JP2542569B2 - X-ray photoelectron spectroscopy - Google Patents

Description

TECHNICAL FIELD The present invention relates to an X-ray photoelectron spectroscopy apparatus capable of forming an image of a sample surface.

(Prior Art) In X-ray photoelectron spectroscopy, energy analysis of electrons emitted from a sample, that is, X-ray photoelectrons when the sample is irradiated with X-rays is performed to obtain information on the constituent elements of the sample and the bonding state of atoms. I will get it. Since it is difficult to converge the X-rays that irradiate the sample, it is difficult to perform local analysis by the X-ray photoelectron analysis method, and since a diaphragm or slit is used to limit the analysis range, it is possible to When you want to know the element distribution state of a certain area, scanning is performed with slits or diaphragms, so the X-ray photoelectrons emitted from the entire area cannot be used at the same time, and two-dimensional analysis of the sample surface is possible. It was very time consuming.

(Problems to be Solved by the Invention) According to the present invention, it is possible to simultaneously analyze the energy of X-ray photoelectrons emitted from the X-ray irradiation area of the sample surface and form an image of the sample surface by the X-ray photoelectrons of each energy. Then, the utilization rate of X-rays and X-ray photoelectrons is improved.

(Means for Solving Problems) In order to solve the above problems, the present invention provides an X-ray photoelectron spectroscopic apparatus in which an X-ray source for irradiating a sample and a spherical surface centered on the center position of the sample are used. A first grid of shapes,
A low-pass filter composed of an electron reflecting surface forming a spheroidal surface having a focal point at each center position of the sample and the image surface and a second grid stretched on the inner front surface in parallel with the electron reflecting surface, and the center of the image surface. A high-pass filter composed of a third grid on the outside and a fourth grid on the inner side, which are doubly installed in a concentric spherical shape centered on the position, and have a two-dimensional imaging property. An imaging means for converting an electronic image of the sample surface formed by the electron energy analyzing means into a video signal on a two-dimensional image sensor arranged on the image surface; and A plurality of image memories for storing a plurality of ranks of energy set in the energy analysis means and the first to third grids are set to have a first potential lower than the potential of the sample and equal to each other. The electric potential of the electron reflecting surface is a second electric potential lower than the first electric potential by a predetermined value, and the electric potential of the fourth grid is a third electric potential lower than the second electric potential by a predetermined value. By setting the energy rank in the electronic energy analysis means by the above, the energy scanning operation of sequentially moving the first to third potentials in association with each other and the output of the imaging means in correspondence with the energy rank A control means for controlling the operation of storing in the image memory is provided.

(Operation) Since a photoelectron image of the sample surface is formed, it is not necessary to narrow down the X-ray irradiating the sample with a slit or the like, and the utilization rate of the X-ray is good. Also, since the image of the sample surface is formed by using the photoelectrons emitted from the sample surface at the same time, all the electrons emitted from each point on the sample surface are used for the measurement during the measurement period. The utilization rate of X-ray photoelectrons is higher than that of the conventional device in which only electrons in a certain minute region are used for measurement at a certain time among all the emitted electrons, and the two-dimensional shape of the sample surface Analysis time is reduced.

(Embodiment) FIG. 1 shows the configuration of an energy analysis unit according to an embodiment of the present invention. S is a sample and X is an X-ray source. Reference numeral 1 is a spherical grid having a center at the center position of the sample S, and a negative potential is applied to the sample to decelerate X-ray photoelectrons emitted from the sample surface. Reference numeral 2 is an electron reflecting surface, and a variable voltage from 0 to negative is applied to the sample S, and a grid 3 is stretched in front of this reflecting surface in parallel with the figure. The same voltage as that of the grid 1 is applied to the grid. The reflecting surface 2 is a spheroidal surface whose focal points are the respective center positions of the sample S and its image plane I, and the grid 3
Together with this, it constitutes a reflection type electronic low-pass filter. Since the reflective surface 2 of the reflective low-pass filter has a low potential, low energy electrons are reflected and high energy electrons overcome the electric field between the grid 3 and the reflective surface 2 and enter the reflective surface 2. Therefore, the electrons reflected are only low-energy electrons, and the electron energy at the reflected boundary changes by changing the potential of the reflecting surface 2. Since the reflecting surface 2 has a spheroidal shape, the reflected electrons form an electron image of the sample surface S on the image surface I. A spherical transmission electron high-pass filter HF is arranged around the center of the image plane I. This high-pass filter consists of double concentric spherical grids 4,5, the outer grid 4 is at the same potential as grid 1 and the inner grid 5 is at a low potential, reflecting low energy electrons. However, only high-energy electrons pass through the grid 5 and form an image on the image plane I. By setting the energy of the boundary electron passing through the grid 5 to be slightly lower than the energy of the boundary electron reflected by the reflecting surface 2, only the electrons within a certain energy width can be set. Image can be formed on the image plane I. A two-dimensional electronic image sensor is arranged on the image plane I. Reference numeral 6 is a grid concentric with the grids 4 and 5, and the electrons passing through the grid 5 are remarkably decelerated.

FIG. 2 shows an embodiment of the two-dimensional electronic image sensor. The MCP is a collection of electron-multiplier channels in the shape of a honeycomb formed by a microchannel plate, and an electron image I is formed on this incident end face. A fluorescent plate F is arranged in parallel with the emission end face of the microchannel plate to convert an electron image into a light image. This optical image is picked up by the TV camera TVC. A CCD image sensor may be arranged in contact with the fluorescent screen F instead of the television camera.

FIG. 3 shows an embodiment of the video signal processing circuit. M1, M2
Mn is an image memory, respectively. The CPU is a control computer that scans the energy of X-ray photoelectrons emitted from the sample by changing the potentials of the reflecting surface 2 and the grids 1 to 6, and scans the TV camera TVC for each rank of energy. The memories M1, M2, ... correspond to the energy ranks of X-ray photoelectrons, the lowest energy rank corresponds to M1, the highest energy rank corresponds to Mn, and the kth energy rank from the lowest corresponds to the memory Mk. , Image data obtained by TVC at a certain energy rank k is stored in a memory Mk corresponding to the energy rank. Thus, when the energy analysis section shown in FIG. 1 completes a series of energy scanning, the data of the image of the sample surface by the X-ray photoelectrons of each energy rank is stored in the memories M1, M2, .... This section describes how to set the energy rank. Since the electron energy analysis means has a configuration in which electrons having an energy within the overlapping range of the transmission regions of both filters are extracted by the low-pass filter and the high-pass filter, the detected electrons are distributed within a certain energy width. . The term "rank" here means this energy range, and one rank is the X of one element in it.
It can be set to include line photoelectrons. Alternatively, a certain energy range may be finely divided and each section may have the above-mentioned rank. In this way, the profile of the energy distribution of X-ray photoelectrons can be measured.

Since the addresses of the memories M1, M2, ... Correspond to the coordinates of the image surface of the TV camera TVC, that is, the coordinates of the points on the sample surface, the above-mentioned ranks are finely divided and correspond to one point on the sample surface. When the data of the same address in the memories M1, M2, ... Is read, and the energy rank is plotted on the horizontal axis and the read image data is plotted on the vertical axis, a curve as shown in Fig. 4 is drawn. X at a point on the sample surface
The energy distribution of line photoelectrons is shown. The printer Pr produces such a graph. Further, when the image data of a certain memory Mk is read out and displayed on the CRT as an image, a distribution image of X-ray photoelectrons of energy rank k on the sample surface as shown in FIG. 5 is obtained. The distribution is converted to light and dark for visual display.
When the CRT is a color CRT and the image data of the three memories Mb, Mg, and Mr corresponding to the three elements are color-displayed as video signals of the three primary colors blue, green, and red, the distribution of the three elements is simultaneously displayed.

(Effect) The apparatus of the present invention is configured as described above, and a two-dimensional X-ray photoelectron image of the sample surface is obtained for selected X-ray photoelectrons, and the data of this image is stored in the image memory for each energy. As a result, the analysis of each point on the sample surface is proceeding in parallel at the same time, and the X-ray photoelectron spectroscopic analysis is performed on one point on the sample as in the conventional case. The X-ray photoelectrons emitted from the above point are not used for analysis and are abandoned. On the other hand, when obtaining the element distribution on the sample surface, the utilization rate of X-ray photoelectrons is good and the analysis time is shortened. In addition, since it is visualized by X-ray photoelectron energy and stored in the image memory,
The data in each memory immediately shows the concentration distribution of a certain element on the sample surface, and when the data is displayed by scanning the same address of each memory, it becomes the elemental analysis data of one point on the sample surface. It can be done easily and quickly.

[Brief description of drawings]

FIG. 1 is a side view of an X-ray photoelectron energy analyzer in one embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of an image sensor unit for an X-ray photoelectron image, and FIG. 3 is a data processing circuit of the same. FIG. 4 is a block diagram showing the structure, FIG. 4 is a graph of an example of display data obtained by the data processing circuit, and FIG. 5 is a video diagram of other display data.

Claims (1)

(57) [Claims] 1. An X-ray source for irradiating a sample, a spherical first grid centered on the center position of the sample, and a spheroidal surface having the center positions of the sample and the image plane as focal points. A low-pass filter consisting of an electron-reflecting surface and a second grid stretched on the inner front surface in parallel with the electron-reflecting surface, and a double-pass outer concentric spherical surface centered on the center of the image plane. Third grid and inner fourth
And a high-pass filter composed of a grid of 2), which has a two-dimensional image-forming property, and an electron energy analyzing unit formed on the two-dimensional image sensor arranged on the image plane. Imaging means for converting the electronic image of the sample surface into a video signal; a plurality of image memories for storing the output of the imaging means for each energy of a plurality of ranks set in the electronic energy analysis means; and the first to third embodiments. The potential of the grid is lower than the potential of the sample and equal to each other, the potential of the electron reflecting surface is a second potential lower by a predetermined value than the first potential, and the potential of the fourth grid is An energy rank is set in the electron energy analysis means by setting a third potential lower than the second potential by a predetermined value, and the first to third potentials are set. An X-ray photoelectron device comprising: an energy scanning operation that moves sequentially in conjunction with each other; and a control unit that controls an operation of storing the output of the imaging unit in the image memory in correspondence with the energy rank. Spectroscopic device.