Charged particle ray device and camera image display method

Abstract

To allow a user to easily see a camera image or utilize the camera image in lifting a sample unit.SOLUTION: In a step of lifting a sample unit 30, a camera image with a height guide is displayed. A display magnification controller 52 increases the display magnification of the camera image at the time point when the representative height of the sample unit 30 reaches a magnification change height. A projection amount computing unit 55 calculates the amount of projection of a sample 32 from a sample holder 31 on the basis of the height of the sample holder 31 at the time point when it receives a registration operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a charged particle beam device and a camera image display method, and more particularly to a charged particle beam device equipped with a camera that captures images of the inside of a sample chamber. [Background technology]

[0002] Charged particle beam devices are devices that irradiate a sample with a charged particle beam for the purpose of observing, processing, etc. Examples of charged particle beams include electron beams and ion beams. Below, we will explain a scanning electron microscope (SEM), a representative charged particle beam device.

[0003] A scanning electron microscope has a sample chamber that houses a movable stage (sample stage). A sample holder on which a sample is placed is attached to the movable stage. Hereinafter, the sample and sample holder will be referred to as the sample unit. The movable stage is a mechanism that changes the position and attitude of the sample unit.

[0004] Prior to observing a sample, the position and orientation of the sample unit are adjusted. Specifically, the observation site on the sample is set on the optical axis. For high-resolution observation, the observation site is brought closer to the objective lens. For this purpose, the sample unit is pulled upward.

[0005] The scanning electron microscope is equipped with several means for preventing the specimen unit from colliding with structures such as the objective lens, etc. A representative means among them is to restrict the movement of the specimen unit when the specimen unit reaches a no-entry space set near the surface of the structure.

[0006] Even under conditions where some of the collision avoidance means described above are working, the sample unit may collide with a structure in the sample chamber due to various causes, such as incorrect setting of the sample protrusion amount. Even if such a collision cannot occur, it may be necessary to check the state of the sample (including its position, attitude, etc.) before observing the sample. For this reason, the scanning electron microscope is provided with a camera (optical camera) that photographs the sample chamber. During the process of adjusting the position and attitude of the sample unit, the camera image acquired by the camera is displayed. The camera image is a real-time image, that is, a live image.

[0007] In particular, during the process of raising the sample unit closer to the objective lens, the user refers to the camera image. At that time, if a small display magnification is set as the display magnification of the camera image, it becomes difficult to accurately identify the spatial relationship between the structure in the sample chamber and the sample unit. As a result, a delay in the decision to stop raising the sample unit due to a delay in recognizing the proximity or collision is likely to occur.

[0008] In addition, the housing surrounding the sample chamber and the structures within the sample chamber are generally made of shiny metal. The sample holder is also usually made of shiny metal. For this reason, a camera image showing the inside of the sample chamber is likely to have glare or halation throughout the entire image. Under such circumstances, it is desirable to provide a user with a camera image that allows the user to easily and specifically identify the spatial relationship between the structures within the sample chamber and the sample unit.

[0009] Patent Document 1 discloses a scanning electron microscope equipped with a camera that photographs the inside of a sample chamber. Patent Document 2 describes how collisions are prevented in a scanning electron microscope by computer simulation. Patent Documents 1 and 2 do not describe display control of camera images during the ascending process of the sample unit. Furthermore, Patent Documents 1 and 2 do not describe utilization of camera images acquired during the ascending process of the sample unit. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2014-93283 A [Patent Document 2] JP 2020-126721 A Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to enable a user to reliably recognize the proximity of a sample unit to a structure during the process of raising the sample unit, or to enable a user to specifically identify the positional relationship between the sample unit and the structure when the sample unit approaches the structure during the process of raising the sample unit. [Means for solving the problem]

[0012] The charged particle beam device of the present invention is characterized in that it includes a movable stage that is provided within a sample chamber and on which a sample unit consisting of a sample and a sample holder holding the sample is attached, an optical camera that photographs the inside of the sample chamber from an observation direction that intersects with the optical axis direction and generates a camera image that includes a sample unit image and an objective lens image, and a controller that 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 closer to the objective lens.

[0013] The camera image display method in a charged particle beam device of the present invention is characterized in that it includes the steps of attaching a sample unit consisting of a sample and a sample holder holding the sample to a movable stage provided in a sample chamber, photographing the inside of the sample chamber with a camera from an observation direction intersecting the optical axis direction, thereby generating a camera image including a sample unit image and an objective lens image, displaying the camera image during the ascending process of raising the movable stage to bring the sample unit closer to the objective lens, and increasing the display magnification of the camera image when the representative height of the sample unit reaches a magnification change height during the ascending process. Effect of the Invention

[0014] According to the present invention, the user can reliably recognize that the sample unit has approached the objective lens during the process of raising the sample unit. Alternatively, according to the present invention, the user can specifically identify the positional relationship between the sample unit and a structure located near the sample unit during the process of raising the sample unit. [Brief description of the drawings]

[0015] [Figure 1] 1 is a block diagram showing an example of the configuration of a scanning electron microscope according to an embodiment; [Diagram 2] FIG. 13 is a diagram showing an image displayed in the observation preparation stage. [Diagram 3] FIG. 1 is a diagram showing a method for generating a composite image (height-guided camera image). [Figure 4] 4 is a flowchart showing a camera image display method according to the embodiment. [Diagram 5] FIG. 13 is a diagram showing a composite image before a display magnification is changed. [Figure 6] FIG. 13 is a diagram showing a composite image after the display magnification is changed. [Figure 7] FIG. 1 shows a composite image including multiple sample images. [Figure 8] FIG. 1 illustrates painted proximity zones. [Figure 9] FIG. 11 is a diagram illustrating a method for calculating a protrusion amount. [Figure 10] 13 is a flowchart showing a protrusion amount registration method. [Figure 11] 13 is a flowchart showing a camera image display method according to a modified example. [Figure 12] 13A to 13C are diagrams showing changes in a composite image in a camera image display method according to a modified example. [Figure 13] FIG. 13 is a diagram showing an image displayed at the horizontal coordinate designation stage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment will be described with reference to the drawings.

[0017] (1) Overview of the embodiment A charged particle beam device according to an embodiment has a movable stage, a camera, and a controller. The movable stage is provided in a sample chamber. A sample unit consisting of a sample and a sample holder holding the sample is attached to the movable stage. The camera captures an image of the inside 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 the objective lens. In a process of raising the movable stage to bring the sample unit closer to the objective lens, the controller increases the display magnification of the camera image when the representative height of the sample unit reaches a magnification change height.

[0018] According to the above configuration, the display magnification of the camera image is automatically increased during the upward movement of the sample unit. That is, the sample unit image and the objective lens image are enlarged and displayed. This change in display magnification makes it possible for a user observing the camera image to reliably recognize that the sample unit has approached the objective lens. Furthermore, by observing the enlarged camera image, it becomes possible to specify in detail the positional relationship between the sample unit and the surrounding structures.

[0019] The camera image is a real-time image, i.e., a live image. The representative height of the sample unit is a height representative of a plurality of heights of the sample unit, and in the embodiment, is the height of the apex of the sample. Usually, the height of the apex of the sample coincides with the height of the highest point of the sample unit. The representative height may be the height of the sample holder, or may be a height defined by adding a standard sample height to the height of the sample holder. The height of the sample holder corresponds to the height of the movable stage or is calculated from the height of the movable stage.

[0020] The magnification change height is a height that is determined to determine a certain degree or considerable proximity to the objective lens (or a structure present above the sample unit). For example, the magnification change height may be determined based on the height of the bottom end of the objective lens. The magnification change height to be actually used may be selected from among a plurality of magnification change heights. In an embodiment, a proximity zone is defined in real space near the bottom end of the objective lens. The lower limit height of the proximity zone is the magnification change height.

[0021] The charged particle beam device according to the embodiment includes a storage unit in which the protruding amount of the sample from the sample holder is registered. The representative height is calculated based on the current height of the sample holder and the protruding amount of the sample. According to this configuration, the height of the highest point of the sample holder is basically the representative height, so that it is possible to reliably avoid a collision between the sample unit and a structure. For example, before placing the sample unit in the sample chamber, the user measures the protruding amount of the sample from the sample holder. Then, the user inputs the protruding amount of the sample into the charged particle beam device. As described later, after placing the sample unit in the sample chamber, specifically, during the process of raising the sample unit, the protruding amount of the sample may be measured and registered.

[0022] In an embodiment, the controller changes the display magnification of the camera image to a second display magnification equal to or greater than the first display magnification when the representative height reaches the magnification change height in a situation where the current display magnification of the camera is smaller than the first display magnification. On the other hand, the controller maintains the current display magnification when the representative height reaches the magnification change height in a situation where the current display magnification is larger than the first display magnification. This configuration executes enlarged display when enlarged display is required. The first display magnification may be the same as the second display magnification. The first display magnification and the second display magnification may each be variably set.

[0023] The charged particle beam device according to the embodiment includes a generator that generates a graphic image including a height guide displayed below the objective lens image. During the ascent process, a composite image consisting of the camera image and the graphic image is displayed. When the representative height reaches the magnification change height, the central part of the composite image is enlarged, whereby the sample unit image, the objective lens image, and the height guide are enlarged. This configuration makes it easy to understand how close the sample unit is to the objective lens.

[0024] In an embodiment, the height guide includes a line indicating the magnification change height. This configuration makes it easier to specifically specify the magnification change height. Also, it is possible to confirm that the display magnification has been changed appropriately.

[0025] 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 proximity zone. The lower limit line is a line indicating the magnification change height. This configuration makes it easy to specifically identify the proximity zone set below the objective lens. The proximity zone is a height range in which the sample unit is allowed to rise, but the rise should be performed with caution. Note that the proximity zone is usually set outside a no-entry space set near the surface of the objective lens, but the no-entry space and the proximity zone may partially overlap each other.

[0026] A charged particle beam device according to an embodiment includes a generator and a calculator. The generator generates a graphic image including a height guide that is displayed below an objective lens image and includes a line indicating a reference height. The calculator identifies a current height of the sample holder when the apex of the sample unit image coincides with the line indicating the reference height during the ascent process, and calculates an amount of protrusion of the sample from the sample holder based on the reference height and the current height of the sample holder.

[0027] The above configuration calculates the amount of sample protrusion based on the visual judgment of the user observing the camera image. With the above configuration, it is not necessary to measure the amount of sample protrusion outside the sample chamber, which reduces the burden on the user. It also reduces the possibility of problems such as erroneous measurements and erroneous input.

[0028] After the protrusion amount is calculated using the camera image, control for changing the display magnification of the camera image may be performed. In this case, the calculated protrusion amount is used in the control of the subsequent display magnification. The calculation of the protrusion amount using the camera image may be performed independently of the change in the display magnification of the camera image.

[0029] In an embodiment, a representative height of the sample unit is calculated based on the protruding amount of the sample, and the controller increases the display magnification of the camera image when the representative height reaches a magnification change height after calculating the protruding amount of the sample.

[0030] The camera image display method according to the embodiment includes an attachment step, an imaging step, a display step, and a control step. In the attachment step, a sample unit consisting of a sample and a sample holder holding the sample is attached to a movable stage provided in a sample chamber. In the imaging step, the inside of the sample chamber is imaged by 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. In the display step, the camera image is displayed during the ascending process in which the movable stage is raised to bring the sample unit closer to the objective lens. In the control step, the display magnification of the camera image is increased when the representative height of the sample unit reaches a magnification change height during the ascending process.

[0031] Another charged particle beam device according to the embodiment includes a movable stage, a camera, a generator, and a calculator. The movable stage is provided in a sample chamber. A sample unit including a sample and a sample holder holding the sample is attached to the movable stage. The camera photographs the inside of the sample chamber from an observation direction intersecting with the optical axis direction, and generates a camera image including a sample unit image and an objective lens image. The generator generates a graphic image including a height guide that is displayed below the objective lens image and includes a line indicating a reference height. The calculator identifies the current height of the sample holder when the apex of the sample unit image coincides with the line indicating the reference height during the upward movement, 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.

[0032] Another camera image display method according to the embodiment includes an attachment step, an image capturing step, a display step, and a calculation step. In the attachment step, a sample unit consisting of a sample and a sample holder holding the sample is attached to a movable stage provided in a sample chamber. In the image capturing step, the inside of the sample chamber is captured by a camera from an observation direction intersecting with the optical axis direction, thereby generating a camera image including a sample unit image and an objective lens image. In the display step, the camera image is displayed during the ascending process in which the movable stage is raised to bring the sample unit closer to the objective lens. In the calculation step, the current height of the sample holder at the time when the apex of the sample unit image coincides with a line indicating the reference height during the ascending process is specified, 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.

[0033] (2) Details of the embodiment A charged particle beam device according to an embodiment is shown in Fig. 1. Specifically, the charged particle beam device is a scanning electron microscope. Some of the features described below may be applied to charged particle beam devices other than a scanning electron microscope.

[0034] The scanning electron microscope comprises a measurement section 10 and an information processing section 12. The measurement section 10 has a lens barrel 14 and a housing 15. A configuration for generating an electron beam and performing two-dimensional scanning with it is provided inside the lens barrel 14. Specifically, an electron gun, a condenser lens, a deflection scanning coil, an objective lens 18, etc. are provided inside the lens barrel 14. The inside of the housing 15 is a sample chamber 16. The lower end of the objective lens 18 enters into the sample chamber 16.

[0035] A movable stage (sample stage) 20 is provided in the sample chamber 16. A sample unit 30 is detachably attached to the movable stage 20. The sample unit 30 is composed of a sample 32 and a sample holder 31 that holds the sample.

[0036] More specifically, the movable stage 20 is composed of a plurality of mechanisms 22, 24, and 26. In practice, the movable stage 20 is equipped with a Z-slide mechanism, a tilt mechanism, an X-slide mechanism, a Y-slide mechanism, a rotation mechanism, and the like. The Z-slide mechanism is a mechanism that slides the sample unit 30 in the height direction, that is, the vertical direction. The tilt mechanism is a mechanism that tilts the sample unit 30 around the tilt axis 28. The X-slide mechanism is a mechanism that slides the sample unit 30 in the X direction, which is the first horizontal direction (for example, the left-right direction in FIG. 1). The Y-slide mechanism is a mechanism that slides the sample unit 30 in the Y direction, which is the second horizontal direction (for example, the direction penetrating the paper in FIG. 1). The rotation mechanism is a mechanism that rotates the sample unit around a vertical axis. Various sample holders are prepared, and the sample holder 31 to be actually used is selected from among them according to the sample 32. Various substances can be observed, that is, the sample 32.

[0037] In the illustrated configuration example, detectors 40, 42, and 44 are provided within the sample chamber 16. The detector 40 is, for example, a secondary electron detector. The detector 42 is, for example, a backscattered electron detector. In the illustrated configuration example, the detector 42 is attached to the lower end surface of the objective lens 18. The detector 44 is, for example, an X-ray detector. More detectors may be provided.

[0038] The housing 15 is provided with a camera 34 for photographing the inside of the sample chamber 16. 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 be provided outside a transparent window provided in the housing 15. The camera 34 has a field of view that spreads forward. The central axis of the field of view is the observation central axis 36. The observation central axis 36 is parallel to the X direction and passes through a point at a predetermined height on the optical axis 39. Reference numeral 38 indicates the intersection point of the observation central axis 36 and the optical axis 39. The focus of the camera 34 is set at or near the intersection point.

[0039] An illuminator is provided to illuminate the sample unit, but is not shown in the figure. The central axis of a light beam emitted by the illuminator passes near the intersection point 38. The illuminator is, for example, composed of one or more white LEDs.

[0040] In FIG. 1, Za indicates 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 indicates the height of the sample 32, specifically, the height of the apex 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 illustrated example, Z0 indicates the minimum height of the sample holder 31, and Zs indicates the height of the lower end surface of the objective lens 18.

[0041] Here, ΔZ2 indicates the distance from the height Zs to the apex of the sample 32, and ΔZ3 indicates the distance from the height Zs to the sample holder 31. Incidentally, the distance from the height Zs to the intersection 38 is within a range of, for example, 2 mm to 15 mm, and may be, for example, 6 mm. All numerical values ​​described in this specification are merely examples.

[0042] Methods for measuring the protrusion amount (specimen apex height) ΔZ1 of the specimen 32 from the specimen holder 31 include a first measurement method and a second measurement method. The first measurement method is a method for manually measuring the protrusion amount ΔZ1 using a measurement tool before the specimen unit 30 is placed in the specimen chamber 16. The measurement tool has a scale formed along the vertical direction, and the specimen protrusion amount ΔZ1 is visually identified by comparing this scale with the specimen apex. A numerical value indicating the identified protrusion amount ΔZ1 is registered in the information processing unit 12 by the user. The second measurement method is a method for semi-automatically measuring the protrusion amount ΔZ1 using a camera image described later after the specimen unit 30 is placed in the specimen chamber 16. This will be described in detail later.

[0043] The information processing unit 12 has a processor 46, a memory unit 47, an input unit 48, and a display unit 49. The processor 46 is, for example, a CPU that executes a program. The operation of the measurement unit 10 is controlled by the processor 46. The memory unit 47 is composed of a semiconductor memory, a hard disk, etc. The input unit 48 is composed of a pointing device, a keyboard, etc. The user uses the input unit 48 to specify coordinate values ​​and to register heights. The display unit 49 is composed of an LCD, an organic EL display, etc. The display unit 49 displays camera images, SEM images, etc.

[0044] 1, a plurality of functions performed by the processor 46 are represented by a plurality of blocks. The processor 46 functions as a stage controller 50, a camera controller 51, a graphic image generator 53, a display processor 54, a protrusion amount calculator 55, etc. The stage controller 50 controls the operation of the movable stage 20.

[0045] The camera controller 51 controls the operation of the camera 34. The camera controller 51 according to the embodiment has a display magnification controller 52. The display magnification controller 52 increases the display magnification of the camera image when a magnification change condition (which may also be called a proximity determination condition) described later is satisfied during the upward movement of the sample unit 30. This will be described in detail later.

[0046] 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 guide. In the embodiment, when the display magnification is automatically changed, a height guide (first height guide) indicating the magnification change height is generated, and when the protrusion amount is measured, a height guide (second height guide) indicating the reference height is generated.

[0047] The display processor 54 generates a composite image by combining the camera image and the graphic image, the composite image being a height-guided camera image.

[0048] The protrusion amount calculator 55 is a module that functions when the second measurement method is performed. When the apex of the sample image coincides with the line indicating the reference height during the upward movement of the sample unit 30, the user performs a registration operation. The protrusion amount calculator 55 specifies the height Za of the sample holder at the time of the registration operation, and calculates the protrusion amount ΔZ1 based on the height Za and the reference height. This will be described in detail later.

[0049] FIG. 2 shows an image 60 displayed in the observation preparation stage. The image 60 includes an image 62 for selecting a holder, and an image 64 for inputting a manually measured protrusion amount. The image 62 includes a plurality of holder images 66a to 66d showing a plurality of sample holders. From among them, a specific holder image corresponding to the sample holder actually used is selected by the user. This selection identifies the shape of the sample holder actually used. The designation of the model number of the holder may be accepted, and the shape of the sample holder may be identified based on the model number.

[0050] The image 64 is used when the first measurement method is implemented. The image 64 includes an image 68 simulating a height measurement tool and an image 70 simulating a holder. A holder image representing a selected holder may be displayed as the image 70. A slider 74 is displayed adjacent to the image 68. By moving the slider 74 in the vertical direction, the amount of protrusion measured in advance can be input. The input amount of protrusion is displayed as a numerical value 76. The input amount of protrusion is also registered in a storage unit in the information processing unit. The amount of protrusion may be input as a numerical value.

[0051] The protrusion amount corresponds to the height of the apex of one sample when one sample is placed on the sample holder, and corresponds to the height of the apex of the highest sample when multiple samples are placed on the sample holder. In addition, when controlling the collision avoidance of the sample unit, a virtual disk 80 having a thickness corresponding to the protrusion amount is assumed on the virtual holder. If the disk 80 attempts to enter the no-entry range, the movement of the sample unit is restricted.

[0052] 3 shows an image processing method according to an embodiment. The camera image 82 is a real-time image, and includes an objective lens image 18A and a sample unit image 30A. Depending on the current position of the sample unit and the current display magnification, only a part of the sample unit image 30A may be captured in the camera image 82. The sample unit image 30A includes a sample holder image 31A and a sample image 32A. Reference numeral 38A indicates the intersection point between the optical axis and the observation central axis. The orientation and height of the camera are adjusted so that the image center coincides with the intersection point 38A.

[0053] The graphic image 84 includes a height guide (first height guide) 86. The illustrated height guide 86 includes a line 88 indicating the lower limit of the proximity zone 87, a line 89 indicating the upper limit of the proximity zone 87, and a line 90 indicating an intermediate height between the lower limit and the upper limit. In the embodiment, the lower limit of the proximity zone 87 coincides with the magnification change height. That is, the line 88 is a line indicating the magnification change height. For example, the distance from the lower surface level of the objective lens to the magnification change height may be within a range of 2 mm to 15 mm. In the embodiment, the distance is, for example, 7 mm. The proximity zone 87 has a plate-like shape having a certain thickness, but the proximity zone 87 may be a planar zone.

[0054] A composite image 91 is generated by combining the camera image 82 and the graphic image 84. The composite image 91 is displayed during the process of moving the movable stage (particularly during the upward movement) before the observation of the sample.

[0055] 4 shows a camera image display method according to an embodiment. In general, prior to sample observation, 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 process of the sample unit, the raising process of the sample unit is performed. The camera image display method according to the embodiment is performed during such an raising process, and more specifically, is performed when the sample unit is raised close to the objective lens.

[0056] In S10, a user's upward operation is accepted. This increases the height of the sample unit. In S12, it is determined whether the sample unit (more precisely, the sample unit including the disk described above) has reached the no-entry space. The no-entry space is a space set along the surface of the structure in the sample chamber. Other collision avoidance measures may be applied.

[0057] If the sample unit has reached the forbidden space, the movement or ascent of the sample unit is restricted in S 14. If the sample unit has not reached the forbidden space, S16 is executed.

[0058] In S16, the current display magnification α for the camera image is specified, and the current representative height for the sample unit is specified. In the embodiment, the current representative height is a height that represents the sample unit, specifically, the height Zb of the sample apex. The height Zb is calculated by adding the registered protrusion amount ΔZ1 to the height Za of the sample holder. The height Za of the sample holder is the height of the movable stage or is specified from the height of the movable stage. The display magnification α can be changed by the user at any time.

[0059] 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, and if the current display magnification α is equal to or larger than the first display magnification αk1, S24 is executed.

[0060] 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.

[0061] 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 may be selected within a range of 1.5 to 8. In S26, it is determined whether or not the movement, i.e., the upward movement, of the sample unit is to be continued. If the upward movement is to be continued, the steps from S10 onwards are executed again.

[0062] According to the camera image display method of the embodiment, when the height representing the sample unit reaches a predetermined height, the display magnification of the camera image is automatically increased. Therefore, it is possible to make the user aware of the proximity state through the change in the display magnification. In addition, it is possible to make the user carefully perform the raising operation of the sample unit by observing the enlarged camera image, the height guide, etc.

[0063] In addition, if the camera image has already been enlarged, no further enlargement is performed, so that the camera image is not enlarged excessively. The first display magnification and the second display magnification may be variably set by the user.

[0064] In the embodiment, the tilt angle is not taken into consideration, but the tilt angle may be taken into consideration in the above control process. That is, the height of the highest point of the sample unit after the tilt movement may be determined as the representative height of the sample unit.

[0065] 5 and 6 show images displayed during the upward movement of the sample unit. In FIG. 5, 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 an objective lens image 18B and a sample unit image 30B. The composite image 96 also includes a height guide 86B. A button 98 is a button for switching between displaying and not displaying the height guide 86B. A slider 100 is for manually changing the display magnification of the composite image. Reference numeral 101 indicates the central portion to be enlarged. In the embodiment, the center of the central portion corresponds to the intersection of the optical axis and the observation central axis, in other words, the center of the central portion is located on the central line of the height guide.

[0066] The image 92C shown in FIG. 6 includes a composite image 96C immediately after the display magnification is increased. The objective lens image 18C, the sample unit image 30C, and the height guide 86C are enlarged and displayed. The apex of the sample in the sample unit image 30C is in contact with the lower limit line in the height guide 86C. The slider 100C has moved to a position corresponding to the changed display magnification.

[0067] The composite image 102 shown in Fig. 7 is after the display magnification has been increased. The specimen unit image includes a plurality of specimen images. The apex 110 of the highest specimen image among them reaches the lower limit line 106 in the height guide 104. In the embodiment, the line indicating the magnification change height, i.e., the lower limit line 106, crosses the entire composite image, so that even if the highest specimen image is not positioned on the optical axis, it is easy to confirm whether the magnification change condition is met.

[0068] 8, the inside of the height guide 114 may be filled with a predetermined color. In this case, a slider 120 for varying the transparency is displayed together with a slider 118 for varying the display magnification. By operating the slider 120, the transparency of the filling color of the height guide 114 is changed.

[0069] Next, a second measurement method for the protrusion amount will be described with reference to Figs. 9 to 12. In the second measurement method, the protrusion amount is indirectly specified by a user referring to a camera image during the upward movement of the sample unit. Note that, when the second measurement method is performed, tilting of the sample unit is prohibited. In other words, the tilt angle is set to 0 degrees.

[0070] 9 shows two composite images 122, 122A acquired step by step during the upward movement of the sample unit. The composite image 122 on the left side includes a sample unit image 126 and also includes a height guide (second height guide) 124. The height guide 124 is formed by a line indicating the reference height Zk2.

[0071] The reference height Zk2 is a height that is a distance ΔZ4 lower than the height Zs of the bottom end face of the objective lens. Za is the height of the sample holder, and Za is known. Zb is the height of the apex of the sample. Since the amount of protrusion of the sample is unknown, Zb is unknown. Button 128 is a button used in the registration operation. After the amount of protrusion is calculated, the amount of protrusion is displayed as a numerical value in display field 130.

[0072] After the sample unit is raised, the apex of the sample unit image 126A reaches the height guide 124 in the composite image 122A on the right side. At that point, the user operates the button 128A. The height Za of the sample holder at the time of the operation is specified. Then, the protrusion amount ΔZ1 of the sample is calculated as follows from the height Za of the sample holder, the height Zs of the lower end surface, and the above-mentioned distance ΔZ4.

[0073] ΔZ1=Zb-Za=(Zs-ΔZ4)-Za (1)

[0074] 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.

[0075] FIG. 10 shows the second measurement method as a flow chart. After the horizontal coordinate of the sample unit is adjusted, an operation to raise the sample unit is accepted in S10. S12 and S14 have already been explained (see FIG. 4). In S30, the user judges whether or not the sample apex 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 apex coincides with the height guide and the user performs a registration operation, the protrusion amount is calculated in S32 according to the above formula (1) and registered in the memory unit.

[0076] After execution of S32, the sample unit is transferred to the observation position as necessary. Prior to this, the sample unit may be temporarily lowered.

[0077] The protrusion amount registered in the storage unit may be used in the display magnification change control. That is, the series of steps shown in FIG. 4 may be executed after the series of steps shown in FIG. 10 is executed. In that case, the specimen apex height is specified based on the protrusion amount registered as described above. The registered protrusion amount may be used in collision avoidance control, electron beam focus control, etc.

[0078] A method according to a modified example is shown in Fig. 11. In Fig. 11, the same steps as those shown in Fig. 4 and Fig. 10 are given the same step numbers, and their explanations will be omitted.

[0079] After S10 and S12 are executed, the current display magnification α is specified, and the current representative height is specified in S16A. In the example shown in Fig. 11, the representative height is the height Za of the sample holder. The height calculated by adding the standard sample height or a margin to the height Za may be used as the representative height.

[0080] 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 coincides with 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 enlarged and displayed.

[0081] When the user judges that the apex of the specimen image reaches the reference height based on the enlarged composite image, the user performs a registration operation in S30. As a result, the protrusion amount is calculated in S32, and the calculated protrusion amount is registered. In S34, the specimen unit is further moved as necessary.

[0082] 12 shows the transition of the composite image in the modified example. The composite image 132 shows the state before the height Za of the sample holder reaches the magnification change height Zk1. The composite image 132 includes a sample unit image 134, a first height guide 136, and a second height guide 138. The first height guide 136 is formed of a horizontal line indicating the magnification change height Zk1. The second height guide 138 is formed of a horizontal line indicating the reference height Zk2.

[0083] The composite image 132A is displayed when the height Za of the specimen holder coincides with the magnification change height Zk1. The upper surface of the specimen holder in the specimen unit image 134A coincides with the first height guide 136. There is a certain space between the specimen unit image 134A and the second height guide 138.

[0084] The composite image 132B is displayed when the apex of the specimen in the specimen unit image 134B coincides with the second height guide 138. In fact, the user's registration operation is accepted at that point in time. As already described, the protrusion amount ΔZ1 is calculated based on the heights Za and Zs of the specimen holder and the distance ΔZ4 at that point in time.

[0085] According to the above modification, after the display magnification is increased, it is possible to determine whether the sample apex has reached the reference height while viewing the enlarged composite image. In the modification, the first height guide is set at a position spaced a certain distance from the second height guide. For example, the maximum protrusion amount Δmax for implementing the modification may be determined, and the magnification change height Δk1 or the reference height Δk2 may be determined based on the relational expression Δk1=Δk2-(Δmax+β), where β corresponds to a margin.

[0086] 13 shows an image 140 displayed before the lifting process is performed. A CG image 146 simulating the holder to be used is displayed in an area 142 in the image 140. An image of the holder that has actually been photographed may be displayed instead of the CG image 146. The image 140 also includes a composite image 144.

[0087] The CG image 146 rotates in response to the user's rotation operation (see reference numeral 148). Two cursors 150, 152 are displayed on the CG image 146. By moving the cursors 150, 152 (see reference numerals 150A, 152A), an observation coordinate 154 on a horizontal plane is specified as their intersection point. The movable stage actually moves in conjunction with the above rotation operation and horizontal coordinate specification. In other words, the movable stage moves horizontally so that the observation coordinate 154 coincides with the optical axis.

[0088] The composite image 144 includes an objective lens image 156, a sample unit image 158, and a height guide 160. The height guide 160 is composed of a horizontal line indicating the magnification change height. As described above, the sample unit image 158 is an image that reflects the movement of the movable stage. Therefore, it is possible to confirm the position of the movable stage, etc., through observation of the composite image 144. After the observation coordinates on the horizontal plane are set, the height of the sample unit is changed. That is, the rising process already described is performed. When the representative height of the sample unit matches the magnification change height, the display magnification of the composite image is increased.

[0089] In addition, when the representative height of the sample unit reaches a certain height during the rising process, the display of the camera image may be started. In this case, the camera image may be displayed at a certain display magnification. The appearance of the camera image allows the user to reliably recognize that the sample unit has reached a certain height.

[0090] According to the above embodiment, the user can reliably recognize that the sample unit has approached the objective lens during the upward movement of the sample unit. In addition, the user can specifically identify the positional relationship between the sample unit and a structure nearby during the upward movement of the sample unit. Furthermore, according to the above second measurement 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 reduced. Furthermore, the possibility of problems such as erroneous measurement and erroneous input can be reduced. [Explanation of symbols]

[0091] 10 measuring unit, 12 information processing unit, 16 sample chamber, 18 objective lens, 20 movable stage, 30 sample unit, 31 sample holder, 32 sample, 34 camera, 51 camera controller, 52 display magnification controller, 53 graphic image generator, 54 display processor, 55 protrusion amount calculator.

Claims

1. a movable stage provided in the sample chamber and on which a sample unit including a sample and a sample holder holding the sample is mounted; a camera that captures an image of the inside of the sample chamber from an observation direction intersecting an optical axis direction and generates a camera image including a sample unit image and an objective lens image; a controller that increases a display magnification of the camera image when a representative height of the sample unit reaches a magnification change height during an upward movement process of the movable stage to bring the sample unit closer to an objective lens; A charged particle beam device comprising:

2. 2. The charged particle beam device according to claim 1, a storage unit in which a protruding amount of the sample from the sample holder is registered; The representative height is calculated based on a current height of the sample holder and a protrusion amount of the sample. A charged particle beam device comprising:

3. 2. The charged particle beam device according to claim 1, The controller: When the representative height reaches the magnification change height in a situation where the current display magnification of the camera is smaller than a first display magnification, the display magnification of the camera image is changed to a second display magnification equal to or greater than the first display magnification; When the representative height reaches the magnification change height in a situation where the current display magnification is greater than the first display magnification, the current display magnification is maintained. A charged particle beam device comprising:

4. 2. The charged particle beam device according to claim 1, a generator for generating a graphic image including a height guide displayed below the objective lens image; During the ascent process, a composite image consisting of the camera image and the graphic image is displayed, When the representative height reaches the magnification change height, a central portion of the composite image is enlarged and displayed, whereby the sample unit image, the objective lens image, and the height guide are enlarged and displayed. A charged particle beam device comprising:

5. 5. The charged particle beam device according to claim 4, The height guide includes a line indicating the magnification change height. A charged particle beam device comprising:

6. 6. The charged particle beam device according to claim 5, the height guide includes lower and upper limit lines indicating the lower and upper limits of a proximity zone; The lower limit line is a line indicating the magnification change height. A charged particle beam device comprising:

7. 2. The charged particle beam device according to claim 1, a generator for generating a graphic image including a height guide displayed below the objective lens image, the height guide including a line indicating a reference height; a calculator for determining a current height of the sample holder when an apex of the sample unit image coincides with a line indicating the reference height during the ascending process, and for calculating an amount of protrusion of the sample from the sample holder based on the reference height and the current height of the sample holder; A charged particle beam device comprising:

8. 8. The charged particle beam device according to claim 7, A representative height of the sample unit is calculated based on a protrusion amount of the sample; the controller increases the display magnification of the camera image when the representative height reaches the magnification change height after calculating the protrusion amount of the sample; A charged particle beam device comprising:

9. a step of mounting a sample unit including a sample and a sample holder holding the sample on a movable stage provided in the sample chamber; taking an image of the inside of the sample chamber with a camera from an observation direction intersecting with the optical axis direction, thereby generating a camera image including a sample unit image and an objective lens image; displaying the camera image during a process of raising the movable stage to bring the sample unit closer to an objective lens; In the ascending process, when the representative height of the sample unit reaches a magnification change height, increasing the display magnification of the camera image; A camera image display method for a charged particle beam device, comprising:

Images