JPH0797092B2 - X-ray photoelectron analyzer - Google Patents

Description

The present invention relates to a so-called mapping device for measuring the composition distribution or state distribution of a sample surface by X-ray photoelectron spectroscopy.

(Prior Art) It is necessary to scan the sample surface two-dimensionally in order to examine the composition distribution, not the average of the composition in a certain area of the sample surface, and it is necessary to scan the sample surface two-dimensionally. By scanning the surface of the sample with an electron beam, secondary electrons emitted from the sample, backscattered electrons, absorption current, characteristic X
A method of detecting a line or the like is used.

X-ray photoelectron spectroscopy is an extremely shallow layer (10) on the sample surface.
Since it is suitable for the analysis of and the element composition and the bonding state of the element can be investigated, it is extremely excellent as a surface analysis method of the sample, but since X-rays are used to excite the sample,
The excitation range cannot be narrowed down like an electron beam, and sufficient position resolution cannot be obtained by the sample plane scanning method using the excitation line.

Therefore, in the mapping of the sample surface by the X-ray photoelectron analysis method, the measurement area of the sample surface is irradiated with excited X-rays, and the X-ray photoelectrons emitted from the sample surface are imaged by an electron lens to form an image of the sample surface by the photoelectrons. A method of forming the image plane and scanning the image plane with an electron optical means to perform energy analysis of X-ray photoelectrons is adopted. FIG. 2 shows an example of such a conventional device. X is an X-ray source, S is a sample, and e is an electron emitted from the sample. L is an electron lens system that forms an image of the sample surface by the electrons emitted from the sample on the entrance slit Is installation surface of the energy analyzer E. Sample S and electron lens L
X, y deflection electrodes Px, Py are arranged between the deflection electrodes, and when a voltage is applied to these deflection electrodes, an electron image of the sample surface moves on the entrance slit surface of the energy analyzer E, and this movement causes an electron image. The surface is scanned.

(Problems to be Solved by the Invention) There are the following problems when the electron image on the sample surface is scanned by changing the energy selected by the energy analyzer in the above apparatus. In FIG. 2, when the voltages applied to the deflection electrodes Px and Py are the same, the deflection angle of the electrons passing between the deflection electrodes becomes larger as the energy becomes smaller. Therefore, the scanning range on the electron image plane becomes smaller or larger depending on the magnitude of the selected energy, and when an image of the sample surface is visualized by electrons of various energies, the magnification of the image varies depending on the energy. For this reason, when the images of the sample surface due to electrons of various energies are compared and examined, it is not possible to simply compare and it is necessary to correct the image magnification, and such magnification correction is performed on the two-dimensional image data. That's a lot of trouble.

For this reason, the present invention is intended to enable direct comparison of data of electron images of various energies without complicated calculation of magnification correction.

(Means for Solving the Problem) The amplitude of the scanning signal applied to the deflection electrode is changed in association with the setting of the selection energy in the energy analyzer.

(Function) The deflection angle caused by the electrons passing between the deflection electrodes is related to the time required for the electrons to pass between the deflection electrodes, and the time required for the passage is related to the energy of the electrons.
The deflection angle is proportional to the voltage between electrodes and inversely proportional to the energy of electrons. Therefore, in order to make the deflection angle constant irrespective of the selection energy, the voltage V applied between the electrodes may be set to be proportional to the energy E of the selected electron. If the shake angle is the same, the image magnification is also the same.

(Embodiment) FIG. 1 shows an embodiment of the present invention. In the figure, X is an X-ray source for excitation, S is a sample, L is an electron lens system, and E is an energy analyzer.

The electron lens system L converges the electrons emitted from the sample surface onto the arrangement surface of the entrance slit Is of the energy analyzer E to form an electron image of the sample surface. This image is a superposition of images of electrons of various energies. An x-direction deflection electrode Px and a y-direction deflection electrode Py are arranged between the sample S and the electron lens system L. The energy analyzer is a double spherical energy analyzer, and among the electrons incident from the entrance slit Is, electrons of specific energy determined by the voltage applied between the double spherical electrodes are converged on the exit slit Io,
It passes through Io and is detected by the electron detector D. U is a voltage generation circuit that outputs a voltage applied to the energy analyzer E, Vx is an x-direction deflection voltage generation circuit that is applied to the x-direction deflection electrode Px, and Vy is a y-direction deflection voltage generation circuit. These voltage generation circuits are circuits that convert a digital signal output from the control device C into an analog voltage signal. The output of the electronic detector D is AD converted and taken into the memory M. B is a CRT for displaying the measurement result as an image, R is an xy recorder, and K is a keyboard for inputting various instructions and data to the control device C.

When the energy of the X-ray photoelectrons to be selected is designated by the keyboard K, the control device C outputs a digital signal corresponding to the energy value to the voltage generating circuit U and applies a predetermined voltage to the energy analyzer E. When the energy scanning instruction is input, the control device C sends a time-varying digital signal to the voltage generating circuit, and normal energy scanning is performed. When the scanning operation is designated and the mapping operation is instructed to the control device C, the control device C determines the basic values of the sawtooth waves of the x deflection signal and the y deflection signal according to the scanning range, and applies them to the energy analyzer E. The basic value is multiplied by a coefficient proportional to the voltage, that is, the selected energy value, and the x-direction and y-direction digital deflection signals are output to the x-direction deflection voltage generation circuit Vx and the y-direction deflection voltage generation circuit Vy to display the sample surface. Scan.

Although the deflection electrodes are used as the X-ray photoelectron deflection means in the above-described embodiments, a deflection coil may be used. In this case, since the deflection angle is inversely proportional to the square root of energy, the current flowing through the deflection coil may be proportional to the selected square root of energy.

(Effect of the Invention) According to the present invention, when the energy of X-ray photoelectrons is arbitrarily set and mapping is performed, the measured data is displayed at the same magnification regardless of the energy.
The X-ray photoelectron images of various energies can be directly compared with each other, and the examination of the analysis result becomes very easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of a conventional example. X ... X-ray source, S ... sample, Px, Py ... x direction and y
Direction-deflecting electrode, L ... Electron lens, E ... Energy analyzer, Is ... Incident slit, Io ... Exit slit, D ...
... Electron detector, U ... Voltage generation circuit for generating voltage applied to energy analyzer E, Vx ... x direction deflection voltage generation circuit, Vy ... y direction deflection voltage generation circuit, C ... Control device, M ...... Memory, B ... CRT, K ... Keyboard.

Claims (1)

[Claims] 1. An energy analyzer for energy analysis of X-ray photoelectrons emitted from a sample surface, and an electron emitted from the sample is converged on an entrance slit arrangement surface of the energy analyzer to form an X-ray photoelectron image of the sample surface. In an X-ray photoelectron analyzer having an electron lens to be formed, a deflection means for polarizing electrons emitted from a sample surface in x and y directions is provided, and the amplitude of a deflection signal applied to this deflection means is applied to the energy analyzer. Set the amplitude of the deflection signal to the selected energy of the energy analyzer so that the above amplitude is increased when the energy selected according to the set selected energy value is large and the above amplitude is decreased when the energy is small. An X-ray photoelectron analysis apparatus characterized in that it is changed in conjunction with.