JPH0583880B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses X-rays for sample excitation in an X-ray photoelectron spectrometer that analyzes the physical properties of a sample that generates photoelectrons by analyzing the energy of photoelectrons generated when excited by X-rays. It concerns the composition of the source.

X-ray photoelectron spectroscopy is useful for observing chemical bond states within a range of about 20 Å from the surface of a sample or for analyzing elemental composition, but for this purpose, the sample must be irradiated with monochromatic X-rays with high energy resolution. It won't happen. Generally, Mg-Ka rays (1253, 6eV) and Al-Ka rays (1486, 6eV) are often used as the X-rays, and the 1010 plane of quartz (lattice constant 2d = 8.51Å) is used as the latter spectroscopic crystal. It is used. In other words, by making the X-rays irradiated onto the sample monochromatic using such a monochromator, the energy resolution can be improved, and the background due to bremsstrahlung and satellite light such as Ka _3,4 can be removed to improve S - It is possible to measure the improvement of the N ratio. Also, magnesium target
By comparing the photoelectron spectra obtained using a ray tube and an X-ray tube with an aluminum target, it is also possible to compare the photoelectron spectra and the Auger electron spectra. However, it occurs at the same time as the target is exchanged.
Conventionally, these exchanges required extremely complicated operations because the line spectroscopic system also had to be changed. Therefore, in an X-ray photoelectron spectrometer, the present invention makes it possible to monochromate X-rays generated from multiple types of anticathodes and irradiate the sample of the X-ray photoelectron spectrometer by monochromating the X-rays generated from a plurality of types of anticathodes using the corresponding spectroscopic systems, and the switching operation is extremely easy. An object of the present invention is to provide an X-ray source for sample excitation that can be performed quickly.

That is, the present invention makes it possible to install any anticathode by replacing a plurality of types of anticathodes at the entrance part of the excitation electron beam that generates X-rays, and to emit the characteristic X-rays generated by each of the anticathodes. A plurality of types of curved spectroscopic crystals are provided to make each monochromatic light incident on the sample. These multiple types of spectroscopic crystals are
Each can be fixed in place or moved and replaced, but in either case the above replacement can be easily and quickly carried out from outside the vacuum vessel. Therefore, the X-ray photoelectron spectrometer equipped with the X-ray source of the present invention can very easily and quickly irradiate any sample with monochromated X-rays with high energy resolution, and also emit background or satellite light due to bremsstrahlung radiation. remove the
Alternatively, there are effects such as being able to discriminate Auger electron spectra.

FIG. 1 is a sectional view of an embodiment of the present invention, in which a thermionic emitting filament 2 and a Wehnelt electrode 3 surrounding it are provided inside a vacuum-tight casing 1 connected to a high-vacuum pump (not shown). is guided to the outside by an insulator 4 fixed to the housing, and magnetic poles 5 generate DC magnetic flux perpendicular to the plane of the paper on both sides of the electron beam e emitted from the filament.
is provided. Therefore, the electron beam e travels in an arc shape as shown in the figure, but a short cylindrical rotating anode cathode 6 is arranged so that the electron beam is incident thereon, and its shaft 7 is supported by a bearing 8 to support the housing 1. It is pulled out outside. The main body of the anticathode 6 is made of copper, for example, and aluminum is deposited, sputtered, or welded on the upper half to form a copper anticathode 6a and an aluminum anticathode 6b. In addition, a telescopic bellows 9 is attached to the shaft pulled out to the outside of the housing.
and connect both ends to the housing 1 and the support plate 11 of the electric motor 10, fit the plurality of screws 12 installed in the housing 1 into the support plate, and tighten the nuts 13 on the housing side. are screwed together, and a vacuum seal 14 is provided in the support plate 11 at the portion through which the shaft 7 passes. Therefore, in the state shown in the figure, the electron beam e is incident on the anticathode 6a, but when a plurality of nuts 13 are simultaneously rotated by an appropriate interlocking mechanism, the anticathode 6 moves to the position shown by the chain line.
The electron beam e becomes incident on the anticathode 6b.

Further, two curved spectroscopic crystals 15a and 15b are provided so that the X-rays generated when the electron beam e is incident on the anticathode 6a or 6b are incident thereon. These are made of, for example, lithium fluoride and TAP (thallium diphthalate) and are formed so that the X-ray incident surface has a concave spherical shape. Further, the spectroscopic crystal 15a is attached to the tip of a column 17 that is slidably fitted into the housing 1 by a vacuum seal 16, and the spectroscopic crystal 15a
5b is a support plate 18 attached to the edge of the spectroscopic crystal 15a.
is attached to the tip of the Further, since a drive mechanism 19 for the support column 17 is provided outside the housing 1, the support column 17 is driven to move the above-mentioned spectroscopic crystals 15a and 15.
b can be moved to the position of the solid line or the dashed line. In other words, in the state shown by the solid line, the spectroscopic crystal 1
The center of 5a is placed at point p, and the characteristic X-rays generated from anticathode 6a are focused at one point s, as shown by the thin line in the figure, and in this case, the spectroscopic crystal 15b is placed outside the path of the X-rays. be done. Further, when the anticathode and the spectroscopic crystal are moved to the positions indicated by the dashed lines, the characteristic X-rays generated from the anticathode 6b are focused on the same point s by the spectroscopic crystal 15b centered on the point q.

The sample 20 of the X-ray photoelectron spectrometer is arranged at the point s as described above. In other words, a sample exchange port 21 is provided on the side of the sample 20, and a focusing lens 22 for the electron beam excited by the X-rays and emitted from the sample is provided opposite to the sample, and the focused electron beam is An electron beam energy analyzer 23 is arranged so that the electron beam is incident. Therefore, anticathode 6
The characteristic X-rays of copper generated from point a are focused by a lithium fluoride spectroscopic crystal 15a and focused on a point s on the sample 20. Further, when the anticathode and spectroscopic crystal are moved as shown by the chain lines, the characteristic X-rays of magnesium generated from the anticathode 6b are focused by the spectroscopic crystal 15b formed by the TAP and focused on the point s. In this way, the device of the present invention changes the wavelength of the X-rays that excite the sample to generate photoelectrons, and focuses the X-rays on the sample using a curved spectroscopic crystal made of an appropriate material according to the wavelength. Since it can be tied together, this switching operation can be performed easily and quickly. Note that the above example is a case in which a spectroscopic crystal is formed using a crystal whose X-ray diffraction angle is relatively close, and as mentioned above, in addition to the Kα rays of Cu and Mg, for example, the Lα ray of Rh and the Kα of Ti line, Lα line of Ag and Kα line of Ti, Kα of Al
line and Kα of Cu, Lα line of Rh or Lα line of Ag and Ti
This applies to Kα rays, etc. Further, in the above embodiment, the anticathode and the spectroscopic crystal are switched in two stages, but they can also be switched in three stages.

FIG. 2 shows an example in which each spectroscopic crystal is formed using a substance having a large difference in X-ray diffraction angle. In other words, when the difference in the X-ray diffraction angles between the spectroscopic crystals 15a and 15b is large, even by fixing the support 17 to the housing 1 in this way, the X-rays emitted from the anticathode 6a can be detected by the spectroscopic crystal 15a onto the sample 20. Since the X-rays focused on are not blocked by the spectroscopic crystal 15b, the apparatus and handling can be simplified. The material of this characteristic X-ray and spectroscopy crystal is, for example, Al.
α- for the Kα line of SiO ₂ and Mg, artificial lattice or TAP for the Kα line, α- for the Kα line of Al
There are combinations such as Ge for the Lα line of SiO ₂ and Ag, Ge for the Lα line of Rh (reflecting surface 111), and LiF or Ge (reflecting surface 220) for the Kα line of Cu. The above combination of Al and Mg for Kα rays is as follows:
The former is used when particularly high resolution is required, and the latter is used when high sensitivity is required. Furthermore, since the artificial lattice has poor crystallinity compared to TAP, the resolution does not improve, but it can provide high sensitivity and is extremely stable even in vacuum.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of a portion of another embodiment of the present invention. In the figure, 1 is a vacuum-tight housing, 6 is X
15a and 15b are curved spectroscopic crystals, 20 is a sample, 22 is a focusing lens, and 23 is an energy analyzer.

Claims (1)

[Claims] 1. A plurality of types of X-ray generating anticathodes made of different materials are replaceably installed at the entrance part of the excited electron beam, and characteristics
An X-ray characterized in that a plurality of curved spectroscopic crystals each made of a different material are arranged between the X-ray generation anticathode and the sample so that the rays are also focused on the sample and photoelectrons are generated from the sample. X-ray source for sample excitation in photoelectron spectrometer.