JPH07128259A - Method for x-ray mapping analysis - Google Patents

Abstract

PURPOSE:To detect an element boundary with the resolution finer than the dimension of a primary beam. CONSTITUTION:A sample stage is scanned in lattice at a feed finer than the width of primary beams 3-6 for exciting an X-ray to form first and second mapping data having X-ray intensities in each point as values. The form and dimension of the primary beam is converted into the dimension of the mapping data, and a beam template in which the part receiving the beam emission is set to a value of 1 and the part receiving no beam emission to a value of 0 is formed. From the intensity distribution 8, the background intensity 9 is taken as a threshold, and the second mapping data is superposed on the beam template in the place where the value of the first mapping data is lower than the threshold. The second mapping data in the part where the value of the beam template is 1 is rewritten to 0. This is performed in all measuring points, whereby the data near a natural boundary 1 is provided in the second mapping data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mapping analysis method for irradiating a sample with an electron beam or X-ray and detecting the X-ray excited by the sample to investigate the distribution state of elements. is there.

[0002]

2. Description of the Related Art Conventionally, an electron beam or X-ray irradiating a measurement sample
With respect to the dimensions of the primary beam such as a line, it is not possible to detect the boundaries of elements with a finer resolution, and the detected results are directly used as mapping data, and the X-ray intensity threshold value is set. Mapping data was output by simply deleting the data.

[0003]

However, according to the conventional method, as shown in the X-ray intensity distribution 8 at the cross section 7 in FIG. 1, a threshold value for detecting 1 which is the original element boundary can be obtained. However, there is a problem that a boundary line is generated in the boundary 1 of the sample depending on the situation.

[0004]

SUMMARY OF THE INVENTION The present invention provides an X-ray mapping apparatus capable of recognizing the shape and size of a primary beam for exciting X-rays: 1. Sample stage with a finer feed than the size of the primary beam Are scanned in a grid pattern, and the X-ray intensity of the element of interest is detected at each position.

2. Using the X-ray intensity as a value, two identical two-dimensional array data in which the measurement positions are arranged in a matrix are created and used as the first and second mapping data. 3. Convert the shape and size of the primary beam into the size of the mapping data, and create a beam template of a two-dimensional array in a rectangle containing the primary beam. In the beam template, the part irradiated with the primary beam is 1, and the part not irradiated is 0.

4. The background intensity of the element of interest is recognized from the intensity distribution in the first mapping data, and the value is used as the threshold value for detecting the element of interest. 5. When the X-ray intensity of the first mapping data is below the threshold value, the first mapping data and the beam template are superposed, and the second mapping data in which the value of the beam template overlaps with 1 is rewritten to 0, This is done at all measuring points.

By the above procedure, the boundary of the element of interest can be detected in the second mapping data with a resolution finer than the size of the primary beam.

[0008]

In the X-ray mapping apparatus which operates as described above, when the sample stage is moved finer than the size of the primary beam and the primary beam moves from outside the boundary of the element of interest to within the boundary, When the edge of the next beam and the boundary line overlap with each other, the X-ray of the element of interest can be detected even if only slightly. At this time, the center of the primary beam has not reached the boundary yet, and it can be said that the center of the primary beam is outside by about ½ of the beam width. At this time, if the shape and size of the primary beam are known, it is possible to recognize where the original boundary is. The shape and size of the primary beam are converted into the size of the mapping data, and a beam template for defining the range irradiated with the primary beam is created.
For the beam template, a value of 1 is set within the primary beam irradiation range, and a value of 0 is set otherwise. The portion where 0 is set indicates that the primary beam is not emitted and there is no information on the position. At the measurement location where the X-ray of the element of interest could not be detected, the element of interest does not exist in the area 1 in the beam template, and the mapping data at the location where this area and the mapping data overlap can be replaced with 0.

By the above procedure, the resolution can be made smaller than the size of the primary beam in the boundary detection of the element of interest.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 3 shows an example of an X-ray mapping apparatus used in the present invention. The sample 25 is irradiated with the primary beam from the primary beam generator controlled by the apparatus controller.
Scan 4 forward, backward, left and right. In FIG. 1, X-rays are used for the primary beams 3 to 6 in the region containing the element of interest 1 and
The sample stage is scanned in a grid pattern with a feed smaller than the width of the next X-ray beam, and the X-ray intensity of the element of interest is detected at each position. To scan in a grid pattern means to move from the upper left corner to the right, and when it reaches the end, move down one step and scan again from the left to the right, and so on.

Using the X-ray intensity as a value, two identical two-dimensional array data in which the measurement positions are arranged in a matrix are created and used as the first and second mapping data. The two-dimensional array data is an information group in which position information is arranged in rows and columns and intensity data at each measurement position is used as a value. For example, the data is as follows.

Data [0] [0]: 1st intensity from the left, 1st intensity from the top Data [0] [1]: 2nd intensity from the left, 1st intensity from the top ... Data [0] [1] : 1st intensity from the left and 2nd intensity from the top On the other hand, convert the shape and dimensions of the primary beam obtained using a photosensitive film into the dimensions of the mapping data. For this purpose, as shown in FIG. 2, a beam template 10 having a rectangular two-dimensional array including the primary beam is created. In the beam template 10, a portion 12 irradiated with the primary beam has a value of 1, and a portion 11 not irradiated with the beam has a value of 0. The details of the beam template are shown in FIG. The beam shape and dimensions are shown in which the part irradiated with the primary beam is 1 (black) and the part not irradiated is 0 (white). If the beam shape is a perfect circle and the diameter is 100 μm, the mapping data shows 10 × 10 grids (100 μm) when the measurement is performed with a horizontal and vertical feed of 10 μm.
A rectangle including a circle of m) is created and 1/0 data is embedded. The result is used as a beam template. The beam template is formed using the photosensitive film as follows.

The photosensitive film is irradiated with the primary beam to expose it to light. Draw a grid line on the photosensitive film and recognize 1/0. Recognize the number of grids and the size of each grid. From the intensity distribution 8 in the first mapping data in FIG. 1, the X-ray intensity threshold value for detecting the element of interest is determined. Normally, the background intensity 9 is used as the threshold value.

At a place where the X-ray intensity of the first mapping data is below the threshold value, the second mapping data and the beam template are superposed, and the second mapping data in which the value of the beam template is 1 is overlapped with 0. , And do this at all measurement points. The above will be described with reference to FIG. An example of performing this processing with one-dimensional data will be described.
The beam is assumed to be a perfect circle. When the element of interest 1 placed on the base material 50 in FIG. 5 is scanned and measured from left to right, the relationship between the beam center position and the detected X-ray intensity is as follows. Since the primary beam is not a point,
As shown in the figure, the detected X-ray intensity of the primary mapping data cannot discriminate clearly the boundary between the target element 1 and the base material 50 because the values do not change discretely.

By the way, in the state immediately before the primary beam impinges on the element of interest as shown in FIG. 5, the detected X-ray intensity is the background intensity (the detected X-ray intensity when the primary beam is irradiated on the base material). Match. At this time, since the primary beam has not yet been applied to the element of interest, the portion corresponding to the primary beam width, that is, the beam template width can be regarded as the background (base material). Therefore, the secondary mapping data that matches the beam template is set to 0 data, and the final secondary mapping data in FIG. 5 is obtained. By the procedure described above, data close to the original boundary line of the target element 1 can be obtained as the second mapping data.

Example 2 Even when an electron beam is used as the primary beam in Example 1 to detect X-rays from a sample, the same procedure as in Example 1 is used with a resolution finer than the size of the electron beam. , The sample boundary can be recognized.

[0017]

INDUSTRIAL APPLICABILITY The present invention brings a great effect to the investigation of the size of a minute defect and the dimension measurement in the X-ray mapping analysis targeted for electronic parts which have been miniaturized in recent years. Especially when X-rays are used for the primary beam, it is very costly to focus the primary X-rays to 50 microns or less,
It was very difficult to obtain a higher mapping resolution, but by using the present invention, a high resolution mapping image can be obtained at low cost.

According to the present invention, in a minute portion analysis such as a minute foreign matter inspection or a material segregation analysis, a beam size that can be prepared at a low cost, a finer distribution can be confirmed, and it is not necessary to collimate the beam more than necessary. Since a suitable detection intensity can be obtained, the measurement time can be shortened, and a number of effects such as a more inexpensive system can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a method for improving the horizontal resolution of mapping data according to the present invention.

FIG. 2 is a schematic diagram of a beam template.

FIG. 3 is a schematic diagram of an X-ray mapping apparatus used in the present invention.

FIG. 4 is a detailed view of a beam template.

FIG. 5 is a mapping data diagram when a sample is scanned in a one-dimensional direction.

[Explanation of symbols]

1 element of interest 2 locus of center point of primary beam when X-ray intensity matches background intensity 3 primary beam for exciting X-ray 4 primary beam for exciting X-ray 5 primary beam for exciting X-ray 1 Next beam 6 Primary beam that excites X-rays 7 X-ray intensities Positions when 8 and 9 are detected 8 X-ray intensity 9 X-ray background intensity 10 Beam template

Claims (2)

[Claims] 1. An excitation radiation source for irradiating a sample with a primary beam to excite X-rays, a controllable sample stage operable at least in front, back, left and right directions, and X-ray detection for detecting the X-rays from the sample. In an X-ray mapping apparatus having a unit and a data processing unit that performs data processing, The sample stage is scanned in a grid pattern with a feed smaller than the size of the primary beam, and the X-ray intensity of the element of interest is detected at each position. 2. Using the X-ray intensity as a value, two identical two-dimensional array data in which the measurement positions are arranged in a matrix are created and used as the first and second mapping data. 3. The shape and dimensions of the primary beam are converted into the dimensions of the mapping data, and in the rectangle containing the primary beam,
Create a two-dimensional array of beam templates. In the beam template, a portion irradiated with the primary beam is 1, and a portion not irradiated is 0. 4. The background intensity of the element of interest is recognized from the intensity distribution in the first mapping data, and the value is used as the threshold value for detecting the element of interest. 5. The second mapping data in which the first mapping data and the beam template are overlapped with each other at a position where the X-ray intensity of the first mapping data is below a threshold value, and the value of the beam template overlaps with 1. Is rewritten to 0 and this is performed at all measurement points. An X-ray mapping analysis method that can detect the boundary of the element of interest on the second mapping data with a resolution finer than the dimension of the primary beam, which is formed by the above procedure. 2. The X-ray mapping analysis method according to claim 1, wherein the primary beam is an X-ray beam.