Charged particle beam apparatus and alignment marker detection method

Abstract

To detect an alignment marker without changing an observation magnification, this charged particle beam apparatus comprises: a sample holder that holds a sample; a charged particle beam source that irradiates the sample with a charged particle beam; a detector that detects secondary particles emitted from the sample and outputs detection signals; and a control unit that generates an observation image of the sample on the basis of the detection signals and controls each component. The charged particle beam apparatus is characterized in that: the sample is provided with an alignment marker serving as a reference point for identifying a position on the sample, and a guide marker having a shape indicating a direction in which the alignment marker is located; and the control unit detects the guide marker from the observation image and moves a field of view in the direction indicated by the guide marker.

Description

Charged particle beam device and alignment marker detection method

[0001] The present invention relates to a charged particle beam device that generates an observation image of a sample by irradiating the sample with a charged particle beam, and more particularly to a method for detecting an alignment marker used for aligning the sample.

[0002] Charged particle beam instruments generate observation images of a sample by detecting secondary particles such as secondary electrons emitted from the sample when the sample is irradiated with a charged particle beam such as an electron beam, and are used, for example, to observe in detail foreign matter or defects on the sample surface detected under an optical microscope.Alignment markers are created on the sample or sample holder as reference points for identifying the position of foreign matter or the like detected under the optical microscope under the charged particle beam instrument.

[0003] However, because the optical axes of an optical microscope and a charged particle beam device do not completely coincide, an alignment marker located at the center of the field of view under an optical microscope may be shifted from the center of the field of view under a charged particle beam device. In particular, it takes time to detect an alignment marker that is out of the field of view of a charged particle beam device.

[0004] Patent Document 1 discloses that a plurality of sub-markers, each having a different planar shape from the alignment marker, are arranged around the alignment marker in all directions, up, down, left, right, and diagonally, in a plan view. In other words, by detecting the sub-markers arranged around the alignment marker, even alignment markers that are out of the field of view can be detected in a relatively short time.

[0005] Japanese Patent Application Laid-Open No. 2006-135104

[0006] However, in Patent Document 1, since it is not possible to appropriately set the direction in which the field of view is moved after detecting the sub-marker, the alignment marker is detected by lowering the observation magnification to enlarge the field of view, which requires time for focus adjustment when the observation magnification is changed.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a charged particle beam device and an alignment marker detection method that are capable of detecting alignment markers without changing the observation magnification.

[0008] In order to achieve the above-mentioned object, the present invention provides a charged particle beam device comprising a sample holder for holding a sample, a charged particle beam source for irradiating the sample with a charged particle beam, a detector for detecting secondary particles emitted from the sample and outputting a detection signal, and a control unit for generating an observation image of the sample based on the detection signal and controlling each unit, wherein the sample is provided with an alignment marker which is a reference point for identifying a position on the sample, and a guide marker having a shape which indicates the direction in which the alignment marker is located, and the control unit detects the guide marker from the observation image and moves the field of view in the direction indicated by the guide marker.

[0009] The present invention also provides an alignment marker detection method for detecting an alignment marker, which is a reference point for identifying a position on a sample, based on an observation image generated by irradiating a charged particle beam onto a sample held in a sample holder, and is characterized by comprising a detection step for detecting a guide marker from the observation image, the guide marker having a shape indicating the direction in which the alignment marker is located, and a movement step for moving the field of view in the direction indicated by the guide marker.

[0010] According to the present invention, it is possible to provide a charged particle beam device and an alignment marker detection method that are capable of detecting alignment markers without changing the observation magnification.

[0011] FIG. 1 is a diagram showing an example of the overall configuration of a charged particle beam device according to a first embodiment; FIG. 2 is a diagram explaining alignment markers; FIG. 3 is a diagram explaining guide markers; FIG. 4 is a diagram explaining the placement of guide markers; FIG. 5 is a diagram explaining an initial guide marker; FIG. 6 is a diagram showing an example of a process flow for creating each marker; FIG. 7 is a diagram showing an example of a process flow for detecting alignment markers; FIG. 8 is a diagram explaining a template image; FIG. 9 is a diagram explaining movement of the field of view;

[0012] Hereinafter, an embodiment of a charged particle beam device according to the present invention will be described with reference to the accompanying drawings. The charged particle beam device is a device that irradiates a sample with a charged particle beam such as an electron beam, detects secondary particles such as secondary electrons, backscattered electrons, Auger electrons, and X-ray photons emitted from the sample, and generates an observation image of the sample. Below, a scanning electron microscope (SEM) that detects secondary electrons emitted from the sample will be described as an example of the charged particle beam device.

[0013] The overall configuration of the scanning electron microscope of Example 1 will be described with reference to Figure 1. The scanning electron microscope includes an electron source 101, a focusing lens 102, a deflector 103, an objective lens 104, a sample stage 106, a detector 107, a control unit 111, an input unit 112, and a display unit 113. Each unit will be described below.

[0014] The electron source 101 is a device that generates an electron beam by emitting and accelerating electrons to irradiate the sample 100. The electron beam generated by the electron source 101 travels along the optical axis, is focused by a focusing lens 102, is deflected by a deflector 103, and is then focused by an objective lens 104. The electron beam is deflected by the deflector 103 to scan the surface of the sample 100 two-dimensionally.

[0015] The sample stage 106 is a device on which the sample holder 105 for holding the sample 100 is placed and which moves the sample holder 105 in the horizontal and vertical directions. The sample holder 105 and the sample stage 106 function as a sample holding unit for holding the sample 100.

[0016] The detector 107 is a device that detects secondary electrons emitted from the surface of the sample 100 scanned with the electron beam, and transmits a detection signal to the control unit 111 .

[0017] The control unit 111 is a device that controls the electron source 101, the focusing lens 102, the deflector 103, the objective lens 104, and the sample stage 106, and is, for example, a general-purpose computer. The control unit 111 includes a processor such as a CPU (Central Processing Unit) and memories such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The control unit 111 also performs processes such as generating an observation image of the sample 100 based on a detection signal transmitted from the detector 107 and calculating a new image using multiple observation images. The processes performed by the control unit 111 may be realized by the processor executing a program loaded in the memory. Note that a portion of the control unit 111 may be configured by hardware such as a dedicated circuit board.

[0018] The control unit 111 is connected to an input unit 112 and a display unit 113. The input unit 112 is a device that allows an operator to input imaging conditions for an observation image, and is, for example, a keyboard, a mouse, or a touch panel. The display unit 113 is a device that displays the imaging conditions and the observation image, and is, for example, a liquid crystal display or a touch panel.

[0019] Charged particle beam devices such as scanning electron microscopes are suitable for detailed observation of the sample 100, and are used, for example, to closely observe foreign particles or defects on the sample surface detected under an optical microscope. Furthermore, alignment markers are created on the sample 100, sample holder 105, and sample stage 106 as reference points for identifying the positions of foreign particles or the like detected under the optical microscope under the charged particle beam device.

[0020] The alignment marker will be described with reference to FIG. 2. FIG. 2 illustrates an alignment marker 201 created on the surface of the sample 100 at a distance D1 from the holder center 200, which is the center of the sample holder 105. The alignment marker 201 may be created, for example, as an indentation made by a Vickers cone under an optical microscope, or as an ion beam mark made by a focused ion beam (FIB-SEM). To improve the throughput of detailed observation of foreign particles and defects on the sample surface, it is desirable to detect the alignment marker 201, which serves as a reference point for identifying a position on the sample 100, in a short time without changing the observation magnification. Therefore, in Example 1, guide markers having a shape indicating the direction in which the alignment marker 201 exists, are created on the sample 100, the sample holder 105, and the sample stage 106.

[0021] The guide markers will be described using FIG. 3. FIG. 3 illustrates four trapezoidal guide markers 300 created at a distance D2 from the alignment marker 201. The guide markers 300 in FIG. 3 point in a direction from the lower base to the upper base of the trapezoid, and the alignment marker 201 exists in the direction indicated by the guide markers 300. Note that the shape of the guide markers 300 is not limited to a trapezoid, and may be a shape pointing in a certain direction, such as an isosceles triangle or an arrow shape. Like the alignment markers 201, the guide markers 300 may be created, for example, as impressions made by a Vickers cone under an optical microscope, or as ion beam impressions made by an FIB-SEM.

[0022] 3 is arranged around the alignment marker 201, it is possible to detect the alignment marker 201 in a relatively short time even if the alignment marker 201 is out of the field of view of the charged particle beam device. In other words, by detecting the guide marker 300, it is possible to detect the alignment marker 201 by moving the field of view in the direction indicated by the guide marker 300. Note that in order to detect the guide marker 300 without changing the observation magnification, it is preferable that at least one guide marker 300 is arranged within the field of view at the observation magnification when observing the alignment marker 201 with the charged particle beam device.

[0023] A preferred arrangement of the guide markers 300 will be described using Figure 4. When two guide markers 300 are placed at a distance D2 from the center 400 of the alignment marker, and are located within both ends of the short side of the field of view 401 at the observation magnification when observing the alignment marker 201, the central angle θ of the two guide markers 300 is set to satisfy θm ≥ θ. Note that θm is expressed by the following formula.

[0024] θm=2 sin －１ (L / (D2+Δ)) (Equation 1) Here, 2L is the length of the short side of the field of view 401, and Δ is the error in the distance D2. The error Δ includes at least one of an error related to the placement of the alignment marker 201 and the guide marker 300, an error related to the distance measurement, and an error related to the movement of the sample stage 106. The maximum error line 402 indicated by a dotted circle has a radius of D2+Δ.

[0025] That is, when the central angle θ between the two guide markers 300 is equal to or less than the value of (Equation 1), at least one guide marker 300 is included in the field of view 401, so that the guide marker 300 can be detected without changing the observation magnification, and the field of view 401 can be moved in the direction indicated by the guide marker 300. Note that, since the field of view 401 is near the holder center 200 when the sample 100 held by the sample holder 105 is placed in the charged particle beam device, it is preferable that the initial guide markers that point to the guide markers 300 and alignment markers 201 be arranged near the holder center 200.

[0026] The initial guide marker will be described using FIG. 5. FIG. 5 illustrates an initial guide marker 500 having a trapezoidal shape created near the holder center 200, which is the center of the sample holder 105. Like the guide marker 300, the initial guide marker 500 in FIG. 5 points in the direction from the lower base to the upper base of the trapezoid, and the guide marker 300 and the alignment marker 201 are located in the direction indicated by the initial guide marker 500. The shape of the initial guide marker 500 is not limited to a trapezoid, and may be an isosceles triangle or an arrow shape. The initial guide marker 500 is also created as an indentation made by a Vickers cone or an ion beam mark made by an FIB-SEM.

[0027] The initial guide marker 500 is preferably placed within the field of view 401 when the sample 100 is placed in the charged particle beam device. That is, the initial guide marker 500 is preferably placed within a distance L from the holder center 200 that is half the short side of the field of view 401 at the observation magnification when observing the alignment marker 201. The initial guide marker 500 placed within the distance L from the holder center 200 is detected by the field of view 401 when the sample 100 is placed in the charged particle beam device.

[0028] An example of the flow of processing for creating each marker will be described step by step with reference to FIG.

[0029] (S601) An alignment marker 201 is created under a first observation device that is different from the charged particle beam device used for detailed observation. The alignment marker 201 is created on at least one of the sample 100, the sample holder 105, and the sample stage 106 as a reference point for identifying a position on the sample 100. The first observation device is, for example, an optical microscope. Note that the first observation device is not limited to an optical microscope, and may be any surface shape measurement device that performs shape measurement using a reflected signal from a probe, such as a scanning white light interferometer (CSI) or an EDS for an electron microscope.

[0030] (S602) Under the first observation device, guide markers 300 are created around alignment marker 201. Guide markers 300 are created so that alignment marker 201 exists in the direction indicated by guide marker 300. Furthermore, it is preferable that the central angle θ formed by two adjacent guide markers 300 at alignment marker 201 is within the value calculated by (Equation 1).

[0031] (S603) Using the first observation device, the distance D1 between the alignment marker 201 and the holder center 200, which is the HOME position, is measured. The value of the measured distance D1 is stored in the storage device of the control unit 111.

[0032] (S604) The first observation device is used to measure the distance D2 between the alignment marker 201 and the guide marker 300. The value of the measured distance D2 is stored in the storage device of the control unit 111.

[0033] (S605) Under the first observation device, an initial guide marker 500 is created near the holder center 200. The initial guide marker 500 is created so that the alignment marker 201 and guide marker 300 are located in the direction indicated by the initial guide marker 500. It is also preferable that the distance between the initial guide marker 500 and the holder center 200 be within the distance L, which is half the short side of the field of view 401 at the observation magnification when observing the alignment marker 201.

[0034] 6, the alignment marker 201, the guide marker 300, and the initial guide marker 500 are created on the sample 100, the sample holder 105, and the sample stage 106. The guide marker 300 and the initial guide marker 500 are used to detect the alignment marker 201.

[0035] An example of the flow of processing for detecting the alignment marker 201 will be described step by step with reference to FIG.

[0036] (S701) The control unit 111 detects the initial guide markers 500 from the observation image. The initial guide markers 500 are detected using a template matching method or a feature point detection method.

[0037] (S702) The control unit 111 sets the movement direction of the field of view 401 based on the shape of the initial guide marker 500 detected in S701. For example, the movement direction is set by rotating a template image 800 that has the same shape as the initial guide marker 500 and points in the positive direction of the x-axis as shown in Fig. 8 and comparing it with the detected initial guide marker 500. More specifically, the correlation value of the pixel values ​​with the initial guide marker 500 is calculated every time the template image 800 is rotated by a predetermined angle, for example, 0.5 degrees, and the movement direction is set from the rotation angle at which the correlation value is maximized.

[0038] (S703) The control unit 111 moves the field of view 401 in the movement direction set in S702. The movement of the field of view 401 is performed by moving the sample stage 106 or by changing the electron beam irradiation field using the deflector 103. Fig. 9 shows an example of the field of view 401 that is moved based on the shape of the initial guide marker 500. In Fig. 9, the field of view 401 is moved in the direction of the white arrow, which is the direction indicated by the initial guide marker 500 detected in the field of view 401. A predetermined value, for example, the distance L that is half the short side of the field of view 401, is set as the movement distance of the field of view 401.

[0039] (S704) The control unit 111 determines whether or not the guide marker 300 has been detected in the field of view 401 after movement. To detect the guide marker 300, a template matching method or a feature point detection method is used, as with the initial guide marker 500. If the guide marker 300 has been detected, the process proceeds to S705; if not, the process returns to S703. That is, the movement of the field of view 401 in S703 is repeated until the guide marker 300 is detected in S704. Note that if the movement limit of the field of view 401 is reached without the guide marker 300 being detected, the field of view 401 may be returned to the holder center 200, which is the HOME position, and the process may be resumed from S701, or an error message may be displayed.

[0040] 6 and stored in the storage device of the control unit 111. When the field of view 401 is moved based on the distance D1 between the alignment marker 201 and the holder center 200, if the guide marker 300 cannot be detected in S704, an error message is displayed and the processing flow is terminated.

[0041] (S705) The control unit 111 sets the movement direction of the field of view 401 based on the shape of the guide marker 300 detected in S704.

[0042] (S706) The control unit 111 moves the field of view 401 in the movement direction set in S705. A predetermined value, for example, the distance L that is half the short side of the field of view 401, is set as the movement distance of the field of view 401.

[0043] (S707) The control unit 111 determines whether or not the alignment marker 201 has been detected in the field of view 401 after movement. Similar to the initial guide marker 500, the alignment marker 201 can be detected using a template matching method or a feature point detection method. A method with higher detection accuracy, such as point detection using a differential image, may also be used. If the alignment marker 201 has been detected, the process flow ends. If the alignment marker 201 has not been detected, the process returns to S706. That is, the movement of the field of view 401 in S706 is repeated until the alignment marker 201 is detected in S707. If the movement limit of the field of view 401 is reached without the alignment marker 201 being detected, an error message is displayed and the process flow ends.

[0044] 6 and stored in the storage device of the control unit 111. When the field of view 401 is moved based on the distance D2 between the alignment marker 201 and the guide marker 300, if the alignment marker 201 cannot be detected in S707, an error message is displayed and the processing flow is terminated. Note that the distance D2 may be indicated by the shape of the guide marker 300.

[0045] An example of a guide marker indicating distance will be described using Figure 10. Figure 10 illustrates a short-distance guide marker 1001 indicating a short distance and a long-distance guide marker 1002 indicating a long distance. Both guide markers are trapezoidal with a lower base of the same length B, but the height of the long-distance guide marker 1002 is 2H, which is twice the height H of the short-distance guide marker 1001. In other words, the two guide markers illustrated in Figure 10 indicate distance by the ratio of the lower base to the height. When creating a guide marker indicating distance, it is necessary to set the distance between the guide marker and the alignment marker 201 prior to creating the guide marker.

[0046] 7, the alignment marker 201 can be detected without changing the observation magnification. In other words, the alignment marker 201 can be detected in a shorter time, which improves the throughput of detailed observation of foreign particles and defects on the sample surface detected under the first observation device.

[0047] In the first embodiment, it has been described that the alignment marker 201 is detected by moving the field of view 401 in the direction indicated by the guide markers 300 arranged around the alignment marker 201. In the second embodiment, a link marker will be described, which is a guide marker for sequentially detecting a plurality of alignment markers 201. Note that some of the configurations and functions described in the first embodiment can be applied to the second embodiment, and therefore the same configurations and functions will be designated by the same reference numerals and will not be described again.

[0048] The link marker will be described with reference to FIG. 11. FIG. 11 illustrates a trapezoidal link marker 1100 created near each of three alignment markers 201. Like the guide marker 300, the link marker 1100 in FIG. 11 points in the direction from the lower base to the upper base of the trapezoid, and the alignment marker 201 exists in the direction indicated by the link marker 1100. The shape of the link marker 1100 is not limited to a trapezoid, and may be an isosceles triangle or an arrow shape. Like the guide marker 300, the link marker 1100 is created as an indentation made by a Vickers cone or an ion beam mark made by an FIB-SEM.

[0049] Note that link marker 1100-1 created near alignment marker 201-1 points to alignment marker 201-2. Link marker 1100-2 near alignment marker 201-2 points to alignment marker 201-3, and link marker 1100-3 near alignment marker 201-3 points to alignment marker 201-1. In this way, link markers 1100 are created so that all alignment markers 201 can be detected by starting from one alignment marker 201 and its neighboring link marker 1100 and sequentially detecting the alignment markers 201 pointed to by the link marker 1100.

[0050] Furthermore, it is preferable that the link marker 1100 be placed within the field of view when observing the alignment marker 201. In other words, it is preferable that the link marker 1100 be placed within a distance L that is half the short side of the field of view 401 from the alignment marker 201. The link marker 1100 placed within the distance L from the alignment marker 201 is detected by the field of view 401 when observing the alignment marker 201.

[0051] An example of the flow of processing for creating the link marker 1100 will be described step by step with reference to FIG.

[0052] (S1201) A plurality of alignment markers 201 are created under a first observation device that is different from the charged particle beam device used for detailed observation. The plurality of alignment markers 201 are created on at least one of the sample 100, the sample holder 105, and the sample stage 106. The first observation device is, for example, an optical microscope, a scanning white light interferometer (CSI), or an EDS for an electron microscope.

[0053] (S1202) Under the first observation device, link markers 1100 are created near alignment marker 201. Link marker 1100-1 near alignment marker 201-1 is created so as to point to alignment marker 201-2. Link marker 1100-2 near alignment marker 201-2 is created so as to point to alignment marker 201-3, and link marker 1100-3 is created so as to point to alignment marker 201-1. Note that the number of alignment markers 201 and link markers 1100 is not limited to three. When the number of alignment markers 201 and link markers 1100 is N, link marker 1100-N points to alignment marker 201-1.

[0054] (S1203) Using the first observation device, the distance between the alignment marker 201 pointed to by the link marker 1100 and the link marker 1100 is measured. The measured distance value is stored in the storage device of the control unit 111. Note that, for measuring the distance, it is preferable to use a scanning white light interferometer (CSI) or an EDS for electron microscope, which is a surface shape measurement device that also measures the depth of the sample surface. By using a surface shape measurement device, the edges of the alignment marker 201 or the link marker 1100 can be detected more accurately, thereby improving the accuracy of the measured distance value.

[0055] 12, a plurality of alignment markers 201 and link markers 1100 arranged near each of them are created on the sample 100, the sample holder 105, and the sample stage 106. The link markers 1100 are used to sequentially detect the plurality of alignment markers 201.

[0056] An example of the flow of processing for sequentially detecting a plurality of alignment markers 201 will be described step by step with reference to FIG.

[0057] (S1301) The control unit 111 detects the alignment marker 201 and the link markers 1100 arranged in the vicinity thereof from the observation image. Note that the movement of the field of view 401 from the holder center 200, which is the HOME position, may be the same as in S701 in FIG. 7, or may be manual. A template matching method or a feature point detection method is used to detect the alignment markers 201 and the link markers 1100. Furthermore, since the link markers 1100 are arranged so that all alignment markers 201 can be detected by tracing the direction indicated by the link markers 1100, markers other than the link marker 1100-1 may be detected in S1301.

[0058] (S1302) The control unit 111 sets the movement direction of the field of view 401 based on the shape of the link marker 1100 detected in S1301.

[0059] (S1303) The control unit 111 moves the field of view 401 in the movement direction set in S1302. A predetermined value, for example, the distance L that is half the short side of the field of view 401, is set as the movement distance of the field of view 401.

[0060] (S1304) The control unit 111 determines whether or not the next alignment marker 201 and link marker 1100 have been detected in the field of view 401 after movement. If the next alignment marker 201 and link marker 1100 have been detected, the process proceeds to S1305; if they have not been detected, the process returns to S1303. That is, the movement of the field of view 401 in S1303 is repeated until the next alignment marker 201 and link marker 1100 are detected in S1304. Note that if the movement limit of the field of view 401 is reached without the next alignment marker 201 and link marker 1100 being detected, an error message is displayed and the process flow ends.

[0061] The movement of the field of view 401 in S1303 may be performed based on the distance between the alignment marker 201 pointed to by the link marker 1100 and the link marker 1100, which is measured in S1203 of Fig. 12 and stored in the storage device of the control unit 111. Even when the field of view 401 is moved based on the distance read from the storage device, if the next alignment marker 201 and link marker 1100 cannot be detected in S1304, an error message is displayed and the processing flow is terminated.

[0062] (S1305) The control unit 111 determines whether the alignment marker 201 detected in S1304 is the same as the alignment marker 201 detected in S1301. If they are the same, the processing flow ends, but if they are not the same, the processing returns to S1302, and the movement direction of the field of view 401 is set based on the shape of the link marker 1100 detected in S1304. That is, sequential detection of multiple alignment markers 201 is repeated until the alignment marker 201 detected in S1304 is the same as the alignment marker 201 detected initially.

[0063] 13, the alignment markers 201 are sequentially detected while tracing the direction indicated by the link marker 1100. By sequentially detecting the alignment markers 201, it is possible to improve the throughput of detailed observation of foreign particles and defects on the sample surface detected under the first observation device.

[0064] The above describes several embodiments of the present invention. The present invention is not limited to the above embodiments, and the components can be modified and embodied without departing from the spirit and scope of the invention. Furthermore, the components disclosed in the above embodiments may be combined as appropriate. Furthermore, some components may be omitted from all the components shown in the above embodiments.

[0065] 100...sample, 101...electron source, 102...focusing lens, 103...deflector, 104...objective lens, 105...sample holder, 106...sample stage, 107...detector, 111...control unit, 112...input unit, 113...display unit, 200...holder center, 201...alignment marker, 300...guide marker, 400...center of alignment marker, 401...field of view, 402...maximum error line, 500...initial guide marker, 800...template image, 1001...short-distance guide marker, 1002...long-distance guide marker, 1100...link marker.

Claims

1. a sample holder for holding a sample; a charged particle beam source that irradiates the sample with a charged particle beam; a detector that detects secondary particles emitted from the sample and outputs a detection signal; a control unit that generates an observation image of the sample based on the detection signal and controls each unit, The sample is provided with an alignment marker, which is a reference point for identifying a position on the sample, and a guide marker having a shape that indicates a direction in which the alignment marker is located; an initial guide marker having a shape indicating the direction in which the alignment marker is located is further provided near the center of the sample holder; The control unit detects the initial guide marker from the observation image, moves a field of view in a direction indicated by the initial guide marker to detect the guide marker, and moves a field of view in a direction indicated by the guide marker.

2. The charged particle beam device according to claim 1, A charged particle beam device, characterized in that at least one of the guide markers is arranged within a field of view at an observation magnification when observing the alignment marker.

3. The charged particle beam device according to claim 2, The central angle θ formed by two adjacent guide markers at the alignment marker is θ≦2 sin －１ A charged particle beam device characterized in that (L / (D2+Δ)) is satisfied.

4. (delete)

5. a sample holder for holding a sample; a charged particle beam source that irradiates the sample with a charged particle beam; a detector that detects secondary particles emitted from the sample and outputs a detection signal; a control unit that generates an observation image of the sample based on the detection signal and controls each unit, a plurality of alignment markers are provided on the sample, which are reference points for identifying a position on the sample, and a link marker having a shape indicating a direction in which a second alignment marker is present is further provided near a first alignment marker; The charged particle beam device is characterized in that the control unit detects the link marker from the observation image and moves a field of view in a direction indicated by the link marker.

6. The charged particle beam device according to claim 5, The control unit moves the field of view based on the distance between the first alignment marker and the second alignment marker, which is measured in advance by an observation device different from the charged particle beam device.

7. The charged particle beam device according to claim 6, The charged particle beam device is characterized in that the observation device is a surface shape measurement device that measures the depth of the sample surface as well as an observation image of the sample surface.

8. The charged particle beam device according to claim 1, the guide marker further has a shape indicating a distance to the alignment marker; The charged particle beam device is characterized in that the control unit moves a field of view based on the distance indicated by the guide marker.

9. 1. A method for detecting an alignment marker, which is a reference point for identifying a position on a sample, based on an observation image generated by irradiating a charged particle beam onto a sample held in a sample holder, comprising: a first detection step of detecting, from the observation image, an initial guide marker that is provided near the center of the sample holder and has a shape that indicates the direction in which the alignment marker is located; a first moving step of moving a field of view in a direction indicated by the initial guide marker; a second detection step of detecting a guide marker having a shape indicating a direction in which the alignment marker is present from the observation image; A method for detecting an alignment marker, comprising a second moving step of moving a field of view in a direction indicated by the guide marker.