JP4119627B2 - Sample holder for electron microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sample holder used in a transmission electron microscope.
[0002]
[Prior art]
FIG. 1 is a view showing a conventional sample holder for an electron microscope, and shows a state in which a conventional sample holder 1 is mounted on an outer cylinder (chamber) 2 of an electron microscope.
[0003]
In FIG. 1, 3 is a sample holder main body. The sample holder main body 3 includes a cylindrical body 3a and a sample mounting base holding portion 3b provided at the tip of the cylindrical body 3a. The sample support holder 3b is provided with an electron beam passage hole 3c. In order to keep the sample chamber 4 of the electron microscope in a vacuum, the cylindrical body 3a and the outer cylinder 2 are vacuum sealed with an airtight O-ring 5.
[0004]
Reference numeral 6 denotes a sample platform, and the sample platform 6 is formed so that four samples S _{1 to} S ₄ can be loaded. The sample platform 6 is attached to the sample moving shaft 7 with screws 8. The sample moving shaft 7 is disposed inside the cylinder 3a, and the sample moving shaft 7 and the cylinder 3a are vacuum-sealed by an airtight O-ring 9 in order to keep the sample chamber 4 in a vacuum. Yes.
[0005]
The sample moving shaft 7 is guided by a moving guide 10, and the atmosphere side end of the sample moving shaft 7 is coupled to a fine adjustment knob 11 by a screw.
[0006]
Reference numeral 12 denotes a sample switching knob. The sample switching knob 12 is fixed to the cam 14 by a screw 13. As shown in FIG. 1 (cam perspective view), the cam 14 is provided with a step-like roller guide hole 15, and a roller 16 fixed to the moving guide 10 is in contact with the roller guide hole 15. Yes. The roller 16 is fixed to the moving guide 10 with a screw 17.
[0007]
Reference numeral 18 denotes a roller guide, and the roller guide 18 is fixed to the sample holder main body 3 by screws 19. The sample moving shaft 7 passes through a roller guide 18, and the roller guide 18 is provided with a restriction hole 20 extending in the axial direction of the cylindrical body 3 a (in the direction of arrow AB in the figure). A screw 17 fixing the roller 16 is fitted in the restriction hole 20, and the movement of the roller 16 is restricted by the restriction hole 20. That is, the roller 16 can move only in the direction of the arrow AB in the figure.
[0008]
The shaft moving mechanism is composed of the above-described components 10 to 20.
[0009]
Further, as shown in FIG. 1 (top view), the holding spring 21 is fixed to the sample platform holding portion 3b, and the sample loading table 6 is pressed against the sample platform holding portion 3b by the holding spring 21. Yes.
[0010]
Although omitted in FIG. 1, an electron gun, a focusing lens, and the like are disposed above the sample chamber 4. On the other hand, below the sample chamber 4, a lens system for enlarging and forming an electron beam transmitted through the sample by electron beam irradiation, a fluorescent plate on which a transmitted electron image is projected, and the like are arranged.
[0011]
In such a configuration, when the sample switching knob 12 is turned, the cam 14 integrated with the knob 12 rotates, and the roller 16 in contact with the roller guide hole 15 of the cam 14 moves in the front-rear direction (arrow in the figure). Move in the AB direction). By this movement, the movement guide 10, the fine movement knob 11, the sample movement shaft 7, and the sample platform 6 connected to the roller 16 are moved by the same amount in the same direction as the roller 16, and the sample is switched. Is called. When the sample is switched, the holding spring 21 prevents the sample platform 6 from being lifted from the sample platform holder 3b.
[0012]
As shown in FIG. 1, when the roller 16 is positioned at the position p ₂ , the fine movement knob 11 is positioned at the position p ₂ ′. At this time, the sample S ₂ is positioned on the electron beam optical axis O. When the roller 16 is positioned at the positions p ₃ and p ₄ , the fine movement knob 11 is positioned at the positions p ₃ ′ and p ₄ ′, respectively, and when the roller 16 is positioned at the position p ₃ , the sample S ₃ is an electron. located on the line optical axis O, the sample S ₄ is positioned on the electron beam optical axis O when the roller 16 located at position p _4.
[0013]
Further, the fine adjustment of the sample with respect to the electron beam is performed by rotating the fine movement knob 11 to rotate the knob by one turn by rotating the fine movement knob 11 because the sample moving shaft 7 and the fine movement knob 11 are joined by a screw. It is possible.
[0014]
[Problems to be solved by the invention]
In order to prevent charge-up of the sample due to electron beam irradiation or to release the heat generated in the sample due to electron beam irradiation to the outside, the above-described sample platform 6, sample holder body 3, and sample moving shaft 7 are It is made of a material having conductivity and high thermal conductivity. In general, copper-based metal materials having good workability and strength are frequently used as the material.
[0015]
However, the following problems occur when the sample stage 6 and the sample moving shaft 7 are formed of a material having high thermal conductivity in order to release the heat generated in the sample to the outside.
[0016]
That is, when the sample is heated by electron beam irradiation, the heat is transferred to the sample moving shaft 7 via the sample mounting base 6, and the sample moving shaft 7 is elongated due to thermal expansion. In particular, the copper-based metallic material forming the sample moving shaft 7 is a material having a relatively large thermal expansion coefficient among metals, and the sample moving shaft 7 is long and has a large heat capacity. It grows greatly over. At this time, when the sample is irradiated with a highly accelerated electron beam in the ultra high voltage electron microscope, the extension of the sample moving shaft 7 is further increased.
[0017]
Since the extension of the sample moving shaft 7 is transmitted to the sample platform 6, the sample drifts for a long time. This sample drift causes an obstacle to image observation, and particularly affects high magnification observation and image photographing.
[0018]
The present invention has been made in view of these points, and an object thereof is to provide a sample holder for an electron microscope that can reduce drift due to heat of the sample.
[0019]
[Means for Solving the Problems]
The sample holder for an electron microscope of the present invention that achieves this object is a cylindrical body, a sample holder main body constituted by a sample mounting base holding portion provided at a front end portion of the cylindrical body, and the inner side of the cylindrical body as a cylindrical body. A sample moving shaft attached to the cylindrical body via a shaft moving mechanism and a sample moving shaft attached to the sample moving shaft via a thermally insulating connecting member so that they can move in the axial direction of the cylindrical body without contact. A sample platform, and when the sample platform is held by the sample platform holder , the connection member is in non-contact with the sample platform holder and the cylinder, and the sample platform and The sample platform holding part and the sample holder main body are made of a material having high thermal conductivity.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 2 is a view showing an example of an electron microscope sample holder of the present invention. 2, the same components as those in FIG. 1 are assigned the same numbers as those in FIG. 1, and the description thereof is omitted.
[0022]
The sample holder of FIG. 2 is different from the configuration of FIG. 1 in that the sample platform 6 is connected to the sample moving shaft 7 via a connection plate (connection member) 22 having a small cross-sectional area. There are no major changes except for.
[0023]
The connection plate 22 is made of a material having thermal insulation and a small coefficient of thermal expansion, such as a tantalum material. The thermal conductivity of the tantalum material is about 1/7 compared with copper, and its thermal expansion coefficient is about 1/2 that of copper. The connection plate 22 and the sample platform 6 are connected by screws 8, and the connection plate 22 and the sample moving shaft 7 are connected by screws 23.
[0024]
In the sample holder of the present invention of FIG. 2, when the sample platform 6 is held by the sample platform holder 3b as shown in FIG. 2, the connection plate 22 is connected to the sample platform holder 3b, the cylinder 3a, and the like. There is no contact. Moreover, the sample moving shaft 7 can move in the axial direction of the cylindrical body 3a without contact with the inner surface of the cylindrical body 3a as in the prior art.
[0025]
Now, now, in the state of FIG. 2, when the electron beam highly accelerated in the sample S ₁ for image observation of the sample S ₁ is being irradiated, the sample S ₁ by the electron beam irradiation is heated. And the heat of the sample is transmitted to the sample platform 6 made of, for example, copper.
[0026]
However, the flow of heat transmitted from the sample to the sample platform 6 is blocked by the connection plate 22 which is a heat insulating member, and the heat of the sample platform 6 is hardly transmitted to the sample moving shaft 7. For this reason, in the sample holder of the present invention, the sample moving shaft 7 does not extend due to thermal expansion as in the prior art, and the drift due to the heat of the sample is greatly reduced.
[0027]
In the sample holder of FIG. 2, since the sample platform 6 and the connection plate 22 are small and have a small heat capacity, even if they thermally expand, the thermal expansion stops immediately. For this reason, after the thermal expansion stops, image observation of the sample can be performed without any sample drift.
[0028]
Moreover, in the sample holder of FIG. 2, in order to enlarge the contact area between the sample mounting base 6 and the sample mounting base holding | maintenance part 3b, those contact surfaces are mirror-finished. For this reason, the heat generated in the sample platform 6 is efficiently transmitted to the sample platform holder 3b made of, for example, copper, and then released to the cylindrical body 3a side. As a result, even if the configuration is such that heat does not escape to the sample moving shaft 7 side as in the present invention, the temperature rise of the sample platform 6 can be prevented.
[0029]
In this case, even if the sample holder main body is heated and thermally expanded, the sample holder main body 6 and the sample mounting base 6 are not integrally formed. Therefore, the sample mounting base 6 is moved by the thermal expansion of the sample holder main body. Never do.
[0030]
The example of the present invention has been described above with reference to FIG. 2, but the present invention is not limited to this example, and includes other modified examples.
[0031]
For example, in the example of FIG. 2, if the sample moving shaft 7 is formed of a material having a thermal insulation and a low thermal expansion coefficient, for example, a tantalum material, like the connection plate 22, the case of the example of FIG. Further, the thermal drift of the sample can be reduced.
[0032]
Further, if the connection plate 22 is formed of a ceramic system having a thermal expansion coefficient close to 0 and a thermal conductivity of 1/30 or less of a copper system, the heat of the sample can be increased as compared with the case of using a tantalum material. The drift can be further reduced. However, in order to prevent charging of the connection plate due to electron beam irradiation, it is necessary to provide a cover or the like so that the electron beam does not hit the connection plate, or to apply a conductive coating to the connection plate.
[Brief description of the drawings]
FIG. 1 is a view showing a conventional sample holder for an electron microscope.
FIG. 2 is a view showing an example of a sample holder for an electron microscope according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sample holder, 2 ... Outer cylinder, 3a ... Cylindrical body, 3b ... Sample mounting base holding part, 3c ... Electron beam passage hole, 4 ... Sample chamber, 5, 9 ... O-ring for airtightness, 6 ... Sample mounting base, 7 ... Sample moving shaft, 8, 13, 17, 19, 23 ... Screw, 10 ... Moving guide, 11 ... Fine movement knob, 12 ... Sample switching knob, 14 ... Cam, 15 ... Roller guide hole, 16 ... Roller, 18 ... roller guide, 20 ... restriction hole, 21 ... presser spring 22 ... connecting _{plates, S 1, S 2, S} 3, S 4 ... sample

Claims (2)

A sample holder main body composed of a cylindrical body and a sample platform holding portion provided at the tip of the cylindrical body;
A sample moving shaft attached to the cylindrical body via a shaft moving mechanism so that the inner side of the cylindrical body can be moved in the axial direction of the cylindrical body without contacting the cylindrical body;
A sample platform attached to the sample moving shaft via a connecting member having thermal insulation,
When the sample platform is held by the sample platform holder , the connection member is not in contact with the sample platform holder and the cylinder ,
The sample holder for an electron microscope, wherein the sample platform, the sample platform holder, and the sample holder main body are made of a material having high thermal conductivity.   The sample holder for an electron microscope according to claim 1, wherein the connecting member, or the connecting member and the sample moving shaft are formed of a material having a small coefficient of thermal expansion.

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