JP2010257675A - Electron beam device having line analysis function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of easily setting analysis points at arbitrary intervals and arbitrary points on the same line segment when performing line analysis by irradiating an electron beam to a sample. <P>SOLUTION: A line analysis position on an HAADF image is specified by using a pointing device such as a mouse. For example, a starting point P1 and a finished point P6 of the line analysis are specified so as to become a right angle to a crystal grain boundary, and the number of analysis points (sample) 6 are specified with a key board. For example, X-ray intensity of an attention element on a line segment orthogonal to the grain boundary is measured by an X-ray detector 13, and the analysis results are displayed with a graph. Analysis points S1 to S6 which are further subdivided rather than a preset interval are automatically specified on a line centralizing attention points with high X-ray intensity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electron beam apparatus such as a transmission electron microscope (TEM) or a scanning electron microscope (SEM) that irradiates a sample with a finely focused electron beam, detects an information carrier generated from the sample, and analyzes the sample More specifically, the present invention relates to an improvement in a method for designating a line analysis position when a sample is analyzed in a linear shape.

  For example, X-rays generated by attaching an analysis device such as an energy dispersive X-ray analyzer (EDS) to a scanning electron microscope (SEM) or scanning transmission electron microscope (STEM) and irradiating a sample with a finely focused electron beam There is a method of analyzing a grain boundary or the like by detecting.

  FIG. 2 is a diagram schematically showing a method of taking a scanning transmission electron image of a region including a crystal grain boundary and setting multi-point analysis positions on a line segment perpendicular to the crystal grain boundary on the image. Each analysis point is set at equal intervals on the line segment.

  In Japanese Patent Publication No. 4-50698 of Patent Document 1, an analysis start point, an analysis end point, and the number of analysis points on a sample are designated, and an analysis point located on a line segment connecting the analysis start point and the analysis end point is automatically set. A technique for automatically and sequentially moving an electron beam to a set analysis point is disclosed.

  Japanese Patent Application Laid-Open No. 5-296754 discloses a differential signal value of a secondary electron signal when a pattern edge is detected using a charged particle beam length measuring device that measures a fine pattern on a semiconductor. There is disclosed a technique for detecting, as an edge, a position where the differential signal value becomes zero within an interval in which the negative value changes to a positive value.

Japanese Patent Publication No. 4-50698 JP-A-5-296754

  When analyzing precipitates in a sample, there is no inconvenience even if analysis points are arranged on a line segment at regular intervals as in the method disclosed in Japanese Patent Publication No. 4-50698 of Patent Document 1. However, when there is a possibility that the element distribution state changes suddenly in a narrow range compared to the surrounding area, such as a grain boundary, it is necessary to increase the number of analysis points at small intervals near the grain boundary. There is. In this case, if the wide range is not analyzed at a relatively large interval, the entire analysis time becomes too long. Therefore, a method for easily determining the analysis position at an arbitrary interval and an arbitrary number of points on the same line segment is required.

  Further, when the analysis position is determined in a minute region on the sample, it is necessary to shorten the time for irradiating the sample with the electron beam before the analysis in order to reduce sample damage and contamination due to the electron beam irradiation. Therefore, a method for automatically determining a singular point such as a grain boundary on a specified line segment is required.

The present invention has been made to solve the above-described problems, and its purpose is as follows.
To perform a line analysis by irradiating a sample with an electron beam, to provide a method for easily setting analysis points at an arbitrary interval and an arbitrary number of points on the same line segment. Another object of the present invention is to automatically detect a singular point such as a grain boundary on a specified line segment and automatically determine analysis points at irregular intervals in the vicinity of the detected singular point. Is to provide.

To solve the above problem,
(1) The invention according to claim 1 is an electron source that generates an electron beam;
Scanning means for irradiating the sample with the electron beam and scanning two-dimensionally;
Detection means for detecting information carrier generated by the interaction between the electron beam and the sample in synchronization with the scanning means;
Signal processing means for converting the information carrier detected by the detection means into signal intensity;
Display means for displaying the signal intensity change obtained by the signal processing means as a two-dimensional image;
The image processing apparatus includes: designation means for designating a line analysis position on the two-dimensional image; and setting means for setting analysis points in the line analysis position designated by the designation means at unequal intervals.

  (2) The invention according to claim 2 is characterized in that the information carrier includes at least one of secondary electrons, reflected electrons, transmitted electrons, characteristic X-rays, and cathodoluminescence.

  (3) The invention according to claim 3, wherein the setting means assumes that the signal strength change of the information carrier in the vicinity of a singular point in the line analysis position is approximated by a Gaussian distribution. The intervals between the analysis points are set at non-equal intervals so that the changes in the intervals become substantially equal.

  (4) The invention described in claim 4 is characterized by further comprising extraction means for extracting the singular point from the line analysis position designated by the designation means.

(5) In the invention according to claim 5, the extraction means uses the differential data of the intensity change data of the information carrier at the line analysis position to indicate the analysis point indicating the change with the greatest intensity change of the information carrier. The electron beam apparatus according to claim 1, wherein the singular point is extracted.

According to the present invention, when a singular point such as a grain boundary is included in a wide line analysis range, the vicinity of the singular point of interest is analyzed finely, and the wide range is not analyzed so that analysis is performed at rough intervals. It can be easily set at regular intervals. In addition, singular point positions such as crystal grain boundaries are automatically detected on the line segment, and analysis points can be set at non-uniform intervals, shortening the electron beam irradiation time before analysis and reducing sample damage and contamination. can do.

It is a figure which shows the schematic structural example of the scanning transmission electron microscope which implements this invention. It is the figure which showed typically the method of setting the analysis position of many points on the line segment at right angles to a crystal grain boundary on an image. It is a figure which shows the example of a display of the line analysis position designation | designated on a HAADF image containing an analysis target site | part, and measurement data. It is a figure which shows the example of a display of the line analysis position designation | designated and measurement data which divide | segment further the space | interval set initially. It is a figure for demonstrating the designation | designated method which allocates the analysis point space | interval on the line which crosses one grain boundary based on Gaussian distribution. It is a figure for demonstrating the designation | designated method which allocates the analysis point space | interval on the line which crosses in the inside of two grains based on Gaussian distribution. It is a figure which shows the example of a display of the HAADF image of the visual field including the attention location which analyzes, and the HAADF signal intensity data of a focus location. It is a figure for demonstrating the procedure which produces a differential profile from the intensity | strength profile of the HAADF signal of an attention location. It is a figure which shows the example which determined the space | interval of the analysis point by fine division | segmentation around the singular point.

  Embodiments of the present invention will be described below with reference to the drawings. However, the technical scope of the present invention is not limited by this illustration. In each figure, the same reference numerals are given to those performing the same or similar operations, and detailed description is not repeated.

  FIG. 1 is a diagram showing a schematic configuration example of a scanning transmission electron microscope embodying the present invention. Reference numeral 1 denotes a mirror body, 2 denotes an electron gun that generates an electron beam 3, 4 denotes an irradiation lens system for focusing the electron beam 3 emitted from the electron gun 2, and 5 denotes an electron beam 3 at an arbitrary position on the sample. A deflector 8 capable of setting an irradiation point is an imaging lens system for projecting an electron beam transmitted through the sample 6 onto the CCD camera 9. Reference numeral 7 denotes a sample holder on which the sample 6 is placed and is supported by a sample stage (not shown). Reference numeral 10 denotes a deflection control device for performing common deflection control in order to synchronize the electron beam scanning by the deflector 5 and the transmission electron signal capture by the CCD camera 9. CCD is an abbreviation for Charge Coupled Devices. The passage of the electron beam 3 in the mirror body 1 is maintained at a high vacuum by a vacuum exhaust device (not shown).

  11 is an annular detector for detecting electrons scattered at a wide angle by the sample, and 12 is an electron for processing a wide angle scattered electron signal taken from the annular detector 11 in synchronization with the two-dimensional scanning of the electron beam 3. It is a signal processing device. A scanning transmission image obtained by using the annular detector 11 is called a high-angle annular dark-field (HAADF) image.

  Reference numeral 13 denotes an X-ray detector for detecting characteristic X-rays generated from the sample, and reference numeral 14 denotes an X-ray signal processing apparatus for processing the X-ray signal taken from the X-ray detector 13. As the X-ray detector, EDS is usually mounted.

  Reference numeral 15 denotes a control arithmetic device such as a personal computer, which is a device for displaying an image taken from the electronic signal processing device 12 and the X-ray signal processing device 14 and controlling the deflection control device 10. The operator can control the STEM and process and display the obtained data using an input device (not shown) such as a mouse and a keyboard provided in the control arithmetic device 15 and a display device such as a liquid crystal display.

  An embodiment of a method for setting a line analysis point according to the present invention in the above-described STEM will be described.

Example 1
The deflector 5 scans the electron beam 3 two-dimensionally, and the HAADF image is captured using the annular detector 11. FIG. 3A is a HAADF image in which the visual field including the crystal grain boundary (hereinafter simply referred to as “grain boundary”) obtained in this way is displayed on the control arithmetic unit 15. The operator designates a line analysis position on the HAADF image using a pointing device such as a mouse. The start point P1 and the end point P6 of the line analysis are designated so as to be perpendicular to the grain boundary, and the number of analysis points is designated as 6 using a keyboard or the like. Six points from P1 to P6 are set as analysis point positions on a line segment perpendicular to the grain boundary.

  For six points from P1 to P6, for example, the X-ray detector 13 measures the X-ray intensity of the element of interest. FIG. 3B shows the analysis result in a graph. In FIG. 3B, the horizontal axis represents the line analysis position, and the vertical axis represents the signal intensity (or concentration-converted value) of the element of interest obtained by measurement. It can be seen that the signal intensity at the analysis point P3 is significantly higher than the other analysis points.

  Therefore, P3 is designated as a point of interest, and the number (for example, four divisions in the example of FIG. 4) for further dividing the interval set first is designated on the line centered on the point of interest. Then, three points S1 to S3 are automatically added between P2 and P3, and three points S4 to S6 are automatically added between P3 and P4, and the analysis of S1 to S6 is performed. FIG. 4B is an example of a graph in which measurement data is displayed as data obtained by plotting all analysis results from P1 to P6 and S1 to S6. As described above, it is possible to easily set the analysis point for knowing in more detail the change in signal intensity near the point of interest (for example, near the grain boundary).

(Example 2)
In some cases, it is possible to predict in advance from the HAADF image that there is a sudden change in signal intensity near a specific analysis point on the line to be analyzed. For example, as shown in FIG. 5A, when a line analysis is performed across a grain boundary, it is often desired to know in detail the steep change in the vicinity of the grain boundary, but also to analyze a wide range other than that. In that case, it is preferable to allocate the analysis point intervals on the line based on the Gaussian distribution around the attention point where a sudden change in signal intensity is expected.

  In FIG. 5 (b), assuming that the element concentration as the grain boundary is maximized, the maximum signal intensity is 0.9, and the change in signal intensity approximated by a Gaussian distribution is about 0.2 to 0.3. An example of determining the interval between analysis points is shown.

  If the remarkable change is not an element that segregates at the grain boundary but a change within the grain, as shown in FIGS. 6A and 6B, the centers of the Gaussian distributions coincide with the centers of the crystal grains on both sides. Thus, the interval between the analysis points may be determined so that the change in signal intensity approximated by the Gaussian distribution is about 0.2 to 0.3.

(Example 3)
Next, analysis points for X-ray analysis, electron energy loss analysis, etc. are automatically used using scanning transmission images, reflected electron images, secondary electron images, etc. for observing the structure, structure, morphology, etc. of the sample. A method of setting will be described.

  FIG. 7 (a) is a HAADF image of the visual field including the point of interest to be analyzed. FIG. 7B is a graph showing the HAADF signal at the point of interest as an intensity profile. In this graph, the horizontal axis represents the distance in the length direction of the HAADF image of FIG. 7A, and the vertical axis represents the average value of the HAADF signal intensity at the site of interest in the width direction.

  FIG. 8 shows a procedure for creating a differential profile by first differentiating the intensity profile of the HAADF signal at the point of interest. In the obtained differential profile, a singular point is a place where a large peak appears on the plus side or the minus side. FIG. 9 shows an example in which the interval between analysis points is determined by fine division around this singular point.

As described above, according to the present invention, when performing line analysis by irradiating a sample with an electron beam, analysis points can be easily set at an arbitrary interval and an arbitrary number of points on the same line segment.

(Common reference numerals are used for the same or similar operations.)
DESCRIPTION OF SYMBOLS 1 ... Mirror body 2 ... Electron gun 3 ... Electron beam 4 ... Irradiation lens system 5 ... Deflector 6 ... Sample 7 ... Sample holder 8 ... Imaging lens system 9 ... CCD camera 10 ... Deflection control device 11 ... Ring detector 12 ... Electronic signal processing device 13 X-ray detector 14 X-ray signal processing device 15 Control arithmetic device

Claims (5)

An electron source that generates an electron beam;
Scanning means for irradiating the sample with the electron beam and scanning two-dimensionally;
Detection means for detecting information carrier generated by the interaction between the electron beam and the sample in synchronization with the scanning means;
Signal processing means for converting the information carrier detected by the detection means into signal intensity;
Display means for displaying the signal intensity change obtained by the signal processing means as a two-dimensional image;
An electron beam comprising: designation means for designating a line analysis position on the two-dimensional image; and setting means for setting analysis points in the line analysis position designated by the designation means at unequal intervals. apparatus. 2. The electron beam apparatus according to claim 1, wherein the information carrier includes at least one of secondary electrons, reflected electrons, transmitted electrons, characteristic X-rays, and cathodoluminescence. When the setting means assumes that the signal strength change of the information carrier in the vicinity of a singular point in the line analysis position is approximated by a Gaussian distribution, the analysis is performed so that the change of the signal strength is substantially equidistant. 3. The electron beam apparatus according to claim 1, wherein the intervals between the points are set at non-uniform intervals. 4. The electron beam apparatus according to claim 1, further comprising an extracting unit that extracts the singular point from the line analysis position specified by the specifying unit. The extraction means uses the differential data of the intensity change data of the information carrier at the line analysis position to extract, as the singular point, an analysis point indicating a change with the greatest intensity change of the information carrier. The electron beam apparatus according to claim 1.

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