JPS58111746A - Energy dispersion type fluorescent x-ray analyzer - Google Patents

Abstract

PURPOSE:To simplify the operatin of an energy dispersion type fluorescenxe analyzer by a method wherein the optimum gain of a rate meter for X-rays of the device fitted for employment to a scanning type electronic microscope is computed from the vertical full scale value and ROI width of a multichannel analyzer. CONSTITUTION:An energy dispersion type fluorescence analyzer 1 is provided with a circuit 8 whereby the optimum gain of a rate meter 6 for analyzing X- rays is operated from a channel showing the crest value level of a separate pulse output of an X-ray detection signal S1 from a semiconductor detection unit (SSD) 4 provided in the scanning unit 3 of the main body of a scanning type electronic microscope 2 fitted with the device 1, and from a histogram indication showing the number of counts per second of said channel, in accordance with a vertical full scale value P given by a multichannel analyzer 5 showing the result of analysis, and with an ROI width W at that time. According to the result of said operation, the gain of the rate meter 6 is set automatically. By this constitution, the operation of the device is simplified remarkably, and automatic measurement is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy dispersive fluorescent X-ray analyzer, and more particularly, to an energy dispersive fluorescent The present invention relates to an energy dispersive fluorescent X-ray analyzer that is used by being attached to a scanning electron microscope.

Conventional energy-dispersive X-ray fluorescence spectrometers that are attached to scanning electron microscopes are equipped with a rate meter for line analysis, and are equipped with energy-dispersive X-ray fluorescence spectroscopy (ED).
S) By passing the X-ray output signal from the multi-channel analyzer making up the system through the rate meter, an analog output signal for line analysis display is obtained, thereby υ,
The line analysis results are displayed graphically on the display of the electron microscope. Therefore, when performing line analysis with an electron microscope, perform the line analysis at a high speed (about 1 second) without cutting, check the progress on the screen, set the rate meter gain, and set the line analysis result. I tried to display it in the easiest way to see it. However, if you perform the actual line analysis at a slow sweep speed, the analysis results will be different from the line analysis performed at a fast sweep speed when setting the gain. In this analysis, it is easy to overlook the situation, and there are problems such as the situation reaching a plateau and the presence of shiashiudo. Therefore, setting the gain of the rate meter to an optimal value based on the results of a temporary analysis at a high sweep speed is complicated and requires experience on the part of the operator.

It is therefore an object of the present invention to provide a scanning electronic An object of the present invention is to provide an energy dispersive fluorescent X-ray analyzer that is used by being attached to a microscope.

A feature of the present invention is that, in an energy dispersive fluorescent X-ray analyzer that is attached to a scanning electron microscope and used, the optimal gain of a rate meter for line analysis is determined by combining the vertical full scale value of a multichannel analyzer with the ROI (region
The present invention is provided with a means for calculating and automatically setting the width of the width of the first interest.

Hereinafter, the present invention will be explained in detail with reference to the illustrated embodiments.

FIG. 1 shows a block diagram of an embodiment of an energy dispersive fluorescent X-ray analyzer according to the present invention. This energy dispersive fluorescent X-ray analyzer 1 is used by being attached to a scanning electron microscope 2, and a semiconductor detector (SS
D) The X-ray detection signal S1 taken out from 4 is applied to the multichannel analyzer 5. The multi-channel analyzer 5 discriminates the peak value of each pulse output constituting the X-ray detection signal S, and as shown in FIG. The analysis results are displayed in a histogram display with the number of counts per second plotted on the axis.

In order to perform line analysis of energy components included in the ROI width W set on the histogram showing the analysis results shown in FIG. 2, the device 1 includes a rate meter 6,
The XI signal output S2 output from the multi-channel analyzer 5 is input to the rate meter 6. The X-ray signal output S2 is a signal consisting of pulses output in response to the output of the pulse of the peak value belonging to the channel included in the set RO width W from the 58D4, and Then, it is converted into a line analysis signal S, which is an analog signal whose level changes depending on the frequency of pulse occurrence, and is displayed on the cathode ray tube display device i1 of the scanning electron microscope 2.
7. An image signal S from the main body scanning section 6 is also input to the display device 7 at the same time.
A microscope image and a line analysis characteristic curve indicating the line analysis results are displayed overlappingly on the cathode ray tube.

An arithmetic circuit 8 is provided to automatically set the gain of the rate meter so that this line analysis characteristic curve is displayed with an optimum amplitude on the display device. The arithmetic circuit 8 includes a full scale signal D1 indicating the vertical full scale value F (CPS) set in the multi-channel analyzer 5, and an ROI width signal indicating the additional value N (number of channels) of the ROI width W at that time. D2 is input from the multi-channel analyzer 5, and based on these signals, the optimum gain G of the rate meter B is given by G = -1, assuming that the full scale value of the line analysis result display is 10 (v). １岨y）−１ ・・・・・・・・・・・・
...(1) Calculated as XNXk.

Here, k is a constant, and the peak of interest P shown in FIG.
If fi has a shape that follows a Gaussian distribution, and the ROI width is set within the half value of the peak of interest, then 0.8
Selected as number 1.

To explain the value of this constant in detail with reference to Fig. 6, the height of the peak P of interest is set to 1, the ROI width is set with the value of the height y, and the ROI width at that time is set at the center. Assume that it is possible.

6- Here, the area of rectangle ABCD is 8a, and the area of the peak defined by the ROI width (the area fit of the diagonal line) is sb.
Then mother = 2 possible.

becomes.

Also, since the ΔX−ρσf surface is becomes.

Therefore, in y-W, it becomes 081 in α.

As can be seen from this calculation result, if the ROI width is selected to be the half-width of the peak of interest, the value equivalent to the 81st coefficient of the FxN value can be taken as the maximum value of the signal indicating the analysis result. By setting the gain of the rate meter according to equation 1), the line analysis result based on the line analysis signal Ss can be displayed on the display device 7 in an optimal size.

In order to automatically set the gain of the rate meter 6 step by step according to the above calculation result, the calculation circuit 8 outputs a gain setting control signal (g) according to the calculation result and is applied to the rate meter B. The gain setting control signal aS can be, for example, a code signal for selecting one of the gains that can be set in the rate meter 6, and the gain of the rate meter B is automatically set according to this code signal. be done.

Similarly, the control of the gain of the rate meter 6 is not limited to the configuration of the above embodiment, but may be configured to control the gain steplessly. As an example of such a configuration, a voltage-controlled variable gain amplifier is provided in the rate meter 6, and an analog voltage signal whose level changes according to the calculation result of equation (1) is output from the calculation circuit 8 as a gain setting control signal. The gain of the voltage-controlled variable gain amplifier is controlled according to the level of the gain setting control signal C8, and thereby the gain of the rate meter 6 is set to a predetermined value according to equation (1). The configuration to control can be mentioned.

As can be seen from the above explanation, the value of k changes depending on how the ROI width is set, but it is customary to set the ROI width to the half value, and the value of k changes depending on the method of setting the ROI width. The setup is traditionally gradual, and furthermore, the ROI
Even if the width setting deviates by about ±20 points from the half-value median value,
For reasons such as the fact that the value of k changes only by about 18,
Even if the arithmetic circuit is constructed using the fixed value of = 0.8.1, there is absolutely no problem in practice.

Further, since the above-described optimum gain value is not related to the resolution or energy value of the SSD, the arithmetic circuit 8 can be configured with an extremely simple circuit configuration.

According to such a configuration, by setting the vertical full scale value and ROI width in the multichannel analyzer, the line analysis rate gain is automatically set to the optimum value. The operation of the apparatus is significantly simplified since the operator does not have to have any experience in setting the rate and gain, which was previously required.

According to the present invention, as described above, the gain of the rate meter for line analysis can be automatically set to the optimum value according to the settings on the multichannel analyzer side, so there is no need to rely on the operator's experience or feeling. This greatly simplifies the operation of the device and is particularly effective when performing automatic measurements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the display of the multichannel analyzer shown in FIG. 1, and FIG. 3 is an automatic gain gain diagram in the device shown in FIG. FIG. 3 is an explanatory diagram for explaining the principle of setting. 1...Energy dispersive fluorescent X-ray analyzer 2...Scanning electron microscope 3...Main body scanning section 10-4...Semiconductor detector (5SD) 5...Multi-channel analyzer 6...・Rate meter 7... Display device 8... Arithmetic circuit Sl... X-ray detection signal S2... X-ray signal output S,... Ray analysis signal S4... Image signal Dl... Full scale signal D2...ROI width signal or more = 11- Fig. 2 Fig. 3

Claims (1)

[Claims] 1. In an energy dispersive fluorescent X-ray analyzer used by being attached to a scanning electron microscope, a rate meter for line analysis, a vertical full scale setting value set in a multichannel analyzer, An energy dispersion type firefly characterized by comprising: an arithmetic circuit for calculating the optimum gain of the rate meter according to the ROI width; and means for setting the gain of the rate meter according to the calculation result in the arithmetic circuit. Optical X-ray analyzer. 2. In the arithmetic circuit, the optimal gain G is expressed by the following formula:
. The energy dispersive X-ray fluorescence spectrometer according to claim 1, wherein the calculation is performed according to the following: XN F: full scale value, N: number of channels indicating ROI width, k: constant.