Charged particle beam device and method for detecting alignment mark

Abstract

In order to detect an alignment mark without changing an observation magnification, a charged particle beam device is provided with: a sample holding unit 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 a detection signal; and a control unit that generates an observation image of the sample on the basis of the detection signal, and that controls each unit so that an alignment mark, which is a reference point for specifying a position on the sample, and a guide mark, which has a shape indicating the direction in which the alignment mark is located, are provided on the sample, the control unit detects the guide mark from the observation image and moves the field of view in the direction indicated by the guide mark.

Description

Technical Field

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

[0002] A charged particle beam device generates an observation image of the sample by detecting secondary particles, such as secondary electrons, emitted from the sample by irradiation with a charged particle beam, such as an electron beam. This device is used, for example, to observe in detail foreign matter and defects on the sample surface detected under an optical microscope. Furthermore, alignment marks are created on the sample or sample holder as reference points for determining the position of foreign matter detected under an optical microscope using the charged particle beam device.

[0003] However, the optical axes of the optical microscope and the charged particle beam device are not completely aligned, so the alignment mark located at the center of the field of view under the optical microscope may be offset from the field of view under the charged particle beam device. In particular, it takes time to detect the alignment mark that is offset from the field of view of the charged particle beam device.

[0004] Patent Document 1 discloses that multiple sub-marks having planar shapes different from those of the alignment mark are arranged around the alignment mark in all directions, including vertical, horizontal, and diagonal, when viewed from above. In other words, by detecting the sub-marks arranged around the alignment mark, even alignment marks that are out of view can be detected in a relatively short time.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-135104 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, in Patent Document 1, after detecting the sub-marks, the direction of moving the field of view cannot be appropriately set, so the alignment marks are detected by reducing the observation magnification to expand the field of view. If the observation magnification is changed, focus adjustment takes time.

[0010] Therefore, an object of the present invention is to provide a charged particle beam apparatus and a method for detecting an alignment mark that can detect an alignment mark without changing the observation magnification.

[0011] Means for solving problems

[0012] In order to achieve the above-mentioned purpose, the charged particle beam device of the present invention comprises: a sample holding part, which holds the sample; a charged particle beam source, which irradiates the sample with a charged particle beam; a detector, which detects secondary particles emitted from the sample to output a detection signal; and a control part, which generates an observation image of the sample based on the detection signal and controls each part to set an alignment mark and a guide mark on the sample, wherein the alignment mark is a reference point for determining the position on the sample, and the guide mark has a shape indicating the direction of the alignment mark, and the control part detects the guide mark from the observation image and moves the field of view in the direction indicated by the guide mark.

[0013] In addition, the present invention is a method for detecting an alignment mark, which detects an alignment mark serving as a reference point for determining a position on the sample based on an observation image generated by irradiating a sample held by a sample holding portion with a charged particle beam. The detection method comprises: a detection step of detecting a guide mark having a shape indicating a direction in which the alignment mark is located from the observation image; and a moving step of moving the field of view in the direction indicated by the guide mark.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a charged particle beam device and a method for detecting an alignment mark that can detect an alignment mark without changing the observation magnification. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram showing an example of the overall configuration of the charged particle beam device of Example 1.

[0017] Figure 2 It is a diagram illustrating an alignment mark.

[0018] Figure 3 This is a diagram illustrating guide marks.

[0019] Figure 4 This is a diagram illustrating the arrangement of guide marks.

[0020] Figure 5 It is a diagram illustrating the initial boot mark.

[0021] Figure 6 This is a diagram showing an example of a process flow for generating each marker.

[0022] Figure 7 This is a diagram showing an example of a processing flow for detecting an alignment mark.

[0023] Figure 8 A diagram illustrating a template image.

[0024] Figure 9 This is a diagram illustrating the movement of the visual field.

[0025] Figure 10 A diagram illustrating guide marks indicating distance.

[0026] Figure 11 This is a diagram illustrating link tags.

[0027] Figure 12 A diagram showing an example of a processing flow for generating a link tag.

[0028] Figure 13 This is a diagram showing an example of a process flow for sequentially detecting a plurality of alignment marks. DETAILED DESCRIPTION

[0029] An embodiment of a charged particle beam device according to the present invention is described below with reference to the accompanying drawings. A charged particle beam device irradiates a sample with a charged particle beam, such as an electron beam, and detects secondary particles emitted from the sample, such as secondary electrons, reflected electrons, Auger electrons, and X-ray photons, to generate an observation image of the sample. As an example of a charged particle beam device, a scanning electron microscope (SEM) for detecting secondary electrons emitted from a sample is described below.

[0030] Example 1

[0031] use Figure 1 The overall structure of the scanning electron microscope of Example 1 is described. 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 is described below.

[0032] The electron source 101 emits and accelerates electrons to generate an electron beam that irradiates the sample 100. The electron beam generated by the electron source 101 travels along the optical axis, is focused by the focusing lens 102, is deflected by the deflector 103, and is focused by the objective lens 104. The deflection by the deflector 103 causes the electron beam to scan the surface of the sample 100 two-dimensionally.

[0033] The sample stage 106 is a device that places the sample holder 105 for holding the sample 100 and 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 portion for holding the sample 100 .

[0034] The detector 107 is a device that detects secondary electrons emitted from the surface of the sample 100 scanned by the electron beam, and transmits a detection signal to the control unit 111 .

[0035] 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 has a processor such as a CPU (Central Processing Unit) and a memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory). In addition, the control unit 111 performs the following processing: generating an observation image of the sample 100 based on the detection signal sent from the detector 107, and calculating a new image using multiple observation images. The processing of the control unit 111 can be achieved by executing a program expanded in the memory by the processor. In addition, a part of the control unit 111 can also be composed of hardware such as a dedicated circuit substrate.

[0036] The control unit 111 is connected to an input unit 112 and a display unit 113. The input unit 112 is a device for the operator to input shooting conditions for the observation image, and is, for example, a keyboard, a mouse, or a touch panel. The display unit 113 is a device for displaying shooting conditions and the observation image, and is, for example, a liquid crystal display or a touch panel.

[0037] Charged particle beam devices such as scanning electron microscopes are suitable for detailed observation of sample 100, for example, when observing foreign matter or defects on the sample surface detected under an optical microscope. Furthermore, alignment marks are generated on sample 100, sample holder 105, and sample stage 106 as reference points for determining the position of foreign matter detected under an optical microscope using the charged particle beam device.

[0038] use Figure 2 Indicates the alignment marks. Figure 2 In the embodiment, an alignment mark 201 is shown as being generated on the surface of the sample 100 at a position at a distance D1 from the center of the sample holder 105, i.e., the center of the holder 200. For example, the alignment mark 201 is generated as an indentation of a Vickers hardness cone under an optical microscope, or as an ion beam mark of a FIB-SEM (Focused Ion Beam). In order to improve the throughput of detailed observation of foreign matter or defects on the sample surface, it is preferable to detect the alignment mark 201, which is a reference point for determining the position on the sample 100, in a short time without changing the observation magnification. Therefore, in Example 1, a guide mark having a shape indicating the direction in which the alignment mark 201 exists is generated on the sample 100, the sample holder 105, and the sample stage 106.

[0039] use Figure 3 Describes the boot mark. Figure 3 , four guide marks 300 having a trapezoidal shape generated at positions at a distance D2 from the alignment mark 201 are exemplified. Figure 3 Guide mark 300 indicates the direction from the lower base of the trapezoid toward the upper base. Alignment mark 201 is located in the direction indicated by guide mark 300. The shape of guide mark 300 is not limited to a trapezoid; it can also be a shape indicating a specific direction, such as an isosceles triangle or an arrow. Similar to alignment mark 201, guide mark 300 can be created, for example, as an indentation of a Vickers hardness cone under an optical microscope or as an ion beam mark in a FIB-SEM.

[0040] By Figure 3 The illustrated guide marks 300 are arranged around the alignment mark 201, and even if the alignment mark 201 is out of the field of view of the charged particle beam device, it can be detected in a relatively short time. In other words, by detecting the guide marks 300, if the field of view is moved in the direction indicated by the guide marks 300, the alignment mark 201 can be detected. In addition, in order to detect the guide marks 300 without changing the observation magnification, it is preferable to arrange at least one guide mark 300 in the field of view at the observation magnification when observing the alignment mark 201 with the charged particle beam device.

[0041] use Figure 4 The preferred arrangement of guide marks 300 will be described. When two guide marks 300 are positioned at a distance D2 from the center 400 of the alignment mark, they are positioned within the short sides of the field of view 401 at the magnification used when observing the alignment mark 201. The central angle θ between the two guide marks 300 satisfies θm ≥ θ. θm is expressed as follows.

[0042] θm=2sin -1 (L / (D2+Δ)) (Equation 1)

[0043] Here, 2L is the length of the short side of field of view 401, and Δ is the error in distance D2. Furthermore, error Δ includes at least one of errors related to the placement of alignment mark 201 or guide mark 300, errors related to distance measurement, and errors related to the movement of sample stage 106. Maximum error line 402, represented by a dotted circle, has a radius of D2 + Δ.

[0044] That is, when the central angle θ between the two guide marks 300 is equal to or smaller than the value of (Equation 1), at least one guide mark 300 is included in the field of view 401. Therefore, the guide mark 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 mark 300. Furthermore, since the field of view 401 is near the center 200 of the holder when the sample 100 held by the sample holder 105 is placed in the charged particle beam device, it is preferable to arrange the initial guide marks indicating the guide marks 300 and the alignment marks 201 near the center 200 of the holder.

[0045] use Figure 5 Describes the initial boot flags. Figure 5 , an initial guide mark 500 having a trapezoidal shape is illustrated, which is generated near the center of the sample holder 105 , that is, the holder center 200 . Figure 5 Initial guide mark 500, like guide mark 300, indicates the direction from the lower base of the trapezoid toward the upper base. Guide mark 300 and alignment mark 201 are located in the direction indicated by initial guide mark 500. The shape of initial guide mark 500 is not limited to a trapezoid; it can also be an isosceles triangle or an arrowhead. Initial guide mark 500 can also be generated as an indentation of a Vickers hardness cone or an ion beam mark in a FIB-SEM.

[0046] The initial guide mark 500 is preferably placed within the field of view 401 when the sample 100 is placed in the charged particle beam apparatus. Specifically, the initial guide mark 500 is preferably placed within a distance L that is half the short side of the field of view 401 at the observation magnification when observing the alignment mark 201 from the center 200 of the holder. The initial guide mark 500 placed within the distance L from the center 200 of the holder is detected by the field of view 401 when the sample 100 is placed in the charged particle beam apparatus.

[0047] use Figure 6 An example of a processing flow for generating each marker will be described for each step.

[0048] (S601)

[0049] Alignment marks 201 are generated using a first observation device, which is different from the charged particle beam device used for detailed observation. Alignment marks 201 are generated on at least one of the sample 100, the sample holder 105, and the sample stage 106 as reference points for determining the position on the sample 100. The first observation device is, for example, an optical microscope. Furthermore, the first observation device is not limited to an optical microscope; any surface shape measurement device that measures shape based on a reflection signal from a probe may be used, such as a scanning white light interference microscope (CSI) or an electron microscope (EDS).

[0050] (S602)

[0051] Under the first observation device, guide marks 300 are generated around alignment mark 201. Guide marks 300 are generated so that alignment mark 201 exists in the direction indicated by guide marks 300. Furthermore, it is preferable that the central angle θ formed by two adjacent guide marks 300 on alignment mark 201 is within the value calculated by (Equation 1).

[0052] (S603)

[0053] The first observation device is used to measure the distance D1 between the alignment mark 201 and the center of the holder 200 as the home position. The measured value of the distance D1 is stored in the storage device of the control unit 111.

[0054] (S604)

[0055] The first observation device is used to measure the distance D2 between the alignment mark 201 and the guide mark 300. The measured value of the distance D2 is stored in the storage device of the control unit 111.

[0056] (S605)

[0057] Under the first observation device, an initial guide mark 500 is generated near the center of the stent 200. The initial guide mark 500 is generated so that the alignment mark 201 and the guide mark 300 are located in the direction indicated by the initial guide mark 500. Furthermore, the distance between the initial guide mark 500 and the stent center 200 is preferably within a distance L that is half the short side of the field of view 401 at the observation magnification used when observing the alignment mark 201.

[0058] By using Figure 6 In the process flow described above, the alignment mark 201 , the guide mark 300 , and the initial guide mark 500 are generated on the sample 100 , the sample holder 105 , and the sample stage 106 . The guide mark 300 and the initial guide mark 500 are used to detect the alignment mark 201 .

[0059] use Figure 7 An example of a process flow for detecting the alignment mark 201 will be described for each step.

[0060] (S701)

[0061] The control unit 111 detects the initial guide mark 500 from the observation image. The initial guide mark 500 is detected using a template matching method or a feature point detection method.

[0062] (S702)

[0063] The control unit 111 sets the moving direction of the visual field 401 based on the shape of the initial guide mark 500 detected in S701. For example, while making the visual field 401 have the same shape as the initial guide mark 500, Figure 8 As shown, template image 800, which indicates the positive direction of the x-axis, is rotated while being compared with the detected initial guide marker 500 to determine the direction of movement. More specifically, each time template image 800 is rotated by a predetermined angle, for example, 0.5 degrees, the correlation value between the pixel values ​​and initial guide marker 500 is calculated, and the direction of movement is determined based on the rotation angle at which the correlation value is maximized.

[0064] (S703)

[0065] The control unit 111 moves the field of view 401 in the movement direction set in S702. The field of view 401 is moved by moving the sample stage 106 and changing the electron beam irradiation field by the deflector 103. Figure 9 FIG. 4 shows an example of a visual field 401 that moves based on the shape of the initial guide mark 500. Figure 9 The visual field 401 is moved in the direction indicated by the initial guide mark 500 detected in the visual field 401, that is, in the direction of the white arrow. A predetermined value, such as a distance L of half the short side of the visual field 401, is set for the moving distance of the visual field 401.

[0066] (S704)

[0067] The control unit 111 determines whether the guide mark 300 is detected in the moved field of view 401. Similar to the initial guide mark 500, the guide mark 300 is detected using a template matching method or a feature point detection method. If the guide mark 300 is detected, the process proceeds to S705; if not, the process returns to S703. In other words, the movement of the field of view 401 in S703 is repeated until the guide mark 300 is detected in S704. If the guide mark 300 is not detected and the field of view 401 reaches its limit of movement, the field of view 401 may be returned to the original position of the center of the holder 200, and the process may be restarted from S701, or an error message may be displayed.

[0068] In addition, based on Figure 6 The field of view 401 is moved in S703 based on the distance D1 between the alignment mark 201 and the center of the holder 200 measured in S603 and stored in the storage device of the control unit 111. If the field of view 401 is moved based on the distance D1 and the guide mark 300 cannot be detected in S704, an error message is displayed and the processing flow ends.

[0069] (S705)

[0070] The control unit 111 sets the movement direction of the field of view 401 based on the shape of the guide mark 300 detected in step S704 .

[0071] (S706)

[0072] The control unit 111 moves the field of view 401 in the movement direction set in S705. The movement distance of the field of view 401 is set to a predetermined value, for example, a distance L that is half the short side of the field of view 401.

[0073] (S707)

[0074] The control unit 111 determines whether the alignment mark 201 is detected in the moved field of view 401. Similar to the initial guide mark 500, the template matching method or the feature point detection method is used to detect the alignment mark 201. Alternatively, a method with higher detection accuracy, such as point detection using a differential image, may be used. If the alignment mark 201 is detected, the processing flow ends; if not, the processing returns to step S706. In other words, the movement of the field of view 401 in step S706 is repeated until the alignment mark 201 is detected in step S707. If the alignment mark 201 is not detected and the movement limit of the field of view 401 is reached, an error message is displayed and the processing flow ends.

[0075] In addition, based on Figure 6 The field of view 401 is moved in S706 based on the distance D2 between the alignment mark 201 and the guide mark 300 measured in S604 and stored in the storage device of the control unit 111. If the field of view 401 cannot be detected in S707 while the alignment mark 201 is being moved based on the distance D2, an error message is displayed and the process ends. The distance D2 can be represented by the shape of the guide mark 300.

[0076] use Figure 10 An example of a guide mark indicating a distance will be described. Figure 10 The example shows a short distance guide mark 1001 indicating a short distance and a long distance guide mark 1002 indicating a long distance. Both guide marks are trapezoidal in shape with the same bottom base length B, but the height of the long distance guide mark 1002 is 2H, which is twice the height H of the short distance guide mark 1001. Figure 10 In the two guide marks shown as examples, the distance is represented by the ratio of the bottom to the height. In addition, when generating a guide mark representing the distance, it is necessary to set the distance between the guide mark and the alignment mark 201 before generating the guide mark.

[0077] By using Figure 7 The described processing flow enables detection of the alignment mark 201 without changing the observation magnification. That is, the alignment mark 201 can be detected in a shorter time, thereby improving the throughput of detailed observation of foreign matter or defects on the sample surface detected by the first observation device.

[0078] Example 2

[0079] In Example 1, the case of detecting alignment marks 201 by moving the field of view 401 in the direction indicated by guide marks 300 arranged around the alignment marks 201 was described. In Example 2, guide marks, or link marks, used to sequentially detect multiple alignment marks 201 are described. Furthermore, in Example 2, some of the structures and functions described in Example 1 are applicable, and therefore, identical structures and functions are denoted by identical reference numerals, and their descriptions are omitted.

[0080] use Figure 11 Describes the link tag. Figure 11 , a link mark 1100 having a trapezoidal shape generated near each of the three alignment marks 201 is illustrated. Figure 11 Link mark 1100, like guide mark 300, indicates the direction from the lower base of the trapezoid toward the upper base. Alignment mark 201 is located in the direction indicated by link mark 1100. The shape of link mark 1100 is not limited to a trapezoid; it can also be an isosceles triangle or an arrowhead. Furthermore, like guide mark 300, link mark 1100 can be generated as an indentation of a Vickers hardness cone or an ion beam mark from a FIB-SEM.

[0081] Furthermore, link mark 1100-1 generated near alignment mark 201-1 indicates alignment mark 201-2. Furthermore, link mark 1100-2 near alignment mark 201-2 indicates alignment mark 201-3, and link mark 1100-3 near alignment mark 201-3 indicates alignment mark 201-1. In this way, starting with one alignment mark 201 and its neighboring link mark 1100, alignment marks 201 indicated by link mark 1100 are sequentially detected, thereby generating link marks 1100 so that all alignment marks 201 can be detected.

[0082] Furthermore, the link mark 1100 is preferably placed within the field of view when observing the alignment mark 201. That is, the link mark 1100 is preferably placed within a distance L that is half the short side of the field of view 401 from the alignment mark 201. The link mark 1100 placed within the distance L from the alignment mark 201 is detected through the field of view 401 when observing the alignment mark 201.

[0083] use Figure 12 An example of a processing flow for generating the link marker 1100 will be described for each step.

[0084] (S1201)

[0085] Using a first observation device, different from the charged particle beam device used for detailed observation, multiple alignment marks 201 are generated. Multiple alignment marks 201 are generated 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 interference microscope (CSI), or an electron microscope (EDS).

[0086] (S1202)

[0087] Under the first observation device, link mark 1100 is generated near alignment mark 201. Link mark 1100-1 is generated near alignment mark 201-1 to indicate alignment mark 201-2. Furthermore, link mark 1100-2 is generated near alignment mark 201-2 to indicate alignment mark 201-3, and link mark 1100-3 is generated to indicate alignment mark 201-1. The number of alignment marks 201 and link marks 1100 is not limited to three. When the number of alignment marks 201 and link marks 1100 is N, link mark 1100-N indicates alignment mark 201-1.

[0088] (S1203)

[0089] Using the first observation device, the distance between the alignment mark 201 indicated by the link mark 1100 and the link mark 1100 is measured. The measured distance value is stored in the storage device of the control unit 111. In addition, when measuring the distance, it is preferable to use a surface shape measurement device that also measures the depth of the sample surface, such as a scanning white interference microscope (CSI) or an electron microscope EDS. By using a surface shape measurement device, the edges of the alignment mark 201 and the link mark 1100 can be detected more accurately, thereby improving the accuracy of the measured distance value.

[0090] By using Figure 12 In the processing flow described above, a plurality of alignment marks 201 and link marks 1100 arranged near the alignment marks 201 are generated on the sample 100, the sample holder 105, and the sample stage 106. The link marks 1100 are used to detect the plurality of alignment marks 201 in sequence.

[0091] use Figure 13 , an example of a processing flow for sequentially detecting a plurality of alignment marks 201 is described for each step.

[0092] (S1301)

[0093] The control unit 111 detects the alignment mark 201 and the link mark 1100 arranged near the alignment mark 201 from the observation image. Figure 7Similar to S701, manual movement is also possible. Template matching or feature point detection is used to detect alignment marks 201 and link marks 1100. Furthermore, since link marks 1100 are configured so that all alignment marks 201 can be detected by tracing the direction indicated by link marks 1100, the link marks detected in S1301 may also be link marks other than link mark 1100-1.

[0094] (S1302)

[0095] The control unit 111 sets the movement direction of the field of view 401 based on the shape of the link mark 1100 detected in S1301 .

[0096] (S1303)

[0097] The control unit 111 moves the field of view 401 in the movement direction set in S1302. The movement distance of the field of view 401 is set to a predetermined value, for example, a distance L that is half the short side of the field of view 401.

[0098] (S1304)

[0099] The control unit 111 determines whether the next alignment mark 201 and link mark 1100 are detected in the moved field of view 401. If the next alignment mark 201 and link mark 1100 are detected, the process proceeds to step S1305. If not, the process returns to step S1303. Specifically, the movement of the field of view 401 in step S1303 is repeated until the next alignment mark 201 and link mark 1100 are detected in step S1304. If the next alignment mark 201 and link mark 1100 are not detected and the movement limit of the field of view 401 is reached, an error message is displayed and the process ends.

[0100] It can also be based on Figure 12 The field of view 401 is moved in S1303 based on the distance between the alignment mark 201 indicated by the link mark 1100 and the link mark 1100, which was measured in S1203 and stored in the storage device of the control unit 111. If the field of view 401 is moved based on the distance read from the storage device and the next alignment mark 201 and link mark 1100 cannot be detected in S1304, an error message is displayed and the processing flow ends.

[0101] (S1305)

[0102] The control unit 111 determines whether the alignment mark 201 detected in step S1304 is identical to the alignment mark 201 detected in step S1301. If they are identical, the processing flow ends. If not, the process returns to S1302, and the movement direction of the field of view 401 is set based on the shape of the link mark 1100 detected in S1304. In other words, the sequential detection of multiple alignment marks 201 is repeated until the alignment mark 201 detected in S1304 is identical to the alignment mark 201 detected initially.

[0103] By using Figure 13 The processing flow described here sequentially detects a plurality of alignment marks 201 in the direction indicated by link mark 1100. By sequentially detecting a plurality of alignment marks 201, the throughput of detailed observation of foreign matter or defects on the sample surface detected by the first observation device can be improved.

[0104] The above describes a plurality of embodiments of the present invention. The present invention is not limited to the aforementioned embodiments, and the constituent elements may be modified and embodied within the scope of the present invention. In addition, the plurality of constituent elements disclosed in the aforementioned embodiments may be appropriately combined. Furthermore, some constituent elements may be deleted from all the constituent elements shown in the aforementioned embodiments.

[0105] Description of Reference Signs

[0106] 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 mark, 300…guide mark, 400…center of alignment mark, 401…field of view, 402…maximum error line, 500…initial guide mark, 800…template image, 1001…short-distance guide mark, 1002…long-distance guide mark, 1100…link mark.

Claims

1. A charged particle beam device comprising: a sample holding portion that holds the sample; a charged particle beam source for irradiating the sample with a charged particle beam; a detector that detects secondary particles emitted from the sample and outputs a detection signal; and a control unit that generates an observation image of the sample based on the detection signal and controls each unit, It is characterized by: An alignment mark and a guide mark are set on the sample. The alignment mark is a reference point for determining the position on the sample. The guide mark has a shape indicating the direction of the alignment mark. The control unit detects the guide mark from the observation image and moves the field of view in the direction indicated by the guide mark.

2. The charged particle beam device according to claim 1, wherein At least one of the guide marks is arranged in a field of view at an observation magnification when observing the alignment mark.

3. The charged particle beam device according to claim 2, wherein When the short side of the field of view is 2L, the distance between the guide mark and the alignment mark is D2, and the error of D2 is Δ, the central angle θ formed by two adjacent guide marks in the alignment mark satisfies θ≤2sin -1 (L / (D2+Δ)).

4. The charged particle beam device according to claim 1, wherein An initial guide mark is further provided near the center of the sample holding portion, the initial guide mark having a shape indicating the direction in which the alignment mark is located. The control unit detects the initial guide mark from the observation image and moves the field of view in the direction indicated by the initial guide mark.

5. The charged particle beam device according to claim 1, wherein A plurality of alignment marks are provided on the sample, and a link mark is further provided near a first alignment mark, the link mark having a shape indicating a direction in which a second alignment mark is located. The control unit detects the link mark from the observation image and moves the field of view in the direction indicated by the link mark.

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

7. The charged particle beam device according to claim 6, characterized in that The observation device is a surface shape measuring device that measures the depth of a sample surface together with an observed image of the sample surface.

8. The charged particle beam device according to claim 1, wherein The guide mark further has a shape indicating the distance to the alignment mark. The control unit moves the field of view according to the distance indicated by the guide mark.

9. A method for detecting an alignment mark, comprising detecting an alignment mark serving as a reference point for determining a position on a sample held by a sample holding portion based on an observation image generated by irradiating the sample with a charged particle beam, It is characterized by: The detection method has the following features: a detection step of detecting a guide mark having a shape indicating a direction in which the alignment mark is located from the observation image; and The moving step moves the field of view in the direction indicated by the guide mark.

Images