JPH05248843A - Scanning type electron microscope - Google Patents

Abstract

PURPOSE:To obtain a scanning electron microscope, which accurately corrects the error of the measured length value caused by the fluctuation of the measuring conditions of magnification, the accelerating voltage of an electron gun and the like and the measuring errors caused between a plurality of measuring devices and which can directly obtain the corrected measured length value as the output. CONSTITUTION:A correcting equation y=ax+b, which corresponds to each measuring conditions such as of the kind of the sample and, with respect to the respective measuring conditions, wherein the measuring the measurement magnification, is formed based on the designed values and the specified measured length value. The equation is stored into a disk device 5 through a terminal device 6. When the length is measured under the specified measuring conditions, the correcting equation corresponding to the measuring conditions is selected among the correcting equations stored in the disk device 6. The measured length value is corrected by this correcting equation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope having a length measuring function, and in particular, corrects and standardizes a length measuring value obtained under various measuring conditions (hereinafter, also referred to as length measuring condition). It relates to a correction method.

[0002]

2. Description of the Related Art FIG. 3 is a diagram for explaining a hardware configuration of a conventional scanning electron microscope having a length measuring function. FIG. 3 (a) shows the entire configuration, and FIG. Shows functional blocks of a central processing unit mounted on the scanning electron microscope. In the figure, reference numeral 1 denotes a scanning electron microscope main body, which is composed of an electron gun, a lens, a beam deflector, etc., which are not shown, and which irradiates an object to be measured (hereinafter also referred to as a measurement sample) 11 while scanning the electron beam A. Irradiation device 10, detector 1 for detecting secondary electrons B from the measurement sample 11
2, a stage 13 for mounting the measurement sample, a driving device 14 for the stage, and various devices such as an exhaust system 15 for maintaining the inside of the electron microscope main body in a predetermined reduced pressure atmosphere. The operation of each device constituting the electron beam irradiation system, stage drive system, and exhaust system of No. 1 is controlled by the control computer 2.

Reference numeral 20 is a data input / output system for measuring the length using the electron microscope main body 1. The system 20 includes a keyboard 6a for inputting information for measuring the length and input information and A terminal device 6 having a display screen 6b for displaying output information, an output device 7 such as a printer for outputting data such as a length measurement value displayed on the display device 6b, and data such as the length measurement value. A disk device 5 for storing input data from the terminal device 6 and a program for length measurement, and a main storage device 4 for storing control programs for the devices 5, 6 and 7 It is configured.

Reference numeral 3 controls each device of the control computer 2 and the data input / output system 20, and outputs the detection signal D of the secondary electron B from the detector 12 of the electron microscope main body 1 to the data input / output system. It is a central processing unit for performing signal processing on the basis of a signal from 20 to obtain a length measurement value. This is a control means M1 for controlling the control computer 2 as means for realizing a length measurement function.
And a noise removing means M2 for removing noise from the secondary electron detection signal D from the detector 12, and its output D1.
Signal processing means M3 for processing the signal to obtain a length measurement value x,
It has a correction operation means M4 for performing operation processing on the output x of the signal processing means M3 based on the correction equation stored in the disk device 5 to correct it.

Here, the disk device 5 has a correction indicating the relationship between the length measurement result (without correction) x calculated based on the secondary electron detection output D of the detector 12 and the corrected value y. The formula y = ax is stored, and this correction formula y = ax
Is calculated in advance by the user based on the measured value, design value, etc. of the reference measurement sample (target object) measured under specific conditions. This correction formula is applicable to all conditions such as the acceleration voltage of the electron gun. Is applied to all samples.

Next, the operation will be described. First, data such as measurement conditions for length measurement, such as sample type, length measurement magnification, electron gun conditions (accelerating voltage, etc.), is input from the terminal device 6, and the central processing unit 3 outputs the data based on the input data. The control computer 2 is controlled so that the measurement conditions are realized in the scanning electron microscope 1, and the scanning electron microscope 1 operates under the input measurement conditions. That is, in the electron microscope main body 1, the electron beam irradiating device 10 scans the object to be measured 11 placed on the stage 13 with the electron beam A, and the object to be measured 11 is measured.
Secondary electrons B from are detected by the detector 12. As a result, the detection signal D of the secondary electron B from the DUT 11 is obtained at the output of the detector 12 of the scanning electron microscope 1, and the central processing unit 3 measures based on this detection signal D. Perform signal processing for length.

The signal processing, that is, the length measuring operation of the scanning electron microscope will be described below with reference to the flowchart of FIG. First, the central processing unit 3 receives the detection signal D of the secondary electron B from the control computer 2 and then
The noise on the detection signal D of the secondary electron B is removed by the noise removing means M2, and the S / N ratio is improved (step S1). Then, the signal processing means M3 causes the means M
From the signal D1 that has been subjected to the noise removal processing by 2, the slope line indicating the predetermined edge portion of the remaining pattern on the measurement sample 11 and the baseline indicating the base portion other than the above pattern are detected (step S2). Based on the slope line and the baseline, the length measurement result x is obtained using a mathematical method such as a linear approximation method or a threshold method (step S3). After that, the correction calculation means M4
A correction calculation process is performed on the length measurement result x on the basis of the data F from the data input / output system 20 for the correction formula y = ax which is given in advance and stored in the disk device 5 (step S4). The correction value of the result x is measured value y
Output as. The output length measurement value y is input to the data input / output system 20, displayed on the display screen 6a of the terminal device 6, and output from the output device 7 such as a printer as necessary (step S5). ..

After that, the central processing unit 3 repeats such a length measuring process for other places set on the measurement sample 11 by the steps S1 to S5,
When the length measurement process is completed for all the measurement points, that is, when it is determined in step S6 that all the length measurements on the measurement sample 11 are completed, the length measurement process is ended.

[0009]

However, when correcting a length measurement value by a conventional scanning electron microscope, a specific correction formula y = ax obtained under specific measurement conditions is used for all samples and measurement conditions. Since it was applied to the obtained length measurement value, the difference in the length measurement value when measuring the dimension of the same location of the same sample with different magnification, so-called magnification error, and the error due to the difference in acceleration voltage, that is, the same sample It has not always been possible to correct correctly the deviation of the measurement value that occurs when the same part is irradiated with different electron gun acceleration voltages. This means that the parameters of the correction formula are different when the measurement conditions are different, and when the correction formula having the parameter a corresponding to a specific measurement condition is applied uniformly to the measurement values obtained under various measurement conditions. This is because the deviation of the measured value is not always corrected in the above.

Further, the correction formula is y = ax + b, that is, the deviation of the measurement value having the offset value b, for example, the design value which becomes a reference when the length measurement is performed on the samples having different dimensions at the same magnification and the same acceleration voltage. Deviation from the measurement values of other length measuring instruments, and measurement values due to differences in microscopes when measuring lengths under the conditions of the same sample, the same magnification, and the same accelerating voltage using several scanning electron microscopes. Regarding the deviation of, there was a problem that the measurement value could not be corrected.

Further, a method of correcting the deviation of the measurement value having the offset value b after the measurement can be considered. However, this is because when the length measurement data is large, the extra time required for the correction work is measured. This is a long work problem and is not a practical method.

The present invention has been made in order to solve the above-mentioned problems, and an error in a measurement value caused by a change in measurement conditions such as a magnification and an acceleration voltage of an electron gun, and an error between a plurality of measuring devices. You can correct the measurement error accurately,
Moreover, it is an object of the present invention to provide a scanning electron microscope capable of directly obtaining a length measurement value whose output is corrected.

[0013]

A scanning electron microscope according to the present invention responds to each measurement condition with reference to a measured value of a specific object to be measured or a design distance between targets on the surface of the object to be measured. Compensation formula storage means for storing a plurality of compensation formulas for compensating the length measurement value under each measurement condition created, and a plurality of compensations stored in the storage device by an external signal specifying a predetermined measurement condition. Compensation formula selecting means for selecting one of the formulas corresponding to the predetermined measurement condition,
The measurement value obtained under each measurement condition is corrected by a correction calculation means by a correction formula corresponding to each measurement condition and output.

[0014]

According to the present invention, the length measurement under each measurement condition is made corresponding to each measurement condition with reference to the length measurement value of the specific measurement target or the design distance between the targets on the surface of the measurement target. From the plurality of correction formulas for correcting the value, the one corresponding to the predetermined measurement condition is selected, and the length measurement value is corrected and output by the correction formula corresponding to the measurement condition. The measurement value measured under each measurement condition will be corrected by the correction formula suitable for that measurement condition,
It is possible to always accurately correct the error in the measurement value caused by fluctuations in the measurement conditions such as the magnification and the acceleration voltage of the electron gun, and the measurement error that occurs between multiple measuring devices. It is possible to directly obtain the measured length value.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a diagram for explaining a hardware configuration of a scanning electron microscope according to an embodiment of the present invention.
1 (a) shows the overall configuration, and FIG. 1 (b) shows the functional blocks of the central processing unit mounted on this scanning electron microscope.

In the figure, the same reference numerals as those in FIG. 3 designate the same components, and 200 is the data input / output system of this embodiment.
In the disk device 5 of the present data input / output system 200, a user previously created corresponding to each measurement condition with reference to a measured value of a specific measured object or a design distance between targets on the surface of the measured object. A plurality of correction formulas for correcting the length measurement value under each measurement condition are stored, and in the present embodiment, the disk device 5 constitutes a correction formula storage means. Further, reference numeral 30 is a central processing unit equipped with a length measurement value correcting function for correcting a measured value obtained under each measuring condition by a correction formula corresponding to each measuring condition. In addition to the respective means M1 to M4 for realizing the length measuring function of the device 3, the predetermined measurement condition is selected from a plurality of correction formulas corresponding to the respective measurement conditions based on an external signal specifying the predetermined measurement condition. Compensation formula selecting means M5 for selecting a corresponding one and judgment executing means M6 for determining whether or not a compensation formula corresponding to the predetermined measurement condition has already been created and stored in the disk device 5 are provided. There is.

Next, the operation will be described. First, similarly to the conventional apparatus, when data such as measurement conditions for length measurement, for example, sample type, length measurement magnification, electron gun conditions (acceleration voltage, etc.) is input from the terminal device 6, the central processing unit 30 inputs the data. The control computer 2 is controlled so that the measurement conditions are realized in the scanning electron microscope 1 based on the data, and the scanning electron microscope 1 operates under the input measurement conditions.

As a result, the detection signal D of the secondary electron B from the DUT 11 is obtained at the output of the detector 12 of the scanning electron microscope 1, and the central processing unit 30 outputs this detection signal D. Based on this, signal processing for length measurement is performed.

The signal processing will be described below with reference to the flowchart of FIG. First, the central processing unit 30 uses the noise removing means M2 to remove the noise from the control computer 2.
S / N ratio improvement processing is performed on the detection signal D of the next electron B (step T1), and then the signal processing means M3 detects the above-mentioned slope line and base line from the output signal D1 of the means M2. (Step T
2) Based on the slope line and the baseline, the length measurement result x is obtained using the above-mentioned mathematical method (step T
3), and in the next step T4, the judgment executing means M6
Thus, it is determined whether or not the correction formula corresponding to the measurement condition for length measurement is known.

When the correction formula for the above measurement conditions is known, the central processing unit 30 carries out each processing of steps T5 to T7 after the judgment at the above step T4.

That is, the correction formula selecting means M5 selects a correction formula y = ax + b corresponding to this length measuring condition from a plurality of correction formulas stored in the disk device 5 (step T5). Next, the correction calculation means M4 corrects the measurement result x using the selected correction formula, and outputs the correction value of the length measurement result x as the length measurement value y (step T6). And the output measurement value y is
The data is displayed on the display screen 6a of the terminal device 6 of the data input / output system 200, and if necessary, output from the output device 7 such as a printer (step T7). After that, it is determined whether or not the correction formula is known in step T8, and then it is determined whether or not to continue the length measurement process of steps T1 to T8 (step T9). Then, such a length measurement process is repeatedly performed for other locations set on the measurement sample 11 in steps T1 to T8,
When the length measurement processing is completed for all the measurement points, that is, when it is determined in step T9 that all the length measurement on the measurement sample 11 is completed, the length measurement processing is ended.

When it is determined in step T4 that the correction formula is not known, the central processing unit 30 skips steps T5 and T6 and performs the process of step T7, that is, the correction process is not performed. The data input / output system 20 allows the measurement result x to be displayed on the display screen 6a of the terminal device 6, stored in the disk device 5, and output from the output device 7 such as a printer as necessary.
Control 0. Then, after the next step T8, it is determined whether or not the correction formula can be created in step T10. If it is possible to create a correction formula based on the measurement result x, it is confirmed that the user has created a correction formula corresponding to the measurement condition in this case and stored it in the disk device 5 ( Step T11), the above step T
Return to processing of 1. If the storage of the correction formula cannot be confirmed, the fact is displayed on the display screen 6a or the like of the terminal device 6 (step T12), and the process returns to the confirmation process of step T11.

As a result of the judgment in step T10,
If the correction formula cannot be created, the length measurement for the other length measurement locations by the processes of steps T1 to T8 is repeatedly performed until it becomes possible.

Table 1 shows the length measurement value obtained by performing the measurement in this way, with the design value as a reference, the length measurement value without correction under the measurement conditions 1 to 4, and the length measurement according to the conventional correction formula. It is shown in comparison with the results. Here, the design value is a target dimension when processing the object to be measured.

[0025]

[Table 1]

Table 1 shows the measurement sample A under the condition 1.
At a magnification of 20000 times, under the condition 2, the same measurement sample A as the above condition 1 at a magnification of 50000 times, and as the condition 3 a measurement sample B different from the above condition 1 at a magnification of 200 times.
As the condition 4, the measurement sample B, which is the same as the condition 3 above, is measured at a magnification of 5000.
The measurement conditions 1 to 4 are different from the measurement sample only in the magnification, and the electron gun conditions (acceleration voltage and the like) are the same.
Further, the length measurement was performed by measuring the pitch lengths of the line portion and the space portion, and the design value was set to the pitch design value. In addition, the conventional correction processing is performed by the above-mentioned condition 1 without correction (x = 1990 μ
m) is a design value of 2000 μm. A correction formula y = ax (y = 2000 / 1990x, x; length measurement value without correction, y; length measurement result after correction) is used for correction. On the other hand, in the correction processing according to the present invention, the correlation expression y = ax + b which relates the uncorrected length measurement value and the design value is created for each measurement condition 1 to 4, that is, the parameters a and b are set for each measurement condition. Is set to a predetermined value, and the length measurement value under each measurement condition is corrected using these correction formulas.

From Table 1, under each measurement condition, the value obtained by the correction processing of the present invention is standardized with respect to the value obtained by the conventional correction processing and the value not corrected, based on the design value. It can be seen that the value is

As described above, in the present embodiment, for each measurement condition having a different measurement sample and measurement magnification, the correction equation (y = ax + b, a, b: parameter) corresponding to each measurement condition is set as the design value. It is created based on a specific length measurement value, stored in the disk device 5 from the terminal device 6, and when the length measurement is performed under a predetermined measurement condition, the correction formula stored in the disk device 5 is used. Since the correction formula corresponding to the measurement condition is selected and the length measurement value is corrected by this correction formula, the length measurement value standardized with the design value as a reference can be directly obtained as the output of the apparatus. Further, since a correction formula for correcting the length measurement value has a parameter suitable for each measurement condition, it is possible to correct the length measurement error having an offset value due to a machine difference between a plurality of measuring devices. It is possible to obtain a correction value with a small error.

In this embodiment, the parameters of the correction formula are set by using the design values, but the length measurement value or cross-sectional dimension of a specific measurement sample may be used for setting the parameters.

Further, in this embodiment, only the case where the dimensional difference caused by the difference in the measurement sample or the length measurement magnification is corrected is shown. However, the dimensional error of the length measurement value is corrected when there are a plurality of length measuring devices. That is, in the case of using scanning electron microscopes of different types for length measurement, it may be one that corrects a dimensional difference generated between length measuring devices (scanning electron microscopes), and further other measurement conditions such as an electron gun. The correction may be made according to the difference in the conditions of the above. Further, since there are a plurality of measurement conditions such as the measurement sample, the magnification, and the electron gun condition as described above, there are a plurality of correction formulas corresponding to each combination of the measurement conditions. Therefore, if all possible correction equations are created and stored in advance, the process of creating the correction equations can be omitted during length measurement.

[0031]

As described above, according to the present invention, the measurement value of a specific object to be measured or the design distance between the targets on the surface of the object to be measured is used as a reference for each measurement condition.
From a plurality of correction formulas for correcting the length measurement value under each measurement condition, select the one corresponding to the predetermined measurement condition, and correct the length measurement value by the correction formula corresponding to the measurement condition. Since the output is performed, it is possible to always accurately correct the error in the measurement value caused by the variation in the measurement conditions such as the magnification and the acceleration voltage of the electron gun and the measurement error that occurs between a plurality of measuring devices. It is possible to obtain a scanning electron microscope capable of directly obtaining a length measurement value corrected for output.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the configuration of a scanning electron microscope according to an embodiment of the present invention.

FIG. 2 is a flow chart for explaining the operation of the scanning electron microscope.

FIG. 3 is a block diagram for explaining the configuration of a conventional scanning electron microscope.

FIG. 4 is a flow chart for explaining the operation of a conventional scanning electron microscope.

[Explanation of symbols]

 1 Scanning Electron Microscope Main Body 2 Control Computer 4 Main Storage Device 5 Disk Device 6 Terminal Device 6a Display Screen 6b Keyboard 7 Output Device 11 Object to be Measured (Measurement Sample) 12 Detector 13 Stage 14 Stage Drive Device 15 Exhaust System 30 Central Processing Apparatus 200 Data input / output system A Electron beam B Secondary electron M1 Control computer control means M2 Noise removal means M3 Signal processing means M4 Correction calculation means M5 Correction formula selection means M6 Judgment execution means

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[Procedure amendment]

[Submission date] March 3, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

Here, the disk device 5 has a correction indicating the relationship between the length measurement result (without correction) x calculated based on the secondary electron detection output D of the detector 12 and the corrected value y. The formula y = ax is stored, and this correction formula y = ax
It is intended to serving as a reference measurement sample user on the basis of the design values or the like to length measurement value measured at a specific condition (DUT) is calculated in advance, the acceleration voltage and Hakabai of this correction equation electron gun
It applies to all samples for all conditions such as rate .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The signal processing, that is, the length measuring operation of the scanning electron microscope will be described below with reference to the flowchart of FIG. First, the central processing unit 3 receives the detection signal D of the secondary electron B from the control computer 2 and then
The noise on the detection signal D of the secondary electron B is removed by the noise removing means M2, and the S / N ratio is improved (step S1). Then, the signal processing means M3 causes the means M
From signal D1 removal process of noise is made by 2 to detect the slope line indicating a predetermined edge portion of the pattern on the measurement sample 11, and a base line indicating a flat portion other than the edge portions (step S2 ), Based on the slope line and the baseline, the length measurement result x is obtained using a mathematical method such as a linear approximation method or a threshold method (step S3). After that, the correction calculation means M4
From the data output system 20 performs correction processing on the measurement result x based on the previously given the disk device 5 is stored in the correction equation y = a x (step S4), and
The correction value of this length measurement result x is output as the length measurement value y. The output measurement value y is input to the data input / output system 20 and displayed on the display screen 6a of the terminal device 6,
Further, it is output from the output device 7 such as a printer as needed (step S5).

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

However, when correcting a length measurement value by a conventional scanning electron microscope, a specific correction formula y = ax obtained under specific measurement conditions is used for all samples and measurement conditions. Since it was applied to the obtained length measurement value, the difference in the length measurement value when measuring the dimension of the same location of the same sample with different magnification, so-called magnification error, and the error due to the difference in acceleration voltage, that is, the same sample It has not always been possible to correct correctly the deviation of the measurement value that occurs when the same part is irradiated with different electron gun acceleration voltages .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

This is the parameter of the correction formula when the measurement conditions are different.
Data a is also different, and the correction formula is y = ax + b.
That is, it has the offset value b. Off here
The set value b is the same for samples with different dimensions, for example.
It is a standard when measuring the length with one magnification and the same acceleration voltage.
Compensate for deviations from design values and length measurement values of other length measuring instruments
Same in case, or using multiple scanning electron microscopes
Length measurement under the conditions of sample, same magnification and same acceleration voltage
It also occurs when the correlation equation between the devices when performing
Of. Therefore, it supports specific measurement conditions of specific samples
In the correction formula y = ax,
When applied uniformly to the measurement values obtained under the measurement conditions of
It is not always necessary to correct the deviation of the measured values.
Yes.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The present invention has been made in order to solve the above-mentioned problems, and is intended for use as a base or film for a pattern of an object to be measured.
It is possible to accurately correct an error caused by a difference in thickness, an error in a measurement value caused by a variation in measurement conditions such as a magnification and an electron gun acceleration voltage, and a measurement error between a plurality of measuring devices. It is an object of the present invention to provide a scanning electron microscope that can directly obtain a length measurement value that has been subjected to correction processing at the output.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

SUMMARY OF THE INVENTION A scanning electron microscope according to the present invention uses a measurement value of a specific object to be measured or a design distance between targets on the surface of the object to be measured as a reference.
Compensation formula storage means that stores multiple compensation formulas for compensating length measurement values under each measurement condition created corresponding to each measurement condition including a class, and an external signal that specifies a predetermined measurement condition. Correction formula selecting means for selecting one corresponding to the predetermined measurement condition from the plurality of correction formulas stored in the storage device, and the measurement value obtained under each measurement condition is corrected by the correction calculating device. The output is corrected by a correction equation corresponding to each measurement condition.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

According to the present invention, the length measurement under each measurement condition is made corresponding to each measurement condition with reference to the length measurement value of the specific measurement target or the design distance between the targets on the surface of the measurement target. From the plurality of correction formulas for correcting the value, the one corresponding to the predetermined measurement condition is selected, and the length measurement value is corrected and output by the correction formula corresponding to the measurement condition. The measurement value measured under each measurement condition will be corrected by the correction formula suitable for that measurement condition,
Errors in measurement values caused by fluctuations in measurement conditions such as magnification and electron gun acceleration voltage, and errors caused by the type of object being measured.
The difference, and further , the length measurement error generated between the plurality of measuring devices can always be accurately corrected, and the output can directly obtain the length measurement value after the correction processing.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

In the figure, the same reference numerals as those in FIG. 3 designate the same components, and 200 is the data input / output system of this embodiment.
The disk device 5 of the present data input / output system 200 corresponds to each measurement condition including the type of the measured object based on the measured value of the specific measured object or the design distance between the targets on the surface of the measured object. A plurality of correction formulas for correcting the length measurement value under each measurement condition, which are prepared by the user in advance, are stored therein. In the present embodiment, the disk device 5 constitutes a correction formula storage means. There is. Further, reference numeral 30 is a central processing unit equipped with a length measurement value correcting function for correcting a measured value obtained under each measuring condition by a correction formula corresponding to each measuring condition. Device 3
In addition to the respective means M1 to M4 for realizing the length measuring function, the above-mentioned predetermined measurement condition is selected from a plurality of correction formulas corresponding to each measurement condition, based on an external signal for specifying the predetermined measurement condition. It comprises a correction formula selection means M5 for selecting one and a judgment execution means M6 for judging whether or not a correction formula corresponding to the predetermined measurement condition has already been created and stored in the disk device 5.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

That is, the correction formula selecting means M5 selects a correction formula y = ax + b corresponding to this length measuring condition from a plurality of correction formulas stored in the disk device 5 (step T5). Next, the correction calculation means M4 corrects the measurement result x using the selected correction formula, and outputs the correction value of the length measurement result x as the length measurement value y (step T6). And the output measurement value y is
The data is displayed on the display screen 6a of the terminal device 6 of the data input / output system 200, and if necessary, output from the output device 7 such as a printer (step T7). Performing scan te <br/> Tsu determines whether continue measurement process flop t1 to t 7 after its (step T9). That is, the measurement process as described above, repeated for other points that have been set on the measurement sample 11 by the step t1 to t 7, the measuring process is completed for all measurement points, i.e. the measurement sample in step T9 When it is determined that all the length measurements on 11 have been completed, this length measurement process ends.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

[0022] In step T4, when it is determined that no known correction equation, the central processing unit 30, determines whether or not to create a correction equation in Step T10 skip steps T5 and T6 I do. Here if of making correction equation based on the measurement result x, creating a correction equation corresponding to the measurement conditions in this case is performed by the user,
It is confirmed that the data is stored in the disk device 5 (step T11), and the process returns to step T1. If the storage of the correction formula cannot be confirmed, the fact is displayed on the display screen 6a or the like of the terminal device 6 (step T12), and the process returns to the confirmation process of step T11.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

As a result of the judgment in step T10,
If the correction formula is not created , the length measurement result without correction is output.
(Step T7).

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction content]

[0024] Table 1, the measured value without correction, with respect to the design value, the measurement conditions 1-4 correction value, and that shows by comparison with measurement results of the conventional correction formula.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Table 1 shows the measurement sample A under the condition 1.
At a magnification of 20000 times, under the condition 2, the same measurement sample A as the above condition 1 at a magnification of 50000 times, and as the condition 3 a measurement sample B different from the above condition 1 at a magnification of 200 times.
00 times, the condition 4, shows the result of measuring the same measurement sample B and the condition 3 at a magnification 5000 0 times. The measurement conditions 1 to 4 are different from the measurement sample only in the magnification, and the electron gun conditions (acceleration voltage and the like) are the same. Further, the length measurement was performed by measuring the pitch lengths of the line portion and the space portion, and the design value was set to the pitch design value. Further, the conventional correction processing is performed by the above-mentioned condition 1 without correction, that is, the length measurement value (x = 1 .
0 μm) is the design value 2 . Performing become such a correction 000μm correction formula y = ax (y = 2. 000/1. 990x,
x; no correction measurement value, y; to the measurement result after the correction)
The correction processing according to the present invention is to perform correction in all cases . On the other hand, the correlation expression y = ax + b which relates the uncorrected length measurement value and the design value is created for each measurement condition 1 to 4. That is, the parameters a and b are set to predetermined values for each measurement condition, and the length measurement value under each measurement condition is corrected using these correction formulas.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

As described above, in the present embodiment, for each measurement condition having a different measurement sample and measurement magnification, the correction equation (y = ax + b, a, b: parameter) corresponding to each measurement condition is set as the design value. It is created based on a specific length measurement value, stored in the disk device 5 from the terminal device 6, and when the length measurement is performed under a predetermined measurement condition, the correction formula stored in the disk device 5 is used. Since the correction formula corresponding to the measurement condition is selected and the length measurement value is corrected by this correction formula, the length measurement value standardized with the design value as a reference can be directly obtained as the output of the apparatus. Further, a correction formula for correcting the length measurement value uses a parameter having parameters suitable for each measurement condition, and further corrects a length measurement error having an offset value due to a machine difference between a plurality of measuring devices. it is also possible.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Further, in this embodiment, only the case where the dimensional difference caused by the difference in the measurement sample or the length measurement magnification is corrected is shown. However, the dimensional error of the length measurement value is corrected when there are a plurality of length measuring devices. may be one for correcting the dimensional difference occurring between measurement device (scanning electron microscope), and other measurement conditions, it may be corrected for example due to differences in the conditions of the electron gun. Further, since there are a plurality of measurement conditions such as the measurement sample, the magnification, and the electron gun condition as described above, there are a plurality of correction formulas corresponding to each combination of the measurement conditions. Therefore, if all possible correction equations are created and stored in advance, the process of creating the correction equations can be omitted during length measurement.

[Procedure 16]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

[0031]

As described above, according to the present invention, each measured object
Corrects the length measurement value under each measurement condition created for each measurement condition based on the measured value of the measured object or the design distance between the targets on the surface of the measured object for each type of fixed object. Since a correction formula corresponding to the predetermined measurement condition is selected from among a plurality of correction formulas for adjusting the measurement value by the correction formula corresponding to the measurement condition and is output, It is possible to always accurately correct the error in the measurement value caused by fluctuations in the measurement conditions such as the accelerating voltage of the gun and the measurement error between multiple measuring devices. It is possible to obtain a scanning electron microscope capable of directly obtaining a value.

[Procedure Amendment 17]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure 18]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. An enlarged image of an object to be measured is provided, comprising an electron beam irradiation device for irradiating an object to be measured while scanning with an electron beam, and a detector for detecting reflected or transmitted electrons from the object to be measured. In addition to the function to form, in the scanning electron microscope equipped with a length measurement function to obtain the length measurement value of the target distance on the surface of the measured object under various measurement conditions based on the output of the detector, Multiple correction formulas for correcting the length measurement value under each measurement condition created based on the length measurement value of the DUT or the design distance between the targets on the surface of the DUT as a reference. And a correction formula selecting means for selecting one of the plurality of correction formulas corresponding to the predetermined measurement condition by an external signal for specifying a predetermined measurement condition. Determined under conditions A scanning electron microscope characterized in that a measured value is corrected by a correction formula corresponding to each measurement condition.