JP2009047450A - Sample analyzing method and sample analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample analyzing method which enables the proper analysis of a sample by analyzing the sample on the basis of the value of characteristic X-ray intensity measured until damage and/or contamination is produced, and a sample analyzer. <P>SOLUTION: The sample 8 is irradiated with an electron beam 9 and the intensity of the characteristic X rays 10 produced from the sample 8 corresponding to the irradiation with the electron beam 9 is measured in a time sharing manner with the elapse of time to analyze the sample 8. In this analysis of the sample, the initial value of the characteristic X-ray intensity measured at the start time of measurement is compared with the value (time elapse value) of the characteristic X-ray intensity measured in each measuring timing at a later time and, when the time elapse value sequentially measured corresponding to the elapse of time is shifted from an allowable value range set within a predetermined ratio of amplifying width with respect to the initial value, measurement is stopped and the sample is analyzed on the basis of the initial value and each time elapse value within the allowable value range. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sample analysis method and a sample analyzer that perform sample analysis using characteristic X-rays such as an electron probe microanalyzer (EPMA).

  In an electron probe microanalyzer, a sample to be analyzed is irradiated with an electron beam (electron probe) focused by a focusing lens and an objective lens, and characteristic X-rays generated from the sample are detected according to the irradiation of the electron beam. , Sample analysis.

  At the time of the analysis, the electron beam is deflected by the deflection coil, and the desired analysis position on the sample is irradiated with the electron beam.

  Here, when the point coil analysis is performed by irradiating one point on the sample with an electron beam by the operation of the deflection coil, or when the electron beam scans the predetermined region on the sample, An area analysis may be performed.

  The characteristic X-ray generated from the sample in response to the electron beam irradiation is detected by an X-ray spectrometer made of EDS or WDS, and the intensity of the characteristic X-ray is detected by a signal processing unit based on the detection signal from the X-ray spectrometer. (Characteristic X-ray intensity) is measured.

  Based on the characteristic X-ray intensity measured in this way, qualitative analysis and / or quantitative analysis as sample analysis is performed.

  In the sample analysis described above, since the sample is continuously irradiated with the electron beam, the sample may be damaged or contaminated over time. Here, the damage corresponds to damage caused by generation of heat caused by electron beam irradiation, charge accumulation, and the like. In addition, contamination includes contamination caused by suspended matter in the sample chamber.

  Here, the irradiation current value of the electron beam and the absorption current value of the sample are measured, the ratio of these values is calculated, and compared with the charge determination condition data obtained in advance, the charge of the sample is calculated. Some monitor the presence or absence (see Patent Document 1).

JP 2006-58033 A

  When the sample is continuously irradiated with an electron beam and the time variation of the measured characteristic X-ray intensity is examined, the electron beam irradiation conditions that cause little change in the characteristic X-ray intensity over time are optimal as analysis conditions. It becomes a necessary condition. Therefore, an optimum electron beam irradiation condition is searched by changing the electron beam irradiation current and acceleration voltage.

  However, it is time-consuming to determine the conditions, and it is difficult to determine whether or not the actually measured characteristic X-ray intensity data is affected by sample damage or contamination.

  In addition, damage and contamination to the sample are reduced under conditions where the irradiation current of the electron beam to the sample is small and the irradiation time is short. Therefore, an analysis is performed under a plurality of conditions, and an analysis result consistent with a result of less damage and contamination is adopted as a correct analysis result.

  However, in this case, although the damage of the sample can be evaluated, a lot of labor is required to perform the analysis a plurality of times.

  In the conventional sample analysis, even if the sample is damaged and / or contaminated by electron beam irradiation, the analyzer continuously analyzes the sample and continues to measure the characteristic X-ray intensity. It is necessary for the operator to judge whether or not the sample analysis result based on the entire characteristic X-ray intensity is appropriate, and it has been troublesome to collect judgment materials as a basis for the judgment.

  The present invention has been made in view of these points, and in the sample analysis in which the sample is damaged and / or contaminated by the electron beam irradiation, the damage and / or the contamination is generated. An object of the present invention is to provide a sample analysis method and a sample analysis apparatus capable of performing an appropriate sample analysis by performing a sample analysis based on the characteristic X-ray intensity value measured in (1).

  In a first sample analysis method according to the present invention, a sample is irradiated with an electron beam, and the intensity of characteristic X-rays generated from the sample in response to the electron beam irradiation is measured in a time-sharing manner over time. A sample analysis method for performing analysis, comparing an initial value of characteristic X-ray intensity measured at the start of measurement with a characteristic X-ray intensity value (time value) measured at each subsequent measurement timing, The measurement is stopped when the time-lapsed values measured sequentially over time deviate from the tolerance range set within the specified range of increase / decrease with respect to the initial value, and become within the initial value and tolerance range. The sample analysis is performed based on the respective time values.

  A second sample analysis method according to the present invention includes a step of irradiating a sample with an electron beam, a step of measuring the intensity of characteristic X-rays generated from the sample according to the irradiation of the electron beam in a time-sharing manner with time. A method of comparing the initial value of the characteristic X-ray intensity measured at the start of measurement with the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing; The step of stopping the measurement when the time-lapsed value measured sequentially with the passage of time deviates from the allowable value range set within the range of increase / decrease with respect to the initial value, and the initial value and allowable value range And performing a sample analysis based on each of the time-lapse values.

  The sample analyzer according to the present invention irradiates a sample with an electron beam, and analyzes the sample by measuring the intensity of characteristic X-rays generated from the sample in response to the electron beam irradiation in a time-sharing manner over time. This is a sample analyzer that compares the initial value of characteristic X-ray intensity measured at the start of measurement with the value of characteristic X-ray intensity (time value) measured at each subsequent measurement timing. Accordingly, the measurement is stopped when the time-measured values sequentially measured deviate from the allowable value range set within the range of increase / decrease with respect to the initial value. Sample analysis is performed based on the time-lapse value.

  In the present invention, the initial value of the characteristic X-ray intensity measured at the start of measurement is compared with the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing. Measurements are stopped when the sequentially measured time values deviate from the allowable value range set within the specified range of increase / decrease with respect to the initial value, and each time value within the initial value and allowable value range Based on the sample analysis.

  When the time-lapse value is out of the allowable range, it is found that the influence on the characteristic X-ray intensity due to the damage and / or contamination of the sample caused by the electron beam irradiation is increased. Execute the sample analysis that is hardly affected by the damage and / or contamination by stopping the measurement at the time and performing the sample analysis based on the initial value and each time-lapse value that is within the allowable range. Can do.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a sample analyzer in the present invention.

  In FIG. 1, an electron beam 9 accelerated by a predetermined acceleration voltage is emitted from the electron gun 1 toward the sample 8. The electron beam 9 emitted from the electron gun 1 is finely focused on the sample 8 by the lens action of the focusing lens 2 and the objective lens 3. As a result, the sample 8 is irradiated with an electron probe including the focused electron beam 9.

  At this time, the electron beam 9 is appropriately deflected by the deflecting action of the deflection coil 4, and the electron beam 9 is irradiated onto a desired analysis position on the sample 8.

  Characteristic X-rays 10 are generated from the analysis position irradiated with the electron beam 9 on the sample 8. This characteristic X-ray 10 is detected by an X-ray spectrometer 7 made of EDS or WDS. A detection signal corresponding to the detected characteristic X-ray 10 is output from the X-ray spectrometer 7 to the signal processing means 7a.

  The signal processing unit 7a obtains the intensity of the characteristic X-ray 10 detected by the X-ray spectrometer 7 based on the detection signal. Thereby, the characteristic X-ray intensity is measured, and the data of the characteristic X-ray intensity is sent to the CPU 12 via the bus line 11.

  The electron gun 1 is driven by the drive control unit 1a. The drive control unit 1 a is connected to the CPU 12 via the bus line 11. Thus, the electron gun 1 is controlled by the CPU 12 via the drive control unit 1a.

  The focusing lens 2, the objective lens 3, and the deflection coil 4 are driven by the corresponding drive control units 2a to 4a. Each drive control unit 2 a to 4 a is connected to the CPU 12 via the bus line 11. Thereby, the focusing lens 2, the objective lens 3, and the deflection coil 4 are controlled by the CPU 12 via the corresponding drive control units 2a to 4a.

  Further, the sample 8 is placed on the stage mechanism 5. The stage mechanism 5 is driven by the drive control unit 5a, whereby the sample 8 on the stage mechanism 5 moves in each of the X, Y, and Z directions, and rotates or tilts. The drive controller 5 a is connected to the CPU 12 via the bus line 11, whereby the stage mechanism 5 is controlled by the CPU 12 via the drive controller 5.

  An irradiation current detector 6 is disposed between the deflection coil 4 and the sample 8. The irradiation current detector 6 is movable between a position on the optical axis of the electron beam 9 and a position retracted from the optical axis.

  When the irradiation current detector 6 is located on the optical axis of the electron beam 9, the electron beam 9 from the electron gun 1 reaches the irradiation current detector 6. Thereby, the irradiation current detector 6 can detect the irradiation current of the electron beam 9.

  In this state, the irradiation current detector 6 outputs a current detection signal to the current detection unit 6a. The current detection unit 6a measures the irradiation current value of the electron beam 9 based on the current detection signal. Thereby, the irradiation current value (irradiation current) of the electron beam 9 is measured, and the data of the irradiation current value is sent to the CPU 12 via the bus line 11.

  The CPU 12 controls the electron gun 1 via the drive control unit 1a so that the irradiation current value of the electron beam 9 becomes a predetermined value set in advance. As a result, the electron gun 1 is irradiated with an electron beam 9 set at a predetermined irradiation current.

  After the irradiation current value of the electron beam 9 is set in this way, the irradiation current detector 6 is moved to a position for retracting from the optical axis. Thereby, the electron beam 9 having the irradiation current value is irradiated from the electron gun 1 toward the sample 8. Thereafter, analysis of the sample under the electron beam irradiation conditions is started.

  That is, characteristic X-rays 10 are generated from the analysis position on the sample 8 irradiated with the electron beam 9, and the characteristic X-rays 10 are detected by the X-ray spectrometer 7. A detection signal corresponding to the detected characteristic X-ray 10 is output from the X-ray spectrometer 7 to the signal processing means 7a.

  At this time, the signal processing unit 7a measures the characteristic X-ray intensity every predetermined period (predetermined period) with the passage of time from the start of measurement. Thereby, the characteristic X-ray intensity is measured by time division at the measurement timing for each predetermined period.

  The CPU 12 sequentially stores each data of the characteristic X-ray intensity at each measurement timing (including the measurement start time) sent from the signal processing unit 7 a in the memory 13. In parallel with this, the CPU 12 measures the initial value of the characteristic X-ray intensity measured at the start of measurement and each subsequent measurement timing based on the data sequentially sent from the signal processing unit 7a. Comparison is made with the characteristic X-ray values (time-lapse values).

  Then, when the elapsed time value of the characteristic X-ray intensity sequentially measured after the start of measurement deviates from the allowable value range set within an increase / decrease range of a predetermined ratio with respect to the initial value, the CPU 12 instructs the drive control unit 1a. Send a stop signal. Thereby, the operation of the electron gun 1 is stopped, the irradiation of the electron beam 9 is stopped, and the measurement is stopped. As a method for stopping the irradiation of the electron beam 9, the electron beam 9 may be blocked by a blanking means (not shown).

  Here, FIG. 2 is a graph showing the change over time of the characteristic X-ray intensity measured in the sample 8 that is easily damaged by the electron beam 9 irradiation. In the figure, a solid line indicates a change in characteristic X-ray intensity measured in the case of the sample 8 that is easily damaged, and a dotted line indicates a change in characteristic X-ray intensity measured in the case of the sample 8 that is hardly damaged. Indicates.

  In the case where the characteristic X-ray intensity decreases significantly with time, as indicated by the solid line in the graph of FIG. 2, qualitative analysis or quantitative analysis is performed based on all of the measured characteristic X-ray intensity data. Such sample analysis cannot be performed. In this case, a lot of data of characteristic X-ray intensity when the damage of the sample 8 due to the electron beam 9 is increased with the passage of time is included, and when the sample analysis is performed based on such data, the analysis This is because the accuracy is significantly lowered.

  Therefore, in the present invention, the CPU 12 stores the initial value of the characteristic X-ray intensity measured at the start of measurement in the memory 13, reads out the initial value from the memory 13, and sequentially measures the characteristic at each subsequent measurement timing. The X-ray intensity is compared with the initial value.

  Specifically, the CPU 12 sets an increase / decrease width of, for example, about 20% (20%) with respect to the initial value read from the memory 13, and the characteristic X-ray intensity (time value) at each measurement timing. Is within an allowable value range based on the increase / decrease width (that is, a range of 0.8K to 1.2K, where K is the initial value). Then, when it is confirmed that the characteristic X-ray intensity at a certain measurement timing is out of the permissible value range, the CPU 12 stops the irradiation of the electron beam 9 on the sample 8.

  Here, FIG. 3 is a graph showing an example in which the characteristic X-ray intensity measured at a certain measurement timing after the start of measurement decreases and deviates from the allowable value range. This figure shows an example in which the characteristic X-ray intensity measured at the sixth measurement timing is determined to be out of a certain allowable value range.

  In this case, when it is determined that the characteristic X-ray intensity measured at the sixth time is out of the allowable range, the CPU 12 stops the irradiation of the electron beam 9 on the sample 8. Then, sample analysis is performed based on the characteristic X-ray intensity data measured from the first time (at the start of measurement) to the fifth time.

  If the measured characteristic X-ray intensity deviates from the allowable value range in a relatively short time after the start of measurement, the number of measurement data that can be used for sample analysis is reduced, so a highly accurate sample Analysis can be difficult.

  In such a case, the analysis conditions can be automatically adjusted so that the irradiation conditions of the electron beam 9 that are optimum for the sample 8 to be analyzed at that time can be set. At this time, the operator (user) needs to set the analysis position of the electron beam 9 on the sample 8 during the automatic adjustment. The automatic adjustment of the analysis conditions may be performed before the analysis of the sample 8 is performed.

  In the automatic adjustment, parameters adjusted as the irradiation condition of the electron beam 9 include (1) irradiation current [from a sufficiently small initial value (for example, about 10 pA) to a final value (measured characteristic X-ray intensity in a short time). Adjustment within the range up to the value that deviates from the tolerance range), (2) Magnification [low magnification as the initial value (user input) to the final value (the measured characteristic X-ray intensity deviates from the tolerance range in a short time) Adjustment within the range up to high magnification)], (3) probe diameter [small probe that causes the measured X-ray intensity to deviate from the allowable value range in a short time from the large probe diameter (user input) as the initial value 4) acceleration voltage [adjustment in the range from low acceleration voltage (user input) to final value (high acceleration voltage (user input)) as initial value] It can be mentioned. Here, in each parameter, the initial value is a condition in which damage or contamination to the sample hardly occurs, and the probability of occurrence of the damage or contamination increases as the closing value is approached.

  In this automatic adjustment, the adjustment may be performed by changing the values of a plurality of parameters, but an example in which one parameter is selected and the value is changed will be described below for simplification.

  In this embodiment, the irradiation current of the electron beam 9 is selected as one parameter. Then, the electron beam 9 with the irradiation current set to the initial value is irradiated onto the sample 8, and the characteristic X-ray 10 from the sample 8 at each value obtained by sequentially changing the irradiation current from the initial value to the final value. The intensity (characteristic X-ray intensity) is measured in a time-sharing manner over time, and the characteristic X-ray intensity at each measurement timing for an element (hereinafter referred to as “specific element”) in which a change in the characteristic X-ray intensity is greatly detected is measured. Graph the data.

  At this time, if the parameter is finely divided and changed from the initial value to the final value, it takes time to measure the characteristic X-ray intensity. Therefore, if the measurement is performed at each value when the parameter is changed by an exponential function or a power, the measurement can be performed efficiently. Further, if simultaneous analysis of all elements for an element to be analyzed is possible, characteristic X-ray intensity for elements other than the specific element can be measured at the time of the measurement.

  Here, FIG. 4 shows an example of a change in characteristic X-ray intensity measured at each measurement timing in the passage of time for each value when the irradiation current as the parameter is sequentially changed for a specific element. In this example, for example, the initial value of the irradiation current is 10 pA, the final value is 50 nA, and values between these values can be set to values of 100 pA, 1 nA, 5 nA, and 20 nA.

  In the figure, the graph of (1) shows the change with time of the characteristic X-ray intensity when the irradiation current is 10 pA, 100 pA, and 1 nA. In each of these values, it is shown that there is almost no change in the characteristic X-ray intensity measured at each of the six measurement timings including the first time.

  In the same figure, the graph (2) shows the change with time of the characteristic X-ray intensity when the irradiation current is 5 nA. At this value, among the characteristic X-ray intensities measured at a total of six measurement timings, a decrease in the characteristic X-ray intensity is observed in the measurement at the sixth measurement timing.

  Furthermore, in the same figure, the graph of (3) shows the time-dependent change of the characteristic X-ray intensity when the irradiation current is 20 nA. At this value, among the characteristic X-ray intensities measured at a total of six measurement timings, a decrease in the characteristic X-ray intensity is observed in the measurement from the third measurement timing.

  In the figure, the graph (4) shows the change with time of the characteristic X-ray intensity when the irradiation current is 50 nA. At this value, among the characteristic X-ray intensities measured at a total of six measurement timings, a decrease in the characteristic X-ray intensity is observed in the measurement from the second measurement timing.

  Based on each measurement data graphed in this way, the optimum irradiation condition of the electron beam 9 is obtained for the sample 8 to be analyzed at that time. In the above example, by setting the irradiation current to 5 nA, the characteristic X-ray intensity data measured at each measurement timing up to five times including the first time can be used for the sample analysis.

  The above operation (method) can be performed based on the control by the CPU 12, and can be applied during the point analysis of the sample.

  Note that the same method as described above can be applied to the surface analysis of a sample. Also in this case, the characteristic X-ray intensity is measured in a time-division manner at predetermined measurement timings over time from the start of measurement. At this time, since the volume of measurement data is large in the surface analysis, it is desirable to divide the measurement time in proportion to an exponent or a power.

  Here, the total sum of all X-ray intensities in one surface analysis is defined as the characteristic X-ray intensity during the one measurement time. Then, as described above, the initial value of the characteristic X-ray intensity at the start of measurement is compared with the characteristic X-ray intensity (time-lapse value) at each subsequent measurement timing.

FIG. 5 shows an example of an acquired image in the surface analysis. (1) in the figure is a measurement acquired image at the start of measurement (first time (first time)). The characteristic X-ray intensity in this case the (total count) to A _1.

Moreover, (2) of the figure is a measurement acquisition image in the second time. The characteristic X-ray intensity at this time is A _2.

Further, (3) in the figure is a measurement acquired image in the third time. The characteristic X-ray intensity at this time is A _3.

And (4) of the figure is a measurement acquisition image in the 4th time. The characteristic X-ray intensity at this time is A _4.

Moreover, (5) of the figure is a measurement acquisition image in the 5th time. The characteristic X-ray intensity at this time is A _5.

  In the example of the figure, the measurement time at each measurement timing is constant. And the brightness | luminance of each said measurement acquisition image respond | corresponds to the said characteristic X-ray intensity, and the said characteristic X-ray intensity in the 5th falls, as it is clear when visually confirming each image in a figure. Yes.

The CPU 12 stores the initial value A ₁ of the characteristic X-ray intensity measured at the start of measurement in the memory 13, reads the initial value A ₁ from the memory 13, and sequentially measures the characteristic measured at each subsequent measurement timing. and it compares the X-ray intensity and the initial value a _1.

For example, the characteristic X-ray intensity A ₅ in the 5th is a predetermined ratio with respect to the initial value A ₁ (e.g., 20%) when it is determined that the off-set tolerance to an increase or decrease in the width of the The CPU 12 stops irradiating the sample 8 with the electron beam 9.

In this case, the sample analysis is performed based on the data of the characteristic X-ray intensities A _{1 to} A ₄ from the first time to the fourth time.

FIG. 6 shows another example of the acquired image in the surface analysis. (11) in the figure is a measurement acquired image at the start of measurement (first time). The characteristic X-ray intensity in this case the (total count) to A _11.

Further, (12) in the figure is a measurement acquisition image in the second time. The characteristic X-ray intensity at this time is A _12.

Furthermore, (13) in the figure is a measurement acquisition image in the third time. The characteristic X-ray intensity at this time is A _13.

And (14) of the figure is a measurement acquisition image in the 4th time. The characteristic X-ray intensity at this time is A _14.

Moreover, (15) of the figure is a measurement acquisition image in the 5th time. The characteristic X-ray intensity at this time is A _15.

  In the example of the figure, the measurement time at each measurement timing is set to a set time that is “2 to the power of n” times. The luminance of each measurement acquired image corresponds to the characteristic X-ray intensity, and the characteristic X-ray intensity in the fifth time is lowered as is apparent from each image in the figure.

In this example, CPU 12 sets the initial value A ₁₁ of the measured at the time of measurement start the characteristic X-ray intensity reading the initial value A ₁₁ from the memory 13 with the stored in the memory 13, sequentially in each subsequent measurement timing the comparison between the measured the characteristic X-ray intensity and the initial value a ₁₁ was performed.

For example, the value obtained by dividing the characteristic X-ray intensity A ₁₅ in the fifth time by “2 to the (n−1) th power” (that is, the intensity value converted into the measurement time in the first time) is the initial value A _11. On the other hand, when it is determined that the deviation is outside the allowable range set within a predetermined range (for example, 20%), the CPU 12 stops the irradiation of the sample 8 with the electron beam 9.

In this case, the sample analysis is executed based on the data of the characteristic X-ray intensities A _{11 to} A ₁₄ from the first time to the fourth time.

  In the surface analysis, when it is known that a specific part in the scanning region (field of view) of the electron beam 9 is damaged, the operator designates the part to be damaged, and the characteristic X-ray from the part Only strength can be the subject of damage assessment.

  At this time, it is desirable that designation of the damaged part can be automatically designated by image processing from an SEM image such as a reflected electron image or a secondary electron image.

  Further, if only the characteristic X-ray intensity from the part is focused, the above-described example of the point analysis can be applied.

  In the present invention, by evaluating the change in the characteristic X-ray intensity during the analysis of the sample, the analyzer automatically determines the damage and contamination of the sample, and automatically performs the sample analysis according to the progress of the damage and contamination. Can be stopped. This makes it possible to perform sample analysis based only on data that is less affected by damage and contamination of the sample, and leave an analysis result based on the data.

  Furthermore, when the damage and contamination of the sample are particularly large, it is possible to automatically adjust to analysis conditions with less damage and contamination.

  Thus, in the sample analysis method according to the present invention, the electron beam 9 is irradiated to the sample 8, and the intensity of the characteristic X-ray 10 generated from the sample 8 according to the irradiation of the electron beam 9 is time-divisionally divided with time. In the sample analysis method in which the sample 8 is measured and analyzed, the initial value of the characteristic X-ray intensity measured at the start of measurement, and the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing, When the time-lapse values measured sequentially over time deviate from the tolerance range set within the specified range of increase / decrease with respect to the initial value, the measurement is stopped and the initial value and tolerance Sample analysis is performed based on each time-lapse value within the value range.

  The sample analysis method also includes a step of irradiating the sample 8 with the electron beam 9 and a step of measuring the intensity of the characteristic X-ray 10 generated from the sample 8 according to the irradiation of the electron beam 9 in a time-sharing manner with time. Comparing the initial value of the characteristic X-ray intensity measured at the start of measurement with the characteristic X-ray intensity value (time value) measured at each subsequent measurement timing, In response, the step of stopping the measurement when the time-lapsed values sequentially measured deviate from the allowable value range set within the range of increase / decrease of a predetermined ratio with respect to the initial value, and within the initial value and allowable value range. Performing a sample analysis based on the respective time values.

  Furthermore, the sample analyzer according to the present invention irradiates the sample 8 with the electron beam 9 and measures the intensity of the characteristic X-ray generated from the sample 8 in response to the irradiation of the electron beam 9 in a time-sharing manner with time. In the sample analyzer for analyzing the sample 8, the comparison between the initial value of the characteristic X-ray intensity measured at the start of measurement and the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing is performed. The measurement is stopped when the time-lapse values measured sequentially as time elapses deviates from the tolerance range set within the specified range of increase / decrease with respect to the initial value. Sample analysis is performed based on each time-dependent value.

  In the above, the irradiation condition of the electron beam 9 is selected as an irradiation condition in which the change of the characteristic X-ray intensity with the passage of time in the sample 8 to be analyzed is relatively small, and the sample 8 is subjected to the irradiation condition based on the irradiation condition. The electron beam 9 can be irradiated.

  The sample analysis can be applied to either point analysis or surface analysis on the sample.

  As a result, in the present invention, the initial value of the characteristic X-ray intensity measured at the start of measurement is compared with the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing. The measurement is stopped when the time-lapsed value measured sequentially according to the value deviates from the allowable value range set within the range of increase / decrease of a predetermined ratio with respect to the initial value, and is within the initial value and allowable value range. Sample analysis is performed based on each time course value.

  When the time-lapse value is out of the allowable range, it is found that the influence on the characteristic X-ray intensity due to the damage and / or contamination of the sample 8 caused by the irradiation of the electron beam 9 is increased. , Stop the measurement at that time, and perform sample analysis that is hardly affected by the damage and / or contamination by performing sample analysis based on the initial value and each time-lapse value within the allowable range can do.

It is a schematic block diagram which shows the sample analyzer in this invention. It is a figure which shows the time-dependent change of the characteristic X-ray intensity measured in the sample which receives damage easily. It is a figure which shows the example in case the characteristic X-ray intensity measured in a certain measurement timing reduces and it remove | deviates from the allowable value range. It is a figure which shows the example of the change of the characteristic X-ray intensity measured at each measurement timing when changing irradiation current sequentially. It is a figure which shows an example of the acquired image in a surface analysis. It is a figure which shows the other example of the acquired image in a surface analysis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Focusing lens, 3 ... Objective lens, 4 ... Deflection coil, 5 ... Stage mechanism, 6 ... Irradiation current detector, 7 ... X-ray spectrometer, 8 ... Sample, 9 ... Electron beam, 10 ... Characteristic X-ray, 11 ... bus line, 12 ... CPU, 13 ... memory, 14 ... display unit, 15 ... input unit, 1a to 5a ... drive control unit, 6a ... current detection unit, 7a ... signal processing unit

Claims (7)

A sample analysis method for analyzing a sample by irradiating a sample with an electron beam and measuring the intensity of characteristic X-rays generated from the sample in response to the electron beam irradiation in a time-sharing manner over time. The initial value of the characteristic X-ray intensity measured sometimes is compared with the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing. , Stop the measurement when it falls outside the tolerance range set within the specified range of increase / decrease with respect to the initial value, and perform sample analysis based on the initial value and each time value within the tolerance range A sample analysis method characterized by the above. A sample analysis method comprising a step of irradiating a sample with an electron beam and a step of measuring the intensity of characteristic X-rays generated from the sample in response to the irradiation of the electron beam in a time-sharing manner with the passage of time. A step of comparing the initial value of the measured characteristic X-ray intensity with the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing, and the time value measured sequentially over time Is stopped when the measurement value is out of the allowable range set within the specified range of increase / decrease with respect to the initial value, and the sample is based on the initial value and each time value within the allowable range. A sample analysis method comprising: performing an analysis. Select the irradiation condition of the electron beam as an irradiation condition in which the change in the characteristic X-ray intensity with time with respect to the sample to be analyzed becomes relatively small, and irradiate the sample with the electron beam based on the irradiation condition. The sample analysis method according to claim 1 or 2. The sample analysis method according to claim 1, wherein the sample analysis is point analysis or surface analysis on the sample. A sample analyzer that analyzes a sample by irradiating the sample with an electron beam and measuring the intensity of characteristic X-rays generated from the sample in response to the irradiation of the electron beam in a time-sharing manner over time. The initial value of the characteristic X-ray intensity measured sometimes is compared with the value of the characteristic X-ray intensity (time value) measured at each subsequent measurement timing. , Stop the measurement when it falls outside the tolerance range set within the specified range of increase / decrease with respect to the initial value, and perform sample analysis based on the initial value and each time value within the tolerance range A sample analyzer characterized by that. Select the irradiation condition of the electron beam as an irradiation condition in which the change in the characteristic X-ray intensity with time with respect to the sample to be analyzed becomes relatively small, and irradiate the sample with the electron beam based on the irradiation condition. The sample analyzer according to claim 5. The sample analysis apparatus according to claim 5 or 6, wherein the sample analysis is point analysis or surface analysis on the sample.

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