JPH03221853A - X-ray photoelectron analyzing apparatus - Google Patents

Abstract

PURPOSE:To eliminate the disturbance effect in measurement of the X-ray photoelectrons radiated from a sample base by grounding the sample base via a voltage source and installing a sample on the sample base via an insulating layer. CONSTITUTION:There is substantially no replenishment of charges from the side of the sample base 1 or there is the replenishment, if any, of just the extremely slight charges even if electrons are released from the sample S by X-ray irradiation and, therefore, the sample S has the potential different from the potential of the sample base 1 when the sample S is held insulated from the sample base 1. A difference by as much as the potential difference between the sample S and the sample base 1 is generated between the acceleration energies of the respective X-ray photoelectrons before the incidence to an electron energy analyzer 5 and the peaks of both electrons are distinctly separated and appear on the energy spectra even if the energies of the respective photoelectrons of the time when the X-ray photoelectrons are released from each of the sample S and the sample base 1 are assumed to be equal. Since a variable voltage is held impressed to the sample base 1, the sample position is so adjusted that the sample has the optimum potential for the energy analyzer 5 by regulating this voltage.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an X-ray photoelectron spectrometer.

- X&'ff irradiation was performed after fixing with adhesive using a stick or the like.

Since X-rays cannot be concentrated on one spot on the sample surface, when the sample is small, a portion of the irradiated X-rays also irradiates the sample stage, and X-ray photoelectrons are also emitted from the sample stage. Conventionally, as mentioned above, the sample and the sample stage were electrically connected to maintain the same potential, so when the energies of the X-ray photoelectrons emitted from the sample and the Xn photoelectrons emitted from the sample stage are close to each other, , on the electron energy spectrum, the X-ray photoelectron beam S emitted from the sample and the X &'! emitted from the sample stage. The photoelectron beams T overlapped as shown in FIG. 3, making it difficult to distinguish and detect the two, making it difficult to quantify the elements in the sample.

(Problems to be Solved by the Invention) The present invention attempts to eliminate the interference effect on measurement of X-ray photoelectrons emitted from the sample stand when the sample stand receives X-ray irradiation during X-ray photoelectron spectroscopy.

(Means for solving the problem) The sample and the sample stage were insulated, and an arbitrary and appropriate variable voltage was applied to the sample stage.

(Function) If there is insulation between the sample and the sample stage, even if electrons are emitted from the sample due to X-ray irradiation, there will be little or no charge replenishment from the sample stage. Since there is only a small amount of charge replenishment, the sample is at a different potential than the sample stage.

Therefore, even if the energy of each X-ray photoelectron is equal when it is emitted from the sample and the sample stage, there is a difference between the acceleration energy of each X-ray photoelectron until it enters the electron energy analyzer. A difference is caused by the potential difference between the electron beam and the sample stage, and peak 1 of both electrons appears clearly separated on the energy spectrum.

Since a variable voltage is applied to the sample stage, by adjusting the voltage, it is possible to adjust the sample potential so that the sample has an optimal potential with respect to the energy analyzer.

(Example) FIG. 1 shows an example of the present invention. Reference numeral 1 denotes a sample stage, which is grounded via a variable voltage source 2. S is a sample, which is fixed to the sample stage 1 with a double-sided adhesive tape 3 smaller in size than the sample. 4 is an X-ray source that irradiates the sample with X-rays. 5 is an energy analyzer, the center potential of which is set to ground potential, and 6 is a voltage source for applying a voltage to the energy analyzer 5, and energy scanning is performed by changing its output voltage. 7 is an electron detector, and 8 is an energy spectrum display device.

When a sample is irradiated with X-rays, X and I photoelectrons are emitted from the sample. Since the sample S and the sample stage 1 are insulated with double-sided adhesive tape 3, and only a very small leakage current flows, the sample S has a higher potential than the sample stage 1 by V' on the positive potential side. In a charged state, the X-ray photoelectron emission current and leakage current are balanced. Therefore, by adjusting the variable voltage source 2 and setting the sample stage 1 to 1° volt, the sample S becomes the ground potential. However, in practice, since the potential difference between the sample S and the sample stage 1 is unknown, the voltage source 2 is adjusted while repeating energy scanning with the energy analyzer 5 to find the voltage that seems most suitable for analysis. Find it and set it to that voltage. Second
The figure shows an example of an energy spectrum obtained by the present invention. T is the peak of Xvp and photoelectrons emitted from the sample stage 1, S is the peak of X-ray photoelectrons to be analyzed emitted from the sample, and K is the peak of X-ray photoelectrons emitted from known elements contained in the sample. . The dotted peak 1' is the peak of X-ray photoelectrons from the sample stage 1 in the case of the conventional analysis method in which the sample S and the sample stage 1 are electrically connected, and its tail overlaps with the peak S to be analyzed for the sample. So, the composite peak of peak T' and S is a chain! It will be like +11Q,
It is not possible to separately detect the peak caused by the sample stage and the peak of the sample. In the case of the present invention, there is an energy difference between 'r' and T that is equivalent to the potential difference V° between sample stage 1 and sample S, and peaks 1' and S are sufficiently separated. There is. However, with this alone, the potential difference between the sample S and the energy analyzer is unknown, and even if the relative energy difference between each peak is known, the absolute value of the energy is unknown. child\
Since the energy of the peak of the known element in the sample is known, the peak S of the unknown element in the sample is calculated based on it.
The energy of the element is determined, making it possible to identify the element.

In the case of the present invention, the sample is charged by X-ray irradiation, but a method may also be used in which an electron beam source for irradiating the sample with an electron beam is provided to neutralize the charge on the sample.

(Effects of the Invention) According to the present invention, even when the sample is small in size and the sample stage protrudes from the sample and is exposed to XvA irradiation,
Since it is possible to separate the peak of X-ray photoelectrons from the sample stage from the peak of sample components on the energy spectrum, it is necessary to focus the irradiated X-rays even more narrowly than for small samples so that only the sample is irradiated. There is no
Since the X-ray photoelectrons emitted from the entire sample can be introduced into the energy analyzer by irradiation with radiation, the signal strength can be increased and the analysis sensitivity can be improved.

[Brief explanation of drawings]

Fig. 1 shows the constituent countries of an apparatus according to an embodiment of the present invention, Fig. 2 shows an energy spectrum diagram of X-ray photoelectrons according to the same embodiment, and Fig. 3
The figure is a graph explaining the problems of the conventional example. DESCRIPTION OF SYMBOLS 1... Sample stage, 2... Voltage source, 3... Double-sided adhesive tape, 4... X-ray source, 5... Electron energy analyzer, 6... Electron detector, 7...・Display device.

Claims (1)

[Claims] An X-ray photoelectron analysis apparatus characterized in that a sample stage is grounded via a voltage source, and a sample is placed on the sample stage through an insulating layer.