WO2002075246A1

WO2002075246A1 - Method for measuring dimensions of pattern

Info

Publication number: WO2002075246A1
Application number: PCT/JP2001/002130
Authority: WO
Inventors: Fumio Mizuno; Mitsugu Sato
Original assignee: Hitachi, Ltd.
Priority date: 2001-03-16
Filing date: 2001-03-16
Publication date: 2002-09-26
Also published as: JPWO2002075246A1

Abstract

A method for measuring process parameters, e.g. dimensions of a patter, by irradiating the surface of a sample, e.g. an wafer, with a probe, e.g. an electron beam. When the positive focal position of an electron beam is measured in a plurality of points on the surface of a sample, incident angle of the electron beam to the surface of the sample can be determined from the difference of the measured positive focal positions. Dimensions of a pattern are measured by adjusting the inclination of the sample utilizing the function of inclining a sample stage so that an incident electron beam is focused positively in all points in an observation position, or altering the incident angle of the electron beam by controlling an electron beam deflector based on the measured incident angle of the electron beam thereby setting the incident angle of the electron beam at a specified value.

Description

Pattern dimension measuring method Technical field

The present invention irradiates a probe such as an electron beam onto a sample surface such as a wafer in a manufacturing process of a semiconductor device, an imaging device, and a display device by pattern processing, and measures and measures process parameters such as pattern dimensions. On how to do. Rice field

Background art

A description will be given of an example of a measuring SEM (Scanning Electron Microscope). The length measurement SEM is used for measuring a pattern dimension in a semiconductor device manufacturing process or the like. The measurement of the pattern size is performed by the following procedure using the SEM sample image and the line profile.

(1) After forming the sample image, accurately focus the electron beam and position the measurement pattern.

(2) One-dimensional scanning of the electron beam across the measurement pattern to form a line profile. The scanning direction of the electron beam matches the direction in which the dimensions on the measurement pattern are to be obtained.

(3) A pattern edge position is determined from the obtained line profile according to a predetermined pattern edge determination algorithm.

(5) Calculate the dimensions of the measurement pattern from the obtained pattern edge position intervals. The calculated value of the edge interval is converted from the corresponding electron beam deflection amount.

(6) The obtained calculated value is output as a pattern dimension measured value.

The above is the standard processing flow for pattern dimension measurement using length-measuring SEM.However, operations to determine and control the angle between the pattern surface and the electron beam (electron beam incident angle) are performed. Absent. Therefore, the electron beam incident angle Δ0 varies due to operations such as sample exchange and beam adjustment, or disturbances such as stray magnetic field fluctuations. In addition to the geometrical difference w (cosA Θ -1) between the dimension measurement value ab and the pattern width w, as shown in Fig. 2, the line at the left and right pattern edges As the profile shape becomes asymmetric, measurement accuracy decreases. In particular, it has been experimentally confirmed that the asymmetrical line profile has a large effect on the dimension measurement accuracy.

In recent years, the required dimension measurement accuracy has been reduced by a factor of 0.7 times in three years with the progress of miniaturization of patterns of semiconductor devices. For example, at the 2005 O O nm technology node, dimensional measurement accuracy of 1.4 nm or less is required to measure an isolated line having a width of 70 nm. In order for the SEM to achieve such required measurement accuracy, it is essential to control each parameter of the electron beam more precisely. In particular, it is important to increase the accuracy of the electron beam incident angle and reduce its dispersion. In order to make the electron beam incident on the sample surface at an accurate angle and to reduce the dispersion of the incident angle, means for accurately measuring the incident angle of the electron beam is required. An object of the present invention is to provide a method and an apparatus for accurately measuring the angle of incidence of a probe such as an electron beam on a sample surface in view of such a situation. Another object of the present invention is to provide a method and an apparatus for measuring a pattern dimension with high accuracy. Disclosure of the invention

If the sample surface is perpendicular to the optical axis of the electron beam (probe) and the incident angle of the electron beam Δ 0 = 0, then the surface between the sample surface and the focal point of the incident electron beam, as shown in Fig. 3 (a). The (focal plane) coincides, and the focal position of the electron beam does not change when the electron beam focuses on the sample plane at any position on the sample plane. On the other hand, if the sample surface and the optical axis of the incident electron beam are not orthogonal and 0 厶 0, the sample surface and the focal plane of the incident electron beam have an angle of △ 0, as shown in FIG. 3 (b). , The focus position changes from place to place. The rising portion or the falling portion of the obtained line profile waveform is a part of the pattern. For example, when the relationship between the sample surface and the incident electron beam is as shown in FIG. 4, the focal position of the electron beam is on the pattern. With a positive focus Although the left end is steep, the incident electron beam does not become a positive focus, and the right end where the focus of the electron beam deviates from above the pattern becomes blunt.

Using this phenomenon, it is possible to adjust the focus position of the electron beam (probe) at each position on the sample surface, or to obtain the correct focus position. Then, when the positive focus position of the electron beam is measured at a plurality of positions on the sample surface, the incident angle formed by the electron beam with the sample surface can be obtained from the obtained difference between the positive focus positions. Also, adjust the tilt of the sample using the tilt function of the sample stage so that the incident electron beam is focused at all points within the observation location, or use the electron beam based on the calculated electron beam incident angle. By controlling the deflector to change the incident direction of the electron beam, the incident angle of the electron beam can be set to a predetermined value.

That is, the pattern dimension measuring method according to the present invention is as follows.

(1) A method of irradiating a sample surface with a finely narrowed probe, detecting a signal generated from the sample due to interaction with the probe, and measuring a dimension of a pattern formed on the sample surface using the detected signal. In multiple fields of view on the sample surface, the incident probe calculates the positive focus position of the incident probe that focuses on the sample surface, and enters the light based on the distance between the visual fields for which the positive focus position was calculated and the difference between the positive focus positions in each field of view. A pattern dimension measuring method characterized in that an incident angle between a probe and a sample surface is obtained.

The positive focus position of the incident probe means the focal position of the incident probe when the incident probe is focused on the sample surface.

(2) A method of irradiating a sample surface with a finely focused probe, detecting a signal generated from the sample by interaction with the probe, and measuring the dimensions of a pattern formed on the sample surface using the detected signal. In, the incident probe finds the positive focus position of the incident probe that focuses on the sample surface in multiple fields of view on the sample surface, and enters based on the distance between the field of view where the positive focus position was found and the difference between the positive focus positions in each field of view. A pattern dimension measuring method comprising: determining an incident angle formed by a probe with a sample surface; adjusting an incident angle of an incident probe and / or a tilt of the sample surface; and setting the incident angle of the probe to a predetermined value.

(3) The sample surface is illuminated with a finely squeezed probe, a signal generated from the sample due to interaction with the probe is detected, and a pattern formed on the sample surface using the detected signal In the method for measuring the dimensions of the sample, the incident probe determines the positive focus position of the incident probe that focuses on the sample surface in multiple fields of view on the sample surface, and calculates the distance between the field of view and the positive focus in each field. A method for measuring a pattern dimension, comprising: obtaining an incident angle between an incident probe and a sample surface from a position difference; and correcting the obtained measured pattern dimension using the incident angle.

(4) A method of irradiating a sample surface with a finely squeezed probe, detecting a signal generated from the sample due to interaction with the probe, and measuring a dimension of a pattern formed on the sample surface using the detected signal. A pattern size measuring method characterized by adjusting the tilt of the sample surface so that the focal point of the incident probe is at the correct focal point where the focus is focused on the sample surface in a plurality of fields on the sample surface, and then measuring the pattern size. .

(5) In the pattern dimension measuring method according to any one of (1) to (4), the operation for obtaining the focus point position is performed at a magnification higher than the magnification at the time of pattern dimension measurement. One dimension measurement method.

(6) In the pattern dimension measuring method according to any one of (1) to (4), the operation for obtaining the focus point position is performed at an incident probe opening angle larger than the incident probe opening angle at the time of pattern dimension measurement. A pattern dimension measuring method characterized by the following.

(7) In the pattern dimension measurement method according to any one of (1) to (6), the operation of obtaining the focus point position is performed by forming a line profile group of the detection signal while changing the focus position of the incident probe. And a focus position at which the steepest line profile is obtained is defined as a focus position.

(8) The pattern dimension measuring method according to any one of (1) to (7), wherein the field of view for determining the focus point position is set outside the range of the pattern dimension measuring field of view. Measuring method.

(9) In the pattern dimension measuring method according to any one of (1) to (8), the movement to the visual field for obtaining the focus point position is performed by electromagnetically deflecting the incident probe. Characteristic pattern dimension measurement method.

(10) In the pattern dimension measuring method according to any one of (1) to (9), the field of view for obtaining the positive focus position passes through the pattern dimension measuring field of view and moves the sample stage. A pattern dimension measuring method characterized by being arranged on one or two straight lines along a moving direction.

(11) The pattern dimension measuring method according to any one of (1) to (10), wherein the probe is an electron beam, an ion beam, or a laser beam. Measuring method.

According to the present invention, since the incident angle of the electron beam can be obtained and the incident angle of the electron beam on the sample surface can be precisely controlled, high-precision measurement of the pattern dimension becomes possible. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a schematic configuration of a length measuring SEM as an example of a pattern shape measuring apparatus according to the present invention.

FIG. 2 is a diagram for showing that the accuracy of re-pattern dimension measurement is reduced due to the non-zero electron beam incident angle.

FIG. 3 is a diagram for explaining the relationship between the electron beam incident angle, the focal plane, and the sample plane, which is the principle of the present invention.

FIG. 4 is a diagram showing a change in the shape of the line profile when the sample is inclined.

FIG. 5 is a diagram showing the relationship between the beam focal position and the line profile shape. FIG. 6 is a diagram showing a flow of an example of a pattern dimension measuring process according to the present invention. FIG. 7 is a diagram for explaining the relationship between the dimension measurement visual field and the focus position measurement visual field.

FIG. 8 is a diagram showing a configuration example for adjusting the sample height on the sample stage.

FIG. 9 is a schematic diagram for explaining a pattern height and a side wall inclination angle.

FIG. 10 is a diagram illustrating an example of an algorithm for obtaining a pattern height and a sidewall inclination angle from a pattern image.

FIG. 11 is an explanatory diagram of a magnification calibration standard sample. BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a length measuring SEM as an example of a pattern shape measuring apparatus according to the present invention. The electron beam 2 emitted from the electron gun 1 is accelerated to a predetermined energy, then narrowed down by the converging lens 3 and the objective lens 4, and passes through the load / unload chamber 10 into the sample chamber 11. Focus on the surface of wafer 5 on sample stage 12 introduced into Generally, the converging lens 3 is used for controlling the electron beam current value, and the objective lens 4 is used for adjusting the focal position of the electron beam 2.

The trajectory of the electron beam 2 whose focus has been adjusted as described below is bent by the upper and lower deflectors 6, and the two-dimensional or two-dimensional surface of the wafer 5 is set with the objective lens aperture 20 as a fulcrum of deflection. One-dimensional scanning. On the other hand, secondary electrons 7 are emitted from the wafer portion irradiated with the electron beam 2. The secondary electrons 7 are detected by the secondary electron detector 8, converted into electric signals, and then subjected to signal processing such as amplification and AZD conversion in the signal processing unit 14. The processed image signal is stored in the memory unit 15 and is used for luminance modulation or Y modulation of the display 9. The scanning lines of the display 9 are scanned in synchronization with the scanning of the electron beam 2 on the wafer surface, and a sample image is formed on the display. If two-dimensional scanning and luminance modulation are applied, a sample image is displayed. If one-dimensional scanning and Y modulation are applied, a line profile is drawn. At this time, the observation magnification of the sample image is inversely proportional to the amount of electron beam deflection on the sample surface, and can be changed by adjusting the strength of the deflector.

Here, for example, the relationship between the electronic beam focal position and the line profile shape as shown in FIG. 5 is used to adjust the focal position for finding the correct focal position. The line profile obtained when the electron beam crosses the pattern has a sharp rising edge and a sharp falling edge if the electron beam is focused on the pattern as shown in Fig. 5 (a). If the pattern is out of focus as shown in Fig. 5 (b), the rising and falling portions become dull. The control unit 17 forms the line profile while changing the output of the lens power supply 18, that is, the objective lens excitation current value, and sets the objective lens excitation current value where the steepest line profile is obtained. To focus the electron beam 2. Fig. 6 shows the procedure for pattern dimension measurement by the length measurement SEM shown in Fig. 1. This will be described below with reference to FIG.

In step 11, the stage is moved to the dimension measurement visual field. After forming the sample image in step 12, the electron beam is accurately focused and the measurement pattern is positioned. Next, proceed to step 13 to change the observation magnification and electron beam opening angle for setting the focal position. Both the focal position setting magnification and the focal position setting electron beam opening angle are set to values larger than the observation magnification and the electron beam opening angle at the time of dimension measurement in order to increase the measurement accuracy of the positive focal position. The aperture angle of the electron beam can be changed by forming a dimension measurement aperture and a focus position setting aperture at the aperture of the converging lens 3 or the objective lens 4 and deflecting and selecting the electron beam at a predetermined aperture. Do.

Next, in step 14, the deflector is controlled to move to the focal position measurement field of view electrically. The focus position measurement field is located outside the dimension measurement field to increase the measurement accuracy of the electron beam incident angle. The position where the focal position measurement field of view is placed is as follows: (1) In order to enable the field of view to be moved in a short time using the electron beam deflector 6, the electron beam is telecentric, that is, perpendicular to the sample surface. And (2) the direction of incidence and angle of use, depending on the application, for example, two points along the X movement direction of the stage, or As shown in Fig. 7, three points are set, two points along the X movement direction and one point along the Y movement direction.

In step 15, in the moved focal position measurement visual field, a line profile is acquired while changing the positional relationship between the electron beam focal position and the sample surface in a predetermined step in the optical axis direction, and the right focus position is determined. . The focal position is changed by, for example, assembling an array of small vertically moving actuators made of piezoelectric elements on a wafer fixing pallet installed on the sample stage 12 as shown in Fig. 8. It is. In other words, assuming that the field of view is now moving to the focal position measurement field of view a, the actuator immediately below the focal point measurement field of view a is moved up and down so that the line profile becomes the steepest, and the wafer height at section a To the focus position.

After adjusting the wafer height to the correct focus position within the focus position measurement field of view a, Step 16 Then, return to step 14 to move to the next focus position measurement field of view, for example, field of view b, and similarly move the actuator immediately below field of view b to adjust the wafer height in section b to the normal focus position . That is, the height of the wafer in section b is adjusted so that the obtained line profile is the steepest. Thus, the correct focus position is determined in all the focus position measurement visual fields. For example, in the case of FIG. 7 in which measurement is performed at two points in the X-axis direction and at one point in the Y-axis direction, the positive focus position is determined in three focus position measurement fields of view a, b, and c, respectively.

Since the conditions for perpendicular incidence of the electron beam on the sample surface have been obtained by the above processing, proceed to step 17 and change the observation magnification and the electron beam opening angle to the dimension measurement magnification and the dimension measurement opening angle. Next, in step 18, the deflector 6 is controlled to electrically move to the dimension measurement visual field and position the measurement pattern. In step 19, it is confirmed that the lens is at the correct focal position, and the flow advances to step 20 to measure a pattern dimension of a desired portion. The pattern dimension measurement is performed according to a known procedure. That is, a line profile is formed by one-dimensional scanning of the electron beam across the measurement pattern in the direction in which the dimension on the pattern is to be obtained, and the pattern edge position is determined from the obtained line profile according to a predetermined pattern edge determination algorithm. The dimensions of the measurement pattern are calculated from the obtained pattern edge position intervals. The obtained calculated value is output as a pattern dimension measured value.

In the present embodiment, a method was used in which the sample 5 was inclined to make the incident angle △ 0 of the electron beam 2 0, but the height of the sample was not changed and the electron beam incident angle on the sample surface was changed. It is also possible to realize Δ = 0 by obtaining the value of 0 and changing the incident angle of the electron beam.

The electron beam incident angle Δ Δ on the sample surface may be measured, for example, separately for the X component and the Υ component. The X component of Δ Θ can be measured as follows. For example, as shown in Fig. 7, the focus position measurement visual fields a and b are set at a distance d in the X direction outside the dimension measurement visual field. The distance d can be obtained based on the deflection current of the deflector 6 when the visual field moves from the visual field a to the visual field b. Then, in the focus position measurement field of view a, the positive focus position fa where the incident electron beam focuses on the sample surface, and in the focus position measurement field of view b, The position fb at which the incident electron beam focuses on the sample surface is determined. The positive focus positions fa and fb can be obtained from the excitation current correction value of the objective lens 4 necessary to obtain the steepest line profile in each field of view.

From the d, f a, and f b obtained in this way, the X-direction component of △ 計算 is calculated as atan {(f b — f a) no d}. The Y-direction component of Δ0 can also be obtained in a similar manner from measurements in two focus position measurement fields set on a straight line parallel to the Y-axis. Once the incident angle Δ Δ of the electron beam on the sample surface is known, = can be achieved by inclining the electron beam by △ 0 and making it incident on the sample surface. The angle of incidence of the electron beam can be adjusted by controlling the outputs of the upper and lower two-stage deflectors 6 as described above.

Note that instead of the positive focus position fa in the focal position measurement field of view a and the positive focus position fb in the focus position measurement field of view, the amount of defocus from the positive focus position in the focus position measurement field of view a and the focus position measurement field b Similar results can be obtained by using the amount of defocus from the correct focus position. The amount of defocus from the positive focus position in the focal position measurement field of view is determined by measuring the line profile of the sample surface at each position while moving the sample in the optical axis direction by the sample stage, and obtaining the steepest line profile. Can also be obtained as the distance in the optical axis direction by which is moved.

As described above, the incident electron beam with respect to the sample surface can be obtained by changing the sample height or (2) changing the excitation current of the objective lens, as described above. A line profile group is formed while changing the focal position of the line, and the focal position at which the line profile having the sharpest rising edge and the sharpest falling edge of the waveform is obtained as the normal focus position. At this time, in order to obtain the correct focus position with high accuracy, it is better to adjust the focus depth in a shallow state. The depth of focus DOF is expressed as DOF oc l / Μα using the observation magnification M and the half-open angle of the electron beam. Therefore, as shown in step 13 in Fig. 6, (1) (2) The electron beam opening angle larger than the electron beam opening angle at the time of pattern dimension measurement is used to obtain the right focus position.

In addition, instead of controlling the electron beam incident angle, the It is also possible to correct the pattern dimension measurement value and output the corrected value as the pattern dimension measurement value. For example, if the effect that the line profile becomes asymmetric is not considered, the influence of △ 0 can be corrected by the following equation. However, in this case, it is difficult to correct the asymmetry of the line profile with a simple algorithm, and a correction algorithm backed by actual measurement data is required to improve measurement accuracy.

(Dimension measurement value output as measurement result) = (Dimension measurement value) / _COS A 0 The effectiveness of the present invention is not limited to the measurement of pattern dimensions. By applying the present invention, all kinds of two-dimensional and three-dimensional shapes can be measured with higher accuracy. For example, the depth and slope of the bottom and side surfaces of holes and grooves calculated using multiple sample images with different incident angles are measured with higher accuracy. It becomes possible.

As an example, FIG. 9 shows a case where the height H of the pattern and the inclination angle 側壁 of the side wall are obtained using the schematic diagram of FIG. 9 and the flowchart of FIG. The pattern height H and the side wall inclination angle 0 are required to precisely control the gate processing and trench processing of a semiconductor device. From the length LP of the side wall on the image when the electron beam is incident vertically and the length L i when the electron beam is incident at an angle of α, the procedure shown in Fig. 10 is used. Obtain the pattern height H, side wall length L, and inclination angle 傾斜. If L p and L i can be measured more accurately and more precisely, it is possible, of course, to calculate more reliable values of H, L and Θ.

First, in step 31, an electron beam is perpendicularly incident on the sample surface, and Lp is measured from the pattern image at that time. Next, in step 32, an electron beam is obliquely incident on the sample surface at an incident angle, and L ρ is measured from the pattern image at that time. In step 33, L and 0 are obtained from the relational expressions L p = L cos 0 and L i = L cos (0-α). Further, in step 3 4, Ru obtains the height H from the equation H = L si _n e.

On the other hand, when the observation magnification is calibrated using a standard sample, calibration with higher accuracy is realized. If the calibration accuracy is high, all measurements using this device can be performed with higher accuracy. Fig. 11 shows an example of a calibration standard sample. The upper part of FIG. 11 is a plan view of the calibration standard sample, and the lower part is a cross-sectional view. This calibration standard sample is a process in which a fine line pattern group is processed on a Si single crystal substrate by a process similar to LSI processing using the optical interference exposure method and the anisotropic jet etching method. . According to this method, a group of lines with extremely accurate pitch can be formed, and it is used to calibrate the magnification of the length measurement SEM.

A pattern image corresponding to the plan view of Fig. 11 is formed by vertically incident an electron beam.The pitch on the image is measured, and the length of the length-measuring SEM is adjusted so that the measured value matches the calibration value of the standard sample pitch. Adjust the observation magnification. In this case as well, the more accurate the pitch measurement, the more accurate the calibration.

In addition, a higher-resolution sample image can be formed over the entire screen. This also means that all measurements using sample images can be performed with higher accuracy.

In the above embodiment, the length measurement SEM using an electron beam has been described as an example. However, the device to which the present invention is applied is not limited to SEM. The present invention can be similarly applied to an apparatus using an ion beam other than an electron beam, a laser beam, or the like as a probe. For example, if a laser beam is used as the scanning beam instead of the electron beam of the measurement SEM, pattern dimensions and the distance between two points can be measured by the same principle. Even in such a case, controlling the incident angle of the scanning laser beam accurately and precisely leads to an improvement in measurement accuracy. Industrial applicability

As described above, according to the present invention, since the electron beam incident angle can be precisely controlled, the pattern size can be reduced by a direct effect or an indirect effect such as a higher resolution of the sample image and an improvement in the calibration accuracy. The three-dimensional shape value such as the two-dimensional shape value or the hole depth can be obtained with higher accuracy.

Claims

The scope of the claims

1. Irradiate the sample surface with a finely squeezed probe, detect the signal generated from the sample due to the interaction with the probe, and measure the dimensions of the pattern formed on the sample surface using the detected signal. In the method,

In a plurality of visual fields on the sample surface, the incident probe obtains a positive focus position of the incident probe that focuses on the sample surface, and calculates a distance between the visual fields for which the positive focus position is obtained and a difference between the positive focus positions in each of the visual fields. A pattern dimension measuring method characterized in that an incident angle between an incident probe and a sample surface is determined from the above.

2. A method of irradiating a sample surface with a finely squeezed probe, detecting a signal generated from the sample due to interaction with the probe, and measuring a dimension of a pattern formed on the sample surface using the detected signal. At

In a plurality of visual fields on the sample surface, the incident probe obtains a positive focus position of the incident probe that focuses on the sample surface, and calculates a distance between the visual fields for which the positive focus position is obtained and a difference between the positive focus positions in each of the visual fields. The incident angle between the incident probe and the sample surface, and the incident angle of the incident probe and / or the inclination of the sample surface are adjusted to set the incident angle of the probe to a predetermined value. Measuring method.

3. A method of irradiating the sample surface with a finely squeezed probe, detecting a signal generated from the sample by the interaction with the probe, and measuring a dimension of a pattern formed on the sample surface using the detected signal. At

In a plurality of visual fields on the sample surface, the incident probe obtains a positive focus position of the incident probe that focuses on the sample surface, and calculates a distance between the visual fields for which the positive focus position is obtained and a difference between the positive focus positions in each of the visual fields. A pattern dimension measuring method comprising: obtaining an incident angle formed by an incident probe with a sample surface from the sample; and correcting the obtained pattern dimension measured value using the incident angle.

4. A method of irradiating a sample surface with a finely focused probe, detecting a signal generated from the sample by the interaction with the probe, and measuring a dimension of a pattern formed on the sample surface using the detected signal. At Adjusting the inclination of the sample surface so that the focal point of the incident probe is at a positive focus position where the focus of the incident probe is focused on the sample surface in the plurality of visual fields on the sample surface, and then measuring the pattern size. Measuring method.

5. The pattern dimension measuring method according to any one of claims 1 to 4, wherein the operation of obtaining the focus position is performed at a magnification higher than the magnification at the time of pattern dimension measurement. Method.

6. The pattern dimension measuring method according to any one of claims 1 to 4, wherein the operation of obtaining the positive focus position is performed at an incident probe opening angle larger than the incident probe opening angle at the time of pattern dimension measurement. A method for measuring a pattern dimension, characterized in that:

7. The pattern dimension measuring method according to any one of claims 1 to 6, wherein the operation of obtaining the positive focus position is performed by forming a line profile group of a detection signal while changing a focus position of an incident probe, A pattern dimension measuring method, wherein a focal position at which a steepest line profile is obtained is set as a normal focal position.

8. The pattern dimension measuring method according to any one of claims 1 to 7, wherein a field of view for obtaining the positive focus position is set outside a field of the pattern dimension measuring field of view.

9. The pattern dimension measuring method according to any one of claims 1 to 8, wherein the movement to the visual field for obtaining the focus position is performed by electromagnetically deflecting the incident probe. Pattern dimension measurement method to be used.

10. The pattern dimension measuring method according to any one of claims 1 to 9, wherein the visual field for obtaining the focus position is one or two along the moving direction of the sample stage through the pattern dimension measuring visual field. A butterfly dimension measuring method characterized by being arranged on a straight line of a book.

11. The pattern dimension measuring method according to any one of claims 1 to 10, wherein the probe is an electron beam, an ion beam, or a laser beam.