Charged particle beam device and camera image display method

Abstract

A charged particle beam apparatus and a camera image display method display a camera image with height guidance during a rising process of a sample unit (30). The display magnification controller (52) increases the display magnification of the camera image at a point in time when the representative height of the sample unit (30) reaches the magnification change height. The protrusion amount calculator (55) calculates the protrusion amount of the sample (32) from the sample holder (31) on the basis of the height of the sample holder (31) at the point in time at which the registration operation has been accepted.

Description

Technical Field

[0001] The present disclosure relates to a charged particle beam apparatus and a camera image display method, and more particularly to a charged particle beam apparatus including a camera for imaging the interior of a sample chamber. Background Art

[0002] A charged particle beam device is a device that irradiates a sample with a charged particle beam for observation, processing, etc. Examples of charged particle beams include electron beams and ion beams. The following describes a scanning electron microscope (SEM), a representative charged particle beam device.

[0003] A scanning electron microscope has a specimen chamber that houses a movable stage (sample stage). A specimen holder, which holds the specimen, is attached to the movable stage. Hereinafter, the specimen and specimen holder are referred to as a specimen unit. The movable stage is the mechanism that changes the position and orientation of the specimen unit.

[0004] Before observing a specimen, adjust the position and orientation of the specimen unit. Specifically, determine the observation area of ​​the specimen on the optical axis. When observing at high resolution, the observation area should be close to the objective lens. To do this, lift the specimen unit upward.

[0005] Scanning electron microscopes are equipped with several devices to prevent the sample unit from colliding with structures such as the objective lens. A typical device is one that restricts the movement of the sample unit when it reaches a restricted space set near the surface of the structure.

[0006] Even when some of the aforementioned collision avoidance devices are in effect, the sample unit may collide with structures within the sample chamber due to various reasons, such as incorrect setting of the sample protrusion amount. Even if such a collision is unlikely to occur, it is sometimes necessary to confirm the state of the sample (including position, posture, etc.) before observing the sample. Therefore, the scanning electron microscope is provided with a camera (optical camera) for photographing the sample chamber. During the process of adjusting the position and posture of the sample unit, the camera image obtained by the above-mentioned camera is displayed. The camera image is a real-time image, that is, an instant (live) image.

[0007] In particular, when the sample unit is being raised toward the objective lens, the user is viewing the camera image. If the camera image display magnification is set to a low magnification, it becomes difficult to accurately determine the spatial relationship between the sample unit and the structures within the sample chamber. Consequently, the determination of the stop of the ascent is likely to be delayed, primarily due to a delay in detecting the approach or collision.

[0008] Furthermore, the outer shell surrounding the sample chamber or the structures within the sample chamber are typically made of a shiny metal. The sample holder is also typically made of a shiny metal. Consequently, camera images depicting the sample chamber tend to produce glaring or vignetting. In such situations, it is desirable to provide users with camera images that make it easier to clearly identify the spatial relationship between the structures within the sample chamber and the sample unit.

[0009] Document 1 (Japanese Patent Publication No. 2014-93283) discloses a scanning electron microscope equipped with a camera for capturing images of the interior of a specimen chamber. Document 2 (Japanese Patent Publication No. 2020-126721) describes collision prevention using computer simulation in a scanning electron microscope. Neither Document 1 nor Document 2 describes display control of camera images during the ascent of the specimen unit. Furthermore, neither Document 1 nor Document 2 describes effective utilization of camera images acquired during the ascent of the specimen unit. Summary of the Invention

[0010] Problems to be solved by the invention

[0011] The present disclosure aims to enable a user to reliably identify the proximity of a sample unit to a structure during the ascent of the sample unit. Alternatively, the present disclosure aims to enable a user to specifically determine the positional relationship between the sample unit and the structure when the sample unit approaches the structure during the ascent of the sample unit.

[0012] Solutions for solving problems

[0013] The charged particle beam device involved in the present disclosure is characterized in that it includes: a movable stage, which is arranged in a sample chamber and is used to install a sample unit composed of a sample and a sample holder that holds the sample; an optical camera, which photographs the interior of the sample chamber from an observation direction intersecting with the optical axis direction to generate a camera image including an image of the sample unit and an image of the objective lens; and a controller, which increases the display magnification of the camera image when the representative height of the sample unit reaches a magnification change height during the process of raising the movable stage to bring the sample unit close to the objective lens.

[0014] The camera image display method of the charged particle beam device involved in the present disclosure is characterized in that it includes: a process of installing a sample unit consisting of a sample and a sample holder holding the sample on a movable stage arranged in a sample chamber; a process of photographing the interior of the sample chamber with a camera from an observation direction intersecting with the optical axis direction, thereby generating a camera image including an image of the sample unit and an image of the objective lens; a process of displaying the camera image during the ascending process of raising the movable stage to bring the sample unit close to the objective lens; and a process of increasing the display magnification of the camera image when the representative height of the sample unit reaches the magnification change height during the ascending process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a block diagram showing a configuration example of a scanning electron microscope according to an embodiment.

[0016] Figure 2 3 is a diagram showing an image displayed in the observation preparation stage.

[0017] Figure 3 A diagram illustrating a method for generating a composite image (a camera image with a height guide).

[0018] Figure 4 This is a flowchart illustrating a camera image display method according to an embodiment.

[0019] Figure 5 FIG. 1 is a diagram showing a composite image before the display magnification is changed.

[0020] Figure 6 FIG. 1 is a diagram showing a composite image after the display magnification is changed.

[0021] Figure 7 A diagram showing a composite image including a plurality of sample images.

[0022] Figure 8 is a diagram showing the drawn proximity zone.

[0023] Figure 9 It is a diagram showing a method of calculating the protrusion amount.

[0024] Figure 10 is a flowchart illustrating a method of registering a protrusion amount.

[0025] Figure 11 This is a flowchart illustrating a camera image display method according to a modification example.

[0026] Figure 12 1 and 2 are diagrams illustrating changes in a synthesized image in a camera image display method according to a modification.

[0027] Figure 131 is a diagram showing an image displayed in the horizontal coordinate designation stage. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments will be described based on the drawings.

[0029] (1) Overview of Implementation

[0030] The charged particle beam device according to the embodiment includes a movable stage, a camera, and a controller. The movable stage is arranged in a sample chamber. A sample unit consisting of a sample and a sample holder for holding the sample is mounted on the movable stage. The camera captures the interior of the sample chamber from an observation direction intersecting the optical axis direction, generating a camera image including an image of the sample unit and an image of the objective lens. When the controller raises the movable stage to bring the sample unit closer to the objective lens, and when the representative height of the sample unit reaches the magnification change height, the display magnification of the camera image is increased.

[0031] According to the above configuration, the display magnification of the camera image is automatically increased during the ascent of the specimen cell. That is, the specimen cell image and the objective lens image are magnified and displayed. This change in display magnification allows the user observing the camera image to reliably identify the specimen cell's proximity to the objective lens. Furthermore, by observing the magnified camera image, the positional relationship between the specimen cell and surrounding structures can be specifically determined.

[0032] The camera image is a real-time image, that is, an instant image. The representative height of the sample unit is the height representing the multiple heights of the sample unit. In the embodiment, it is the height of the top of the sample. Generally, the height of the top of the sample is consistent with the height of the highest point in the sample unit. The height of the sample holder can be used as the representative height, or the height defined by adding the standard sample height to the height of the sample holder can be used as the representative height. The height of the sample holder is equivalent to the height of the movable stage or is calculated from the height of the movable stage.

[0033] The magnification change height is a height determined in order to determine whether the object lens (or a structure present above the sample unit) is close to or quite close to a certain extent. For example, the height of the lower end of the object lens can be used as a reference to determine the magnification change height. The magnification change height actually used can also be selected from a plurality of magnification change heights. In an embodiment, in real space, a proximity zone is determined near the lower end of the object lens. The lower limit height of the proximity zone is the magnification change height.

[0034] The charged particle beam device involved in the embodiment includes a storage unit for registering the amount of sample protrusion from the sample holder. The above-mentioned representative height is calculated based on the current height of the sample holder and the amount of sample protrusion. According to this structure, since the height of the highest point in the sample holder basically becomes the representative height, it is possible to reliably avoid collisions between the sample unit and the structure. For example, before the sample unit is placed in the sample chamber, the user measures the amount of sample protrusion from the sample holder. Thereafter, the user inputs the amount of sample protrusion into the charged particle beam device. As described later, after the sample unit is arranged in the sample chamber, specifically, during the ascent of the sample unit, the amount of sample protrusion can be measured and registered.

[0035] In an embodiment, when the current display magnification of the camera image is smaller than the first display magnification, the controller changes the display magnification of the camera image to a second display magnification that is greater than the first display magnification when the representative height reaches the magnification change height. On the other hand, when the current display magnification is greater than the first display magnification, the controller maintains the current display magnification when the representative height reaches the magnification change height. This configuration is a configuration for performing an enlarged display when an enlarged display is required. The first display magnification can be set to be the same as the second display magnification. The first display magnification and the second display magnification can also be set variably.

[0036] The charged particle beam device that embodiment is involved in includes a generator, and the generator generates a graphic image including a height guide (guide) displayed on the lower side of the objective lens. During the rising process, a composite image consisting of a camera image and a graphic image is displayed. When the representative height reaches the magnification change height, the central portion of the composite image is magnified and displayed, thereby, the sample unit image, the objective lens image and the height guide are magnified and displayed. According to this structure, it is easy to understand to which extent the sample unit approaches the objective lens.

[0037] In the embodiment, the height guide includes a line indicating the height at which the magnification is changed. This configuration makes it easier to specifically determine the height at which the magnification is changed. In addition, it is possible to confirm that the display magnification has been appropriately changed.

[0038] In an embodiment, the height guide includes a lower limit line and an upper limit line indicating the lower limit and upper limit of the approach zone. The lower limit line is a line indicating the height at which the magnification is changed. According to this configuration, it is easy to specifically identify the approach zone set on the lower side of the objective lens. The approach zone is a height range in which the ascent of the sample unit is allowed but the ascent should be performed with caution. In addition, the approach zone is usually set outside a prohibited entry space set near the surface of the objective lens, but the prohibited entry space and the approach zone may also partially overlap with each other.

[0039] A charged particle beam apparatus according to an embodiment includes a generator and a calculation unit. The generator generates a graphic image including a height guide, wherein the height guide is displayed below the objective image and includes a line indicating a reference height. The calculation unit determines the current height of the sample holder at the point in time when the vertex of the sample unit image aligns with the line indicating the reference height during the ascending process, and calculates the amount of sample protrusion from the sample holder based on the reference height and the current height of the sample holder.

[0040] The above configuration calculates the sample protrusion amount based on the visual judgment of the user observing the camera image. This configuration reduces the burden on the user because the sample protrusion amount does not need to be measured outside the sample chamber. Furthermore, it reduces the possibility of problems such as mismeasurement or erroneous input.

[0041] Alternatively, after calculating the amount of protrusion using the camera image, control may be performed to change the display magnification of the camera image. In this case, the calculated amount of protrusion is used in subsequent display magnification control. Calculation of the amount of protrusion using the camera image may also be performed independently of changing the display magnification of the camera image.

[0042] In an embodiment, the representative height of the sample unit is calculated based on the protrusion amount of the sample. After calculating the protrusion amount of the sample, the controller increases the display magnification of the camera image when the representative height reaches the magnification change height.

[0043] The camera image display method according to the embodiment includes an installation process, a photographing process, a display process, and a control process. In the installation process, a sample unit consisting of a sample and a sample holder for holding the sample is installed on a movable stage disposed in a sample chamber. In the photographing process, the interior of the sample chamber is photographed by a camera from an observation direction intersecting the optical axis direction, thereby generating a camera image including an image of the sample unit and an image of the objective lens. In the display process, the camera image is displayed during the process of raising the movable stage so that the sample unit approaches the objective lens. In the control process, during the raising process, when the representative height of the sample unit reaches the magnification change height, the display magnification of the camera image is increased.

[0044] Another charged particle beam device according to an embodiment of the present invention comprises a movable stage, a camera, a generator and an arithmetic unit. The movable stage is arranged in a sample chamber. A sample unit consisting of a sample and a sample holder for holding the sample is mounted on the movable stage. The camera captures the interior of the sample chamber from an observation direction intersecting with the optical axis direction, and generates a camera image including an image of the sample unit and an image of an objective lens. The generator generates a graphic image including a height guide displayed on the lower side of the objective lens and including a line indicating a reference height. The arithmetic unit determines the current height of the sample holder at a time point when the vertex of the sample unit image coincides with the line indicating the reference height during the ascending process, and calculates the amount of protrusion of the sample from the sample holder based on the reference height and the current height of the sample holder.

[0045] Another camera image display method according to an embodiment includes an installation step, a photographing step, a display step, and a calculation step. In the installation step, a sample unit consisting of a sample and a sample holder for holding the sample is installed on a movable stage disposed within a sample chamber. In the photographing step, the interior of the sample chamber is photographed by a camera from an observation direction intersecting the optical axis, thereby generating a camera image including an image of the sample unit and an image of the objective lens. In the display step, the camera image is displayed while the movable stage is being raised to bring the sample unit closer to the objective lens. In the calculation step, the current height of the sample holder is determined at the time point when the vertex of the sample unit image aligns with a line representing a reference height during the raising process, and the amount of protrusion of the sample from the sample holder is calculated based on the reference height and the current height of the sample holder.

[0046] (2) Details of implementation methods

[0047] exist Figure 1 , a charged particle beam device according to an embodiment is shown. Specifically, the charged particle beam device is a scanning electron microscope. Several features described below can also be applied to charged particle beam devices other than scanning electron microscopes.

[0048] The scanning electron microscope consists of a measuring unit 10 and an information processing unit 12. The measuring unit 10 includes a lens barrel 14 and a housing 15. Within the lens barrel 14 are components for generating an electron beam and performing two-dimensional scanning. Specifically, the lens barrel 14 includes an electron gun, a converging lens, a deflection scanning coil, and an objective lens 18. Within the housing 15 is a sample chamber (cavity) 16. The lower end of the objective lens 18 extends into the sample chamber 16.

[0049] A movable stage (sample stage) 20 is provided in the sample chamber 16. A sample unit 30 is detachably mounted on the movable stage 20. The sample unit 30 is composed of a sample 32 and a sample holder 31 that holds the sample 32.

[0050] To explain in more detail, the movable stage 20 is composed of a plurality of mechanisms 22, 24, and 26. In practice, the movable stage 20 includes a Z sliding mechanism, a tilting mechanism, an X sliding mechanism, a Y sliding mechanism, and a rotating mechanism. The Z sliding mechanism is a mechanism that causes the sample unit 30 to slide in the height direction, i.e., the vertical direction. The tilting mechanism is a mechanism that causes the sample unit 30 to tilt around the tilt axis 28. The X sliding mechanism is a mechanism that causes the sample unit 30 to tilt in the X direction (e.g., the first horizontal direction) as shown in FIG. Figure 1 The Y sliding mechanism is a mechanism for sliding the sample unit 30 in the Y direction (for example, in the left and right directions). Figure 1 The rotatable mechanism is a mechanism that slides in the direction (through the paper). A variety of sample holders are available, and the sample holder 31 that is actually used is selected according to the sample 32. A wide variety of materials can be used as the observation target, i.e., the sample 32.

[0051] In the illustrated example, detectors 40, 42, and 44 are provided within the sample chamber 16. Detector 40 is, for example, a secondary electron detector. Detector 42 is, for example, a reflected electron detector. In the illustrated example, detector 42 is mounted on the lower end surface of objective lens 18. Detector 44 is, for example, an X-ray detector. Additional detectors may also be provided.

[0052] A camera 34 for photographing the inside of the sample chamber 16 is provided in the housing 15. Specifically, the camera 34 is a black and white optical camera. A color optical camera may be used instead of the black and white optical camera. In the illustrated configuration example, the lens of the camera 34 is located inside the sample chamber 16. The camera 34 may also be provided on the outside of a transparent window provided in the housing 15. The camera 34 has a field of view extending forward. The central axis of the field of view is the observation center axis 36. The observation center axis 36 is parallel to the X direction and passes through a point at a predetermined height in the optical axis 39. Reference numeral 38 indicates the intersection of the observation center axis 36 and the optical axis 39. The focus of the camera 34 is set at or near the intersection.

[0053] An illuminator is provided to illuminate the sample cell, but is not shown in the figure. The central axis of the light beam emitted by the illuminator passes near the intersection 38. The illuminator is composed of, for example, one or more white LEDs.

[0054] exist Figure 1In the example shown, Za represents the height of the sample holder 31, specifically, the height of the surface of the sample holder. The height Za of the sample holder 31 corresponds to the height of the movable stage or is calculated from the height of the movable stage. Zb represents the height of the sample 32, specifically, the height of the top of the sample 32. The height Zb of the sample 32 is calculated by adding the registered protrusion amount ΔZ1 of the sample 32 to the height Za of the sample holder 31. In the example shown in the figure, Z0 represents the lowest height of the sample holder 31, and Zs represents the height of the lower end surface of the objective lens 18.

[0055] Furthermore, ΔZ2 represents the distance from height Zs to the top of sample 32, and ΔZ3 represents the distance from height Zs to sample holder 31. Incidentally, the distance from height Zs to intersection 38 is, for example, in the range of 2 mm to 15 mm, and can be set to, for example, 6 mm. The numerical values ​​described in this specification are merely examples.

[0056] As methods for measuring the protrusion amount ΔZ1 of the sample 32 from the sample holder 31 (sample vertex height) ΔZ1, a first measuring method and a second measuring method can be listed. The first measuring method is a method of manually measuring the protrusion amount ΔZ1 using a measuring tool before placing the sample unit 30 into the sample chamber 16. The measuring tool has a scale formed along the vertical direction, and the protrusion amount ΔZ1 of the sample is visually determined by comparing the scale with the sample vertex. The numerical value representing the determined protrusion amount ΔZ1 is registered by the user to the information processing unit 12. The second measuring method is a method of semi-automatically measuring the protrusion amount ΔZ1 using a camera image described later after placing the sample unit 30 into the sample chamber 16. This will be described in detail later.

[0057] The information processing unit 12 includes a processor 46, a storage unit 47, an input device 48, and a display 49. The processor 46 is, for example, a CPU that executes a program. The processor 46 controls the operation of the measurement unit 10. The storage unit 47 is composed of a semiconductor memory, a hard disk, etc. The input device 48 is composed of a pointing device, a keyboard, etc. The user uses the input device 48 to specify coordinate values ​​and register heights. The display 49 is composed of an LCD, an organic EL display, etc. Camera images, SEM images, etc. are displayed on the display 49.

[0058] exist Figure 1 In FIG. 4 , the multiple functions performed by the processor 46 are represented by multiple blocks. The processor 46 functions as a stage controller 50, a camera controller 51, a graphics image generator 53, a display processor 54, and a protrusion amount calculator 55. The stage controller 50 controls the movement of the movable stage 20.

[0059] The camera controller 51 controls the operation of the camera 34. The camera controller 51 according to the embodiment includes a display magnification controller 52. During the upward movement of the specimen unit 30, the display magnification controller 52 increases the display magnification of the camera image if a magnification change condition (also referred to as a proximity determination condition) described later is satisfied. This will be described in detail later.

[0060] The graphic image generator 53 is a module that generates a graphic image to be superimposed on the camera image. The graphic image includes a height indicator. In the embodiment, when automatically changing the display magnification, a height indicator (first height indicator) indicating the height at which the magnification is changed is generated. When measuring the protrusion amount, a height indicator (second height indicator) indicating the reference height is generated.

[0061] The display processor 54 is a processor that generates a composite image by combining the camera image with the graphic image. The composite image is the camera image with the height guide.

[0062] The protrusion amount calculator 55 is a module that functions when implementing the second measurement method. During the ascent of the sample unit 30, when the vertex of the sample image aligns with the line representing the reference height, the user performs a registration operation. The protrusion amount calculator 55 determines the height Za of the sample holder at the time of the registration operation and calculates the protrusion amount ΔZ1 based on this height Za and the reference height. This will be described in detail later.

[0063] exist Figure 2 , an image 60 displayed during the observation preparation phase is shown. Image 60 includes an image 62 for selecting a holder and an image 64 for inputting the manually measured protrusion amount. Image 62 includes multiple holder images 66a to 66d representing multiple sample holders. From these, the user selects a specific holder image corresponding to the sample holder actually being used. This selection determines the shape of the sample holder actually being used. Alternatively, the user can specify a holder model and determine the sample holder shape based on the model.

[0064] Image 64 is an image used when the first measurement method is implemented. Image 64 includes an image 68 simulating a height measuring tool and an image 70 simulating a retainer. As image 70, a retainer image showing the selected retainer can be displayed. A slider 74 is displayed adjacent to image 68. By moving slider 74 in the up and down directions, the amount of protrusion measured in advance can be input. The input protrusion amount is displayed as a numerical value 76. In addition, the input protrusion amount is registered in the storage unit of the information processing unit. The protrusion amount can also be input as a numerical value.

[0065] The protrusion amount corresponds to the height of the top of a single specimen when the specimen holder is loaded. When multiple specimens are loaded, it corresponds to the height of the top of the tallest specimen. Furthermore, during collision avoidance control of the specimen unit, a virtual disk 80 having a thickness corresponding to the protrusion amount is assumed on the virtual holder. If this disk 80 attempts to enter the prohibited entry range, movement of the specimen unit is restricted.

[0066] exist Figure 3 , an image processing method according to an embodiment is shown. Camera image 82 is a real-time image that includes object image 18A and sample unit image 30A. Depending on the current position of the sample unit or the current display magnification, only a portion of sample unit image 30A may be displayed in camera image 82. Sample unit image 30A includes sample holder image 31A and sample image 32A. Reference numeral 38A indicates the intersection of the optical axis and the observation center axis. The camera's orientation and height are adjusted so that the image center coincides with intersection 38A.

[0067] The graphic image 84 includes a height guide (first height guide) 86. The height guide 86 shown in the figure includes a line 88 indicating the lower limit of the approach area 87 and a line 89 indicating the upper limit of the approach area 87, and also includes a line 90 indicating the intermediate height between the lower limit and the upper limit. In an embodiment, the lower limit of the approach area 87 is consistent with the magnification change height. That is, line 88 is a line indicating the magnification change height. For example, the distance from the horizontal height of the lower surface of the objective lens to the magnification change height can be set within a range of 2 mm to 15 mm. In an embodiment, the distance is, for example, 7 mm. The approach area 87 has a flat plate shape with a constant thickness, but the approach area 87 can also be set to a planar area.

[0068] A composite image 91 is generated by combining the camera image 82 and the pattern image 84. The composite image 91 is displayed while the movable stage is moving (particularly, while it is ascending) before the sample observation.

[0069] exist Figure 4 , a camera image display method according to an embodiment is shown. Generally speaking, before observing a sample, the horizontal position of the sample unit is determined, and then the vertical position (height) of the sample unit is determined. In other words, after the horizontal movement of the sample unit, the sample unit is raised. The camera image display method according to an embodiment is performed during this raising process, more specifically, when the sample unit is raised to the vicinity of the objective lens.

[0070] In S10, the user's raising operation is accepted. As a result, the height of the sample unit is increased. In S12, it is determined whether the sample unit (more precisely, the sample unit including the above-mentioned disk) has reached the prohibited entry space. The prohibited entry space is a space defined along the surface of the structure within the sample chamber. Other collision avoidance measures may also be applied.

[0071] If the sample unit has reached the prohibited entry space, the movement of the sample unit, ie, the upward movement, is restricted in S14. If the sample unit has not reached the prohibited entry space, S16 is executed.

[0072] In S16, the current display magnification α for the camera image is determined, and the current representative height for the specimen unit is also determined. In an embodiment, the current representative height is the height of the representative specimen unit, specifically, the height Zb of the specimen vertex. This height Zb is calculated by adding the registered protrusion amount ΔZ1 to the specimen holder height Za. The specimen holder height Za is the height of the movable stage, or is determined from the height of the movable stage. Furthermore, the display magnification α can be changed by the user at any desired timing.

[0073] In S18 , it is determined whether the current display magnification α is smaller than the first display magnification αk1 . If the current display magnification α is smaller than the first display magnification αk1 , S20 is executed. If the current display magnification α is greater than the first display magnification αk1 , S24 is executed.

[0074] In S20 , it is determined whether the current representative height Zb has reached the magnification change height Zk1 . If the current representative height Zb has not reached the magnification change height Zk1 , S24 is executed. If the current representative height Zb has reached the magnification change height Zk1 , S22 is executed.

[0075] In S24, the display magnification α is maintained. In S22, the display magnification α is increased to a second display magnification αk2. In the embodiment, the second display magnification αk2 is the same as the first display magnification αk1. The second display magnification αk2 can be selected from a range of 1.5 to 8. In S26, it is determined whether the sample unit continues to move, i.e., to ascend. If ascending is continued, the steps from S10 onwards are repeated.

[0076] According to the camera image display method of the embodiment, when the height representing the specimen unit reaches a predetermined height, the display magnification of the camera image is automatically increased. Thus, this change in display magnification allows the user to reliably identify the approaching state. Furthermore, by observing the magnified camera image and height guidance, the user can carefully perform the specimen unit raising operation.

[0077] Furthermore, if the camera image has already been magnified, no further magnification is performed, thereby preventing the camera image from being over-magnified. The user may be able to variably set the first display magnification and the second display magnification.

[0078] In the embodiment, the tilt angle is not considered, but the tilt angle may be considered during the control process. That is, the height of the highest point of the sample cell after tilting may be determined as the representative height of the sample cell.

[0079] exist Figure 5 as well as Figure 6 In the figure, an image showing the rising process of the sample unit is shown. Figure 5 In the figure, the image 92 includes an SEM image display area 94 and also includes a composite image 96 before the display magnification is increased. The composite image 96 includes the objective lens image 18B and the specimen unit image 30B. In addition, the composite image 96 includes a height guide 86B. Button 98 is a button for switching the display of the height guide 86B or not. The slider 100 is used to manually change the display magnification of the composite image. Reference numeral 101 indicates the central portion to be magnified. In the embodiment, the center of the central portion is equivalent to the intersection of the optical axis and the observation center axis. In other words, the center of the central portion is located on the center line of the height guide.

[0080] exist Figure 6 Image 92C shown includes a composite image 96C immediately after the display magnification has been increased. Objective image 18C, sample unit image 30C, and height indicator 86C are displayed in magnified form. The sample vertex in sample unit image 30C is in contact with the lower limit line of height indicator 86C. Slider 100C has moved to a position corresponding to the changed display magnification.

[0081] Figure 7 The composite image 102 shown shows an image after the magnification is increased. The sample unit image includes multiple sample images. The apex 110 of the highest sample image reaches the lower limit line 106 of the height guide 104. In this embodiment, because the line indicating the magnification change height, namely, the lower limit line 106, crosses the entire composite image, even when the highest sample image is on the optical axis, it is easy to confirm that the magnification change condition is met.

[0082] like Figure 8 As shown, the interior of the height guide 114 can also be filled with a predetermined color. In this case, a slider 120 for changing transparency is displayed together with a slider 118 for changing the display magnification. By operating the slider 120, the transparency of the fill color of the height guide 114 is changed.

[0083] Next, use Figures 9 to 12The second method for measuring the protrusion amount is now described. In this second method, the user indirectly specifies the protrusion amount by referring to the camera image while the sample unit is ascending. Furthermore, when implementing this second method, tilting of the sample unit is prohibited. Specifically, the tilt angle is set to 0 degrees.

[0084] exist Figure 9 , two composite images 122 and 122A are shown, which are acquired in stages during the ascent of the sample unit. The left composite image 122 includes a sample unit image 126 and a height guide (second height guide) 124. The height guide 124 is composed of a line indicating the reference height Zk2.

[0085] Reference height Zk2 is the height lower by a distance ΔZ4, using the height Zs of the lower end face of the objective lens as a reference. Za is the height of the sample holder, and Za is known. Zb is the height of the sample vertex. Since the amount of sample protrusion is unknown, Zb is unknown. Button 128 is used for registration. After the protrusion amount is calculated, it is displayed as a numerical value in display field 130.

[0086] After the specimen unit ascends, the apex of specimen unit image 126A reaches height indicator 124 in right-side composite image 122A. At this point, the user operates button 128A. The specimen holder height Za at that point in time is determined. Based on this, the specimen protrusion amount ΔZ1 is calculated as follows, using the specimen holder height Za, the lower end surface height Zs, and the aforementioned distance ΔZ4.

[0087] ΔZ1=Zb-Za=(Zs-ΔZ4)-Za… (1)

[0088] In the above (1), (Zs-ΔZ4) corresponds to Zk2. The calculated protrusion amount ΔZ1 is displayed in the display field 130A. The protrusion amount ΔZ1 is stored in the storage unit.

[0089] exist Figure 10 The second measurement method is shown as a flow chart. After adjusting the horizontal coordinates of the sample unit, the operation of raising the sample unit is accepted in S10. S12 and S14 have been explained (refer to Figure 4 ). In S30, the user determines whether the sample vertex has reached the height guide based on the composite image. If it has not reached the height guide, the steps from S10 onwards are executed again. In S30, if the sample vertex is consistent with the height guide and the user performs a registration operation, in S32, the protrusion amount is calculated according to the above formula (1) and registered in the storage unit.

[0090] After executing S32, the sample unit is moved to the observation position as needed. Before this, the sample unit may be temporarily lowered.

[0091] The protrusion amount registered in the storage unit can also be used in the display magnification change control. Figure 10 After the series of steps shown, perform Figure 4 In this case, the height of the sample top is determined based on the registered protrusion amount as described above. The registered protrusion amount can also be used in collision avoidance control, electron beam focus control, etc.

[0092] exist Figure 11 In the embodiment, the method of the modification is shown. Figure 11 In, with Figure 4 and Figure 10 The same steps as those shown are denoted by the same step numbers, and their descriptions are omitted.

[0093] After executing S10 and S12, in S16A, the current display magnification α is determined, and the current representative height is determined. Figure 11 In the example shown, the sample holder height Za is used. Alternatively, a height calculated by adding a standard sample height or a margin to the height Za may be used as a representative height.

[0094] If it is determined in S18 that the current display magnification is smaller than the first display magnification and in S20A that the representative height Za matches the magnification change height Zk1, the display magnification α is changed to the second display magnification α2 in S22. That is, the composite image is displayed in an enlarged manner.

[0095] If the user determines, based on the magnified composite image, that the top of the sample image has reached the reference height, a registration operation is performed by the user in S30. Consequently, in S32, the protrusion amount is calculated and the calculated protrusion amount is registered. In S34, the sample unit is further moved as needed.

[0096] exist Figure 12 , illustrates the transition of a composite image in a modified example. Composite image 132 shows the state of the sample holder before its height Za reaches the magnification change height Zk1. Composite image 132 includes a sample unit image 134, a first height indicator 136, and a second height indicator 138. First height indicator 136 is composed of a horizontal line indicating the magnification change height Zk1. Second height indicator 138 is composed of a horizontal line indicating the reference height Zk2.

[0097] The composite image 132A is displayed when the sample holder height Za matches the magnification change height Zk1. The sample holder top surface in the sample unit image 134A matches the first height index 136. A certain space exists between the sample unit image 134A and the second height index 138.

[0098] Composite image 132B is displayed at the time when the sample apex in sample unit image 134B coincides with second height indicator 138. In reality, the user registration operation is accepted at this time. As already explained, the protrusion amount ΔZ1 is calculated based on the sample holder height Za, height Zs, and distance ΔZ4 at that time.

[0099] According to the above modification, after increasing the display magnification, it is possible to determine whether the specimen vertex has reached the reference height while viewing the magnified composite image. In this modification, the first height guide is set at a constant distance from the second height guide. For example, the maximum protrusion amount Δmax when implementing this modification can be predetermined, and the magnification change height Δk1 or the reference height Δk2 can be determined based on the relationship Δk1 = Δk2 - (Δmax + β). Here, β corresponds to the margin.

[0100] exist Figure 13 , an image 140 is shown before the lifting process is performed. Within region 142 of image 140, a CG image 146 simulating the holder to be used is displayed. An actual image of the holder taken may be displayed instead of CG image 146. Furthermore, image 140 includes a composite image 144.

[0101] In response to the user's rotation operation, CG image 146 rotates (see reference numeral 148). Two cursors 150 and 152 are displayed on CG image 146. By moving cursors 150 and 152 (see reference numerals 150A and 152A), observation coordinates 154 on the horizontal plane are specified as their intersection. The movable stage moves in conjunction with the rotation operation or horizontal coordinate specification. In other words, the movable stage moves horizontally so that observation coordinates 154 are aligned with the optical axis.

[0102] The composite image 144 includes an objective lens image 156, a sample unit image 158, and a height indicator 160. The height indicator 160 is composed of horizontal lines indicating the height at which the magnification is changed. As described above, the sample unit image 158 is an image that reflects the movement of the movable stage. Therefore, by observing the composite image 144, the position of the movable stage, etc. can be confirmed. After setting the observation coordinates on the horizontal plane, the height of the sample unit is changed. In other words, the ascending process already described is implemented. At the time when the representative height of the sample unit coincides with the height at which the magnification is changed, the display magnification of the composite image is increased.

[0103] Furthermore, during the ascent, the camera image can be displayed starting at the point when the representative height of the specimen unit reaches a constant height. In this case, the camera image can be displayed at a constant magnification. The appearance of the camera image allows the user to reliably identify that the specimen unit has reached a constant height.

[0104] According to the above embodiment, the user can reliably identify that the sample unit is close to the object lens during the rising process of the sample unit. In addition, the user can specifically determine the positional relationship between the sample unit and the structure located near it during the rising process of the sample unit. In addition, according to the above-mentioned second measuring method, it is not necessary to measure the protrusion amount of the sample outside the sample chamber, so the burden on the user can be alleviated. In addition, the possibility of generating problems such as mismeasurement or misinput can be reduced.

Claims

1. A charged particle beam device, characterized in that Include: A movable stage (20) is disposed in the sample chamber (16) and is used to mount a sample unit (30) consisting of a sample and a sample holder for holding the sample; A camera (34) that captures the interior of the sample chamber (16) from an observation direction intersecting the optical axis direction to generate a camera image including a sample unit image and an object image; and A controller (52) increases the display magnification of the camera image when the representative height of the sample unit (30) reaches a magnification change height during the process of raising the movable stage (20) to bring the sample unit (30) closer to the objective lens.

2. The charged particle beam device according to claim 1, characterized in that comprising a storage unit (47) for recording the amount of protrusion of the sample from the sample holder, The representative height is calculated based on the current height of the sample holder and the protrusion amount of the sample.

3. The charged particle beam device according to claim 1, characterized in that The controller (52) In a condition where the current display magnification of the camera image is smaller than the first display magnification, when the representative height reaches the magnification change height, the display magnification of the camera image is changed to a second display magnification that is greater than the first display magnification, In a situation where the current display magnification is larger than the first display magnification, when the representative height reaches the magnification change height, the current display magnification is maintained.

4. The charged particle beam device according to claim 1, characterized in that comprising a generator (53) for generating a graphic image including a height guide displayed on the lower side of the objective lens, During the ascending process, a composite image composed of the camera image and the graphic image is displayed, When the representative height reaches the magnification change height, the central portion of the synthetic image is displayed in an enlarged manner, whereby the specimen unit image, the objective image, and the height guide are displayed in an enlarged manner.

5. The charged particle beam device according to claim 4, characterized in that The height guide includes a line indicating the magnification change height.

6. The charged particle beam device according to claim 5, characterized in that The altitude guidance includes a lower limit line and an upper limit line indicating the lower limit and the upper limit of the approach zone, The lower limit line is a line indicating the magnification change height.

7. The charged particle beam device according to claim 1, characterized in that Include: a generator (53) for generating a graphic image including a height guide, the height guide being displayed on the lower side of the object image and including a line indicating a reference height; and A calculator (55) determines the current height of the sample holder at a time point when the top of the sample unit image coincides with the line representing the reference height during the ascending process, and calculates the protrusion amount of the sample from the sample holder based on the reference height and the current height of the sample holder.

8. The charged particle beam device according to claim 7, characterized in that The representative height of the sample unit (30) is calculated based on the protrusion amount of the sample, After calculating the protrusion amount of the sample, the controller (52) increases the display magnification of the camera image when the representative height reaches the magnification change height.

9. A camera image display method for a charged particle beam device, characterized in that: Include: A step of installing a sample unit (30) composed of a sample and a sample holder for holding the sample on a movable stage (20) disposed in a sample chamber (16); A step of photographing the interior of the sample chamber (16) by a camera (34) from an observation direction intersecting the optical axis direction, thereby generating a camera image including a sample unit image and an object image; A step of displaying the camera image during the process of raising the movable stage (20) to bring the sample unit (30) close to the objective lens; and A step of increasing the display magnification of the camera image when the representative height of the sample unit (30) reaches a magnification change height during the ascending process.

Images