JP2003007245A - Element mapping apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce correct average element information related to position resolution. SOLUTION: An element mapping apparatus, which passes, for scanning, a sample stage or an electron beam 6 in X-and Y-directions for irradiating a sample with the electron beam, measures characteristic X-ray generated in each position and displays measurement position information and element information relationally, has a modulating means 11 for modulating X- and Y- scanning signals for the electron beam 6, so as to conduct rectangular scanning, corresponding to unit X- and Y-scanning distances.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element mapping apparatus for measuring an element distribution of a sample with a scanning electron microscope. 2. Description of the Related Art When measuring the element distribution of a sample with a scanning electron microscope, a sample stage or an electron beam is scanned in the X and Y directions to irradiate the sample with the electron beam, and characteristics generated at each position. X-rays are measured and positional information and element information are displayed in association with each other. A conventional element mapping apparatus will be described with reference to FIG. An electron beam 6 emitted from an electron gun (not shown)
Is deflected and scanned by the deflecting device 4 to converge and irradiate it on the sample 7, and the characteristic X-rays generated at each position are detected by the X-ray detector 8 and converted into electric signals to obtain position information and elemental information. . A deflection signal for driving the deflection device 4 is based on D / A based on X and Y data sequentially generated by the scan generator 9.
The power is converted into a voltage or a current by the converter 10 and supplied. An electron beam scanning signal is, for example, an X scanning signal (FIG. 5) that changes in one step ΔEX as shown in FIG.
(A)) and a Y scanning signal (FIG. 5 (b)) that changes by one step ΔEY for every scanning in the X direction. A predetermined area of the sample is scanned by the X and Y scanning signals. Elemental mapping can be performed. [0005] In the conventional element mapping apparatus shown in FIG. 4, since scanning is performed digitally, measurement points become discontinuous. That is, as shown in FIG. 6, one step width EX, EY in the X direction and the Y direction.
A specific point in the area defined by the above, for example, the center point P of each area is scanned discontinuously and measured. When the measurement points are discontinuous in this way, the element information of the measurement point P is measured as representative of the average composition in the vicinity thereof, but this cannot be guaranteed. As a method of solving this, the beam diameter of the electron beam to be measured must be increased, or the primary electron beam must be formed into a rectangular beam by a rectangular slit. In this case, there is a problem that the intensity distribution of the expanded beam is not uniform. Further, if the resolution of the measurement points in the X and Y directions is made finer and the position resolution is increased, it takes a long time to perform the measurement. Measurement is required. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to obtain correct average element information in position resolution. For this purpose, the present invention scans the sample stage or the electron beam in the X and Y directions to irradiate the sample with the electron beam, measures characteristic X-rays generated at each position, and associates the measured position information with the element information. In the element mapping apparatus to be displayed, the X,
Modulating means for modulating the Y scanning signal is provided, and rectangular scanning corresponding to the unit X, Y scanning amount is performed. [0008] Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an element mapping apparatus of the present invention, FIG. 2 is a diagram showing an electron beam scanning signal,
FIG. 3 is an explanatory diagram for performing rectangular scanning on the sample. The sample 7 is irradiated with an electron beam emitted from the electron gun 1 through the anode 2, the converging lens 3, the deflecting device 4, and the objective lens 5, and characteristic X-rays generated from the sample are detected by the X-ray detector 8. Deflection device 4
Converts the X and Y data sequentially generated by the scan generator 9 into a voltage or a current by the D / A converter 10,
Further, a deflection signal obtained by superimposing and modulating an analog minute AC wave by the modulator 11 is supplied, and the electron beam 6 is rectangularly scanned based on this signal. The detected X-rays are amplified by a preamplifier, and the signal processing circuit 13 scans the scan generator 9.
Perform mapping in correspondence with the position signal sent from
The signal is processed by the computer 14 for display. When the measurement is started, the scan generator 9 outputs a sequence of numbers to the D / A converter 10 by, for example, incrementing the value of X by a predetermined value. The D / A converter 10 outputs an analog voltage based on the value, and shifts the electron beam by a constant value. When X reaches a predetermined value, it is reset to an initial value, and at the same time, Y is increased by a predetermined value. When Y reaches a predetermined value in this series, Y is reset to an initial value. The modulator 11 superimposes, on the output of the D / A converter, an analog minute AC wave such that the scanning area becomes a rectangle equal to the increment of X and Y. That is, as shown in FIG. 2, the modulator 11 outputs an X-scan signal (FIG. 2A) that changes stepwise with a change width ΔEX, and outputs one step Δ for every scan in the X direction.
Each of the Y scanning signals (FIG. 2B) that changes by EY is converted to an analog minute AC wave (for example, a sawtooth wave or a triangular wave).
Is output. Thereby, as shown in FIG. 3, one step EX, EY of the X scan signal and the Y scan signal
Is scanned, and as a result, the area S
Average element information is obtained. As described above, according to the present invention, the X and Y scanning signals are modulated in the element mapping device and the unit X, Y
By performing a rectangular scan corresponding to the Y scan amount, it is possible to obtain average element information at a position resolution.
Then, since the X and Y movements are performed in synchronization with the number of frames of the rectangular modulation, a correct average composition in the unit analysis area can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of an element mapping device of the present invention. FIG. 2 is a diagram showing an electron beam scanning signal. FIG. 3 is an explanatory diagram for performing rectangular scanning on a sample. FIG. 4 is a diagram showing a conventional element mapping apparatus. FIG. 5 is a diagram illustrating an electron beam scanning signal. FIG. 6 is a diagram illustrating that measurement points are discontinuous. [Description of Signs] 1 ... Electron gun, 2 ... Anode, 3 ... Converging lens, 4 ... Deflection device, 5 ... Objective lens, 6 ... Electron beam, 7 ... Sample, 8 ... X-ray detector, 9 ... Scan generator, 10 D / A converter, 11 modulator, 12 preamplifier, 13
... Signal processing device, 14 ... Computer.

Continuation of front page    (72) Inventor Hironori Maeda             3-1-2 Musashino, Akishima City, Tokyo Japan             Electronic Engineering Co., Ltd. (72) Inventor Takao Minami             3-1-2 Musashino, Akishima City, Tokyo Japan             Electronic Engineering Co., Ltd. (72) Inventor Kiyoshi Kawazu             3-1-2 Musashino, Akishima City, Tokyo Japan             Electronic Engineering Co., Ltd. F-term (reference) 2G001 AA03 BA05 CA01 GA01 GA06                       GA10 HA13 KA20                 5C033 FF03 UU04 UU05

Claims (1)

Claims 1. A sample stage or an electron beam is scanned in X and Y directions to irradiate the sample with an electron beam, and characteristic X-rays generated at each position are measured. An element mapping device for displaying information in correspondence with a device, comprising a modulating means for modulating an X, Y scanning signal of an electron beam to perform a rectangular scan corresponding to a unit X, Y scanning amount. apparatus.