JPWO2015053209A1 - Charged particle equipment - Google Patents

Abstract

In a charged particle device, the distance from the outer periphery of the device to the lens barrel is shortened, and a charged particle device that makes it easy to insert and remove a holder for sample replacement in the sample stage and to observe an observation image from a fluorescent screen viewing window The purpose is to provide. In the charged particle apparatus, a lens barrel (101), a charged particle beam optical system provided inside the lens barrel (101), a sample stage (102) provided in the lens barrel (101), and a lens barrel (101) ) Supporting a load plate (14), a vibration isolation mount (15) supporting the load plate (14), and a gantry (16). The load plate (14) has three vibration isolation mounts (15). ) And the lens barrel (101) on the load plate (14) is installed in the vicinity of the vibration isolation mount (15).

Description

  The present invention relates to a charged particle device.

  The charged particle apparatus has a charged particle beam optical system housed in a lens barrel as in Patent Document 1 (Japanese Patent Laid-Open No. 2011-124145), for example, and a sample stage and an observation chamber are installed in the lens barrel. ing. Furthermore, the lens barrel is supported by a support structure such as a gantry, and a vibration isolation device that suppresses transmission of external vibration is provided in the support structure.

JP 2011-124145 A

  In recent years, the axial length of the lens barrel tends to increase due to the higher functionality of charged particle devices. As the axial length of the lens barrel increases, it is necessary to increase the support width for stable support. Therefore, as in Patent Document 1, in the charged particle device in which the four corners of the device are supported by four vibration isolation devices and the lens barrel is arranged at the center of the gantry, the distance from the device outer periphery, that is, the load plate outer periphery to the lens barrel Will be far away. When the distance from the outer circumference of the device to the lens barrel is long, a holder for exchanging the sample is inserted into the sample stage installed in the lens barrel, and if it is a transmission electron microscope, the fluorescent screen installed in the lens barrel The operability of the apparatus, such as observing the observation image from the viewing window, is deteriorated.

  Accordingly, an object of the present invention is to shorten the distance from the outer periphery of the device to the lens barrel in a charged particle device, and to insert and remove a holder for exchanging the sample on the sample stage, or to observe an observation image from the fluorescent screen viewing window. An object of the present invention is to provide a charged particle device that facilitates this.

  The present invention relates to a lens barrel, a charged particle beam optical system provided inside the lens barrel, a sample stage provided in the lens barrel, a load plate that supports the lens barrel, and a vibration isolation mount that supports the load plate, The charged particle device has a gantry, a load plate is supported by three vibration isolation mounts, and a lens barrel on the load plate is installed in the vicinity of the vibration isolation mount.

  According to the present invention, in a charged particle device, it is easy to shorten the distance from the outer periphery of the device to the lens barrel, to insert / remove a holder for exchanging the sample to / from the sample stage, and to observe the observation image from the viewing window of the fluorescent screen. become.

It is explanatory drawing of the conventional charged particle apparatus. It is a perspective view of the charged particle apparatus in Example 1 of this invention. It is a simple model of the apparatus supported by the three anti-vibration mounts in Example 1 of this invention. It is a figure which shows the relationship between the gravity center position in the simple model in Example 1 of this invention, and the amount of vibrations of an observation point. It is a figure which shows the vibration response resulting from floor vibration at the time of supporting with the three vibration isolator mounts in Example 1 of this invention. It is a figure which shows the vibration response resulting from a floor vibration at the time of supporting with the four vibration isolating mounts in Example 1 of this invention. It is the response comparison of the apparatus supported by the vibration isolating mount of 3 places and 4 places in Example 1 of this invention. It is a simple model of the apparatus supported by the three anti-vibration mounts in Example 1 of this invention. It is a perspective view of the charged particle apparatus in Example 2 of this invention. It is a figure which shows the position which installs the sample stage in Example 2 of this invention. It is a figure which shows the direction where the column in Example 2 of this invention does not vibrate easily.

  An outline of a charged particle apparatus is shown with reference to FIG. The present invention relates to a charged particle device, and will be described using the structure of a transmission electron microscope which is one of charged particle devices. The charged particle device includes a main body 10, a load plate 14 that supports the main body, a gantry 16 that supports the load plate 14, a vibration isolation mount 15 provided between the load plate and the gantry, a control device 11, a monitor 12, and a console 13. Have. The main body 10 has a lens barrel 101. The lens barrel 101 is a cylinder and has a structure that is long in the axial direction. The lens barrel 101 is provided with an electron gun 111, an emitter 112, a condenser lens 113, an objective lens 114, an intermediate lens 115, a projection lens 116, a detector 117, a fluorescent plate 118, and a camera film 119. Although not shown, a fluorescent screen viewing window is provided below the lens barrel.

  A sample stage 102 is fixed to the side surface of the lens barrel 101, and an observation sample can be placed at an observation point at the tip of the sample stage. The observation point can be moved and tilted in the horizontal direction and the vertical direction. An observer directly inserts and removes the rod-shaped holder to put in and out the sample. The ion pump 103 is fixed to the side surface of the lens barrel, so that the inside of the lens barrel can be evacuated.

  At the time of imaging with a transmission electron microscope, the electron beam generated by the emitter 112 of the electron gun 111 is irradiated toward the observation point through the condenser lens 113 and the objective lens 114. The electron beam that has passed through the sample is magnified by the objective lens 114, the intermediate lens 115, and the projection lens 116, detected by the detector 117, and imaged on the fluorescent screen 118 and the camera film 119. An observation image is obtained through the above process. The console 13 includes a control device 11 that controls the transmission electron microscope and a monitor 12 that displays an observation image. Further, the observation image on the fluorescent screen is also observed from the fluorescent screen viewing window. The control device 11 transmits a signal from the console 13 to each element of the transmission electron microscope.

Example 1
FIG. 2 shows Example 1 of the present invention. The lens barrel 101 is a cylinder having a long axial structure, and includes an electron gun, various lenses, a detector, and the like for observation. In general, since the ratio of the weight of the lens barrel to the weight of the apparatus is large, the position of the center of gravity in the horizontal plane and the position of the lens barrel substantially coincide. The load plate 14 is supported by three anti-vibration mounts, and the lens barrel 101 is a triangular corner formed by connecting these anti-vibration mounts in a straight line among the three anti-vibration mounts. It may be installed in the vicinity of the anti-vibration mount at the top of the lens, or the part where the lens barrel 101 is installed may be in the vicinity of any anti-vibration mount. The range in which the lens barrel is installed is about 1/4 of the shorter straight line when this anti-vibration mount and another anti-vibration mount are connected with a straight line centering on the anti-vibration mount closest to the lens barrel. Within a circular arc with radius. Further, the vibration isolation mount 15 is supported by the mount 16 from below.

  With the configuration as described above, the lens barrel position is arranged closer to the outer periphery of the apparatus than in the past. As shown in FIG. 3A, when the position of the center of gravity, that is, the lens barrel position is moved from the vibration isolation mount 3 toward the vibration isolation mount 1, the relationship between the position of the center of gravity and the amount of vibration at the observation point is shown in FIG. As shown, the vibration amount decreases as the vibration isolation mount is approached, and the vibration amount becomes the largest at the center of the two vibration isolation mounts farthest from the vibration isolation mount. In particular, if the center of gravity is within the range of 1/4 distance between the two vibration isolation mounts from the vibration isolation mount, the amount of vibration is reduced compared to the case where the center of gravity is between the vibration isolation mounts. If a lens barrel is installed in the area, the device will have less vibration.

  Furthermore, in order to compare the effects relating to the vibration characteristics of Example 1 with a charged particle device of the prior art in which the device is supported by four vibration isolation mounts, the models shown in FIGS. 4A and 4B are used. Determine the vibration response due to floor vibration when supported by 3 vibration isolation mounts and when supported by 4 vibration isolation mounts. When vibration is excited by floor vibration, the main body vibrates as a whole, so this model considers the main body as a rigid body, simulates the mass of the main body with a concentrated mass, and installs this mass at the center of gravity. ing. Further, a spring element is installed at a position where the vibration isolation mount is installed.

  From FIG. 5, it can be seen that the vibration response has a large vibration amount but a small number of vibration modes to be excited as compared with the case where the vibration response is supported by the conventional four vibration isolation mounts. This is because the direction in which vibration is likely to occur is smaller than the case where it is supported by the conventional four vibration isolation mounts, and the number of vibration modes to be considered at the time of design is small.

  The design of the anti-vibration mount generally predicts a large number of vibration modes from the rigidity and the support position, and prevents vibrations when these vibration modes are excited. A method for designing the rigidity and support position of the vibration isolation mount will be described using the model shown in FIG. 6, which is a simplified version of the model shown in FIG. 4. In order to simplify the explanation, the model of FIG. 6 is limited to expressing a vibration phenomenon in which the device is likely to vibrate and tilts forward, backward, left and right. Furthermore, since the center of gravity is below the observation point, the positions of both are generally not the same, but it is assumed that the center of gravity and the position of the observation point are the same, and the center of gravity and the support position are the same height. ing. Equation 1 shows the equation of motion of the simplified model.

  Where [M] is the mass matrix, [K] is the stiffness matrix, z is the displacement of the center of gravity (observation point) in the Z direction, θ is the rotation angle of the center of gravity (observation point) around the X axis, and φ is Y Represents the rotation angle of the center of gravity (observation point) around the axis. [M] is expressed by Equation 2, and [K] is expressed by Equation 3.

Here, M represents a device mass, I _xx represents a device inertia moment about the X axis, I _yy represents a device inertia moment about the Y axis, and k _z represents a spring stiffness in the Z direction of the vibration isolation mount. Further, l _xi represents the center of gravity (observation point) and the distance in the X direction of the vibration isolation mount, l _yi represents the center of gravity (observation point) and the distance in the Y direction of the vibration isolation mount, and the suffix i is shown in FIG. Indicates the identification number of the vibration isolation mount.

  If the off-diagonal term in Equation 3 is 0, the vibration in each direction is independent, but if there is an off-diagonal term, the vibration in each direction is coupled with the vibration in the other direction, and the vibration direction Becomes complicated. When the vibration isolator mount 3 of FIG. 6 has a center of gravity as in the present invention, Equation 3 becomes Equation 4.

The rigidity of the anti-vibration mount is to be the same, the distance in the X direction of variables that determine the Hiren Naruko until anti-vibration mount other two places not barrel is installed from the center of gravity l _x1, l _x2 and The distances in the Y direction are l _y1 and l _y2 . That is, when the apparatus is supported by three vibration isolation mounts and a lens barrel is installed in the vicinity of the vibration isolation mount, the vibration mode is determined by the positional relationship between the two vibration isolation mounts. On the other hand, when the device is supported by four vibration isolation mounts, the vibration mode is determined by the positional relationship of the four vibration isolation mounts. In general, in order to reduce the vibration excited by floor vibration, the design is performed in consideration of the position and rigidity of the vibration isolation mount. If there are a large number of vibration isolation mounts, the rigid body mode of the device is changed to the desired vibration mode. It is not easy.

  As described above, when the device is supported by three anti-vibration mounts and the center of gravity is installed in the vicinity of the anti-vibration mount, the vibration mode is set as compared with the case where the device is supported by four anti-vibration mounts. Since there are few variables to be determined, it is easy to design a vibration isolation mount that achieves a desired vibration mode.

(Example 2)
A second embodiment of the present invention will be described. FIG. 7 shows a charged particle device according to a second embodiment. In the second embodiment, as shown in FIG. 8A, the sample stage includes two straight lines 2 and 3 that are two straight lines connecting the vibration isolation mount closest to the lens barrel and another vibration isolation mount, and the lens barrel. It is installed in a region sandwiched between a straight line 1 connecting two vibration isolation mounts other than the vibration isolation mount closest to and a straight line 1 ′ passing through the center of the lens barrel in parallel.

  The vibration mode in which the main body tilts can be obtained from the relationship between the position of the vibration isolation mount and the position of the center of gravity. However, when a lens barrel is installed in the vicinity of the vibration isolation mount, as shown in FIG. The body tilts with the axis parallel to the straight line as the tilt axis. The portion shown by the fan-shaped broken line in FIG. 8B is the direction in which the center of the lens barrel is most difficult to vibrate. As shown in FIG. 8B, this portion includes two straight lines 2 and 3 that connect the vibration isolation mount closest to the lens barrel and the other vibration isolation mounts, and the center of the lens barrel parallel to the straight line 1. Since it is in the region sandwiched between the passing straight line 1 ', the amount of vibration at the observation position is reduced when the sample stage is placed in this direction.

DESCRIPTION OF SYMBOLS 10 Main body 11 Control apparatus 12 Monitor 13 Operation desk 14 Load board 15 Anti-vibration mount 16 Base 101 Lens tube 102 Sample stage 103 Ion pump 111 Electron gun 112 Emitter 113 Condenser lens 114 Objective lens 115 Intermediate lens 116 Projection lens 117 Detector 118 Fluorescent screen 119 Camera film

Claims (3)

A lens barrel,
A charged particle beam optical system provided inside the lens barrel;
A sample stage provided in the lens barrel;
A load plate for supporting the lens barrel;
An anti-vibration mount that supports the load plate;
A frame,
A charged particle device comprising:
The load plate is supported by three anti-vibration mounts,
The position of the lens barrel is installed in the vicinity of any one of the vibration isolation mounts,
Centering on the vibration isolation mount that is closest to the lens barrel, the installation range of the lens barrel is 1/4 of the shorter straight line when this vibration isolation mount and another vibration isolation mount are connected by a straight line. A charged particle device within an arc of radius. The charged particle device according to claim 1,
The sample stage is mirrored in parallel with two straight lines connecting the vibration isolation mount closest to the lens barrel and another vibration isolation mount and a straight line connecting two vibration isolation mounts other than the vibration isolation mount closest to the lens barrel. A charged particle device installed in a region sandwiched between straight lines passing through the center of a cylinder. A lens barrel provided with a sample stage;
A load plate for supporting the lens barrel;
An anti-vibration mount that supports the load plate at three locations;
With
The charged particle device, wherein the lens barrel is installed closer to one of the three gravity centers of the vibration isolation mount on the load plate.