JPH06130005A - Analyzer - Google Patents

Abstract

PURPOSE:To prevent target dust from being lost and to reduce time for searching when analyzing the dust by connecting a fluorescent spectral microscope to an X-ray micro analyzer. CONSTITUTION:An X-ray micro analyzer performs spectral analysis of characteristic X rays 13 generated by applying electron beams 12 from an electron gun 11 to a sample 1 using a spectroscope. The fluorescent spectral microscope has the same light axis as that of the electron beams 12, selects excitation beams 22 from a mercury lamp 21 with a filter 23, and applies them to the sample 1 by a mirror 24. Fluorescence 25 generated by the sample 1 is detected by a detector 29 via a filter 26, a mirror 27, and an interference filter 28 and then is converted to fluorescent spectra. Holes are provided at each center of the mirror 24, the filter 26, and the mirror 27 and the electron beams 12 pass through the holes. A stage for mounting the sample 1 is controlled so that it moves automatically by a control part consisting of a computer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzer for analyzing dust and impurities in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In recent years, it has become more and more important to analyze the dust generated in the semiconductor manufacturing process and environmental dust, clarify the source, and remove the source as the semiconductor process becomes finer. Getting important.

Conventionally, this kind of dust analysis has been carried out by using an X-ray microanalyzer, a fluorescence spectroscopic microscope, etc. independently, so that when measuring the same unknown dust sample by different devices, It was difficult to measure the same place or the work was complicated. In addition, since the fluorescence spectroscopic microscope measures in the atmosphere, it is necessary to put the sample in a vacuum for analysis by the X-ray microanalyzer after performing the measurement with the fluorescence spectroscopic microscope.
At this time, there are problems that the sample moves and it is complicated to find the same location.

[0004]

As described above, in the conventional analyzer, when the dust is analyzed, the target dust is lost or it takes time to find it.
There was a problem that another dust was mixed in during the measurement.

The present invention solves the above problems,
It is an object of the present invention to provide an analyzer that does not lose the target dust, takes a long time to find out the dust, and does not allow another dust to be scattered during the measurement when the dust is analyzed.

[0006]

In order to solve the above-mentioned problems, the present invention provides an X-ray microanalyzer as a first analysis section, which has a second optical axis which is the same as the optical axis of the electron beam.
The fluorescence spectroscopic microscope as the analysis unit is combined and integrated, and the stage of the sample is automatically moved by computer control, and the moving direction of the stage is changed along the X-axis, Y-axis, and Z-axis until a series of measurement is completed. With a computer control unit that always moves only in a fixed direction with respect to the axis and theta axis, the error due to backlash is suppressed by detecting the current or voltage flowing to the pulse motor,
Further, each search system for searching a known sample similar to an unknown sample from results of an X-ray microanalyzer, a fluorescence spectroscopic microscope, etc. is integrated to construct one comprehensive search system.

[0007]

In the above structure, X as the first analysis unit
By combining a line micro-analyzer with a fluorescence spectroscopic microscope as a second analysis section having the same optical axis as the electron axis of the electron beam, unknown dust is separated from the first analysis section and the second analysis section. Can be quickly measured in the department,
X in the moving direction of the stage until a series of measurements is completed
By moving the axis, Y-axis, Z-axis, and θ-axis only in a fixed direction at all times, it is possible to measure the same point with high accuracy, and a known sample similar to an unknown sample from the results of X-ray microanalyzer, fluorescence spectroscopic microscope, etc. Since the respective search systems for searching for are integrated into one comprehensive search system to search for the one most similar to the unknown dust, the measurement performance can be surely improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the analyzer according to the present invention has a configuration in which an X-ray microanalyzer 10 as a first spectroscopic unit and a fluorescence spectroscopic microscope 20 as a second spectroscopic unit are combined.

That is, the X-ray microanalyzer 10 is
The spectroscope 14 is configured to disperse the characteristic X-rays (specific X-rays) 13 generated by irradiating the sample 1 with the electron beam 12 from the electron gun 11. Although not shown, this analyzer is provided with a mechanism for bringing the electron beam passage portion of the X-ray microanalyzer 10 into a vacuum state, and when driving the X-ray microanalyzer 10, the electron beam passage portion is in a vacuum state. It is said that On the other hand, when the fluorescence spectroscopic microscope 20 described later is driven, the vacuum state may be maintained, or the atmosphere may be opened.

Further, the fluorescence spectroscopic microscope 20 has the same optical axis as the electron beam 12 of the X-ray microanalyzer 10, and the excitation light 22 emitted from the mercury lamp 21 is selected by the filter 23 to obtain 404.7 nm and 435.8 nm. The sample 1 is irradiated with wavelengths of nm and 546.1 nm by the first mirror 24, and the fluorescence 25 generated from the sample 1 is excited by the excitation light cut filter 26 and the second
Detector 27 through mirror 27 and interference filter 28 of
It is composed of a system for detecting in (1) and converting into a fluorescence spectrum.

Here, the first mirror 24 is fixed at a predetermined position, and a hole is formed in the central portion so that the electron beam 12 can pass through this hole. In addition, the excitation light cut filter 26 and the second mirror 27 were fixed in this embodiment, a hole was opened in the center, and the electron beam 12 was allowed to pass through this hole. However, the excitation light cut filter 26 and the second mirror 27 may be manually or automatically removed from the optical path of the electron beam 12 except when used as a fluorescence microscope.

The first mirror 24 is fixed as described above so that the same sample 1 measured by the fluorescence spectroscopic microscope 20 can be immediately analyzed by the X-ray microanalyzer 10. It is desirable to have a structure in which a hole is formed to secure the optical path. However, the electron beam 12
If the optical axes of the excitation light 22 and the excitation light 22 can be made the same, the first mirror 24 may have a detachable structure.

FIG. 2 is a view conceptually showing the coordinates on the stage on which the sample 1 to be inspected is placed, and this stage is controlled so as to be automatically moved by a control unit composed of a computer. A method of controlling the movement of the stage by this control unit will be described below.

Now, the origin is set to O (0, 0), and the test sample is
Positions a, b, c of a, b, c are surrounded by O, P, Q, R, O
The origin O is determined so that it can be set inside. Furthermore
The procedure for storing the position of the origin O in the computer
First, move the stage to position X (x_x1, Y_x1) Manually
The position X is moved and stored in the computer. That
The x-axis and y-axis when moving from position X to origin O
There is no turning back in both directions, and always in the positive direction (x-axis,
Amount of movement | x _x ｜,
｜ y_x Move with |. Movement amount in this case | x_x |, |
y_x | Is the electric pulse used for x-axis and y-axis, respectively
To be greater than the motor backlash value
Set. The origin O is stored in the computer by the above procedure.
Let By doing this, the set origin O
The position and the optical axes of the electron beam 12 and the excitation light 22 are aligned with each other.
Let it hit.

Next, the position A (x _A , y _A ) of the sample a to be inspected
The same method as in the case of aligning the origin O is also stored in the computer. First, position A ₁ (x _A1 ,
The position A ₁ is stored in the computer by manually moving the stage to y _A1 ), but x _A −x _A1 > 0, y _A −y _A1 >
The position A is stored by moving the stage from the position A ₁ which is 0 to the position A in both the x-axis and the y-axis in the positive direction without moving in the negative direction. Also at this time, the movement amount (x _A −
The values of x _A1 ) and (y _A −y _A1 ) are set to be larger than the backlash values of the x-axis and y-axis electric pulse motors, respectively. Then, by setting the stage at this position A, the electron beam 12 and the excitation light 2
The optical axis of 2 coincides with this position A.

Similarly, the positions B and C of the test samples b and c are measured.
To set. Then, it is stored in the computer. Note that the Z-axis direction (the direction perpendicular to the plane of the paper in FIG. 2 that is used for vertical movement and focusing of the sample to be tested) and the θ direction (indicating the rotation direction around the Z-axis) are also always fixed if necessary Move to.

The moving directions of the x-axis, the y-axis, the z-axis and the θ rotation may be freely changed according to the position of the test sample on the plane constituted by the x-axis and the y-axis. That is, in the above-described embodiment, the movement is always performed in the positive direction, but the x-axis may be always moved in the positive direction and the y-axis may be always moved in the negative direction. The same applies to the z axis and the θ direction.

Next, a method for moving the stage to the positions A, B and C of the test samples a, b and c stored in the computer during actual measurement will be described. Figure 3
It shows the fluctuation of the current flowing through the pulse motor when the pulse motor used to move the stage is changed from the reverse rotation direction to the normal rotation direction (or from the normal rotation to the reverse rotation). In FIG. 3, the fluctuation of the current during reverse rotation is shown from point T to point U, and the point is switched to forward rotation. That is, the fluctuation of the current at the time of backlash is shown from the point U to the point V, the stage does not move, and the pulse motor has a point T-U.
It rotates in the forward rotation direction, which is the opposite direction to the space. Then, the movement of the stage is started at the point V, and the stage is also moved between the points V and W according to the rotation scale of the pulse motor. In the present example, the current value M (during forward rotation) in FIG. 3 was 3 amps, and the current value N (during backlash) was 0.84 amps. It is also possible to confirm the reverse rotation, backlash, and forward rotation by the fluctuation of the pulse motor voltage.

In order to automatically and reproducibly move to the position of the sample to be inspected, the stage is moved from an arbitrary position to position X'to determine the origin O of the stage in FIG. At this time, the position X ′ (x _x ′, y _x ′) is
Although it corresponds to the numerical value stored in the computer, it is not at the position X initially determined. In order to accurately determine the position X from the position X ', the phenomenon of current change of the pulse motor shown in FIG. 3 is used. Explaining the x-axis, the point U in FIG.
Corresponds to the point x _x ′, and the point V also corresponds to the point x _x of the regular x coordinate. The state of the current flowing through the pulse motor is detected, and the point at which the current changes from small to large is taken as the x _x point on the x axis. The y-axis is determined similarly. X determined in this way
The stage is moved from the (x _x , y _x ) point to the position of the origin O (0, 0). This moving method is, as described above, always moved in the positive direction under the condition that the movement in the positive direction of the x-axis or the y-axis matches the positive rotation direction of the pulse motor, and the positive direction of the x-axis is changed. To | x _x |, to the positive direction of y-axis | y
_x | The moved point is set to the origin O (0, 0). And
The positions A, B, and C of the test samples a, b, and c are determined by the same procedure as when the origin O is determined.

In this way, in the stage automatically moved by the control unit composed of the computer, when the position of the sample a, b, c made of dust is stored in the computer, a micromotor for moving the stage is used. Backlash can be minimized for accurate alignment.

FIG. 4 shows the result of actual measurement by positioning the test sample as described above. FIG. 4 is a result of the fluorescence spectroscopic microscope 20 of the test sample a shown in FIG. 2. Similarly, the result of the X-ray microanalyzer 10 was measured according to a conventional measuring method, and Ti and C were detected as detection elements.
1, Ba, Ca, K, etc. were obtained. In FIG. 4, the horizontal axis represents wavelength and the vertical axis represents peak intensity for each wavelength. The vertical axis is an enlarged display of the spectrum actually obtained. The solid line is the test sample a, and the dotted line (1)
The spectrum is measured by scraping off the sole of clean shoes used in a clean room, and the one-dot broken line (2) is measured for human skin.

In this analyzer, a plurality of results obtained by spectrally analyzing the characteristic X-rays 13 generated by irradiating the sample 1 with the electron beam 12 by the X-ray microanalyzer 10 are stored, and the known results accumulated so far are known. A first search system that searches and displays a spectral result similar to the spectral result of an unknown sample measured by the X-ray microanalyzer 10 from the spectral results of the sample, and generates by irradiating the sample 1 with the excitation light 22. A plurality of results obtained by dispersing the fluorescence 25 to be obtained by the fluorescence spectroscopic microscope 20 are accumulated, and from the spectral results of the known samples accumulated so far,
A second search system for searching and displaying a spectral result similar to the spectral result of the unknown sample measured by the fluorescence spectroscopic microscope 20 is provided.

FIG. 4 shows the result of selecting the spectrum closest to the test sample a by the second search system from the spectra of 26 known samples. In addition, elements previously detected by the X-ray microanalyzer 10,
First search system for selecting a known sample closest to the test sample a by comparing constituent elements of 15 known samples measured by the X-ray microanalyzer 10 based on Ti, Cl, Ba, Ca, K Searched for clean shoe soles, grating paint materials, cassette cases, etc. Of the known samples, the sample a is a sample collected in a clean room, and is characterized by containing Ba element. Therefore, the sample a is likely to have clean shoe soles. However, by further combining the results of the first and second search systems, it can be seen that the clean shoe sole applies as a common known sample. In this example, since the sample a to be tested was characterized by containing Ba element, X
Although it was possible to narrow down considerably with the X-ray microanalyzer 10, when the test sample is an organic material, the X-ray microanalyzer 10 can mainly detect only C, O, N and the like as elements. Therefore, no distinction can be made between organic materials. However, by using the fluorescence spectroscopic method together, a clearer search can be performed from the spectrum, chromaticity diagram and the like.

An example of the implementation of the search system is as described above. In the first search system using the X-ray microanalyzer 10, as the data of the known sample, a plurality of elements having the constituent element names registered from the sample name and the measurement result of the X-ray microanalyzer 10 in the order of high X-ray intensity were used. In addition, a plurality of elements were selected in descending order of X-ray intensities of constituent elements from the results of measurement of unknown samples.
Then, a known sample closest to the constituent element name of the unknown sample and each X-ray intensity (relative intensity) was selected. As a criterion for selection, the one with the highest degree of agreement is 1, 2, 3, ...
And decided the rank.

Rank 1: Constituent elements and their X-ray intensities are almost the same Rank 2: Constituent elements are almost the same, X-ray intensities are different Rank 3: Of the constituent elements, several elements are relatively the same. The standard of is set in advance, and the rank is displayed at the same time in the search result. From this, the degree of coincidence could be determined.

On the other hand, the basic concept of the second retrieval system based on the fluorescence microscopic method is the same as that of the X-ray microanalyzer 10. As a criterion for selection, the rank was determined in the same manner as the X-ray microanalyzer 10 from the degree of coincidence of the spectrum, the degree of coincidence of the chromaticity display, or both coincidences.

In this analyzer, known samples selected at the same time by both search systems based on known samples of ranks 1 to 2 in the degree of coincidence between the first search system and the second search system, respectively. We also constructed a comprehensive search system that uses the search results of unknown samples. With this comprehensive search system, X-ray microanalyzer and fluorescence spectroscopic microscopy were individually measured, and the results of the automatic search were finally searched by the comprehensive search system and displayed as the search results for unknown samples. Of course, a single search result by the X-ray microanalyzer 10 and the fluorescence spectroscopic microscope 20 can also be displayed.

In the above embodiment, the case where the fluorescence spectroscopic microscope is used as the second spectroscopic unit has been described, but it is also possible to use a laser light spectroscopic microscope instead of the fluorescence spectroscopic microscope.

[0029]

As described above, according to the present invention, the first beam splitting unit for splitting the generated characteristic X-rays by irradiating the sample with the electron beam, and the electron beam and its light are provided on the same sample. By combining with a second spectroscopic section that disperses the generated luminescence by irradiating the same axis of light, unknown dust is required in the first analysis section and the second analysis section. It can be measured quickly without. In addition, the moving direction of the sample stage is
By moving the X-axis, Y-axis, Z-axis, and θ-axis only in a constant direction until a series of measurements is completed, the same point can be measured with high accuracy. Further, the first spectroscopic section and the second spectroscopic section
Search for known samples that are similar to unknown samples from the results of the spectroscopic part of the system, and integrate each search system to construct one comprehensive search system to find the most similar sample to unknown dust. Therefore, the measurement performance can be surely improved. As a result, in particular, a fixed search operation for a sample such as an organic substance can be easily performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an analyzer according to an embodiment of the present invention.

FIG. 2 is a diagram showing coordinates on a sample stage of the analyzer.

FIG. 3 is a diagram showing a current fluctuation when the pulse motor for stage movement of the analyzer is converted from reverse rotation to normal rotation.

FIG. 4 is a diagram showing a search result by a fluorescence spectroscopic microscope of the analyzer.

[Explanation of symbols]

 1 sample 10 X-ray microanalyzer 11 electron gun 12 electron beam 13 characteristic X-ray 14 X-ray spectroscope 20 fluorescence spectroscopy microscope 21 mercury lamp 22 excitation light 23 filter 24 first mirror 25 fluorescence 26 excitation light cut filter 27 second mirror 28 interference filter 29 detector

Claims (3)

[Claims] 1. A first spectroscopic section that disperses the generated characteristic X-rays by irradiating a sample with an electron beam, and irradiates the same sample with light having the same optical axis as the electron beam. An analysis device comprising: a second spectroscopic unit that disperses the generated luminescence. 2. A stage which automatically moves a sample under computer control, and a true amount of movement by detecting backlash from a change in current or voltage flowing through a pulse motor for driving the stage when sequentially measuring a plurality of samples. Until the series of measurement of the sample on the same stage is completed, the moving direction of this stage is changed to X-axis, Y-axis, Z-axis.
The analysis device according to claim 1, further comprising a control unit that always moves in a constant direction with respect to the axis and the θ axis. 3. A plurality of results obtained by dispersing a characteristic X-ray generated by irradiating a sample with an electron beam by a first spectroscopic unit are accumulated, and among the spectral results of known samples accumulated so far, ,
A first search system that searches for and displays a spectral result similar to the spectral result of an unknown sample measured by the first spectroscopic unit, and the luminescence generated by irradiating the sample with light is dispersed by the second spectroscopic unit. A plurality of results obtained by the above are accumulated, and a spectral result similar to the spectral result of the unknown sample measured by the second spectroscopic unit is searched and displayed from the spectral results of the known samples accumulated so far. 2. The analysis apparatus according to claim 1, further comprising: a search system according to claim 1, and a comprehensive search system that searches for a known sample closest to the unknown sample based on the results obtained from the first and second search systems.