JP2002062270A - Method of displaying face analysis data in surface analyzer using electron beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily compare an element distribution map with a spatial extent of an X-ray generating area, and accurately grasp resolution for the element distribution map. SOLUTION: In this face analysis data displaying method in a surface analyzer using an electron beam having means 9, 10 for making spectral diffraction and detecting a characteristic X-ray generated in a surface of a sample 6 irradiated with the electron beam, and a display 17 for displaying, as the element distribution map, a characteristic X-ray counted value provided two- dimensionally by scanning the electron beam on a sample stage 7 two- dimensionally, the spatial extent of the plane-directional generating area of the characteristic X-ray found preliminarily theoretically or by observation is displayed on the element distribution map in the display to be superposed at the same time with a conformed scale. Both of them are accurately compared intuitively, thereby determines the resolution on the element distribution map accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface analysis data display method capable of grasping an accurate spatial resolution of an element distribution map on a sample surface obtained by a surface analyzer using an electron beam.

[0002]

2. Description of the Related Art Conventionally, an electron probe microanalyzer (EPMA) for irradiating a sample surface with a finely focused electron beam and performing elemental analysis on the sample surface, and a scanning electron microscope (analysis SEM) having an analysis function, have been used. In a surface analyzer using an X-ray, an electron beam or a sample mounting table is digitally scanned, and characteristic X-rays generated from the sample surface are converted into a wavelength-dispersive X-ray.
X-ray spectrometer (EDS)
DS), the X-ray count value obtained for each pixel by digital scanning is stored in a storage device, and the X-ray count value of each pixel is classified into levels of an arbitrary width to obtain an arbitrary color or An element distribution map on the sample surface is obtained by designating monochrome shading or the like and displaying it two-dimensionally.

[0003] At this time, the spatial spread (X-ray diffusion region) of the X-ray generation region is separately obtained using Monte Carlo simulation or the like, and the spatial resolution on the element distribution map obtained as described above is obtained. That is, it is estimated whether the blur of the boundary region of the element distribution map is caused by the expansion of the X-ray generation region based on the expansion of the electron beam (X-ray diffusion region) or the gradient of the element distribution.

[0004]

As described above, when an electron beam is incident on a sample material, the electrons and the atoms constituting the material repeatedly collide and scatter, and the characteristic X-ray generation region generated in the process is also a space. It has a natural spread. The spatial expansion of the characteristic X-ray generation region largely depends on the energy of the electron beam to be irradiated and the composition of the sample.

A method for theoretically estimating the spatial spread of the characteristic X-ray generation region is conventionally known as described above, but the value is displayed on a surface analyzer as a display result as a measurement result of the sample. Does not directly relate to the element distribution map displayed on the display means, and does not correspond to the element distribution map on the display means whose display scale is specified, and is a theoretical value of the spatial spread of the characteristic X-ray generation region. Is difficult to compare with the element distribution map, and it is extremely difficult to estimate the exact resolution in the element distribution map.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem in the surface analysis data display method in the conventional surface analysis apparatus, and the surface analysis data such as an element distribution map and the spatial expansion of the X-ray generation region ( X-ray diffusion region), and it is possible to easily grasp the accurate resolution of surface analysis data such as an element distribution map.
An object of the present invention is to provide a surface analysis data display method in a surface analysis device.

[0007]

In order to solve the above-mentioned problems, the present invention provides a means for spectrally detecting and detecting characteristic X-rays generated from a sample surface irradiated with an electron beam, and a two-dimensional electron beam or sample stage. A display means for displaying a characteristic X-ray count value obtained two-dimensionally as an element distribution map by scanning in a surface analysis apparatus using an electron beam. Means are characterized in that the spatial spread of the generation region in the plane direction of the characteristic X-ray, which has been theoretically or actually measured in advance, is simultaneously superimposed and displayed on the element distribution map in accordance with the scale. .

As described above, the spatial extent of the X-ray generation region, which is theoretically or actually measured, is simultaneously displayed in accordance with the scale of the element distribution map showing the result of the surface analysis of the sample, so that both are displayed. The comparison can be made intuitively and accurately. The blurred portion of the element distribution map may be due to the gradient (spread) of the element distribution in the sample, or may be spread due to the spread of the X-ray generation region (X-ray diffusion region). Can be quantitatively determined, and the resolution on the element distribution map can be accurately grasped.

[0009]

Next, an embodiment will be described. FIG. 1 is a block diagram showing the overall configuration of an electron probe microanalyzer (EPMA) to which an embodiment of a method for displaying surface analysis data in a surface analyzer using an electron beam according to the present invention is applied. In FIG. 1, 1
Is an electron gun of EPMA, 2 is a focusing lens, 3 is an objective lens, 4 is a scan coil, 5 is an optical microscope, 6 is a test sample for surface analysis, 7 is a sample stage including a driving device,
8 is an electron beam scanning device for driving the scan coil 4, 9 is a WDS spectral crystal, 10 is an X-ray detector, 11 is a driving device of the spectral crystal 9 for WDS wavelength scanning, and 12 is an X-ray detector 10
A storage device for the X-ray intensity data obtained by the X-ray signal processing device 12, a driving device for the sample stage 7, an electron beam scanning device 8, and a spectral crystal driving device Reference numeral 11 denotes an interface, 15 denotes an arithmetic unit for controlling the EPMA device and various processes of collected data, 16 denotes a database for storing data necessary for obtaining the spatial expansion of the X-ray generation area, and 17 denotes an arithmetic unit 15 A display device 18 capable of superimposing and displaying the X-ray intensity distribution data of the element subjected to the predetermined processing and the spatial expansion of the X-ray diffusion region, etc., is an input device such as a mouse and a keyboard.

Next, the EPMA configured as described above
Will be described with reference to the flowchart shown in FIG. The electron beam emitted from the electron gun 1 is narrowed down by the focusing lens 2 and the objective lens 3 and irradiated onto the sample 6 to generate characteristic X-rays from the sample surface. The characteristic X-rays from the sample surface are separated by the spectral crystal 9 and detected by the X-ray detector 10, and the detected X-ray signal is processed by the X-ray signal processor 12 to obtain X-ray intensity data.

At this time, X-ray intensity distribution data (element distribution map) of the elements on the sample surface is obtained by scanning the electron beam two-dimensionally using the scan coil 4 or scanning the sample stage 7 two-dimensionally. Data) can be collected (step S1). X-ray intensity distribution data is stored in a storage device
13 and subjected to predetermined processing by the arithmetic unit 15 and displayed on the display device 17 as an element distribution map. Then, at this time, the spatial spread of the X-ray generation area,
That is, it is determined whether or not the X-ray diffusion region is to be superimposed on the element distribution map (Step S2). When the X-ray diffusion region is to be superimposed and displayed, the acceleration voltage of the electron beam and the sample when the X-ray intensity distribution is measured are determined. When data on the X-ray diffusion corresponding to the composition is stored in the database 16, the data is read out (steps S3 and S4), and the display method of the X-ray diffusion region and the display conditions of the element distribution map are designated (step S3). (S7, S8), the X-ray diffusion region and the element distribution map are superimposed and displayed on the display device 17 (step S7).
9).

On the other hand, when data relating to X-ray diffusion is not stored in the database 16, the operation starts to calculate the size of the X-ray diffusion region. In this operation step, first, a diffusion region calculation condition is specified (step S5), and an X-ray diffusion region is calculated based thereon (step S5).
6). The size of the X-ray diffusion region can be calculated by a method such as Monte Carlo simulation or by performing a line analysis on a bonded surface where different materials are bonded.
There is a method of obtaining from actual measurement values.

FIG. 3 is a diagram showing an embodiment in which an X-ray diffusion region is obtained from the intensity distribution of generated X-rays in the plane direction when the electron beam diameter can be ignored by Monte Carlo simulation.
Is the electron beam irradiating the surface of the sample 22, 23 is the trajectory of the electron beam in the cross section of the sample 22, and 24 is the X-ray generation intensity distribution corresponding to the electron beam trajectory on the horizontal axis. It is shown as a position (distance). This X-ray intensity distribution can be determined by giving the acceleration voltage of the electron beam, the composition of the substance, and the average density. The mode shown in FIG. 3 is a mode in which the electron beam diameter is ignored. However, when the electron beam diameter is taken into consideration, the electron beam diameter may be added to the center of the diffusion region. Note that the distribution mode shown in FIG. 3 is a distribution mode viewed from one direction, and the spread of X and Y in each plane direction is obtained by rotating the distribution mode of FIG. 3 in the plane direction. .

FIG. 4 is an explanatory view showing a mode of obtaining the spread of the X-ray generation region (X-ray diffusion region) from the X-ray intensity data obtained by linearly analyzing the bonding surface where different materials are bonded. In FIG. 4, reference numeral 31 denotes an actually measured X-ray intensity data curve obtained by the line analysis, and reference numeral 32 denotes an X-ray intensity distribution curve obtained by conversion from the line analysis X-ray intensity data curve 31. The X-ray intensity distribution curve 32 is obtained as follows. First, the X-ray intensity data curve 31 obtained by the line analysis is vertically divided into an arbitrary division number k. The i-th X-ray intensity of the division is Fi,
Assuming that the i-th intensity of the intensity distribution to be obtained is fi, fi can be obtained from the relationship of the following equation (1). Fi = (Σfi) / (Σfi) (1) Here, the sum range of the sum symbol Σ of the numerator is i = 1 to i, and the sum range of the sum symbol Σ of the denominator. Is i = 1 to k.
That is, the intensity distribution curve 32 is a line analysis X-ray intensity data curve.
Calculated as the derivative of 31.

The data of the X-ray diffusion region obtained by the calculation method shown in FIG. 3 or the data of the X-ray diffusion region obtained based on the line analysis data (X-ray intensity distribution data) shown in FIG. , The relationship between the distance on the horizontal axis and the intensity may be represented by a combination of numerical values and used as it is,
Alternatively, only parameters of a necessary function may be stored by approximation with an error function and used. Further, the data of these X-ray diffusion regions may be obtained in advance by calculation and stored in the database 16 to read and use data meeting the conditions, or may be calculated according to the measurement conditions of the map data. It may be used.

Next, a method of superimposing the element distribution map and the X-ray diffusion region on the display device 17 will be described. FIG. 5 is a diagram showing a mode in which an X-ray diffusion region (expansion of the X-ray generation region) represented by a concentric circle is superimposed and displayed on the element distribution map. In the X-ray diffusion region represented by the concentric circles, for example, the innermost side of the concentric circles indicates the electron beam diameter, and from the next circle toward the outside, from the maximum value of the X-ray intensity distribution obtained in the manner shown in FIG. Each time the intensity decreases by 20%, the radius is changed and displayed. It should be noted that the scale of the X-ray intensity distribution and the scale of the element distribution map indicated by concentric circles are displayed together. The position at which the concentric circle representing the X-ray generation intensity distribution is displayed can be appropriately designated or dragged to an appropriate position using a pointing device such as a mouse.

The element distribution map and the X-ray diffusion region (X
When the intensity distribution of the element distribution map is displayed as a line profile as shown in FIG. 6 in addition to the concentric circle as shown in FIG. Also, it is preferable that the X-ray intensity distribution curve as shown in FIG. 4 be represented as an intensity distribution profile and displayed by being superimposed on the element distribution map.

In the EPMA shown in FIG. 1, the characteristic X-ray generated from the sample surface is spectrally detected using WDS, but the characteristic X-ray is detected using an EDS detector instead of WDS. The present invention can be similarly applied to a device configured to detect the image, and similar superimposed display can be performed. Further, the present invention can be similarly applied to not only EPMA but also other surface analyzers such as a scanning electron microscope having an analysis function.

[0019]

As described above with reference to the embodiments, according to the present invention, X-rays obtained theoretically or by actual measurement in accordance with the scale of an element distribution map for displaying the results of surface analysis of a sample. Since the spatial spread of the generation region (X-ray diffusion region) is simultaneously displayed in an overlapping manner, the element distribution map and the spatial spread of the X-ray generation region can be intuitively and accurately compared, and the It is possible to accurately grasp the resolution on the distribution map.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an EPMA to which a surface analysis data display method in a surface analysis apparatus according to the present invention is applied.

FIG. 2 is a flowchart for explaining an operation of the EPMA shown in FIG. 1;

FIG. 3 is a diagram showing a mode of obtaining a spatial spread (X-ray diffusion region) of an X-ray generation region from a generated X-ray intensity distribution when an electron beam diameter can be ignored by Monte Carlo simulation.

FIG. 4 is a diagram showing a mode of obtaining a spatial spread (X-ray diffusion region) of an X-ray generation region from measured data obtained by linear analysis of a bonding surface where different materials are bonded.

FIG. 5 is a diagram showing an aspect in which an X-ray diffusion region represented by a concentric circle is displayed on an element distribution map.

FIG. 6 is a diagram showing an aspect in which an X-ray diffusion region represented by an X-ray intensity distribution profile is superimposed and displayed on an element distribution map.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Focusing lens 3 Objective lens 4 Scan coil 5 Optical microscope 6 Sample 7 Sample stage 8 Electron beam scanning device 9 WDS spectral crystal 10 X-ray detector 11 Spectrum crystal driving device 12 X-ray signal processing device 13 Storage device 14 Interface 15 Computing unit 16 Database 17 Display unit 18 Input unit

Claims (1)

[Claims] 1. A means for spectrally detecting and detecting characteristic X-rays generated from the surface of a sample irradiated with an electron beam, and a characteristic X-ray meter obtained two-dimensionally by scanning an electron beam or a sample stage two-dimensionally. In a surface analysis data display method in a surface analyzer using an electron beam having a display means for displaying a numerical value as an element distribution map, the element distribution map display means, on an element distribution map, in advance by theoretical or actual measurement A surface analysis data display method characterized in that the spatial expansion of the generated region in the plane direction of the characteristic X-rays is displayed at the same time while being scaled.