.

[Invention or problem to be solved]

In the device shown in Figure 9, the problems when using a two-dimensional array detector are that the sensitivity is not sufficient, so clear analysis cannot be done, the resolution is determined by the number of arrays, and it is digital. There are some drawbacks, such as the processing circuit becoming complicated.

Another essential drawback is that since the image is formed over a certain area of the selection electrode, there may be differences in the energy selection function due to electric field distortion between the center and the periphery, resulting in unreliability.

For these reasons, it has had many problems as a practical device.

An object of the present invention is to improve the above-mentioned drawbacks and to provide an apparatus that can irradiate synchrotron radiation light and efficiently analyze the two-dimensional distribution state of emitted photoelectrons.

[Means to solve the problem]

FIG. 1 is a diagram showing the basic configuration of the present invention. In FIG. 1, 1 is a synchrotron radiation beam, 2 is a sample, 3 is a photoelectron flux, 5 is an energy selection electrode, 6 is an electron multiplication detector,
Reference numeral 7 indicates a photoelectron convergence/deflection means, and 8 indicates a hole electrode.

It is equipped with an electron optical system that irradiates the sample 2 with synchrotron radiation light 1 and converges the emitted photoelectrons 3, and an electron multiplication detector 6 that forms an image of the photoelectrons via the energy selection electrode 5. The present invention has the following configuration in an apparatus for measuring the energy distribution of photoelectrons using the double detector 6 and analyzing the surface of a sample. That is, it is equipped with means 7 for converging and electromagnetically deflecting the photoelectrons 3, and a hole electrode 8 installed near the energy selection electrode 5 through which the photoelectron flux can pass, and to obtain positional information on the photoelectron distribution. Configure.

[Effect]

A sample 2 is irradiated with synchrotron radiation 1, and the emitted photoelectrons 3 are converged by a convergence/deflection means 7 and then deflected and scanned vertically and horizontally. Further, in FIG. 1, the hole electrode 8 is inserted immediately after the energy selection electrode 5.

Initially, the convergence/deflection means 7 is adjusted so that the enlarged image of the sample 2 corresponding to the irradiation position of the sample 2 is positioned on the surface of the hole electrode 8 . Therefore, when the magnified image itself is deflected by the deflecting means 7, the electron multiplier detector 6 can detect what has passed through the hole electrode 8. When the synchrotron radiation light 1 is irradiated onto the sample 2 to be subjected to surface analysis, the magnified image of the photoelectrons is a serial signal obtained from the electron multiplier detector 6 via the hole electrode 8. Since the signal corresponds to the surface state of the photoelectron, it is possible to obtain a two-dimensional image by sequentially arranging the intensities on a plane, that is, to obtain positional information on the photoelectron distribution.

〔Example〕

As an embodiment of the present invention, an electron multiplication detector will first be described. The electron multiplier detector is composed of, for example, a scintillator and a photomultiplier tube. A scintillator is a photodiode that converts photoelectrons into voltage pulses, and a photomultiplier tube is a secondary electron multiplier that increases the photocurrent generated by photoelectrons. The photoelectronic signal is multiplied and measured by both.

Next, in the configuration of Fig. 1, the hole electrode has a plate-like shape with a small hole in the center, and the electron multiplier detects only the one through which the photoelectron flux deflected by the deflection system 7 passes. In another embodiment, a hole electrode with a flat hole formed in the horizontal direction is used, and a device is provided for moving the entire hole electrode in the vertical direction of the figure. Then, without using a deflection system, when a simply converged photoelectron flux passes through a horizontally opened hole as in the conventional technique, the position of the hole electrode is moved downward to correspond to the next focused photoelectron flux. move it.

Image resolution can be changed by changing the hole diameter of the hole electrode. Furthermore, the same operation can be achieved even if the hole electrode is provided in front of the energy selection electrode instead of immediately after it.

Next, in the configuration shown in FIG. 1, a means for correctly forming a surface image of a sample on the hole-shaped extreme surface will be explained. In FIG. 2, reference numeral 10 denotes an electron beam, and 6-1 denotes an electron multiplication detector, which may have the same configuration as in FIG. 1 or may be replaced with the hole electrode 8. Instead of irradiating the sample 2 with synchrotron radiation l, an electron beam 10 is applied to the same irradiation position. A secondary electron image of the secondary electrons emitted from the sample 2 is formed and observed by the electron multiplication detector 6-1 via a convergence/deflection system. For this reason, sample 2 is used as a focusing/deflecting system.
It is easy to place the electron multiplier detector at the exact position of the light source.

Next, when analyzing the surface state of a sample or obtaining a surface image using the configuration shown in FIG. 1, circuits and the like that are additionally used are shown in FIG. In FIG. 3, 11 is a power source for the convergence/deflection means, 12 is a power source for the energy selection electrode, 13 is a data acquisition circuit, 14 is an image scanning control section, 15 is a differentiation circuit, 16 is a data display/image display circuit, 17 indicates the image display section.

First, a predetermined voltage from the power sources 11 and 12 is applied to a predetermined location, and an electron beam is irradiated onto the sample and focused.

Irradiating synchrotron radiation light 1 to a predetermined location of sample 2,
When the negative voltage of the energy selection electrode 5 is sequentially changed from image to high by the power source 12, the amount of electrons passing through the upper electrode 8 is measured, as shown in FIG. 4. In this case, the relationship between the negative voltage and the amount of passing electrons is not a straight line, but varies greatly at different positions depending on the material of the sample. As for the state of change, a signal of the amount of electrons is taken in by the data acquisition circuit 13, and then differentiated by the differentiation circuit 15, and the state of the sample is determined based on the obtained characteristics. The states are the main peaks of core electrons inside and on the surface of the sample crystal, Is of silicon, 2s,
2p, IS of aluminum Al, 2p, 3s, oxygen 0
This can be determined by observing IS, etc.

Further, regarding the analysis results shown in FIG. 4, if the amount of electrons in the vertical axis direction is divided into colors and displayed on the image display section 17, the surface state of the substance and the distribution of the excited state of specific core electrons can be clearly understood. For example, as shown in FIG. 5, when the voltage of the energy selection electrode is kept constant and the two-dimensional distribution on the sample surface is examined, it is found that Al1. C
It can be observed at various locations such as 1○. For example, the locations indicated by Si have the same energy, and the equal energy distribution state is shown in a map shape. Therefore, the presence of different elements is detected when the irradiation energy is different.

FIG. 6 shows, as a second application example of the present invention, that when the material of the sample surface is changed by irradiation light, the change can be detected. If we take each core electron on the horizontal axis and examine the distribution of the amount of electrons at the beginning of irradiation, we can change the state of the solid line as shown by the broken line. Since the state can be observed in real time, it is possible to accurately determine the processing end time.

FIG. 7 is a diagram showing another embodiment of the present invention in which sector electrodes are used instead of energy selection electrodes. In FIG. 7, 18 indicates a sector electrode which is made of two parallel plates or curved with similar radii, ie parallel to each other.

Furthermore, the differential circuit shown in FIG. 3 is not used. Then, as in FIG. 3, photoelectrons from the sample irradiated with X-rays are taken into the electron optical system and focused by predetermined voltages Vf and Va applied to the extraction electrode and anode. Next, it is deflected by a voltage from a scanning deflection power source. When the electron distribution amount is calculated for the electrons that pass through the sector electrode 18 and the slit 19 at the same time after passing through the upper electrode 8, the amount of electrons is distributed depending on the characteristics of each energy as shown in FIG. The horizontal axis in FIG. 8 represents the voltage applied to the sector electrode 18. In this case, you can see where the "peak" occurs without using a differentiator. That is, unlike the case shown in FIG. 1, compared to passing only high energy through an energy selection electrode, it is possible to easily and effectively extract two electrons per element having a specific energy.

〔Effect of the invention〕

In this way, according to the present invention, it is possible to easily obtain a two-dimensional distribution image of a sample irradiated with synchrotron radiation light so that the crystallinity, stable state of the surface, etc. can be evaluated not only in minute parts but also in macroscopic areas. There is. This is because an upper electrode is used, and the resolution of the image can be easily changed by changing the size of the hole in the upper electrode. Furthermore, when modifying the crystal structure of a sample using synchrotron radiation, changes in material properties can be obtained in real time, which has the effect of accurately determining the processing end time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of the present invention, FIG. 2 is an explanatory diagram of a means for forming an image for FIG. 1, FIG. 3 is a diagram showing the configuration of an embodiment of the present invention, and FIGS. The figure is a diagram for explaining the operation of Figure 3, Figure 6 is an operation diagram of sample modification, Figure 7 is a diagram showing the configuration of another embodiment of the present invention, and Figure 8 is the operation of Figure 7. Explanatory diagram: FIG. 9 is a diagram showing a conventional sample surface analysis device. 1- Synchrotron radiation 2-Sample 3 Photoelectron 5-Energy selection electrode 6 Electron multiplication detector 7/Convergence/deflection means 8-Upper electrode Patent applicant Fujitsu Ltd. Representative Patent attorney Eisuke Suzuki tII + Kei 11+- Utan

Claims (1)

[Claims] 1. Synchrotron radiation (1) is irradiated onto a sample (2), and photoelectrons are generated via an electron optical system that focuses emitted photoelectrons (3) and an energy selection electrode (5). The electron multiplier detector (6) is equipped with an electron multiplier detector (6) that forms an image of the electron multiplier detector (6).
) to measure the energy distribution of photoelectrons and analyze the surface of a sample, the device includes means (7) for converging and electromagnetically deflecting the photoelectrons (3).
); and a hole electrode (8) installed near the energy selection electrode (5) through which a photoelectron flux can pass, and obtaining positional information of photoelectron distribution. 2. It is characterized by comprising means for moving the hole electrode according to claim 1 in the X and Y directions, and positional information of the photoelectron distribution is obtained without using means for electromagnetically deflecting the photoelectron flux. Sample surface analysis device. 3. The sample according to claim 1 is first irradiated with an electron beam from a direction different from the synchrotron radiation irradiation direction, and the emitted secondary electron image is observed by an electron optical system, and the image on the sample is A sample surface analysis device characterized by determining an irradiation position in advance. 4. In an apparatus that irradiates a sample with synchrotron radiation light and images the emitted photoelectrons on an electron multiplier detector using an electron optical system to obtain a distribution on the sample surface, the photoelectrons are focused and electromagnetically 1. An apparatus for analyzing the surface of a sample, comprising means for deflecting, a hole electrode for imaging, and a sector-type energy analyzer.