JP2002134059A - Focused ion beam equipment - Google Patents

Abstract

(57) [Summary] An optical system automatic correction apparatus for a charged particle beam apparatus is an FI
When applied to the B apparatus, there was a problem in each performance such as lack of analysis means, no analysis result verification function, and large sample dependency. Kind Code: A1 Abstract: An SI photographed with settings of a FIB lens, a correction deflector, a beam limiting aperture, and the like changed.
The axis shift, the focus position shift, and the astigmatism are automatically corrected based on the position shift amount between the M images. [Effect] Since the analysis method based on the displacement amount has little dependence on the sample, the applicable range is expanded when the beam current is changed or when drift occurs in the ion gun. In addition, the device correction accuracy is improved by one digit by adopting this position shift analysis method. Since the reliability of the displacement analysis result can be verified from the degree of coincidence, unattended operation with a malfunction prevention flow added becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an apparatus for automatically adjusting an optical system of a focused ion beam apparatus.

[0002]

2. Description of the Related Art When a sample is processed with a focused ion beam (hereinafter referred to as FIB), an appropriate irradiation current is changed by changing a beam limiting aperture according to a shape and a size. Every time the beam limiting aperture is changed, the operator performs the axis shift correction or the focus correction by means of minutely changing the setting of the FIB lens, the correction deflector, or the astigmatism corrector. Further, the operator frequently changes the FIB extraction conditions (extraction voltage and the like) depending on the state of the ion emitter of the ion gun, so that an axis shift and a focus position shift occur. As described above, in the FIB apparatus, the axis deviation correction or the focus correction is frequently performed by the operator.

[0003] Three known examples relating to the automatic correction of the axis deviation or the automatic focus of the charged particle beam apparatus are shown below.

[0004] A known example 1 is an automatic axis deviation correcting device for a scanning electron microscope disclosed in Japanese Patent Application Laid-Open No. H6-176721. To adjust the electron beam to pass through the center of the objective lens, acquire images before and after changing the excitation current of the objective lens, binarize the obtained image, and then move the image due to misalignment. The direction and the movement amount are calculated, and the alignment device is controlled so that the movement amount becomes zero.

[0005] A known example 2 is an automatic focus correcting device for a scanning electron microscope disclosed in Japanese Patent Application Laid-Open No. 7-176285. The convergence state of the charged particle beam is changed, the high-frequency components of the image acquired in each convergence state are extracted, and the integral value of the absolute amount for one screen is recorded. The integrated values in each convergence state are compared, and the convergence state when the integrated value becomes the maximum is determined to be the in-focus state.

A known example 3 is JP-A-11-138242 which is an automatic focus correction device for a transmission electron microscope. If the sample is located on the focal plane, the image before and after the change in the electron beam incident angle does not move, but if the sample is out of the focal plane, the image moves before and after the change in the electron beam incident angle. The amount of displacement due to this parallax is analyzed by a method based on the phase difference image of the Fourier transform image,
The focus is corrected by converting to a defocus amount.

[0007]

The correction of the axis deviation or the correction of the focus in the FIB apparatus not only burdens the operator but also reduces the efficiency of observation and processing. In addition, FI
If the B irradiation amount increases, the destruction of the sample surface progresses. Therefore, it is necessary to shorten a scanning ion microscope (SIM) image acquisition time for correcting the axis deviation or the focus correction. However, the reduction of the SIM image acquisition time relies only on the skill of the operator.

The problem 1 is that the axis shift analysis method used in the known example 1 has no function of numerically indicating the reliability of the analysis result.
It is. In the axis shift analysis method, an incorrect analysis result is output as it is even if the analysis result of the movement amount cannot be analyzed due to image degradation. For example, because the shift angle is too large, the sample may be out of the field of view due to a change in the focal position, and the position shift may not be analyzed. Further, there is a case where an image blur occurs due to an excessively large focal position change amount, and the displacement analysis becomes impossible. The automatic correction device does not guarantee that all the analysis will be performed correctly. Therefore, a means for evaluating the reliability of the analysis result and a function for canceling the correction when the reliability is low are required.

The second problem is that the analysis accuracy of the automatic focus correcting apparatus of the second prior art depends on the sample. If the sample itself has a sharp structure, a clear difference can be seen in the integrated value of the high-frequency component of the image between the focal point and the defocus, but if there is no sharp structure in the sample itself, the difference between the focal point and the defocus will occur. The difference between the integrated values of the high frequency components almost disappears.

Further, a so-called asymptotic method for changing the state of the objective lens and searching for the state of the objective lens at which the sharpness of the image is maximized requires a large amount of data. Data acquisition time is limited by physical factors such as the brightness of the charged particle source and the sensitivity of the detector. Therefore, if the acquisition time per data is excessively shortened, the S / N of the data deteriorates and the analysis becomes difficult. Also, the reduction in the number of data acquisitions causes a deterioration in analysis accuracy.

Also, as in the case of the prior art 1, since there is no index for evaluating the reliability of the analysis result, even if the focus cannot be analyzed because there is no sharp structure in the field of view used for the analysis, the wrong analysis result is used as it is. Output.

The third problem is the necessity of a correcting deflector for changing only the incident angle of an electron beam in the focus correcting device for a transmission electron microscope according to the known example 3. The only reason that the angle of the electron beam incident on the sample changes when the setting of the correction deflector is changed is that
It is only when the deflection fulcrum of the correcting deflector and the focal plane of the objective lens coincide. An apparatus without a deflector for correction in which the deflection fulcrum almost coincides with the focal plane could not analyze the defocus amount.

Therefore, the objects of the present invention are: 1. a function for numerically indicating the reliability of the analysis result in the axis deviation correction; 2. an index for evaluating the reliability of the analysis result with little sample dependence in the focus correction; FI where the fulcrum does not match the focal plane of the objective lens
It is an object of the present invention to provide an FIB apparatus which realizes automatic axis shift correction or automatic focus correction using a focus analysis method in the apparatus B, and enables high-speed, high-precision observation and processing.

[0014]

The means for realizing high-speed and high-precision observation and processing by automating the fine adjustment of the optical system of the FIB apparatus are described below. Each time the beam limiting aperture is changed to an appropriate irradiation current according to the shape and size of the processing,
The axis shift or the focus position shift is automatically corrected by changing the setting of the FIB lens, the correction deflector, or the astigmatism corrector. In addition, the axis deviation that occurs each time the FIB extraction condition from the ion gun is changed is automatically corrected. The function of automatically correcting the axis shift or the focus in the FIB device is realized by a unique mechanism different from the known examples 1 to 3.

Means for solving the problem 1 is an axis shift analysis method using a phase difference of a Fourier transform for an image position shift analysis before and after a setting change of an objective lens or a beam limiting aperture. An analysis image obtained by performing an inverse Fourier transform on the phase difference image of the Fourier transform image of each image has δ at a position corresponding to the amount of displacement.
It can be assumed that only typical peaks are present. Accordingly, the position of the δ-like peak, that is, the amount of displacement between the images, can be obtained with an accuracy of one pixel or less by calculating the center of gravity of the δ-like peak. Further, the intensity of the δ-like peak calculated after normalizing the intensity of the analysis image can be regarded as the degree of coincidence between the images. Since the degree of coincidence can be regarded as the reliability of the analysis result, a pass / fail judgment function of the analysis result using the degree of coincidence is provided.

Means for solving the problem 2 is to employ a focus analysis method based on parallax having little sample dependence (known example 3). After manually adjusting the focal point in advance, parameters necessary for a focus analysis method based on parallax are measured, and when the focus position is shifted, focus correction is performed based on the parameters.

Means for solving the problem 3 utilizes the fact that a focus analysis method based on parallax is established even in a device having a correction deflector whose deflection fulcrum does not coincide with the focal plane of the objective lens. Known examples 2 of images set by the operator or images
In a first defocus amount F ₁ identified by the sharpness evaluation criteria and the analysis method to acquire the images before and after correction for the deflector or a beam limiting aperture configuration changes, a first positional deviation between said image to analyze the amount D _1. Here, the control value is a voltage value or a digital signal for controlling them. Swing angle .delta..alpha the incident charged particle beam, the magnification M, when the spherical aberration coefficient Cs, positional displacement D ₁ and defocus F ₁ is _{D 1 = M · δα (S} + F 1 + Cs · δ
α ² ). S is a term of image movement that occurs because the deflection fulcrum does not coincide with the focal plane of the objective lens. Then if the defocus amount is acquired images before and after the deflector control value change at the position of F ₁ + δF, positional displacement amount D between the image _{D 1 + δD = M · δα} (S + F 1 + δF + Cs · δα ²⁾ and since, first defocus amount F from the difference δD a first position deviation amount D ₁
The difference ΔF from ₁ can be obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows a basic configuration of an FIB apparatus according to an embodiment of the present invention.

The FIB apparatus according to the present invention comprises a movable sample stage 2 on which a substrate such as a semiconductor wafer or a semiconductor chip is placed, and a sample position for controlling the position of the sample stage 2 for specifying the position of the substrate to be analyzed. A control device 9, an ion gun 11, a condenser lens 18, a beam limiting aperture 13, a beam limiting aperture control device 13, a correction deflector 5, a astigmatism corrector 14 in the focused ion beam column 1, It has a scanning deflector 4 and an objective lens 19, and has an image analyzer 12 connected to the scanning deflector 4 and the secondary particle detector 8. The FIB irradiation current to the sample is controlled by the beam limiting aperture 13. The scanning deflector 4 scans the FIB in the focused ion beam column 1, and the image analyzer 12 receives an image signal sent from the secondary particle detector 8 in synchronization with the scanning deflector 4. The focused ion beam column 1, the sample position controller 9, the image analyzer 12, and the like are controlled by the central processing unit 6.

First, steps required to obtain a first SIM image will be described. The FIB apparatus is initialized so that the sample can be irradiated with an appropriate amount of current FIB. Z parallel to optical axis
A plane orthogonal to the direction and the optical axis is defined as an XY plane. The sample 24 is inserted, and coarse adjustment of the Z position of the sample table 2 is performed. Alternatively, the image of the sample 24 may be confirmed at a low magnification, and the focus position may be roughly adjusted. This rough adjustment may be performed by adjusting the control value of the objective lens 19. The visual field for optical system adjustment is selected using the XY movement of the sample stage 2. Next, the deviation angle of the FIB from the optical axis of the objective lens 19 is corrected. The image movement when the focal position of the condenser lens 18 is changed is visually recognized, and the control value of the correction deflector 5 is adjusted so that the image movement is minimized. Next, FIB astigmatism adjustment is performed. The image deformation when the control value of the astigmatism corrector 14 is changed is visually recognized, and the control value of the astigmatism corrector is adjusted so that the image deformation is minimized. After the completion of the axis shift correction, the focus correction, and the astigmatism correction, the sample is moved to the field of view using the sample table 2, and after finely adjusting the focal position of the objective lens 19, an image is captured.

The present invention described below relates to automation of FIB axis deviation correction and automatic adjustment of the focus position of an objective lens.

FIG. 2 shows a basic configuration of an automatic axis deviation correcting device for the objective lens 19. After setting the field of view, the magnification, and the like, the first lens is set to the first state, and a first image is captured.
The objective lens 19 is moved to the second position by changing the control value of the objective lens 19.
And the second image is photographed. Central processing unit
In step 6, the amount of misalignment D and the degree of coincidence between the first and second images are calculated using a misalignment analysis method based on the phase difference analysis of the Fourier transform image, and axis misalignment is corrected based on the degree of coincidence. _Then , the control values (I _{AL_x} , I _{AL_y} ) of the correction deflector 5 necessary to make the displacement amounts (D _x , D _y ) substantially zero are calculated. At magnification M, α = α from the optical axis of objective lens 19.
The FIB 32 incident with a shift of (α _x , α _y ) is incident on the sample like the FIB 33 when the focal position Z coordinate of the objective lens is changed by δF. XY of sample incidence position between FIB32 and FIB33
The coordinate shift amount is (D _x , D _y ) = M · ΔF · (α _x , α _y ). Therefore, the first image captured in the first objective lens state and the second image
The second image photographed in the state of the objective lens has a position shift of (D _x , D _y ). Using this relationship, the deviation angles (α _x , α _y )
Ask for. Calculating the control values (I _{AL_x} , I _{AL_y} ) of the correction deflector 5 necessary to make the deviation angles (α _x , α _y ) substantially zero _enables the axis deviation to be corrected. However, it is difficult for the FIB apparatus to measure the physical absolute amount of the focal position change amount due to the control value change of the objective lens 19 and the shift angle change amount due to the control value change of the correction deflector 5. In addition, since it is not necessary to know the focal position change amount and the absolute amount of the shift angle for the purpose of making the axis shift substantially zero, the position shift amount D is directly converted to the control value change amount of the deflector 5 for correction, and The control value of the correction deflector 5 is set based on the calculation result, and the axis deviation is corrected.

FIG. 3 is an explanatory diagram of a displacement analysis method using a phase component of the Fourier transform. Misalignment D = (D _x ,
D image pair S1 (n with _{y), m) = S2 (} n + D x, m + D y) assuming,
The two-dimensional discrete Fourier transform of S1 (n, m) and S2 (n, m) is expressed as S1 (k,
l), S2 (k, l). F {S (n + D _x , m +
D _y )} = F {S (n, m)} exp (iD _x・ k + iD _y・ l)
1 (k, l) = S2 (k, l) exp (iD _x · k + iD _y · l). That S1 (k, l) and S2 (k, l) positional deviation of the phase difference exp (iD _x · k + iD
_y · l) = P (k, l). P (k, l) has a period of (D _x ,
Since also the wave of D _y), the phase difference image P (k, image P (n that inverse Fourier transform l), in m) is δ peak at a position of (D _x, D _y) occurs. Note that instead of removing all information of the amplitude, S1 (k, l) · S2 (k, l) ^* = | S1 || S2 | exp (iD _x · k + iD _y · l)
An image in which the amplitude component is suppressed by performing log or 処理 processing on the amplitude component of 振幅 is calculated, and even if the image is subjected to inverse Fourier transform, a δ-like peak is obtained at the position (D _x , D _y ) of the displacement vector. Since this occurs, the position shift analysis may be performed on the image.
Since the phase difference image P (k, l) be the Fourier transform of (D _x, is δ peak in D _y to generate, execute a displacement analysis in the Fourier transformed image of the phase difference image P (k, l) You may.

Since it can be assumed that only the δ-like peak exists in the image P (n, m), the position of the δ-like peak can be accurately obtained with the precision below the decimal point by calculating the position of the center of gravity. In addition, since peaks other than δ-like peaks can be regarded as noise,
The ratio of the intensity of the δ-like peak to the intensity of the entire image P (n, m) can be regarded as the degree of coincidence between the images. It is difficult to evaluate the reliability of the displacement analysis results using the conventional displacement analysis method, and even if an incorrect displacement is output due to out-of-field or image blur, correction is performed based on the displacement. Changes the deflector 5 for use. Since the degree of coincidence is output in the present displacement analysis method, a lower limit value of the degree of coincidence is set, and if the degree of coincidence is equal to or less than the lower limit, the axis deviation is not corrected. As a result, a malfunction due to out-of-field or image blur can be prevented.

In order to convert the displacement D into the control value change ΔI _AL of the correction deflector 5, the relationship between the control value change ΔI _AL of the correction deflector 5 and the displacement D is measured in advance. Need to be kept. At the magnification M _m1 , the control value of the objective lens 19 is ΔI
_{OBJ_m1} when _{changing, I AL = (I AL_x,} I AL_y) positional deviation amount D in _{0 = (D x_0, D y_0} ) _{analyzes, I AL + δI AL = (} I AL_x, + δ
I _{AL_x} , I _{AL_y} + δI _{AL_y} )
A difference ΔD _m1 = (ΔD _{m1_x} , ΔD _{m1_y} ) from D ₀ is obtained.

The deviation angle α of the incident FIB is determined by a correcting deflector.
While 5 is substantially proportional to the control value I _AL of the deflector 5 as shown in FIG. 2 because it is provided in the upper portion of the objective lens 19, is incident on the sample by the electric field of the objective lens 19 F
The position of the IB changes. In order to cope with a large change in the height of the sample, the position of the FIB incident on the sample
D is obtained by an equation introducing a correction term using the control value I _OBJ value of the objective lens 19 as a parameter, ΔD _{m1_θ} ∝ (A + B · I _OBJ ) ΔI _AL . Here, A, B and C are coefficients specific to the device.
The focal position change amount is DerutaefuarufaderutaI _OBJ is proportional to the control value variation amount of the objective lens 19. _{δD m1_θ} = M _m1・ δI
And _{OBJ_m1 · (a + b · I} OBJ) δI AL, measures the positional deviation amount [delta] D _{M1_shita} in each I _OBJ, identifies the coefficients a and b. When calculating the control value change amount of the correction deflector 5 from the displacement amount,
ΔD _{m1_θ} ′ = ΔD _{m1_θ} / (a + b · I _OBJ ) is used.

As described above, the control value change amount ΔI _{AL of the} correction deflector 5
And the positional deviation amount ΔD are specified and recorded in the central processing unit 6, and then the axial deviation correction is executed. When the control value of the objective lens 19 is changed by ΔI _OBJ at the magnification M,
In the case of D = (D _x , D _y ), the position shift amount D is corrected for the objective lens control value and converted into D _θ ′. The control value change amount of the correction deflector required to cancel the axis deviation _is- (M _m1・ δI _{OBJ_m1} / M ・
δI _OBJ ) ・ (D _{θ_x} '・ δI _{AL_x} / _{δD m1_x_θ} ', D _{θ_y} '・ δI
_{AL_y} / _{δD m1_y_θ} ').

Here, the magnitude of ΔI _OBJ which is an input parameter in the axis deviation correction will be considered. As ΔI _OBJ, that is, ΔF, is larger, the positional deviation amount D corresponding to the deviation angle α is larger, and the deviation angle analysis accuracy is improved. However, if the focal position change amount ΔF is too large, the positional deviation amount D also becomes large, and thus a field of view is lost. In particular, at high magnifications, the visual field range is narrowed, so that the visual field often deviates. The upper limit value of ΔF needs to be inversely proportional to the magnification M so that the visual field does not deviate.
Further, if the focal position change amount ΔF is large, the image blur becomes large, and even if the field of view does not deviate, it may be impossible to analyze the displacement. Since the upper limit value of the focal position change amount ΔF determined by the image blur depends on the focal depth of the objective lens 19 and the structure of the sample 24, the focal position change amount ΔF is actually changed by changing the focal position.
It is better to determine the upper limit. Therefore, the following determination flow is provided. First, the displacement analysis is performed with the focus position amount ΔF determined by the magnification or the like. When the displacement analysis is impossible, that is, when the degree of coincidence between the images is equal to or less than the lower limit value, the focal position change amount is reduced and the displacement analysis is performed again. Almost change in focal position
If the displacement cannot be analyzed even when the value becomes 0, that is, if the degree of coincidence is equal to or less than the lower limit value, it is considered that there is a problem in the visual field itself, for example, the visual field has no feature. In this case, it is necessary to perform the analysis again after reducing the magnification or changing the field of view.

The axis deviation correction is executed according to the flow shown in FIG. After inputting the correction parameters, when an instruction to execute axis deviation correction is given, the first image capture in the first state of the objective lens 19 is started. After the control value of the objective lens 19 is changed and set to the second state, a second image is captured, and the displacement between the images is analyzed. The degree of coincidence between the images obtained by the positional deviation analysis is referred to, and if the degree of coincidence is equal to or greater than the lower limit, the amount of positional deviation is converted into the amount of change in the control value of the correction deflector 5 to correct the axis deviation. After performing the axis deviation correction a predetermined number of times, the axis deviation correction ends. If the degree of coincidence is insufficient, first, the control value change amount is reduced and the capture of the image pair is restarted. If the degree of coincidence is insufficient even after reducing the control value change amount, the magnification and the field of view are changed, and the capture of the image pair is restarted. In any case, if the degree of matching is insufficient, the processing is interrupted.

Even if the deflection fulcrum of the correcting deflector 5 does not coincide with the focal plane of the objective lens 19, it is said that when the shift angle approaches 0, the amount of image shift due to a change in the focus position approaches 0. The phenomenon does not change. In addition to the correction for setting the shift angle to 0, the operator sets a certain shift angle, records the position shift amount due to a change in the control value of the objective lens 19 at the shift angle, and records the position shift amount in the recorded position shift amount. By adjusting the correction deflector 5 so that the deviation angle can be corrected to the specified deviation angle.

As a cause of the axial deviation, there is a positional deviation of the beam limiting aperture 13 when changing the beam current. Beam limiting aperture 13
When the hole position is off the optical axis, it enters the objective lens 19
FIB will have a deviation angle. FIG. 5 shows a correction flow of the automatic correction device for controlling the hole position of the beam limiting aperture 13. After setting the field of view, the magnification, and the like, the user inputs correction parameters such as the control value change amount of the objective lens 19 on the screen of the central processing unit 6, and clicks a correction execution button, so that the FIB apparatus starts correction. After the first image is taken with the objective lens 19 in the first state, the control value ΔI _OBJ of the objective lens 19 is changed to set the second state, and the second image is taken. The captured first and second images are analyzed for the degree of coincidence and the position shift by a position shift analysis method based on a phase difference analysis of the Fourier transform image.
Determining whether to execute axis deviation correction based on the degree of coincidence,
The control value (I) of the beam limiting aperture control device 13 of the beam limiting aperture 13 necessary to make the displacement amount (D _x , D _y ) substantially zero
_{AP_x} , _{IAP_y} ) are calculated. This calculation is also made in advance by the control value change amount δ of the beam limiting aperture control device 13 of the beam limiting aperture 13.
Measuring the relationship between the position deviation amount D and I _AP, it is performed using the conversion coefficient and the necessary correction term was estimated. Note that the axis deviation correction by the beam limiting aperture control device 13 is performed by a mechanical method using a motor, gears, and the like, so that the movable range is wide but the setting accuracy is insufficient. On the other hand, since the axis deviation correction by adjusting the control value of the correction deflector 5 is performed by an electric method, the movable range is narrow but the setting accuracy is high. Therefore, in an apparatus having both the position adjusting mechanism of the beam limiting aperture 13 and the deflector 5 for correction, after the coarse adjustment of the axis offset by adjusting the position of the beam limiting aperture 13, the fine adjustment of the axis offset by adjusting the deflector 5 for correction is performed. Do.

FIG. 6 shows the automatic correction flow of the astigmatism corrector 14. After setting the field of view, the magnification, and the like, a correction parameter such as a control value change amount of the astigmatism corrector is input on the screen of the central processing unit 6, and correction is started by clicking a correction execution button. After setting the field of view, magnification, deflection amount, etc., the astigmatism corrector 14
When the first control value is set to the first control value, the focus position of the objective lens is set to the first position and a first image is taken.
Next, a second image is taken with the focal position of the objective lens set at the second position. The image analyzer 12 calculates the amount of misalignment and the degree of coincidence between the first and second images by a misalignment analysis method based on the phase difference analysis of the Fourier transform image. And the device parameters at that time are recorded. Next, when the control value of the astigmatism corrector 14 is set to the first control value and the focal position of the objective lens is set to the third position, a third image is taken. The fourth image is captured by setting the focal position of the objective lens to the fourth position. Image analysis device
In 12, the position shift amount and the degree of coincidence of the third and fourth images are calculated by the position shift analysis method based on the phase difference analysis of the Fourier transform image,
It is determined whether or not to perform the astigmatism correction based on the degree of coincidence, and the control value (I _{STEIGX_x} ) for the first astigmatism corrector 14 required to make the displacement (D _x , D _y ) substantially zero. , I _{STIGX_y} ). In this calculation, the control value change amount ΔI
The relationship between _STEIGX and the amount of positional deviation D is measured, and is executed using the estimated conversion coefficient and necessary correction terms.

Next, focus correction will be described. As the focus correction method, there are an analysis method using a positional shift due to parallax, an analysis method using an image sharpness as an evaluation criterion, and an analysis method based on a comparison between a Fourier transform image of an image and a simulation image of an incident electron beam intensity distribution. The analysis method based on parallax is used in a transmission electron microscope or the like, and when it is assumed that the fulcrum of the correction deflector 5 and the focal plane are almost coincident, when the sample is located at the focal plane. Although there is no movement between the images before and after the change in the electron beam incident angle, if the sample is out of the focal plane, the movement between the images occurs before and after the change in the electron beam incident angle. where δα is the swing angle of the incident electron beam, M is the magnification, and Cs is the spherical aberration coefficient.
There is a relationship of D = M · δα (F + Cs · δα ² ), and if the amount of positional deviation D due to parallax can be measured, the amount of defocus F can be obtained.

However, in the FIB apparatus, the deflection fulcrum of the correcting deflector 5 does not coincide with the focal plane of the objective lens 19. The focus analysis method in that case will be described with reference to FIG. In a first defocus amount F _1, it acquires the image before and after the control value change in deflector 5, analyzes the first deviation amount D ₁ of the between said image. Assuming that the incident FIB 31 has a shift angle of almost 0, the incident FIB 32 has a shift angle of δα, the magnification M, and the spherical aberration coefficient Cs, the positional shift amount D ₁ and the focus shift amount F ₁ have D ₁ = M · δα (S + F ₁ + Cs ・ δα ² )
Becomes S is a term of image movement caused by the fact that the deflection fulcrum does not coincide with the focal plane. Next, the image before and after the control value change of the correction deflector 5 is acquired at the defocus amount F ₁ + ΔF,
The amount of displacement between the images is calculated. Assuming that the incident FIB 31 has a shift angle of almost 0 and the incident FIB 33 has a shift angle of δα, the positional shift amount is D ₁ + δD = M · δα (S + F ₁ + δF + Cs · δα ² ). from the difference δD between a position deviation amount D ₁ of the 1 first defocus amount F ₁ the difference δF can be obtained for. Image analysis device 12
Then, the focus shift ΔF is calculated from the positional shift amount ΔD, and the focus is set to F ₁
The objective control value change amount ΔI _OBJ required to set the objective lens 19 is obtained, and the objective lens 19 is corrected based on the obtained amount. As described above, even if the deflection fulcrum of the correction deflector 5 does not coincide with the focal plane of the objective lens 19, it is possible to keep the focal position deviation with respect to the sample constant.

Although the analysis method based on sharpness is a method used for astigmatism analysis as well as focus, there is some sample dependence. Further, there is a problem that it takes time to collect a sharpness state because it is a so-called asymptotic method of comparing various astigmatism and focus states. An analysis method based on a Fourier transform image is a method used for astigmatism analysis as well as focus. Although the number of images used for analysis is small, there is a problem that it takes time to perform fitting with simulation. In addition, there is a great dependence on the sample, and in many cases, it does not operate in a general field of view. On the other hand, the analysis method based on parallax has a problem that it is necessary to specify a focal plane as described above, but it is possible to set all the visual fields to the same focus state. It has the lowest sample dependence and can be analyzed with two images, so that the speed can be increased. In consideration of the above, an analysis method based on sharpness or Fourier transform image is used to identify the focal plane using the optical system adjustment sample and astigmatism correction, and analysis using parallax is used for fine focus adjustment in each field of view. It is most efficient to use the method.

FIG. 8 shows a basic configuration of an automatic focus correcting apparatus for an objective lens using parallax. According first flow shown in FIG. 9, analyzing and recording the positional deviation amount D ₁ of the in-focus plane. The field of view and magnification for optical adjustment are set, and the control value of the objective lens 19 is set to a value corrected by a correction method based on sharpness or Fourier transform, or a value specified by the operator. Inputting the correction parameters such as the control value change amount of the correction deflector 5 on the screen of the central processing unit 6 and clicking the record button starts the analysis. A first image in which the control value of the correction deflector 5 is the first control value is captured. The control value of the correction deflector 5 is set to the second setting, and the sample is irradiated with the FIB 32 having the deviation angle of δα to capture a second image. The image analyzer 12 calculates the amount of misalignment and the degree of coincidence between the first and second images by a misalignment analysis method based on the phase difference analysis of the Fourier transform image. And the device parameters at that time are recorded.

The automatic focus correction is executed according to the flow shown in FIG. The field of view, the magnification, etc. are set, the correction parameters such as the control value change amount of the correction deflector 5 are input on the screen of the central processing unit 6, and the focus correction starts when the execution button is clicked. Device parameters when it was recorded as positional deviation amount D ₁ are read out. If the position deviation amount D ₁ is not recorded error message. Next, the correction deflector 5
Is set to the third setting, and a third image is shot. The control value of the correction deflector 5 is set to a fourth value, and the sample is irradiated with the FIB 33 having a deviation angle of δα, thereby capturing a fourth image. The image analyzer 12 calculates the amount of misalignment and the degree of coincidence between the third and fourth images by a misalignment analysis method based on the phase difference analysis of the Fourier transform image, and determines whether to execute the axial misalignment correction based on the degree of coincidence. Judgment and calculation of the control value of the objective lens 19 necessary to make the displacement (D _x , D _y ) approximately D ₁ are performed.

This calculation is also performed by measuring the relationship between the control value change amount ΔI _{OBJ of the} objective lens 19 and the positional deviation amount D in advance, and using the estimated conversion coefficients and necessary correction terms. Magnification M _m2
When the control value of the deflector 5 was .delta.I _{AL_m2} change in the amount of position shift in the objective lens 19 control value I _{OBJ_0} D ₀ =
(D _{x_0} , D _{y_0} ) is analyzed and the objective lens 19 control value I _{OBJ_0} + δI
Difference from displacement amount in _OBJ ΔD _m2 = ( _{δD m2_x} , δ
D _{m2_y} ). In the magnification M, the difference between the positional deviation amount D ₁ of the case where the control value of the objective lens 19 is .delta.I _OBJ change [delta] D =
In the case of (δD _x , δD _y ), the positional deviation amount ΔD is corrected to ΔD using the control value I _OBJ of the objective lens 19, and the positional deviation ΔD due to parallax is corrected.
Then, the control value change amount of the objective lens 19 necessary for canceling out is obtained. The change in the control value of the objective lens 19 is ± (M _m2・ δI _{AL_m2}
/ M · ΔI _AL ) · ΔI _OBJ · | ΔD ′ | / | ΔD _m2 |.

Example 2 FIG. 11 is a basic configuration diagram of an FIB apparatus for producing a fine sample, which is an example of an embodiment of the present invention.

The FIB apparatus according to the present invention comprises a movable sample stage 2 on which a substrate such as a semiconductor wafer or a semiconductor chip is placed, and a sample position control system for controlling the position of the sample stage to specify the position of the substrate to be analyzed. The apparatus 9 and the probe 151 are moved to the vicinity of the analysis position of the substrate, and the probe 151 is moved to the sample stage 2.
And an image analyzer 12 connected to the secondary particle detector 8 and the scanning deflector 4 in the focused ion beam column 1. Probe 15
1 and the probe control device 152 constitute a manipulator. In the focused ion beam column 1, the scanning deflector 4 is
By scanning the IB, the image analysis device 12
The image signal sent from the secondary particle detector 8 is received in synchronization with the image signal. The focused ion beam column 1, the sample position controller 9, the probe controller 152, the image analyzer 12, and the like are controlled by the central processing unit 6.

First, steps required until a first SIM image is obtained will be described. The FIB apparatus is initialized so that the sample can be irradiated with an appropriate amount of current FIB. Z parallel to optical axis
A plane orthogonal to the direction and the optical axis is defined as an XY plane. The sample 24 is inserted, and coarse adjustment of the Z position of the sample table 2 is performed. Alternatively, the image of the sample 24 may be confirmed at a low magnification, and the focus position may be roughly adjusted. This rough adjustment may be performed by adjusting the control value of the objective lens 19. The visual field for optical system adjustment is selected using the XY movement of the sample stage 2. Next, the deviation angle of the FIB from the optical axis of the objective lens 19 is corrected. The image movement when the focal position of the objective lens 19 is changed is visually recognized, and the control value of the correction deflector 5 is adjusted so that the image movement is minimized. Next, the optical axis of the astigmatism corrector 14 is adjusted. The image movement when the control value of the astigmatism corrector 14 is changed is detected, and the control value of the astigmatism corrector is adjusted so that the image movement is minimized. After the axial deviation correction, the focal point and the astigmatism are corrected in the optical system adjustment visual field. Next, after moving to the field of view for photographing using the sample stage 2 and finely adjusting the focal position of the objective lens 19, an image is captured.

The present invention described below relates to automation of fine adjustment of the focal position of an objective lens and measurement of the distance between a probe and a sample stage.

The automatic focus correction for the sample 24 is executed according to the flow shown in FIG. The field of view, the magnification, etc. are set, the correction parameters such as the control value change amount of the correction deflector 5 are input on the screen of the central processing unit 6, and the focus correction starts when the execution button is clicked. Device parameters when it was recorded as positional deviation amount D ₁ are read out. If the position deviation amount D ₁ is not recorded error message. Next, a third image in which the control value of the correcting deflector 5 is the third control value is captured. The control value of the correction deflector 5 is set to the fourth control value, and a fourth image is taken. The image analyzer 12 calculates the amount of misalignment and the degree of coincidence between the third and fourth images by a misalignment analysis method based on the phase difference analysis of the Fourier transform image, and determines whether to execute the axial misalignment correction based on the degree of coincidence. Judgment and displacement amount (D
_x, the calculation of the control value of the objective lens 19 required to substantially D ₁ to D _y) performed.

This calculation is also executed by measuring the relationship between the control value change amount ΔI _{OBJ of the} objective lens 19 and the positional deviation amount D in advance, and using the estimated conversion coefficients and necessary correction terms. Magnification M _m2
When the control value of the deflector 5 was .delta.I _{AL_m2} change in the amount of position shift in the objective lens 19 control value I _{OBJ_0} D ₀ =
(D _{x_0} , D _{y_0} ) is analyzed and the objective lens 19 control value I _{OBJ_0} + δI
Difference from displacement amount in _OBJ ΔD _m2 = ( _{δD m2_x} , δ
D _{m2_y} ). In the magnification M, the difference between the positional deviation amount D ₁ of the case where the control value of the objective lens 19 is .delta.I _OBJ change [delta] D =
In the case of (δD _x , δD _y ), the positional deviation amount ΔD is corrected to ΔD using the control value I _OBJ of the objective lens 19, and the positional deviation ΔD due to parallax is corrected.
Then, the control value change amount of the objective lens 19 necessary for canceling out is obtained. Objective lens 19 control value change is ΔI _OBJ-S = ± (M _{m2
ΔI AL — m2} / M · _{ΔI AL} ) · ΔI _OBJ || ΔD ′ | / | ΔD _m2 |.

Next, according to the flow of FIG.
Is performed, and the control value change amount of the objective lens 19 required to cancel the positional shift ΔD due to parallax is determined to be ΔI _OBJ-P . At this time, the distance between the probe and the sample is h = ΔF · | ΔIOBJ _-P- ΔIOBJ _-S |. The relationship between the control value change amount ΔI _OBJ of the objective lens 19 and the focal length change amount ΔF is measured in advance, and this calculation is performed using the estimated conversion coefficient and necessary correction terms.
The distance h between the probe and the sample determined as described above is shown in FIG.
Are displayed on the central processing unit 6 indicated by. Display screen 155
The SIM image display section 157 and the probe height display section 153 can be displayed as child screens. Further, the display screen 155 includes a size display bar 156 for displaying a scale, and a probe-sample distance display section 154 for displaying the distance h between the probe and the sample obtained as described above in a numerical value. With this display screen 155, the operator can intuitively recognize, and the operation efficiency of the FIB device is improved.

<Embodiment 3> FIG. 13 shows an overall configuration diagram of an apparatus combining a focused ion beam column and a scanning electron microscope column. This apparatus includes an ion gun 351, a condenser lens 352 for focusing an ion beam emitted from the ion gun 351, a scanning deflector 353, and a correcting deflector 37.
3. A focused ion beam column 381 including an objective lens 371, an electron gun 357, a lens 359 for focusing an electron beam 358 emitted from the electron gun 357, a scanning deflector 360, a correcting deflector 374, and an objective lens 372. And the like, and a scanning electron microscope column 382, which is composed of the above, and a vacuum sample chamber. Also, this device is a FIB35
4 is irradiated on the sample 361 to control a secondary particle detector 356 for detecting secondary electrons or secondary ions from the sample, a movable sample stage 362 on which the sample 361 is mounted, and a position of the sample stage. A sample position control device 363. Further, in this apparatus, the probe 364 is moved to the sample piece extracting position, and an image for analyzing observation images from the probe control device 365, the deposition gas supply device 367, and the secondary particle detector 356, which is driven independently of the sample stage 362. An analysis device 366 and a central control display device 355 for displaying an observation image are provided.

Next, the operation of the present apparatus will be described. First, the ions emitted from the ion gun 351 are supplied to the condenser lens 352, the scanning deflector 353, and the correction deflector 37.
3 and irradiate the sample 361 through the objective lens 371. FIB 354 has a diameter of several nanometers to 1
It is narrowed to about a micrometer. When the sample 361 is irradiated with the FIB 354, constituent atoms on the sample surface are released into a vacuum by a sputtering phenomenon. Therefore, by scanning the FIB 354 using the scanning deflector 353,
Processing from the micrometer to the submicrometer level can be performed. The deposition film formed by the irradiation of the FIB 354 is used to connect the sample to the contact portion at the tip of the probe 364 and to fix a micro sample manufactured by FIB processing to a sample holder. Also, FIB354
Is scanned, secondary electrons and secondary ions emitted from the sample are detected by the secondary particle detector 356, and the intensity thereof is converted into the brightness of the image, whereby the sample 361 and the probe 36 are detected.
4 etc. can be observed.

In the present apparatus, if the ion beam irradiation axis deviates from the central axis, the ion beam diameter is enlarged and the shape is deteriorated, and a desired processed shape may not be produced. Therefore, in order to maintain high processing performance,
It is necessary to minimize the axial deviation of ion beam irradiation before processing. Therefore, an example in which the present invention is applied to the axial deviation correction of ion beam irradiation in the present apparatus will be described. First, the objective lens 371 is set to the first state, and the FIB 354 is set.
Is irradiated on the sample 361 to capture a first image. When the control value of the objective lens 371 changes, the objective lens 371 is moved to the second position.
The state is changed to the state of 2, and a second image is taken. The image analyzer 366 calculates the amount of misalignment and the degree of coincidence between the first and second images using a misalignment analysis method based on the phase difference analysis of the Fourier transform image, and corrects the axis misalignment based on the degree of coincidence. It is determined whether or not to execute the calculation, and the control value of the correction deflector 373 required to make the displacement amount substantially zero is calculated. Further, in the present apparatus, similarly to the scanning electron microscope described above, the amount of change in the focal position due to the change in the control value of the objective lens 371,
It is difficult to measure the physical absolute amount of the shift angle change due to the control value change of the correction deflector 373. In addition, since it is not necessary to know the focus position change amount and the absolute amount of the shift angle for the purpose of making the axis shift substantially zero, the shift amount is directly converted into the control value change amount of the correction deflector 373, and The control value of the correction deflector 373 is set based on the calculation result, and the axis deviation is corrected.

Here, in order to convert the amount of positional deviation into the amount of control value change of the axis deviation correcting deflector 373, the relationship between the amount of control value change of the axis deviation correcting unit 373 and the amount of positional deviation is measured in advance. However, since this can be performed in the same manner as the FIB apparatus described above, the details are omitted.

Further, in the present apparatus, the sample irradiation positions of the ion beam and the electron beam are matched. However, when the height of the sample changes, the sample irradiation positions do not match. Therefore, in the automatic focus correction in the present apparatus, the correction of the focus and the deflection are performed simultaneously. First, the following operation is performed to analyze and record the amount of displacement on the focal plane before automatic correction. The field of view and magnification for optical adjustment are set, and the control value of the objective lens 371 is set to a value corrected by a correction method based on sharpness or Fourier transform or a value specified by the operator. When a correction parameter such as a control value change amount of the correction deflector 373 is input on the screen of the central control display device 355 and the recording button is clicked, the analysis starts. When the control value of the correction deflector 373 is
A first image having a control value of 1 is photographed. The control value of the correction deflector 373 is set to the second setting, and a second image is captured. A first positional deviation amount D ₁ and coincidence degree of the second image with an image analyzer displacement analysis method based on the phase difference analysis of the Fourier transformed image in 366 computes the positional deviation if the degree of coincidence is equal to or greater than the lower limit value Record the analysis results and the device parameters at that time. Next, fix the sample at the observation position, set the field of view, magnification, etc., enter correction parameters such as the control value change amount of the correction deflector 373 on the screen of the central control display device 355, and click the execute button. Then, focus correction starts. Device parameters when it was recorded as positional deviation amount D ₁ are read out. If the position deviation amount D ₁ is not recorded error message. Next, the control value of the correction deflector 373 is set to the third setting, and a third image is captured. The control value of the correction deflector 373 is set to a fourth value, and a fourth image is taken. The image analysis device 366 calculates the amount of misalignment and the degree of coincidence between the third and fourth images by a misalignment analysis method based on the phase difference analysis of the Fourier transform image, and determines whether to execute the axial misalignment correction based on the degree of coincidence. Judgment and displacement amount (D _x , D _y )
The calculation of the control value of the objective lens 371 needed to D _1.

This calculation is also executed by measuring the relationship between the control value change amount δI _{OBJ of the} objective lens 371 and the positional deviation amount D in advance, and using the estimated conversion coefficients and necessary correction terms. magnification
When .delta.I _{AL_m2} changes the control value of the deflector 373 in M _{m @ 2,} positional deviation amount _{D 0 = (D x_0, D} y_0) in the objective lens 371 control value I _{OBJ_0} analyzes, control values of the objective lens 371 I _{OBJ_0} + _ΔI Difference from the displacement amount in _OBJ ΔD _m2 =
( _{δD m2_x} , _{δD m2_y} ) is obtained. At the magnification M, the displacement amount when the control value of the objective lens 371 is changed by δI _OBJ
When the difference from D ₁ is δD = (δD _x , δD _y ), the objective lens 371
Is corrected to ΔD using the control value I _OBJ of (1), and the control value change amount of the objective lens 371 required to cancel the positional shift ΔD due to parallax is obtained. The amount of change in the control value of the objective lens 371 is ± (M _m2 · _{ΔI AL_m2} / M · δI _AL ) · δI _OBJ · | δ
D '| / | δD _m2 |. Further, a control value of the correction deflector 373 which is proportional to the difference β between the irradiation angle of the electron beam and the focused ion beam and the control value change amount of the objective lens 371 is calculated.

Next, a case will be described in which a part of a sample is extracted as a minute sample by using the FIB and the probe in the present apparatus, and a cross section of the minute sample is observed by an electron microscope function. First, as shown in FIG. 14, the sample 361 is irradiated with the FIB 354, and the groove is formed so as to surround the observation analysis position by combining the rotation of the sample table. This processing area has a length of about 5μ
m, the width is about 1 μm, and the depth is about 3 μm, and one side surface is connected to the sample 361. After that, the sample table 362 is rotated, and the FIB 354 is processed to form a slope of a triangular prism. However, in this state, the minute sample 391 and the sample 36
1 is connected by a support portion s2. Next, probe 3
64 is brought into contact with the end of the micro sample 391, and then the FIB3
The deposition gas is deposited on the contact point 393 by the irradiation of 54, and the probe 364 is bonded to and integrated with the micro sample 391. Next, the support s2 is cut by the FIB 354 to cut out the minute sample 391. The micro sample 391 is supported by the probe 364, and the preparation for taking out the surface and the internal cross section for observation / analysis as the observation / analysis surface of the micro sample 391 is completed. Next, as shown in FIG. 15, the probe controller 365 is operated to
1. Lift up to a height above the surface. Then, in order to further process the micro sample 391 while being supported by the probe 364, a desired observation section p3 is produced by additional processing in which the irradiation angle of the FIB 354 is appropriately set by rotating the probe. Next, the micro sample 391 is rotated, and the sample holder 392 of the probe control device 365 is moved so that the electron beam 358 of the scanning electron microscope column 382 is substantially perpendicularly incident on the observation section p3, and the posture of the micro sample 391 is changed. Stop after controlling. Thereby, the secondary particle detector 356
, The detection efficiency of the secondary electrons is almost the same as when observing the outermost surface of the wafer, the observation conditions of the observation section p3 of the micro sample 391 are very good, and the observation analysis plane p2 and the observation section p3 Adjustment to a desired angle enables detailed observation and analysis.

At the time of this shape observation, the field of view may be shifted due to a sample drift, a stage fine movement error, or the like. In order to correct this visual field deviation, position deviation adjustment using observation of a minute sample is executed. First, a first image of the micro sample is obtained, then a second image of the micro sample is obtained, and the amount of misregistration with the recorded first image is used for the phase difference analysis of the Fourier transform image. Based on the analysis, the amount of displacement and the degree of coincidence are calculated. If the degree of coincidence is equal to or greater than the lower limit, the field deviation is corrected by the sample stage or the correction deflector. If the degree of coincidence falls below the lower limit, there is a possibility of out of view,
The second image is acquired by reducing the image acquisition magnification, and the positional deviation analysis is performed with the image obtained by reducing the recorded first image in the computer. If the displacement cannot be analyzed even in the second analysis, an error message is displayed and the observation is interrupted. As described above, it was possible to correct the drift of the minute sample and observe and process the sample with high accuracy.

[0054]

The analysis accuracy of the shift angle α is proportional to the analysis accuracy of the position shift amount D. Since the displacement analysis method based on the phase difference analysis of the Fourier transform image employed in the present invention has a sub-pixel analysis accuracy that is one digit higher than the conventional displacement analysis method, the analysis accuracy of the displacement angle of the present invention is the same as that of the conventional device. One order of magnitude better. The present axis deviation correcting apparatus can perform the correction with the same accuracy as a skilled operator in a few seconds.

Further, in the present displacement analysis method, the degree of coincidence between images is calculated. The lower limit of the degree of coincidence is set as a criterion for disabling the analysis of positional deviation due to out-of-field or blurring of the image.
In addition, when the displacement analysis becomes impossible, the amount of change in the focal position and the magnification are reduced, and a flow for performing the correction again is provided.
Unmanned operation of the IB device is also possible.

This focus correction method has a small sample dependency,
The work efficiency of observation and processing by IB is improved.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an FIB device as an example of an embodiment of the present invention.

FIG. 2 is a basic configuration diagram of an automatic axis deviation correction device using a correction deflector in the FIB device.

FIG. 3 is an explanatory diagram of a displacement analysis method.

FIG. 4 is a flowchart showing a process of automatic axis deviation correction using a correction deflector.

FIG. 5 is a flowchart of an automatic correction device for a beam limiting aperture position.

FIG. 6 is a flowchart of the correction of the automatic correction device by the astigmatism corrector.

FIG. 7 is an explanatory diagram of an image position shift amount and a focus shift amount due to a shift angle change from the optical axis.

FIG. 8 is a basic configuration diagram of an automatic focus correcting apparatus for an objective lens using parallax.

FIG. 9 is a flowchart of automatic focus correction of an objective lens using parallax.

FIG. 10 is a flowchart showing a process of automatic focus correction in the FIB apparatus.

FIG. 11 is an overall configuration diagram of a sample preparation apparatus in which a focused ion beam column and a probe are combined.

FIG. 12 is a diagram showing a display example of a distance between a probe and a sample on the central processing unit.

FIG. 13 is an overall configuration diagram of a sample observation device in which a focused ion beam column and a scanning electron microscope column are combined.

FIG. 14 is a diagram showing sample preparation by a sample observation device.

FIG. 15 is a diagram in which a sample is extracted by a sample observation device and a cross section is observed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Focused ion beam column, 2 ... Sample table, 4 ... Scanning deflector, 5 ... Correction deflector, 6 ... Central processing unit, 8 ... 2
Secondary particle detector, 9: sample position controller, 11: ion gun, 12: image analyzer, 13: beam limiting aperture, 13
... Beam limiting aperture control device, 14 ... Astigmatism corrector, 18 ...
Condenser lens, 19: Objective lens, 24: Sample, 3
1 ... optical axis of lens, 32 ... FIB of first setting, 33 ... second
FIB of setting, 151 ... probe, 152 ... probe control device, 153 ... probe height display section, 154 ... probe-sample distance display section, 155 ... display screen, 156 ... size display bar, 157 ... SIM image display section, 351, ion gun, 352, condenser lens, 353, scanning deflector, 354, FIB, 356, secondary particle detector, 357
... Electron gun, 358 ... Electron beam, 359 ... Lens, 360 ...
Scanning deflector, 361: sample, 362: sample stage, 363
... Sample position control device, 364 ... Probe, 365 ... Probe control device, 367 ... Deposition gas supply device, 355 ... Central control display device, 366 ... Image analysis device, 371 ... Objective lens, 372 ... Objective lens, 373 ... For correction Deflector,
374: correction deflector, 381: focused ion beam column, 382: scanning electron microscope column, 391: minute sample, 392: sample holder, 393: contact point, s2: support, p2: observation analysis surface, p3 ... Observed cross section.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Satoshi Tomimatsu 1-280 Higashi Koikebo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Within the Central Research Laboratory (72) Inventor: Takashi Ishitani 882 Ma, Hitachinaka-shi, Ibaraki F-term in the Measuring Instruments Group, Hitachi, Ltd. 5C030 AA06 AB05 5C033 MM03 5C034 DD03 DD05

Claims (5)

[Claims] An ion gun, a focused ion beam lens for focusing an ion beam from the ion gun, a sample stage on which a sample is placed, and a focal position of the focused ion beam lens are at a first position. Sometimes, the focused ion beam passes through the focused ion beam lens and irradiates the sample, and the first scanning ion microscope image obtained by charged particles from the sample and the focal position of the focused ion beam lens are 2. Image analysis for recording a second scanning ion microscope image obtained when it is at position 2 and analyzing the amount of displacement and the degree of coincidence between the first scanning ion microscope image and the second scanning ion microscope image A focused ion beam device comprising: a device; a control unit that converts the displacement amount into a deflection correction signal; and a deflection control device that controls an optical path of the focused ion beam. 2. An ion gun, a stigmator for changing the cross-sectional shape of the focused ion beam incident on the sample, a focused ion beam lens for focusing the ion beam, a sample stage for holding the sample, and the astigmatism When the corrector is at the first position, when the focal position of the focused ion beam lens is at the first position, the focused ion beam passes through the focused ion beam lens and irradiates the sample to irradiate the sample. A first positional shift amount between a first scanning ion microscope image obtained by the charged particles of Example 1 and a second scanning ion microscope image obtained when the focal position of the focused ion beam lens is at the second position An image analysis device for analyzing the
Image analysis for analyzing the second displacement between the third and fourth scanning ion microscope images obtained when the focal position of the focused ion beam lens is at the third and fourth positions. An apparatus and a control unit for calculating a change amount of a control parameter of the astigmatism corrector from a difference between the first position shift amount and the second position shift amount and correcting the astigmatism of the focused ion beam. Focused ion beam device. 3. An ion gun, a deflection control device for controlling an optical path of an ion beam, a focused ion beam lens for focusing an ion beam, a sample stage for holding a sample, and a focal position of the focused ion beam lens. Is at the first position, and when the deflection control device is at the first setting, the focused ion beam passes through the focused ion beam lens and irradiates the sample to obtain charged particles from the sample. First
An image analyzer for analyzing a first positional shift amount between a scanning ion microscope image of the second scanning ion microscope image and a second scanning ion microscope image obtained when the deflection control device is at the second setting; When the focal position of the lens is at the second position, the deflection control device analyzes a second positional shift amount between the third and fourth scanning ion microscope images obtained when the third and fourth settings are made. The image analysis device, the first displacement amount and the second
Determine the control value of the focused ion beam lens required to set the focal position to the sample position from the difference in the amount of displacement,
A focused ion beam device comprising a controller for correcting the focal position to a sample position. 4. An ion gun, a deflection control device for controlling an optical path of an ion beam from the ion gun, a focused ion beam lens for focusing an ion beam, a sample stage for holding a sample, and a probe. In the focused ion beam apparatus provided, the focused ion beam passes through the focused ion beam lens when the focal position of the focused ion beam lens is at the position of the sample and the deflection control device is in the first setting. And irradiating the sample with the probe position in a first scanning ion microscope image obtained by charged particles from the sample, and a second scanning ion obtained when the deflection control device is at a second setting. An image analyzer for analyzing the amount of displacement between the probe position in the microscope image,
A focused ion beam apparatus comprising a distance display unit for calculating and displaying a difference between a distance between the probe and the sample from the amount of displacement. 5. A first lens barrel having an ion gun, a deflection control device for controlling an optical path of an ion beam from the ion gun, a first lens for focusing the ion beam, an electron gun, and an electron gun. And a second lens barrel having a second lens for focusing an electron beam, and the deflection control device is in a first setting when the focal position of the first lens is at a first position. An image analyzer for analyzing a first displacement amount between a first scanning ion microscope image obtained at the time and a second scanning ion microscope image obtained when the deflection control device is at the second setting; A second displacement between the third and fourth scanning ion microscope images obtained when the deflection controller is at a third and fourth setting when the focal position of the first lens is at the second position; An image analysis device for analyzing the amount, and a difference between the first position deviation amount and the second position deviation amount Determine the control value of the focused ion beam lens required to set the focal position to the sample position, the control unit to correct the focal position of the first lens to the sample position, the focal position of the first lens and A deflection amount display unit that calculates and displays a deflection amount that overlaps the center of the electron beam scanning area of the scanning electron microscope and the center of the scanning area of the focused ion beam from the difference between the sample incident angle of the electron beam and the ion beam; A focused ion beam device comprising a deflection control device for deflecting to a deflection amount.