JP2005005151A - Charged particle beam device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to quickly focus on a sample, of which charged voltages change from the time when it is grounded to the time when it is irradiated with charged particles with retarding voltage impressed. <P>SOLUTION: A wafer is grounded to measure charged voltage and at the same time, retarding voltage is impressed on the wafer by a retarding focus system after it is conveyed in a sample chamber, and charged voltage of the wafer when it is irradiated with charged particle beams is measured to find a difference of charged voltages of the wafer. A method of focusing afterwards is changed according to the size of the difference. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charged particle beam apparatus such as a scanning electron microscope or a focused ion beam apparatus.
[0002]
[Prior art]
In recent years, with the high integration and miniaturization of semiconductor devices, a scanning electron microscope has been used for evaluation of the shape of semiconductor elements and measurement of dimensions in the manufacturing process of semiconductor devices in place of optical microscopes. In order to automatically and rapidly process mass-produced semiconductors, it is necessary to detect each measurement point on the wafer at high speed. It is necessary to adjust the focus of the electron beam. In addition, a part of a semiconductor element is cut out from a wafer using a focused ion beam apparatus and processed into a sample for a transmission electron microscope, but focusing is also necessary for a focused ion beam for processing. .
[0003]
In a charged particle optical system that handles electrons and ions, the focus condition on the wafer is uniquely determined by the acceleration voltage of the charged particle irradiated on the wafer and the height of the wafer. The acceleration voltage of the charged particles is determined by the extraction voltage of the charged particles, the retarding voltage applied to the wafer to decelerate the charged particles, and the charging voltage of the wafer surface. In order to obtain a desired acceleration voltage, the extraction voltage is usually kept constant, and the retarding voltage is controlled in accordance with the charging voltage of the wafer. Here, as described in Patent Document 1, for example, the wafer charging voltage is measured by measuring the potential of the wafer grounded outside the sample chamber using an electrostatic potentiometer, and fed back to the retarding voltage so as to cancel the influence. Thus, it is possible to control the influence on the focus condition while keeping the acceleration voltage constant. Further, in order to measure the height of the wafer, as described in, for example, Patent Document 2, the wafer is irradiated with laser light, the height of the wafer is detected using the reflected light, and the obtained height is obtained. Information is fed back to an objective lens which is one of charged particle optical systems, and at the same time as the movement to the measurement point is completed, excitation necessary for focusing is applied to the objective lens. By simultaneously controlling the acceleration voltage and the wafer height, the charged particles can be focused at the same time as the movement to an arbitrary measurement point is completed.
[0004]
However, in recent years, wafers whose surface charging voltage varies are sometimes seen when they are grounded and when they are irradiated with a charged particle beam by applying a retarding voltage. For example, when the potential distribution on the surface is measured after grounding the wafer and removing static electricity that can be removed, a fixed potential distribution with central symmetry is confirmed, but a retarding voltage is applied to the wafer. When the charged voltage is measured in a state where the charged particles are irradiated, the central symmetry of the potential distribution is still maintained, but the charged voltage is deviated from several tens to several hundreds volts compared to when the charged voltage is grounded. In another case, there is a wafer that shows a charge distribution with central symmetry of several tens to several hundreds of volts when a retarding voltage is applied and charged particles are irradiated, although there is almost no charging voltage when measured in a grounded state. is there.
[0005]
The difference in charge amount under electrically different conditions depends on the production environment unique to each wafer, the film thickness of the charged layer, etc., and is not constant even for wafers undergoing the same production process. Even when the charge amount changes under different conditions, the potential distribution tendency with central symmetry is always maintained. Even if such a wafer is grounded and its charging voltage is measured with an electrostatic potentiometer, the charging condition changes when observing the pattern on the wafer, so the focus condition also changes, and the wafer moves to the measurement point. Will fail to detect the measurement point. As a result, an auxiliary operation by the operator is required, so that automatic measurement cannot be performed.
[0006]
In order to solve such a problem, for example, there is a retarding focus system. As described above, the focusing condition on the wafer is determined by the acceleration voltage of the charged particles irradiated on the wafer and the wafer height. If the wafer height can be measured correctly, this is the acceleration voltage of the charged particles when focusing on the wafer. Means unique. Therefore, the focus condition is changed by changing the retarding voltage while keeping the extraction voltage of the charged particles constant, and the measurement point is determined from the acceleration voltage when the focus is on the wafer, the extraction voltage value, and the retarding voltage value. The wafer surface potential can be calculated backward. In addition, as described in Patent Document 3, a method has been devised in which a plurality of electrostatic potentiometers are installed in the sample chamber at a location close to the sample, and a value based on the measurement result is fed back to the retarding voltage. Has been.
[0007]
[Patent Document 1]
WO03 / 007330
[Patent Document 2]
JP-A-11-126573 [Patent Document 3]
Japanese Patent Laid-Open No. 2001-52642
[Problems to be solved by the invention]
However, there are several problems with the above method. First, since the charge amount of the wafer is not constant even if it goes through the same manufacturing process, the swing width when changing the retarding voltage of the retarding focus system is set widely assuming that the charge amount is always large. It takes a long time to adjust the focus. Further, since the measurement is repeated for all measurement points on the wafer, there is a great influence on the speed of automatic measurement. In addition, when using an electrostatic electrometer installed in the sample chamber as described in Patent Document 3, in order to avoid the charged particle beam and the electrostatic electrometer from having electrical influences such as noise, in actuality, Particle beam irradiation and measurement with an electrostatic potentiometer cannot be performed at the same time, and as a result, it is not possible to deal with wafers whose charging voltage changes during charged particle beam irradiation. In addition, when it is desired to measure the amount of charge near the edge of the wafer, even if a plurality of electrostatic electrometer probes are installed around the observation point, there are actually probes that come off the wafer, which is not practical. In addition, there is a problem that it is necessary to adjust so that a plurality of electrometers always use the same output.
[0009]
In view of such a problem of the prior art, the present invention can be applied to a sample in which the charging voltage is changed between being grounded and applying a retarding voltage to irradiate a charged particle beam. It is an object of the present invention to provide a charged particle beam apparatus capable of focusing on a lens.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the charged particle beam apparatus of the present invention first grounds the wafer, measures its charging voltage, and after the wafer is transferred into the sample chamber, at least on the wafer by the retarding focus system. Applying a retarding voltage at one measurement point, measuring the wafer charging voltage when irradiating a charged particle beam, and comparing this with the measurement result under the wafer ground, the wafer under electrically different conditions Find the difference in charging voltage. The subsequent focusing method is changed according to the magnitude of this difference. When the difference between the charging voltages does not affect the focus, the measurement result of the charging voltage when grounded can be applied as it is, so that it is not necessary to perform focusing thereafter and the wafer processing time can be shortened. Even when the difference is large, as a subsequent process, the measurement result of the charging voltage when grounded is used as a reference value, and each measurement point is focused with a narrower amplitude of retarding voltage than the conventional retarding system. This makes it possible to shorten the processing time required for focusing.
[0011]
A charged particle beam apparatus according to the present invention includes a charged particle beam source, an extraction electrode for extracting a charged particle beam from the charged particle beam source, a deflector for two-dimensionally scanning the charged particle beam on a sample, and charged particles An objective lens for focusing the line on the sample, a secondary charged particle detector for detecting secondary charged particles generated from the sample by irradiation of the charged particle beam, and a height for detecting the height of the sample A detector, a retarding means for applying a voltage to the sample to decelerate the charged particle beam from the charged particle beam source to a desired voltage, and applying the voltage by the retarding means to irradiate the charged particles. A charging means for measuring the charging voltage of the sample when it is in contact, the information on the charging voltage of the sample when grounded and the height information of the sample detected by the height detector Les A focus control unit that controls the focus and adjusts the focus. The focus control unit has a difference between the sample charging voltage when grounded and the sample charging voltage measured by the sample charging voltage measuring means exceeds a predetermined threshold. It is characterized in that the focusing process is changed depending on whether or not it is. Specifically, the focus control unit changes the voltage applied to the sample by the retarding means around the sample charging voltage when grounded when the difference exceeds the threshold, and the difference is the threshold. In the following cases, the sample charging voltage when grounded is set.
[0012]
The sample charging voltage when grounded may be measured by an electrostatic potentiometer installed outside the sample chamber. The charge voltage distribution of the entire sample may be expressed by an approximate function using the symmetry (central symmetry) of the sample charge voltage distribution from the measurement result of the charge voltage of a part of the sample surface measured by the electrostatic potentiometer. . At this time, it is preferable that the measurement result of the sample charging voltage when the charged particle beam is applied by applying a voltage by the retarding means is reflected in the approximate function and corrected.
[0013]
The sample charging voltage measuring unit can employ the following method as a method for obtaining the sample charging voltage when the charged particles are irradiated by applying a voltage by the retarding means.
(1) The voltage applied when the focusing is achieved by changing the voltage applied by the retarding means is calculated.
(2) The voltage applied to the extraction electrode is changed and calculated from the voltage value when the focus is achieved.
(3) Obtained from the current value when focusing is performed by changing the excitation current of the objective lens.
(4) Using the sample charging voltage when grounded as a reference value, it is estimated by assuming that it is within a certain range including the reference value.
[0014]
According to the present invention, the time required for focusing can be minimized and automatic measurement can be speeded up.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, a case where a wafer is used as a sample will be described.
FIG. 1 is a schematic view showing an example of a charged particle beam apparatus according to the present invention. The primary charged particle beam 1 extracted from the charged particle source 3 by the extraction electrode 4 is two-dimensionally scanned on the wafer 12 by the condenser lens 5 and the scanning deflector 7. The primary charged particle beam 1 superimposes a negative retarding voltage applied to the wafer 12 from the power source 23 via the sample stage 13 in the sample chamber 14 and a fixed charging voltage that the wafer 12 has inside. Due to the deceleration voltage, the speed is reduced between the objective lens 8 and the wafer 12, and is narrowed down on the wafer 12 by the lens action of the objective lens 8. The difference between the extraction voltage and the deceleration voltage applied to the extraction electrode 4 becomes the acceleration voltage of the primary charged particle beam 1. Each part of the charged particle beam apparatus is controlled by the control unit 19. The control unit 19 also includes a charging voltage measurement unit 24 and a focus control unit 25 described later.
[0016]
When the primary charged particle beam 1 is irradiated onto the wafer 12, secondary charged particles 2 are generated, captured by the secondary charged particle detector 6, and used as a luminance signal of the secondary charged particle image display device 18 through an amplifier. Is done. Further, since the deflection signal of the secondary charged particle image display device 18 and the deflection signal of the deflection coil 7 are synchronized, the pattern shape on the wafer is faithfully reproduced on the secondary charged particle image display device.
[0017]
In order to inspect and observe the pattern on the wafer at high speed, it is necessary to detect the wafer height when the sample stage moves to the desired observation point, and to match the excitation current of the objective lens according to that height. is there. Therefore, a wafer height detection mechanism using light is provided. From the time when the sample stage 13 approaches the vicinity of a predetermined observation point, the height detecting laser emitter 9 irradiates the laser beam 10 toward the wafer 12, and the reflected light is received by the position sensor 11, and from the light receiving position. Detect the height of the wafer.
[0018]
The excitation current of the objective lens required for focusing on the wafer is generally expressed by a function as shown in equation (1).
I _obj = F (Va, Z) (1)
Here, I _obj is the excitation current of the objective lens, F is a function for calculating the excitation current of the objective lens, Va is the acceleration voltage of the charged particles, and Z is the height of the wafer. Moreover, the acceleration voltage Va is calculated | required by the relational expression shown in Formula (2).
Va = Vo− (Vr−Vs (r)) (2)
Here, Vo is the extraction voltage of the charged particle source, Vr is the retarding voltage applied to the wafer, and Vs (r) is the charging voltage of the wafer when the retarding voltage is applied and irradiated with the charged particle beam. Since it has almost central symmetry, it is expressed as a function of the distance r from the wafer center. On the other hand, the acceleration voltage can be estimated using the measurement result of the charging voltage of the wafer when grounded.
Va ′ = Vo− (Vr−Vso (r)) (3)
Here, Va ′ is an approximate acceleration voltage defined by the equation (3), Vso is a charging voltage of the grounded wafer, and this is also expressed as a function of the distance r from the wafer center because it has central symmetry. .
[0019]
FIG. 3 shows the relationship among Vo, Vr, Vs, Vso, Va, Va ′. Normally, Vo is kept constant, and if Vso (r) is correctly measured, Va ′ can be kept constant by controlling Vr accordingly. When Vs (r) is equal to Vso (r), the following equation holds.
Va = Va ′ (4)
[0020]
From this and the result of wafer height detection, the excitation current at the time of just focus can be calculated from Equation (1). However, if Vs and Vso are different, Expression (4) does not hold, and the actual I _obj is different. _{Therefore, the} focus is not adjusted and detection of the observation point fails, and automatic measurement becomes impossible. The reason why Vs (r) and Vso (r) are different is considered to be a change in the polarization state of the wafer insulating layer when placed under electrically different conditions. Vs (r) and Vso (r) Even if they are different from each other, the charge distribution tendency having the central symmetry is maintained.
[0021]
In the present invention, the charging voltage of the wafer having the central symmetry is measured by grounding the wafer before the charged particle irradiation, and at least 1 on the wafer while irradiating the charged particle by applying the retarding voltage. Similarly, by measuring the charging voltage and comparing the two measurement results to change the processing method for subsequent focusing, the processing time required for focusing can be shortened, and the automatic measurement can be speeded up.
[0022]
The measurement of the charging voltage when the wafer is grounded measures the potential distribution in a straight line including the center position on the wafer by utilizing the central symmetry of the charging voltage distribution of the wafer. The method of grasping the potential distribution of is adopted. Specifically, the electrostatic potential meter probe 15 is fixed on the transfer path when the wafer 16 is transferred to the sample chamber 14 through the gate valve 21 by the wafer transfer device 20, and the movement of the transfer arm 17 is used to make a straight line. A method of measuring the shape is suitable. Here, the conveyance path may be outside the vacuum or inside the vacuum. The charging voltage data of the wafer 16 measured by the electrostatic potentiometer probe 15 is taken into the charging voltage measuring unit 24.
[0023]
Note that even if the entire wafer cannot be measured due to the limitation of the fixed space of the probe, the potential across the wafer can be measured due to the central symmetry if the measurement can be performed in the amount equivalent to the radial distance of the wafer from one edge of the wafer to the wafer center. Distribution can be grasped. Further, even if measurement of the portion corresponding to the radial distance is impossible, an approximate function for the radius r may be obtained from the measurement result of a part of the measurement result and applied to the entire wafer surface.
[0024]
FIG. 2 is a flowchart showing a processing procedure for focusing after the wafer charging voltage is measured.
First, the wafer charging voltage when grounded is measured (S11). Based on the measurement result, an approximate function Vso (r) is obtained by an even function (quaternary function in FIG. 2) of the distance r from the wafer center (S12). Next, a retarding voltage is applied to at least one point on the wafer under the control of the charging voltage measuring unit 24, and the wafer charging voltage when the charged particle beam is irradiated is measured (S13). Specifically, the wafer moves to a measurement point at a distance R from the center of the wafer, and the charging voltage Vso (R) at the time of grounding the wafer is obtained from the obtained approximate function Vso (r). Next, Vr that gives a desired Va ′ is obtained from the equation (3), fed back to the retarding voltage, and the excitation current of I _obj is set based on the following equation.
I _obj = F (Va ′, Z) (5)
At this time, if Va and Va ′ are equal, the focus is achieved, but the charging voltage Vso (R) when grounded and the wafer charging voltage Vs (R) when the retarding voltage is applied and charged particles are irradiated are different. Because they are not equal, they are not in focus.
[0025]
FIG. 4 is a diagram illustrating a method for obtaining Vs (R) at this time. First, Vr for obtaining a desired Va ′ is set as a reference value, and the retarding voltage is changed within a range of the amplitude including the reference value, so that the retard at the best focus where the contrast of the secondary charged particle image becomes maximum is obtained. Find the ding voltage. At this time, the following equation holds.
Va ′ = Vo− (Vrn−Vs (R)) (6)
Here, Vrn is a retarding voltage at the time of best focus, and Vs (R) is a wafer charging voltage when charged particles are irradiated by applying a retarding voltage at a measurement point at a distance R from the wafer center. Vs (R) is obtained from equation (6).
[0026]
The focus control unit 25 determines that the difference between Vs (R) and Vso (R), that is, the absolute value of the difference is lower than the threshold value (determination in S14 is “NO”), the expression (4) holds, In subsequent focusing, the wafer charging voltage at the next stage stop position is calculated from the approximate function Vso (r) while the stage is moving, and the retarding voltage Vr is corrected so as to obtain the desired Va ′ from the equation (3). At the same time, if I _obj according to Va ′ and the wafer height is calculated from Equation (5) and applied (S15), the stage is already in focus when the stage movement is completed.
[0027]
On the other hand, when the above difference exceeds the threshold (the determination in S14 is “YES”), equation (4) does not hold, so when the stage movement occurs thereafter, I _obj calculated from equation (5) is not in focus. It is expected that. Therefore, the focus control unit 25 performs focusing by changing the retarding voltage within the range of the amplitude including the reference value, using Vr obtained from Equation (3) after the stage movement is completed as a reference value (S16).
[0028]
For example, in the equation (6), when the approximate acceleration voltage Va ′ is 800 V and the extraction voltage Vo is 2 kV, in order to focus at measurement points where Vso (R) is −500 V and Vs (R) is −550 V, first, the equation (3) If Vr obtained from (3), that is, 700V is set as a reference value, and the retarding voltage is changed with an appropriate amplitude such as 600V to 800V including the reference value, the focus is achieved when Vr is 650V. Become. In the conventional retarding focus system, the retarding voltage is always changed with reference to Vr when Vso is 0 V in Formula (3), that is, 1.2 kV, regardless of Vso (R). The time required for matching can be shortened.
[0029]
Further, the charging voltage measuring unit 24 or the focus control unit 25 may perform Vs (R) even when focusing is performed by changing the extraction voltage Vo of the primary charged particle beam instead of changing the retarding voltage Vr in the equation (6). ). Alternatively, focusing may be performed by changing the excitation current of the objective lens. That is, if Equation (1) is obtained in advance by experiment or electron optical simulation, when the exciting current I _obj when the focus is obtained at the measurement point at the distance R from the wafer center is determined, Va more accurate than Equation (1). And Vs (R) can be obtained from equation (2).
[0030]
Further, as the number of measurement points of the wafer charging voltage Vs when the retarding voltage is applied and the charged particle beam is irradiated is increased, the accuracy of the determination for determining the processing content of the subsequent focusing is increased. For example, the difference between Vs (R1) and Vso (R1), the difference between Vs (R2) and Vso (R2) at a total of N measurement points located at radii R1, R2,. RN) and Vso (RN) are each compared with a threshold value, and if even one point exceeds the threshold value, it is determined that Equation (4) does not hold, and thereafter, the retarding voltage is changed every time the stage movement is completed to focus. It is necessary to match. Here, the amplitude of the retarding voltage to be changed may be changed according to the maximum value among the N differences.
[0031]
FIG. 5 is an explanatory diagram of an embodiment in which focusing after moving the stage is performed at higher speed using the measurement results of Vs (R1), Vs (R2),..., Vs (RN) in FIG.
As shown in the figure, if the wafer charge distribution function Vso (r) is corrected each time Vs is measured, the difference between Vs and Vso gradually decreases, and the retarding is changed after the subsequent stage movement. The amplitude of the voltage can be gradually reduced, and the automatic processing can be further speeded up. As a method for correcting Vso (r), for example, there is a method of calculating the approximate function again by adding the measurement result of Vs (R1) to the measurement result of the wafer charging voltage measured when obtaining the approximate function Vso (r). At that time, if each measurement data is weighted so that Vs (R1) has a stronger influence on the calculation result of the approximate function than other measurement results, the difference between Vs (r) and Vso (r) is shortened more quickly. . When the absolute value of the difference between Vs and Vso falls below the threshold, Vs (r) = Vso (r) may be considered, and the retarding voltage may not be changed after the subsequent stage movement.
[0032]
【The invention's effect】
As described above, according to the present invention, since the charged voltage is different between the case where it is grounded and the case where the charged particle beam is applied by applying the retarding voltage, the focus shift occurs and the automatic measurement is performed. Even if the success rate of pattern detection at the time has decreased, focusing can be performed at high speed, and if the charging voltage matches, focusing can be performed at the same time as the stage movement is completed, speeding up automatic measurement Is possible.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a charged particle beam apparatus according to the present invention.
FIG. 2 is a diagram showing processing contents of focusing according to the amount of change in the charging voltage of a wafer under electrically different conditions.
FIG. 3 is a diagram showing a relationship among Vo, Vr, Vs, Vso, Va, Va ′.
FIG. 4 is a view showing a method of measuring a wafer charging voltage by changing a retarding voltage.
FIG. 5 is a diagram showing a method for correcting a wafer charge distribution function from a measurement result of a wafer charge voltage when a charged particle beam is applied by applying a retarding voltage.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Primary charged particle beam, 2 ... Secondary charged particle beam, 3 ... Charged particle source, 4 ... Extraction electrode, 5 ... Condenser lens, 6 ... Secondary charged particle detector, 7 ... Deflection coil, 8 ... Objective lens, DESCRIPTION OF SYMBOLS 9 ... Laser emitter, 10 ... Laser beam, 11 ... Position sensor, 12 ... Wafer, 13 ... Sample stage, 14 ... Sample chamber, 15 ... Electrostatic electrometer probe, 16 ... Wafer, 17 ... Transfer arm, 18 ... Two Next charged particle image display device, 19 ... control unit, 20 ... wafer transfer device, 21 ... gate valve, 23 ... power source, 24 ... charge voltage measurement unit, 25 ... focus control unit,
Vo ... extraction voltage, Vr ... retarding voltage, Vs ... wafer charging voltage when irradiated with charged particle beam by applying a retarding voltage, Vso ... wafer charging voltage when grounded, Va ... acceleration voltage, Va '… Approximate acceleration voltage, Vrn… Retarding voltage at the time of just focus

Claims (9)

A charged particle beam source;
An extraction electrode for extracting a charged particle beam from the charged particle beam source;
A deflector for two-dimensionally scanning the charged particle beam on the sample;
An objective lens for focusing the charged particle beam on the sample;
A secondary charged particle detector for detecting secondary charged particles generated from the sample by irradiation of the charged particle beam;
A height detector for detecting the height of the sample;
Retarding means for applying a voltage to the sample to decelerate the charged particle beam from the charged particle beam source to a desired voltage;
A sample charging voltage measuring unit that measures a charging voltage of the sample when a charged particle is irradiated by applying a voltage by the retarding means;
A focus control unit that controls the retarding means and the objective lens to perform focusing using information on the sample charging voltage when grounded and information on the height of the sample detected by the height detector; ,
The focus control unit changes the focusing process depending on whether or not the difference between the sample charging voltage when grounded and the sample charging voltage measured by the sample charging voltage measuring means exceeds a predetermined threshold value. Characterized charged particle beam device. 2. The charged particle beam apparatus according to claim 1, wherein the focus control unit calculates a voltage applied to the sample by the retarding unit, and a sample charging voltage when the grounding is performed when the difference exceeds the threshold value. A charged particle beam apparatus characterized in that the charged particle beam apparatus is set to the sample charging voltage when the grounding is performed when the difference is equal to or less than the threshold value. 2. The charged particle beam apparatus according to claim 1, further comprising an electrostatic potentiometer, wherein the sample charged voltage when grounded is measured by the electrostatic potentiometer. 4. The charged particle beam apparatus according to claim 3, wherein the charge voltage distribution of the entire sample is approximated by using the symmetry of the sample charge voltage distribution from the charge voltage measurement result of a part of the sample surface measured by the electrostatic electrometer. A charged particle beam device represented by: 2. The charged particle beam apparatus according to claim 1, wherein the sample charging voltage measurement unit applies the voltage applied by the retarding unit to irradiate the charged particles, and applies the sample charging voltage applied by the retarding unit. The charged particle beam apparatus is calculated from a voltage value when the focus is achieved by changing the angle. The charged particle beam apparatus according to claim 1, wherein the sample charging voltage measurement unit applies a sample charging voltage when a charged particle beam is applied by applying a voltage by the retarding unit to the extraction electrode. A charged particle beam apparatus, wherein the voltage is calculated from a voltage value when the focus is adjusted by changing a voltage. The charged particle beam apparatus according to claim 1, wherein the sample charging voltage measurement unit uses a charging voltage applied by the retarding unit to irradiate a charged particle beam as a sample charging voltage. The charged particle beam apparatus is characterized in that it is obtained from the current value when the focus is adjusted by changing the angle. 2. The charged particle beam apparatus according to claim 1, wherein the sample charging voltage measurement unit applies the voltage by the retarding means and irradiates the charged particle beam with the sample charging voltage when grounded. A charged particle beam apparatus characterized in that a charging voltage is used as a reference value and is estimated by assuming that the charging voltage is within a certain range including the reference value. 5. The charged particle beam apparatus according to claim 4, wherein a measurement result of a sample charging voltage when a charged particle beam is irradiated by applying a voltage by the retarding means is reflected and corrected in the approximate function. Charged particle beam device.

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