JPS61163548A - Electron beam system - Google Patents

Abstract

PURPOSE:To avoid the gap of the luminescent spot display position and the spot irradiation point of a cathode-ray tube, and display an analyzing point correctly by the luminescent spot, by converting and correcting the phase delay of the sample scanning coil when the scanning speed is rapid, and the scanning signal level to feed the scanning delay of the cathode-ray tube. CONSTITUTION:A signal of scanning speed S from the scanning speed setting circuit 22 and the amplitude A of the horizontal scanning signal from the amplitude converting circuit 9 are added to the correction signal generating circuits 23 and 25, and to the horizontal scanning signal generating circuit 1. The correction signal from the circuit 23 is added to the magnification converting circuit 3 through the addition circuit 24, and the correction signal from the circuit 25 is added to the scanning coil of the cathode-ray tube 5 through the addition coil 26. When the amplitude A is maximum, the converting coils 2 and 19 are set at the scanning mode by the signal of the mode setting circuit 21, and the DC signal generating circuit 17 is handled to overlap the analyzing point on the screen of the cathode-ray tube 5 over the sample image, and when the circuit 22 is placed at a high speed scanning, the phase delay of the coil and the level of the scanning signal of the cathode-ray tube 5 are converted to correct the display point of the luminescent spot and the spot irradiation point.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention displays a mark at an arbitrary position by superimposing it on a scanned image of a sample on a negative Li-ray tube, etc., and then switches to spot mode to place an electron beam on the mark. The present invention relates to an electron beam device that analyzes a sample by irradiating it onto a corresponding position on the sample.

[Prior art 1] FIG. 3 is for explaining a conventional device. In the figure, 1 is a horizontal scanning signal generation circuit, and the horizontal scanning signal from this circuit 1 is sent to terminal a of the first switching circuit 2. The signal is supplied to the magnification switching circuit 3 via the amplifier 4, and also to the horizontal scanning coil 5X of the cathode ray tube 5 via the amplifier 4. A scanning signal amplified by a predetermined amplification factor by the magnification switching circuit 3 based on the signal from the magnification setting circuit 6 is sent to the X-direction deflection coil 8x via the amplifier 7. EB represents a narrowly focused electron beam, and the electron IEB is deflected by the deflection coil 8X and irradiated onto the sample 10. Reference numeral 9 denotes an amplitude switching circuit for sending a control signal to the horizontal scanning signal generating circuit 1 and switching the amplitude of the horizontal scanning signal generated by the circuit 1 into, for example, three levels.

This amplitude switching circuit 9 is used when observing a fine image by reducing the amplitude of the scanning signal generated by the circuit 1. 11 is a secondary electron detector for detecting secondary electrons generated from the sample 10 by irradiation with the electron beam EB, and the signal from the secondary electron detector 11 is transmitted to the amplifier 1.
2. The signal is sent to the grid 5g of the cathode ray tube 5 via the adder circuit 13. 14 is an X-ray detector for detecting X-rays generated from the sample 10, and a signal from the X-ray detector 14 is sent to a recorder 16 via a signal processing circuit 15. Reference numeral 17 denotes a variable DC signal generation circuit for the horizontal direction, and the DC signal from the circuit 17 is sent to the terminal a of the first switching circuit 2 via the amplifier 18, and is also sent to the terminal a of the second switching circuit 19. is sent to the comparator 20 via. A scanning signal from the horizontal scanning signal generation circuit 1 is also sent to the other input terminal of the comparator 20. The output signal of the comparator 20 is sent to the fraud circuit 13. 21 is the first and second
22 is a mode switching circuit for sending a switching signal to the switching circuit 2.19, and 22 is a scanning speed setting circuit for sending a setting signal for setting the scanning speed to the horizontal scanning signal generation circuit 1. Although not shown, a vertical scanning signal generating circuit, a variable direct current signal generating circuit for the vertical direction, and the like are also provided completely symmetrically with respect to the horizontal direction.

Next, the operation of such a conventional device will be explained, but since it is exactly the same in the vertical direction, only the horizontal direction will be explained.

First, the mode setting circuit 21 is operated so that the first and second switching circuits are connected to the terminal a side, and then the scanning speed setting circuit 22 is operated to set the scanning speed to low speed scanning. As a result, from the horizontal scanning signal generating circuit 1, as shown in FIG.
A horizontal scanning signal as shown by the solid line A is generated. This horizontal scanning signal flows through the deflection coil 8x as a signal with almost no phase delay, as shown by the dotted line in FIG. 5x.As a result, the signal from the detector 11 accompanying the scanning of the electron beam EB is sent to the cathode ray tube 5, so that a sample image as shown in FIG. 5(a) is displayed on the cathode ray tube 5. Therefore, by operating the DC signal generation circuit 17, as shown in FIG.
If a DC signal as shown by R is generated in a), a matching pulse as shown in FIG. As shown in FIG. 5(b), a bright spot P indicating an analysis point is displayed on the screen 5, superimposed on the sample image. Therefore, by operating the mode setting circuit 21 and switching the mode to the spot mode, the first. The second switching circuit 2.19 is b
It is connected to the terminal side, and the signal from the DC signal generation circuit 17 is sent to the deflection coil 8x and also to the deflection coil 5X of the cathode ray tube 5, as shown in FIG. 5(d) showing the spot irradiation point on the cathode ray tube screen. A bright spot P' as shown is displayed, and a point on the sample 10 corresponding to P' is fixedly irradiated with an electron beam EB. Therefore, based on this electron beam irradiation, the characteristic X-rays generated from the sample 10 are detected! 1lt14, the detection signal is processed by the signal processing circuit 15, and the X-ray spectrum is displayed on the recorder 16 based on the processed signal, thereby obtaining the xm analysis result of the analysis point corresponding to the bright point P. Can be done.

[Problems to be solved by the invention] However, at the stage of setting analysis points,
When the scanning speed setting circuit 22 is operated to switch the scanning speed to ^ speed, for example Sr, the horizontal scanning signal generated from the horizontal scanning signal generating circuit 1 changes as shown by the solid line A in FIG. 4(C). However, due to this change, the current flowing through the deflection coil 8x causes a phase delay corresponding to the level Va, as shown by the dotted line in the same figure, and the current flowing through the deflection coil 5x causes a phase delay, as shown by the dashed line in the same figure. level v
A phase delay corresponding to b is generated. The delay on the coil 8X side is large because the scanning signal is supplied to the deflection coil 5x only via the amplifier 4, whereas the deflection coil 8x has many circuits such as the magnification switching circuit 3 and the amplifier 7. This is because the scanning signal is supplied via the coil, so the delay in each circuit is added to the delay in the response of the coil itself. In addition, in FIG. 4, K indicates a non-blanking period. the result,
As shown in FIG. 5(C), the display position of the bright spot P on the cathode ray tube 5 is shifted in the horizontal direction by an amount corresponding to the spot irradiation position and level vb when the spot mode is set, and
The area of the sample displayed is shifted in the horizontal direction by an amount corresponding to Va - Vb, and the bright spot P cannot accurately display the analysis point.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional drawbacks and provide an electron beam apparatus that can accurately display analysis points even when the scanning speed is changed to high speed.

[Means for Solving the Problems] In order to achieve such objects, the present invention provides a deflection coil for deflecting a narrowly focused electron beam, and a scanning signal for scanning the electron beam on a sample. a scanning signal generating circuit that generates a scanning signal, a means for controlling the scanning signal generating circuit and switching the scanning speed, and scanning based on the scanning signal and supplying a detection signal based on the scanning of the electron beam. a cathode ray tube for displaying a sample image; a DC signal generation means for generating a variable DC signal for irradiating a fixed point on the sample with an electron beam; An apparatus comprising means for displaying a mark superimposed on the sample image at a screen position of the display means corresponding to a DC signal, and means for switching and supplying the scanning signal and the DC signal to the deflection coil, a first correction means for correcting the level of the scanning signal sent to the deflection coil side in order to automatically correct the phase d shift of the scanning signal flowing through the deflection coil when the scanning speed is increased; In order to automatically correct the phase delay of the scanning signal flowing through the cathode ray tube when the cathode ray tube side
It is characterized by having a correction means.

[Example] Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 shows one embodiment of the present invention, and in FIG. 1, the same components as in FIG. 3 are given the same numbers. In FIG. 1, reference numeral 23 denotes a first correction signal generation circuit, to which a signal representing the scanning speed S is supplied from the scanning speed setting circuit 22, and a horizontal A signal representing the amplitude A of the scanning signal is provided. Based on these two signals, the first correction signal generation circuit generates a negative DC correction signal Vl whose absolute value increases as the scanning speed S and amplitude A increase.
Generate (S, A). When the above-mentioned St is selected as the scanning speed when the amplitude A is the maximum, this correction signal is designed to exactly match -Va. The correction signal from the correction signal generation circuit 23 is sent to the addition circuit 24. The signal from the first switching circuit 2 is not directly sent to the magnification switching circuit 3, but is sent to the magnification switching circuit 3 via the tampering circuit 24. 25 is a second correction signal generation circuit;
The correction signal generation circuit 25 is also supplied with a signal representing the scanning speed S from the scanning speed setting circuit 22, and is also supplied with a signal representing the amplitude of the horizontal scanning signal - from the amplitude switching circuit 9. Based on these two signals, the second correction signal generation circuit also generates a negative DC correction signal V2 (S, A
> is generated. If the above-mentioned S[ is selected as the scanning speed when the amplitude is maximum, this correction signal is exactly -v
b. Correction signal generation circuit 25
This correction signal is sent to an adder circuit 26. The signal from the first switching circuit 2 is added to the signal from the correction circuit 25 by an adding circuit 26 and sent to the knitting coil 5x.

In such a configuration, when the amplitude A is selected to be the maximum, the first . After connecting the second switching circuit 2.19 to the a terminal and setting the scanning image mode, the DC signal generation circuit 17 is operated to generate an analysis signal on the screen of the cathode ray tube 5 as shown in FIG. 5(b). A bright spot P indicating a point is displayed superimposed on the sample image. Therefore, when the scanning speed setting circuit 22 is operated to switch the scanning speed to ^ speed Sf, the first. Second correction signal generation circuit 23°25
Correction signals Vl (S, A), V2 (S,
A) has levels -Va and -Vb as shown by solid lines a and b in FIG. 2(a), respectively. Therefore,
When the scanning signal generated by the horizontal scanning signal generation circuit 1 is indicated by a solid line A in FIG. 2(b), the scanning signal sent to the magnification switching circuit 3 via the addition circuit 24 is indicated by a solid line A' in the figure Also, the scanning signal sent to the amplifier 4 becomes the one shown by the solid line A in the figure. As a result, the scanning signal flowing to the deflection coil 8X and the deflection coil 5x of the cathode ray tube 5 is horizontal as shown by the solid line A. Therefore, even if the scanning speed is changed and the display position of the bright spot P on the cathode ray tube 5 does not deviate from the spot irradiation position when the spot mode is selected, the displayed sample Since the area does not shift, the analysis point can be displayed accurately using the bright spot P.

Incidentally, if the amplitude of the scanning signal is reduced to 1/2 by operating the amplitude switching circuit 9, the level of the correction signal generated by the correction signal generation circuit 23, 25 will also be reduced to 1/2, so that the correction signal will not be excessively large. There is no problem, and optimal correction can be performed.

The present invention is not limited to the embodiments described above, and can be modified in many ways.

For example, in the embodiment described above, a correction signal whose level changes depending on the scanning speed is generated.
Since the movement of the image becomes noticeable only when the scanning speed is high, a correction signal of a certain level may be added to the scanning signal only when the scanning speed becomes faster than a certain reference value.

Further, in the above-described embodiment, a 'cH point is displayed as a mark to indicate the analysis position, but the mark is not limited to a bright spot, but a cross mark or the like may be used.

[Effects of the Invention] As is clear from the above explanation, the phase delay in the sample scanning coil when the scanning speed is increased and the scanning delay in the cathode ray tube are corrected by changing the level of the scanning signal supplied. , it is possible to eliminate both the discrepancy between the display position of the bright spot P on the cathode ray tube and the spot irradiation position when the spot mode is set, as well as the discrepancy in the sample area displayed as a scanned image, and the bright spot P can accurately display the analysis point. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing signal waveforms to explain the operation of the device of the embodiment shown in FIG. 1, and FIG. 3 is a diagram showing a conventional example. FIG. 4 is a diagram for explaining the device, FIG. 4 is a diagram showing signal waveforms for explaining the operation of the conventional device, and FIG. 5 is a diagram for explaining the drawbacks of the conventional device. 1: Horizontal scanning signal generation circuit 2.19: Switching circuit 3: Magnification switching circuit 4.7, 12,
18: Amplifier 5: Cathode IIA tube 6: Magnification setting circuit 8x: Deflection coil 9: Amplitude switching circuit 10: Sample 11
: Secondary electron detector 13.24.26 : Addition circuit 14 : X1il detector 15 : Signal processing circuit 16
: Recorder 17: DC signal generation circuit 20: Comparator 21: Mode setting circuit 22: Scanning speed setting circuit 23.25: Correction signal generation circuit EB: Electron beam

Claims (2)

[Claims] (1) A deflection coil for deflecting a finely focused electron beam, a scanning signal generation circuit for generating a scanning signal for scanning the electron beam on a sample, and a scanning signal generation circuit for controlling the scanning signal generation circuit to control the scanning speed. a cathode ray tube for scanning based on the scanning signal and displaying a sample image based on supply of a detection signal based on the scanning of the electron beam; a DC signal generating means for generating a variable DC signal for irradiating the sample; and a mark superimposed on the sample image at a screen position of the display means corresponding to the DC signal based on the signal from the DC signal generating means. In an apparatus comprising means for displaying and means for switching and supplying the scanning signal and the DC signal to the deflection coil, the phase delay of the scanning signal flowing through the deflection coil is automatically corrected when the scanning speed is increased. a first correction means for correcting the level of the scanning signal sent to the deflection coil side for correction; and a first correction means for automatically correcting the phase delay of the scanning signal flowing through the cathode ray tube when the scanning speed is increased. An electron beam apparatus comprising a second correction means for correcting the level of the scanning signal sent to the tube side. (2) It is equipped with a means for switching the amplitude of the scanning signal generated by the scanning signal generating circuit, and automatically switches the level correction amount by the first and second correction means in accordance with the amplitude switching by the means. An electron beam apparatus according to claim 1, further comprising means.