JP6857449B2 - X-ray analyzer - Google Patents

Description

The present invention is an analyzer that irradiates a sample with an electron beam, detects an X-ray signal or the like generated from the sample while linearly scanning the sample stage on which the sample is placed, and obtains a signal intensity on the scanning line, particularly. Regarding electron probe microanalyzer (EPMA).

As a scanning method for EPMA ray analysis to obtain X-ray intensity while linearly scanning an electron beam in an arbitrary direction on a sample, a beam scanning method in which the sample stage is fixed and the electron beam is scanned, and an electron beam are fixed. Then, there are two methods of the stage scanning method of scanning the sample stage. The beam scanning method is mainly used when the scanning area is several tens of μm or less. The stage scanning method is used when the scanning region is wide, and it is possible to obtain X-ray intensity in a linear region of about several mm.

Since feed screws, gears, and the like are used in the scanning mechanism of the sample stage, these backlashes may become a problem when scanning the sample stage. In addition to line analysis, surface analysis (two-dimensional mapping) is another EPMA analysis method that detects X-ray signals while scanning the sample stage, but in the case of surface analysis, the scanning direction of the sample stage is always constant. Therefore, the back crash problem is solved by driving the sample stage in a direction that is not affected by the back crash and incorporating control for removing the back crash at a fixed timing.

As a method of solving the backlash problem that occurs when the sample stage is moved in an arbitrary direction, the amount of backlash corresponding to the change in the sample stage moving direction is obtained in advance, and when the sample stage is moved, the sample stage is moved. There is a method of correcting backlash by adding the amount of backlash to the movement distance. In this method, the observation field of view on the sample can be accurately moved to a desired position (see Patent Document 1).
Japanese Patent Application Laid-Open No. 8-129985

In the stage scanning EPMA line analysis, when the scanning direction of the sample stage is the direction affected by backlash, the sample stage does not substantially move immediately after the start of stage scanning (analysis start). At this time, the interval for acquiring the X-ray signal (the interval between the sample stage position for acquiring a certain X-ray data and the sample stage position for acquiring the next X-ray data. Step size) is set larger than the backlash amount. If so, the effects of backlash are almost negligible. On the other hand, when the interval for acquiring the X-ray signal is set smaller than the backlash amount, the detection position (sample stage position) data attached to the X-ray signal detected before the sample stage starts to move is actually Since the sample stage position of the sample is not reflected, there is a problem that accurate line analysis data cannot be obtained.

As an example, FIG. 6 shows the results of line analysis of a sample in which the concentration of a certain element changes continuously at a constant rate. The vertical axis is the intensity of the X-ray signal, and the horizontal axis is the moving distance of the sample stage. Here, the interval 60 of each X-ray signal data corresponds to the step size. If there is no backlash effect and data is obtained in which the X-ray intensity increases at a constant rate with movement, as shown by a series of points in FIG. 6 (a), there is an effect of backlash. In this case, the data is as shown in FIG. 6 (b). Section 70 in FIG. 6B is a section in which the stage did not actually move immediately after the start of analysis, and since the four data in this section were actually acquired at the same sample stage position, the X-ray intensity. It can be seen that the detection position data is stepped forward and does not reflect the correct sample stage position, even though they are the same.

Further, due to the influence of backlash, the line analysis end position on the sample deviates from the preset line analysis end position. As a result, in line analysis (continuous line analysis) that scans on a plurality of continuous straight lines (continuous straight lines such that the end point of the first straight line and the start point of the second straight line are at the same position), the second straight line is used. There is also a problem that the subsequent analysis position deviates from the preset analysis position.

Since line analysis detects X-ray signals while scanning the sample stage in any direction, the method used in surface analysis (always performing backlash removal operation in a certain direction) is used in line analysis. The backlash problem cannot be solved. Further, in the backlash correction method of Patent Document 1, it is not possible to accurately match the detection position data attached to the X-ray signal immediately after the start of line analysis with the actual sample stage position.

An object of the present invention is to obtain accurate data without the influence of backlash in the stage scanning EPMA line analysis.

(1) The analyzer according to the present invention is
In an analyzer that irradiates a sample with an electron beam and detects a signal generated from the sample while moving the sample stage on which the sample is placed in the X-axis direction and the Y-axis direction.
A stage scanning unit that scans the sample stage and
A stage control unit that controls the stage scanning unit and
Input section for inputting analysis conditions and
An analysis condition storage unit that stores the analysis conditions,
At the start of the analysis, Oite the analysis condition stored in the analysis condition storing section, the direction of moving the stage when performing line analysis, X-axis direction the effect of the backlash of the sample stage exits, the Y-axis direction A backlash judgment unit that determines whether or not there is a sample,
Including
In the case of an analyzer that removes backlash in the positive direction with respect to the axis of the sample stage, if the backlash determination unit determines that the stage is moved in the minus X direction or the minus Y direction when performing line analysis, The stage control unit is characterized in that the stage scanning unit executes a backlash removing operation in the minus direction with respect to an axis including the minus direction.

With such an analyzer, it is possible to obtain data that is not affected by backlash in the line analysis of the stage scanning method.

(2) The analyzer according to the present invention further comprises
The stage control unit controls the stage scanning unit so that when the sample stage moves and then stops, the backlash of the sample stage always exists in a specific direction.

In such an analyzer, in the stage scanning type line analysis, the backlash determination and backlash are performed with reference to the backlash control information preset in the analyzer (the direction in which the backlash always exists when the sample stage is stopped). By executing the rush removal operation, it is possible to obtain line analysis data that is not affected by backlash.

(3) The analyzer according to the present invention further comprises
A moving direction storage unit for storing the moving direction of the sample stage is included.
At the start of analysis, the backlash determination unit compares the latest moving direction of the sample stage stored in the moving direction storage unit with the stage scanning direction under the analysis conditions stored in the analysis condition storage unit. , It is determined whether or not the scanning direction of the stage is the direction affected by the back crash of the sample stage.

In such an analyzer, in the line analysis of the stage scanning method, the back crash determination and the back crash removing operation are executed with reference to the moving direction of the sample stage stored in the moving direction storage unit, thereby affecting the back crash. You can get the data of the line analysis without the memory.

(4) The analyzer according to the present invention further comprises
A beam scanning unit that scans the electron beam, a beam position correction unit that corrects the irradiation position of the electron beam, an electronic image creating unit that creates a two-dimensional image of detected secondary electrons or backscattered electrons, and an electronic image creating unit.
The amount of deviation for calculating the amount of deviation of the image by comparing the reference image storage unit that saves one of the created electronic images as a reference image with the acquired electronic image and the reference image stored in the reference image storage unit. Calculation part and
Including
The deviation amount calculation unit analyzes by comparing the reference image stored with the sample stage located at the analysis start position and the electronic image acquired after the stage scanning unit executes the backlash removing operation. The start position deviation amount is calculated, and the beam position correction unit corrects the beam position by the analysis start position deviation amount at the start of analysis.

In such an analyzer, by using probe tracking, it is possible to match the observation field of view at the time of setting the analysis start position and at the time of starting the analysis in the line analysis of the stage scanning method.

(5) The analyzer according to the present invention is
Feedback control by a linear encoder may be used as a means for matching the observation field of view at the time of setting the analysis start position and the time of starting the analysis in the line analysis of the stage scanning method.

In such an analyzer, by using a linear encoder, it is possible to match the observation field of view at the time of setting the analysis start position and at the time of starting the analysis in the line analysis of the stage scanning method.

The figure which shows typically the analyzer which concerns on 1st Embodiment. The figure for demonstrating the backlash of a sample stage. The flowchart which shows the operation of 1st Embodiment. The figure which shows typically the analyzer which concerns on 1st Embodiment. The flowchart which shows the operation of 2nd Embodiment. Example of line analysis data.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

1. 1. First Embodiment First, the analyzer according to the first embodiment will be described with reference to the drawings. FIG. 1 is a diagram schematically showing the analyzer 100 according to the first embodiment. The analyzer 100 is an electron probe microanalyzer (EPMA). EPMA irradiates a sample with an electron beam, detects characteristic X-rays generated from the sample in response to the irradiation of the electron beam, and performs qualitative analysis, quantitative analysis, line analysis, surface analysis, etc. of the elements contained in the sample. Do.

The analyzer 100 includes an electron gun 11, a focusing lens 12, a deflector 13, an objective lens 14, a sample stage 15, a stage scanning unit 16, a secondary electron detector 17, and a backscattered electron detector 18. , The wavelength dispersion type spectroscope 19 and the control unit 20 are included. The control unit 20 includes an input unit 21, an analysis condition storage unit 22, a stage control unit 23, a backlash determination unit 24, a beam control unit 25, a beam scanning system 26, an image processing unit 29, and an X-ray. It is configured to include a processing unit 33 and a display unit 34.

The electron gun 11 generates an electron beam EB. The electron gun 11 emits an electron beam EB accelerated by a predetermined acceleration voltage toward the sample S. The focusing lens 12 is arranged at the rear stage (downstream side of the electron beam EB) of the electron gun 11. The focusing lens 12 is a lens for focusing the electron beam EB. The deflector 13 is arranged after the focusing lens 12. The deflector 13 can deflect the electron beam EB. When the scanning signal is input from the beam scanning system 26 to the deflector 13, the electron beam EB focused by the focusing lens 12 and the objective lens 14 scans the sample S. The objective lens 14 is arranged after the deflector 13. The objective lens 14 is a lens for focusing the electron beam EB on the sample S and irradiating the sample S with the electron beam EB as an electron probe.

The sample stage 15 can support the sample S. Sample S is placed on the sample stage 15. The stage scanning unit 16 allows the sample stage 15 to move in the X and Y directions in the horizontal plane. The operation of the stage scanning unit 16 is controlled by the stage control unit 23. By moving the sample stage 15, the analysis position (analysis point) on the sample S irradiated with the electron beam EB (electron probe) can be relatively moved.

The secondary electron detector 17 is a detector for detecting the secondary electrons emitted from the sample S. A secondary electron image (SEM image) can be obtained from the measurement result (output signal) of the secondary electron detector 17. The backscattered electron detector 18 is a detector for detecting the backscattered electrons emitted from the sample S. A reflected electron image can be obtained from the measurement result (output signal) of the reflected electron detector 18. These electronic images are generated by the image generation unit 30 included in the image processing unit 29. The generated image is displayed on the display unit 34.

The wavelength dispersive spectroscope 19 separates and detects characteristic X-rays generated when the sample S is irradiated with the electron beam EB. The wavelength dispersive spectroscope 19 separates X-rays of a specific wavelength by utilizing, for example, Bragg reflection of X-rays by a spectroscopic crystal. From the detected characteristic X-rays, data such as a characteristic X-ray spectrum and two-dimensional mapping can be obtained. These data are generated by the X-ray processing unit 33. The generated data is displayed on the display unit 34. In the present embodiment, an apparatus for detecting characteristic X-rays with a wavelength dispersive spectroscope will be described, but the analyzer according to the present invention detects X-rays with a wavelength dispersive spectroscope and at the same time, is an energy dispersive type. X-rays may be detected by a spectroscope.

The input unit 21 is, for example, a keyboard or a touch panel type display, and the operator inputs various parameters for controlling the analyzer 100 using the input unit 21 and analysis conditions for desired analysis. Parameters for controlling the analyzer include stage position information and beam position information. These pieces of information are sent to the stage control unit 23 and the beam control unit 25, respectively. The analysis conditions include analysis types (qualitative analysis, quantitative analysis, line analysis, surface analysis, etc.), analysis positions, analysis target X-rays, detector conditions, electro-optical system conditions, and the like. In the analyzer according to the present embodiment, the input analysis type is line analysis by the stage scanning method. Since the line analysis by the stage scanning method is an analysis method for detecting characteristic X-rays while scanning the sample stage 15, the analysis conditions include the sample stage scanning direction. The input analysis conditions are stored in the analysis condition storage unit 22.

The stage control unit 23 controls the stage scanning unit 16. When a stage position different from the current stage position is input to the input unit 21, the stage control unit 23 moves the stage scanning unit 16 so that the sample stage 15 is located at the input stage position. Further, at the time of analysis, the data of the analysis position is read from the analysis condition storage unit 22, and the stage scanning unit 16 is moved so that the sample stage 15 is located at the set analysis position.

Further, the stage control unit 23 controls the stage scanning unit 16 so that the backlash of the sample stage 15 always exists in a specific direction after the stage scanning unit 16 is moved and stopped. This operation will be described in detail later.

At the start of analysis, the backlash determination unit 24 determines whether or not the stage scanning direction under the analysis conditions stored in the analysis condition storage unit 22 is the direction affected by the backlash of the sample stage 15. The stage control unit 23 receives the determination result of the backlash determination unit 24, and causes the stage scanning unit 16 to execute the backlash removing operation as needed. This operation will be described in detail later.

The beam control unit 25 scans the electron beam EB by the beam scanning system 26 via the deflector 13 at the time of analysis by the beam scanning method. The beam scanning system 26 includes a beam scanning unit 27 and a beam position correction unit 28.

The image processing unit 29 includes an image generation unit 30, a reference image storage unit 31, and a deviation amount calculation unit 32. The image generation unit 30 generates a secondary electron image and a backscattered electron image from the measurement results of the secondary electron detector 17 and the backscattered electron detector 18. The reference image storage unit 31 stores the image generated by the image generation unit 30 as a reference image as needed. The deviation amount calculation unit 32 compares the reference image stored in the reference image storage unit 31 with the generated image, and calculates the displacement amount between the two images. The misalignment amount calculated by the misalignment amount calculation unit 32 is sent to the beam position correction unit 28. The beam position correction unit 28 scans the electron beam EB via the deflector 13 so as to correct the beam position by the amount of the position shift in the direction of canceling the position shift of the image.

(Backlash removal operation of sample stage)
Here, the backlash removing operation of the sample stage 15 will be described. The sample stage 15 (stage scanning unit 16) is moved by a feed screw method. FIG. 2 is a schematic view of the stage scanning unit 16 and the feed screw 40. The sample stage 15 can be moved in the X-axis direction and the Y-axis direction, but for the sake of simplicity, only the movement in the X-axis direction is considered here.

When the sample stage 15 moves from the minus side to the plus side in the X-axis direction, the relationship between the stage scanning unit 16 and the feed screw 40 when stopped is as shown in FIG. 2A. When the sample stage 15 moves from the positive side to the negative side in the X-axis direction, the relationship between the stage scanning unit 16 and the feed screw 40 when stopped is as shown in FIG. 2 (b). The EPMA is usually controlled so that the gap 50 shown in FIG. 2 is always located on the same side (either the plus side or the minus side) when the sample stage 15 is stopped, that is, the sample is always in a specific direction. Control is performed so that the backlash of the stage 15 exists.

For example, when controlling so that the gap 50 is always located on the minus side, after the sample stage 15 moves from the plus side to the minus side and stops (state of FIG. 2B), the stage control unit 23 moves. The sample stage 15 (stage scanning unit 16) is moved to the minus side by a certain distance and further to the plus side by the same distance. At this time, the moving distance needs to be larger than the gap 50. As a result, the relationship between the stage scanning unit 16 and the feed screw 40 changes from the state shown in FIG. 2B to the state shown in FIG. 2A. That is, the gap 50 is located on the minus side. Moving the sample stage 15 (stage scanning unit 16) in a certain direction by a distance larger than the gap 50 and moving it in the opposite direction by the same distance in this way is called backlash removal.

In addition, when the control is performed so that the gap 50 is always located on the minus side, when the sample stage 15 moves from the minus side to the plus side and stops, the gap 50 is located on the minus side at the time of stopping. Therefore, it is not necessary to perform the backlash removing operation (the state shown in FIG. 2A).

In this way, controlling the gap 50 so that it is always located on the minus side, that is, controlling the sample stage 15 to be stopped after always moving from the minus side to the plus side, is described here as "in the plus direction". Take backlash. " The control of stopping the sample stage 15 after moving it from the plus side to the minus side is called "performing backlash removal in the minus direction".

Next, the operation of the present embodiment will be described in more detail. 3A and 3B are flowcharts showing the operation of the present embodiment, in which FIG. 3A shows a line analysis condition input stage, and FIG. 3B shows a subsequent line analysis execution stage.

(Input of analysis conditions for line analysis by stage scanning)
When the operator instructs the start of line analysis condition input in FIG. 3A, the stage control unit 23 performs the sample stage 15 (stage scanning) so that the sample stage 15 is located at the stage position input to the input unit 21. Part 16) is moved (S101). After the sample stage 15 is stopped, the stage control unit 23 causes the stage scanning unit 16 to perform backlash removal, if necessary, according to the direction of movement immediately before. Here, it is assumed that the analyzer 100 is an apparatus that removes backlash in the plus direction in both the X-axis direction and the Y-axis direction (S103).

The operator observes the electronic image displayed on the display unit 34, and when it is determined that the current visual field is the desired analysis start position, the operator starts inputting the analysis conditions (S105). The current stage position and the direction for performing line analysis (stage scanning direction) are input to the input unit 21 as the analysis start position. In addition, the step size (movement interval of the sample stage 15 when acquiring an X-ray signal) and the element to be analyzed (type of characteristic X-ray) are also input. The input analysis conditions are stored in the analysis condition storage unit 22.

The image generation unit 30 generates a secondary electron image or a backscattered electron image from the measurement results of the secondary electron detector 17 and the backscattered electron detector 18 at the analysis start position, and the reference image storage unit 31 uses this image as a reference image. It is saved as (S107). That is, the reference image was acquired in a state in which the backlash in the plus direction was removed (the relationship between the stage scanning unit 16 and the feed screw 40 is in the state of FIG. 2A).

(Backlash judgment in the stage scanning direction of analysis conditions)
When the operator instructs the start of line analysis in FIG. 3B, the stage control unit 23 reads the analysis conditions from the analysis condition storage unit 22 and moves the sample stage 15 (stage scanning unit 16) to the line analysis start position. (S109). After the sample stage 15 is stopped, the stage control unit 23 causes the stage scanning unit 16 to perform backlash removal in the positive direction, if necessary, according to the immediately preceding moving direction (S111).

Next, the backlash determination unit 24 reads out the stage scanning direction of the line analysis to be executed from the analysis condition storage unit 22 (S113), and in the read stage scanning direction, either the X-axis direction or the Y-axis direction. It is determined whether or not scanning in the minus direction is included in (S115). When the stage scanning direction includes scanning in the negative direction, the backlash determination unit 24 sends a determination of the influence of backlash to the stage control unit 23 (S117). If the stage scanning direction does not include scanning in the negative direction, the backlash determination unit 24 ends the backlash determination and starts line analysis (S127).

(Backlash removal operation in the minus direction)
When the stage control unit 23 receives a determination from the backlash determination unit 24 that there is an influence of backlash, the stage scanning unit 16 executes a negative backlash removing operation with respect to the axis including the negative scanning. (S119). For example, when scanning in the minus direction is included in the X-axis direction, the stage control unit 23 moves the sample stage 15 (stage scanning unit 16) to the plus side by a certain distance, and further moves the sample stage 15 (stage scanning unit 16) to the minus side by the same distance. Move. At this time, the moving distance needs to be larger than the gap 50. When the backlash removal in the negative direction is executed, the relationship between the stage scanning unit 16 and the feed screw 40 becomes the state shown in FIG. 2B.

(Field of view alignment by probe tracking)
At this time, the sample stage position (coordinates) is at the analysis start position (coordinates) as a coordinate value, but the sample stage position, that is, the observation field of view is actually deviated from the time when the analysis start position is set by the gap 50. It may be. Probe tracking is performed to correct the deviation of the observation field of view. The probe tracking is a process of calculating the amount of misalignment of the visual field from the reference image and the comparative image and feeding back the amount of misalignment to the beam scanning system to match the visual fields.

The image generation unit 30 generates a secondary electron image or a backscattered electron image from the measurement results of the secondary electron detector 17 and the backscattered electron detector 18 at the stage when the backlash removal in the negative direction is completed (S121). The deviation amount calculation unit 32 compares the reference image (image acquired in S107) stored in the reference image storage unit 31 with the image generated at the present time, and calculates the displacement amount between the two images. (S123). The calculated misalignment amount is sent to the beam position correction unit 28. The beam position correction unit 28 scans the electron beam EB via the deflector 13 so as to correct the beam position by the amount of the position shift in the direction of canceling the position shift of the image (S125). As a result, both the sample stage position (coordinates) and the observation field of view coincide with the sample stage position (coordinates) and the observation field of view at the time when the analysis start position is set.

(Start of line analysis)
The sample at the time when the analysis start position is set, both the sample stage position (coordinates) and the observation field are in a state where the stage scanning unit 16 and the feed screw 40 are not affected by backlash with respect to the stage scanning direction. Line analysis is started (stage scanning is started) from a state in which the stage position (coordinates) and the observation field of view are in agreement with each other (S127). Since the actual movement of the sample stage 15 starts immediately after the start of analysis (start of stage scanning), the detection position data attached to the X-ray signal detected immediately after the start of analysis reflects the actual sample stage position. As a result, accurate line analysis data can be obtained.

(Continuous line analysis)
When the sample stage 15 moves to the position where the line analysis ends, the line analysis ends (stage scanning ends) (S129). Here, it is determined whether or not the execution of the line analysis starting from the current sample stage position (line analysis end position) is instructed in advance (S131), and if instructed (on a plurality of continuous straight lines). In the case of continuous line analysis for scanning), the process returns to S111, and the processes S111 to S129 are repeated until all the instructed line analyzes are completed. By such a process, the continuous line analysis is executed without the analysis position after the second straight line deviating from the set analysis position.

As described above, in the analyzer according to the present embodiment, at the start of line analysis, the backlash control information preset in the analyzer (the direction in which the backlash always exists when the sample stage 15 is stopped) is referred to and backlashed. By executing the rush judgment and backlash removal operations, it is possible to obtain line analysis data that is not affected by backlash. Further, by executing probe tracking, the observation field of view at the start of analysis can be matched with the observation field of view at the time of setting the analysis start position.

2. Second Embodiment Next, the analyzer according to the second embodiment will be described with reference to the drawings. FIG. 4 is a diagram schematically showing the analyzer 200 according to the second embodiment. The analyzer 200 is configured to include a moving direction storage unit 35 in the control unit 20 in addition to the configuration of the analyzer 100 according to the first embodiment. Hereinafter, a configuration different from that of the first embodiment will be described.

The stage control unit 23 controls the stage scanning unit 16. When a stage position different from the current stage position is input to the input unit 21, the stage control unit 23 moves the stage scanning unit 16 so that the sample stage 15 is located at the input stage position. Further, at the time of analysis, the data of the analysis position is read from the analysis condition storage unit 22, and the stage scanning unit 16 is moved so that the sample stage 15 is located at the set analysis position.

When the stage control unit 23 changes (moves) the sample stage position, the stage control unit 23 determines the sample stage 15 from the current sample stage position (coordinates) and the changed (after moving) sample stage position (coordinates). Calculate the movement direction.

The moving direction storage unit 35 stores the moving direction of the sample stage 15 calculated by the stage control unit 23. The moving direction of the sample stage 15 stored in the moving direction storage unit 35 is updated every time the sample stage position is changed. That is, the moving direction storage unit 35 stores information from which direction the sample stage 15 has moved to the current sample stage position.

At the start of analysis, the backlash determination unit 24 determines whether or not the stage scanning direction under the analysis conditions stored in the analysis condition storage unit 22 is the direction affected by the backlash of the sample stage 15. At the time of determination, the backlash determination unit 24 refers to the movement direction of the sample stage 15 stored in the movement direction storage unit 35. This operation will be described in detail later.

Next, the operation of the present embodiment will be described in more detail. 5A and 5B are flowcharts showing the operation of the present embodiment, in which FIG. 5A shows a line analysis condition input stage, and FIG. 5B shows a subsequent line analysis execution stage.

(Input of analysis conditions for line analysis by stage scanning)
When the operator instructs the start of line analysis condition input in FIG. 5A, the stage control unit 23 performs the sample stage 15 (stage scanning) so that the sample stage 15 is positioned at the stage position input to the input unit 21. Part 16) is moved (S201). At this time, the moving direction of the sample stage 15 is stored in the moving direction storage unit 35.

The operator observes the electronic image displayed on the display unit 34, and when it is determined that the current visual field is the desired analysis start position, the operator starts inputting the analysis conditions (S205). The current stage position and the direction for performing line analysis (stage scanning direction) are input to the input unit 21 as the analysis start position. In addition, the step size (movement interval of the sample stage 15 when acquiring an X-ray signal) and the element to be analyzed (type of characteristic X-ray) are also input. The input analysis conditions are stored in the analysis condition storage unit 22.

The image generation unit 30 generates a secondary electron image or a backscattered electron image from the measurement results of the secondary electron detector 17 and the backscattered electron detector 18 at the analysis start position, and the reference image storage unit 31 uses this image as a reference image. It is saved as (S207).

(Backlash judgment in the stage scanning direction of analysis conditions)
When the operator instructs the start of line analysis in FIG. 5B, the stage control unit 23 reads the analysis conditions from the analysis condition storage unit 22 and moves the sample stage 15 (stage scanning unit 16) to the line analysis start position. (S209). At this time, the moving direction of the sample stage 15 is stored in the moving direction storage unit 35.

Next, the backlash determination unit 24 reads out the latest moving direction of the sample stage 15 from the moving direction storage unit 35 (S211), and further reads out the stage scanning direction of the line analysis to be executed from the analysis condition storage unit 22. (S213). The backlash determination unit 24 compares the read stage scanning direction with the latest moving direction of the sample stage 15. That is, it is determined whether or not scanning in the direction opposite to the moving direction of the latest sample stage 15 is included in either the X-axis direction or the Y-axis direction of the stage scanning direction (S215). When the stage scanning direction includes scanning in the direction opposite to the moving direction of the latest sample stage 15, the backlash determination unit 24 sends a determination of the influence of backlash to the stage control unit 23 (S217). If the stage scanning direction does not include scanning in the direction opposite to the latest moving direction of the sample stage 15, the backlash determination unit 24 ends the backlash determination and starts line analysis (S227).

(Backlash removal operation)
When the stage control unit 23 receives a determination from the backlash determination unit 24 that there is an influence of backlash, the stage control unit 23 refers to an axis in which the stage scanning unit 16 includes scanning in the direction opposite to the movement direction of the latest sample stage 15. The backlash removing operation is executed (S219). In the backlash removing operation here, the sample stage 15 (stage scanning unit 16) is moved by a certain distance in the direction opposite to the stage scanning direction of the line analysis to be executed, and further in the opposite direction (the line analysis to be executed from now on). It is an operation of moving the same distance in the stage scanning direction). At this time, the moving distance needs to be larger than the gap 50. As a result, the stage scanning unit 16 and the feed screw 40 are in a state where the backlash does not affect the stage scanning direction.

(Perform line analysis)
Probe tracking is performed to match both the sample stage position (coordinates) and the observation field of view with the sample stage position (coordinates) and the observation field of view at the time when the analysis start position is set (S221 to S225). Since the operation of probe tracking is the same as that of the first embodiment, the description thereof will be omitted.

The sample at the time when the analysis start position is set, both the sample stage position (coordinates) and the observation field are in a state where the stage scanning unit 16 and the feed screw 40 are not affected by backlash with respect to the stage scanning direction. Line analysis is started (stage scanning is started) from a state in which the stage position (coordinates) and the observation field of view are in agreement with each other (S227). Since the actual movement of the sample stage 15 starts immediately after the start of analysis (start of stage scanning), the detection position data attached to the X-ray signal detected immediately after the start of analysis reflects the actual sample stage position. As a result, accurate line analysis data can be obtained. In the case of continuous line analysis, the processes S211 to S229 are repeated until all the instructed line analyzes are completed. By such a process, the continuous line analysis is executed without the analysis position after the second straight line deviating from the set analysis position.

As described above, in the analyzer according to the present embodiment, the back crash determination and the back crash removing operation are executed by referring to the movement direction of the sample stage 15 stored in the movement direction storage unit 35 at the start of the line analysis. , Line analysis data that is not affected by backlash can be obtained. In the analyzer according to the present embodiment, it is not necessary to control so that the backlash of the sample stage always exists in a specific direction as is performed in a normal EPMA.

3. 3. Modifications The present invention is not limited to the above-described embodiments, and various modifications can be carried out within the scope of the gist of the present invention. In the above-described embodiment, probe tracking is used as a means for matching the observation field of view at the time of setting the analysis start position and the time of starting the analysis, but feedback control by a linear encoder may also be used.

When using a linear encoder, the following operations are performed. After the backlash determination and the backlash removing operation are executed at the start of the line analysis, the stage control unit 23 moves the sample stage 15 to the analysis start position with reference to the linear scale. As a result, the observation field of view at the start of analysis can be precisely adjusted to the observation field of view at the time of setting the analysis start position.

The above-described embodiments and modifications are merely examples, and the present invention is not limited thereto. For example, each embodiment and each modification can be combined as appropriate.

The present invention includes substantially the same configurations as those described in the embodiments (eg, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. The present invention also includes a configuration that exhibits the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

11 ... electron gun, 12 ... focusing lens, 13 ... deflector, 14 ... objective lens, 15 ... sample stage, 16 ... stage scanning unit, 17 ... secondary electron detector, 18 ... backscattered electron detector, 19 ... wavelength dispersion Type spectroscope, 20 ... control unit, 21 ... input unit, 22 ... analysis condition storage unit, 23 ... stage control unit, 24 ... backlash determination unit, 25 ... beam control unit, 26 ... beam scanning system, 27 ... beam scanning Unit, 28 ... Beam position correction unit, 29 ... Image processing unit, 30 ... Image generation unit, 31 ... Reference image storage unit, 32 ... Deviation amount calculation unit, 33 ... X-ray processing unit, 34 ... Display unit, 35 ... Movement Direction storage unit, 50 ... gap, 100, 200 ... analyzer, EB ... electron beam, S ... sample

Claims (5)

In an analyzer that irradiates a sample with an electron beam and detects a signal generated from the sample while moving the sample stage on which the sample is placed in the X-axis direction and the Y-axis direction.
A stage scanning unit that scans the sample stage and
A stage control unit that controls the stage scanning unit and
Input section for inputting analysis conditions and
An analysis condition storage unit that stores the analysis conditions,
At the start of the analysis, Oite the analysis condition stored in the analysis condition storing section, the direction of moving the stage when performing line analysis, X-axis direction the effect of the backlash of the sample stage exits, the Y-axis direction A backlash judgment unit that determines whether or not there is a sample,
Including
In the case of an analyzer that removes backlash in the positive direction with respect to the axis of the sample stage, if the backlash determination unit determines that the stage is moved in the minus X direction or the minus Y direction when performing line analysis, The stage control unit is an analyzer, characterized in that the stage scanning unit executes a backlash removing operation in a minus direction with respect to an axis including a minus direction.
In claim 1,
The stage control unit is an analyzer that controls the stage scanning unit so that when the sample stage moves and then stops, the backlash of the sample stage always exists in a specific direction. In claim 1,
A moving direction storage unit for storing the moving direction of the sample stage is included.
At the start of analysis, the backlash determination unit compares the latest moving direction of the sample stage stored in the moving direction storage unit with the stage scanning direction under the analysis conditions stored in the analysis condition storage unit. An analyzer for determining whether or not the scanning direction of the stage is the direction affected by the back crash of the sample stage. In any one of claims 1 to 3,
A beam scanning unit that scans the electron beam, a beam position correction unit that corrects the irradiation position of the electron beam, an electronic image creating unit that creates a two-dimensional image of detected secondary electrons or backscattered electrons, and an electronic image creating unit.
The amount of deviation for calculating the amount of deviation of the image by comparing the reference image storage unit that saves one of the created electronic images as a reference image with the acquired electronic image and the reference image stored in the reference image storage unit. Calculation part and
Including
The deviation amount calculation unit analyzes by comparing the reference image saved with the sample stage located at the analysis start position and the electronic image acquired after the stage scanning unit executes the backlash removing operation. An analyzer that calculates a start position shift amount, and the beam position correction unit corrects the beam position by the analysis start position shift amount at the start of analysis. In any one of claims 1 to 3,
A linear encoder for reading the position of the sample stage,
Including
The stage control unit is an analyzer, characterized in that, after the stage scanning unit executes the backlash removing operation, the sample stage is positioned at an analysis start position based on control by the linear encoder.

Images