JP2850275B2 - Sample transfer device for electron microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sample moving device for an electron microscope, and more particularly to a sample moving device for an electron microscope having a side entry structure in which one end of a sample holder is supported by a rod.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional electron microscope having a side entry structure.

In FIG. 1, a metal fitting 4 is hermetically fixed to the side surface of a mirror body 1 via an O-ring 3. The sample stage 13 is accommodated in the metal fitting 4. A sample holder 15 is slidably and airtightly inserted into a hole provided at the center of the sample stage 13 along the axial direction. An end (hereinafter, referred to as a sample mounting end) 15a of the sample holder 15 on which the sample 10 is mounted has a triangular pyramid-like convex shape.

[0004] A spherical body 11 is integrated with the tip of the sample stage 13, and the spherical body 11 is supported by a concave spherical surface 2 provided at an end in a metal fitting 4. The sample stage 13 is a sphere 11
Swings in the metal fitting 4 with the center of the fulcrum as a fulcrum.

The guide 5 of the sample stage 13 is fixed to a hole provided in the receiving member 4. This guides the sample stage 13 so as to be movable in a plane perpendicular to the optical axis. The push rod 8 is housed in a holder 7 embedded in a part of the metal fitting 4, and always presses the sample stage 13 against the tip of the fine movement knob 14 by the pressing force of the pressing spring 6. The fine adjustment knob 14 is screwed into a female screw provided on the metal fitting 4 at a position facing the push rod 8, and the tip thereof is in contact with the sample stage 13.

On the other hand, on the side of the side of the mirror body 1 facing the metal fitting 4, a metal fitting 18 is airtightly fixed via an O-ring 19. A shaft 1 airtightly supported by an O-ring 17 is provided in a passage provided in an axial direction inside a receiving member 18.
6 is slidably inserted, and the shaft 16 is provided with a female screw 21 and a spring 20 provided at the rear end of the receiving member 18.
Defines the axial movement.

[0007] One end 16a of the shaft 16 has a mortar-shaped concave shape, and the rod 9 is sandwiched between the one end 16a of the shaft 16 and the sample mounting end 15a of the sample holder 15. One end 9 a of the rod 9 has a mortar-shaped concave shape, the other end 9 b has a triangular pyramid-shaped convex shape, and one end 9 a of the rod 9, the sample mounting end 15 a of the sample holder 15, and the other end of the rod 9. 9b and one end 16a of the shaft 16 have a pivot structure.

In such a configuration, fine movement knob 14
Is rotated in a certain direction, the sample stage 13
Is moved along. Since both ends of the rod 9 are supported so as to be able to pivot, the sample stage 13 is
Is swung around the fulcrum, so that the sample 10 in the sample holder 15 can move in an arbitrary direction.

[0009]

In the electron microscope having the side entry structure described above, since the sample mounting end 15a of the sample holder 15 is supported via the rod 9, the sample mounting end 15a is not affected by external vibration. This has been one of the major causes of impairing the resolution of the electron microscope.

The vibration mode of the rod 9 which adversely affects the resolution includes a mode in which both ends of the rod 9 vibrate at the nodes and a center portion as an antinode (hereinafter referred to as a first vibration mode), and a mode in which one end 9a of the rod 9 is provided. There is a mode in which the antinode and the other end 9b vibrate as nodes (hereinafter, referred to as a second vibration mode).

Vibration sources that hinder the resolution of the electron microscope include vibrations on the order of several Hz from the floor, vibrations around 800 to 1200 Hz by a turbopump, and vibrations due to sound or sound waves from an air conditioner. External vibration around 1200 Hz is likely to occur. However, such external vibrations are not so large in amplitude and have little effect on resolution by themselves.

However, when the natural frequency of the rod 9 and the natural frequency of the sample support system including the rod 9, the sample holder 15, the sample stage 13 and the like coincide with the frequencies of these disturbances, the rod 9 is activated by resonance. Also, the vibration amplitude of the sample support system becomes large, and this has a large adverse effect on the resolution.

For example, in the above-mentioned conventional electron microscope,
Since the rod 9 is made of a solid material of phosphor bronze, its natural frequency is about 1120 Hz, and the natural frequency of the sample supporting system including the rod 9 is 360 Hz to 690 Hz.
In some cases, the rod 9 and the sample support system including the rod 9 resonate due to external vibration around 200 Hz.

Moreover, when the rod 9 vibrates in the second vibration mode and the one end 9a of the rod 9, that is, the sample mounting end 15a of the sample holder 15 becomes an antinode of the vibration, the vibration amplitude increases and the resolution is further adversely affected. There was a problem that would affect.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a sample moving apparatus for an electron microscope having a structure which is hardly affected by external vibration.

[0016]

In order to achieve the above-mentioned object, according to the present invention, there is provided a sample fine-moving means in which a sample mounting end oscillates, and one end of which is pivoted with respect to a sample mounting end of the sample fine-moving means. A sample moving device for an electron microscope having a rod supported movably is characterized by the following means. ( 1 ) The center of gravity of the rod is located on the other end side of the center of the rod. ( 2 ) Another contact body was provided in addition to the both end support portions of the rod.

[0017]

According to the above configuration (1), the test of the sample holder is performed.
Since the material loading end does not become an antinode of vibration, vibration amplitude is reduced.
So high resolution can be obtained is.

[0018]

According to the above configuration ( 2 ), friction attenuation is caused by the contact body, and the attenuation ratio of the rod is increased, so that vibration of the sample mounting end is suppressed, and high resolution can be obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic concept of the present invention will be described.

According to the vibration theory, as in the rod 9 shown in FIG. 4, the lowest-order mode natural frequency f of a beam (round bar) having a uniform cross section supported at both ends is expressed by the following equation (1). .

F = π · (EI / ρA) ^1/2 / 2L ² (1) where L: length d: diameter E: Young's modulus ρ: specific gravity I: second moment of area (= π · d ⁴⁾ / 64) a: cross sectional area ^{(= π · d 2/4} ) (1) as apparent from the equation, in order to increase the natural frequency of the uniform cross-section beams supported at both ends, the short length of the beam (L
→ small), thick (d → large), large Young's modulus (E →
It can be seen that it is sufficient to reduce the specific gravity (ρ → small). However, among the above four parameters, the length L
The thickness d is limited due to the size of the vacuum chamber 1.

Therefore, the present invention pays particular attention to the specific gravity ρ,
By setting this appropriately, the natural frequency of the rod and the sample support system is made higher than the expected frequency of the disturbance, so that the rod and the sample support system hardly resonate with the disturbance.

That is, phosphor bronze (specific gravity: 8.93 × 10
^-6 kgf / mm ³ ), the natural frequency of the conventional rod 9 formed is about 1120 Hz, the natural frequency of the entire sample support system including the rod 9 is 360 Hz to 690 Hz, and the frequency of external vibration is 0 to 0 Hz. It overlapped with 1200Hz.

Therefore, in the first embodiment of the present invention, in order to increase the natural frequency of the rod, titanium (specific gravity: 8.93 × 10 ⁻⁶ kgf / mm ³ ) and aluminum having a lower specific gravity than phosphor bronze are used. A rod was formed using an alloy (specific gravity 2.69 × 10 ⁻⁶ kgf / mm ³ ), and the natural frequency of the rod was shifted to a higher side than the frequency of external vibration.

According to the present embodiment, since the natural frequency of the rod does not overlap with the frequency of the external vibration, resonance due to the external vibration is suppressed, and high-resolution observation on the order of submicrons becomes possible.

In the above-described embodiment, only the natural frequency of the rod is increased. However, according to experiments by the present inventors, when the natural frequency of the rod is increased,
Accordingly, it was confirmed that the natural frequency of the entire sample support system including the rod also increased.

For example, in the sample support system having the structure described with reference to FIG. 4, the natural frequency of the rod 9 is set to 2000 Hz.
If the natural frequency of the sample support system is increased to 1200H
z or more.

As described above, if the natural frequency of the rod is set such that the natural frequency of the rod and the entire sample supporting system including the rod is shifted to a higher side than the frequency of the external vibration, the resolution is further improved. Can be improved.

FIG. 1 is a view showing the structure of a sample support system of an electron microscope according to a second embodiment of the present invention, FIG. 2 is a sectional view taken along line AA, and FIG. 3 is a sectional view taken along line BB. The same reference numerals as those described above denote the same or equivalent parts.

In FIG. 2, a cylindrical shaft 40 hermetically supported by an O-ring 17 is inserted through a passage provided in the axial direction inside the metal fitting 18, and provided in the axial direction inside the shaft 40. A cylindrical pusher 50 hermetically supported by an O-ring 47 is inserted through the passage.

One end 100b of the rod 100 is tapered, and a spherical body 100a is integrated with the other end. As can be seen, the center of gravity of the rod 100 is at the other end. The end surface of the rod 100 on the one end 100b side has a mortar-shaped concave shape, and the sample mounting end 1 of the sample holder 15 is formed.
5a that is pivotally movable with the spherical body 100a
Is rotatably supported by a shaft lid 41 and a concave portion 40s of the flange portion 40f described later.

A concave portion 40s (FIG. 3) for supporting the spherical body 100a of the rod 100 is provided at the center of the flange portion 40f provided inside the shaft 40. Nails 50a, 50b, 50c
(FIG. 2) through which three openings 40a, 40b,
40c are formed.

At both ends of the shaft 40, shaft covers 41 and 42 are arranged, respectively. An opening for rotatably holding the spherical body 100a of the rod 100 together with the concave portion 40s of the flange portion 40f is formed in the center of the shaft lid 41. A screw 45 engaged with the worm gear 46 is inserted through the center of the shaft lid 42,
The screw 45 is screwed to the rear end of the pusher 50. The axial movement of the shaft 40 is defined by a knob 21 that is screwed into a female screw provided at the rear end of the bracket 18.

In such a configuration, when the sample mounting end 15a of the sample holder 15 is moved in any direction of XYZ in the same manner as described above, one end 100b of the rod 100 is also rotatable about the spherical body 100a. Move.

When the positioning of the sample holder 15 is completed in this way, the screw 45 is rotated via the worm gear 46 to drive the pusher 50 in the X direction in the shaft 40, and the claws 50a, 50b, 50c are moved to the rod 100. Is brought into contact with the spherical body 100a at an arbitrary pressure so that the vibration of the rod 100 is frictionally attenuated by the claws 50a, 50b, 50c.

According to the present embodiment, the position of the center of gravity of the rod 100 is set to the other end side (the side of the spherical body 100a) from the center and away from the sample mounting end 15a of the sample holder 15, and the vicinity of the sample mounting end is vibrated. Since it is not hungry, the influence of external vibration can be further suppressed.

Further, according to this embodiment, since the damping ratio of the rod 100 is increased by the friction with the claws 50a, 50b, 50c, the vibration near the sample mounting end 15a is further reduced.

In this embodiment, the rod 100
Is formed from a material having a relatively small specific gravity, such as aluminum alloy or titanium, and the natural frequency of the rod 100 and the sample supporting system including the rod 100 is shifted to a higher side than the expected frequency of the external vibration. , As before, the rod 100
And resonance due to external vibration of the sample support system is prevented.
High-resolution observation on the order of submicrons is possible.

In the above embodiment, the rod 100
Contact body (claws 50a-5)
0c) is a movable rigid body, which has been described as being brought into contact with the rod 100 after positioning is completed. However, the present invention is not limited to this, and the contact body is formed of an elastic body such as a leaf spring, and the rod 100 May be contacted.
If the contact body is constituted by a leaf spring, a contact body that comes into contact with the rod 9 to cause frictional damping can be easily provided in the embodiment described with reference to FIG. The effect is achieved.

[0041]

As described above, according to the present invention, the following effects are achieved. (1) The natural frequency of the rod and the sample support system including the rod is set higher than the expected frequency of the disturbance,
Since the rod and the material support system are not resonated by external vibration, the vibration of the sample mounting end is suppressed, and a high resolution can be obtained. (2) Separate the center of gravity of the rod from the sample mounting end of the sample holder,
Since the position of the antinode when the sample supporting system vibrates is prevented from overlapping with the sample mounting end, the vibration of the sample mounting end is suppressed, and high resolution can be obtained. (3) A separate contact structure is provided in addition to the support at both ends of the rod, and frictional attenuation is generated by the contact body so that the rod's damping ratio is increased. Will be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a sample support system of an electron microscope according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a diagram showing a configuration of a sample support system of a general electron microscope.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... mirror body, 2 ... concave spherical surface, 3, 17, 19, 47 ... O-ring, 4 ... metal fitting, 5 ... guide, 8 ... push rod, 9, 100 ...
Rod, 10: sample, 11: sphere, 13: sample stage, 15: sample holder, 15a: sample mounting end, 16, 4
0: shaft, 18: metal fitting, 46: worm gear, 5
0: presser, 50a, 50b, 50c: claw, 100a: spherical body

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-291347 (JP, A) JP-A-2-123057 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 37/20 H01J 37/26

Claims (5)

(57) [Claims] 1. A sample loading device, wherein a part thereof is rotatably supported.
The sample fine-moving means with the setting end oscillating, and one end pivoted with respect to the sample-cut end of the sample fine-moving means
Supported, the other end is rotatably supported by the fixed end,
A rod whose center of gravity is located on the other end side of the center.
A sample moving device for an electron microscope. 2. The natural frequency of said rod is expected
A contract that is set higher than the frequency of disturbance
The sample moving device for an electron microscope according to claim 1. 3. The method according to claim 2 , wherein the natural frequency of the sample support system is outside the range.
Claims wherein the frequency is set higher than the frequency of the disturbance.
Item 3. A sample moving device for an electron microscope according to Item 2. 4. A friction damping device that contacts a part of the rod to reduce frictional attenuation.
And a contact body for increasing the rod damping ratio.
4. The method according to claim 1, wherein
4. The sample moving device for an electron microscope according to claim 1. 5. The contact body is an elastic body.
The sample moving device for an electron microscope according to claim 4.