JPS61263036A - Cryogen separation type sample cooler - Google Patents

Abstract

PURPOSE:To insulate a sample from a vibration caused by the flow, evaporation or the like of a cryogen, by supporting a sample holder on a moving stage, thermally coupling the holder to a cryogen tank as a cooling source, and attaching the holder to a member to block the vibration. CONSTITUTION:A sample holder 1 for holding a sample cylinder 11 filled with a sample cylinder 11 is located between pole pieces 2. A cryogen tank 4 is supported as a cooling source on an outer shield 5 over the holder 1. The tank 4 and the sample holder 1 are thermally coupled to each other in such a manner that a vibration is blocked by a heat transfer member 24. A sample cooler is thus constructed for an electron microscope or the like. The sample cylinder 11 is cooled by the cryogen tank 4 through the heat transfer member 24 while the vibration caused by the flow or evaporation of a cryogen in the tank is absorbed. Therefore, the sample is stabilized so that an image of the sample is made with high resolving power.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cryogen separation type sample cooling device for an electron microscope or the like.

[Conventional technology]

In devices such as electron microscopes that irradiate a sample with charged particles, the sample is cooled and alt-detected in order to prevent heat generation. FIG. 2 is a vertical cross-sectional view showing a sample cooling device for a conventional transmission electron microscope. In FIG. has been done. Reference numeral 4 denotes a cryogen tank that supports and cools the sample holder 1, and is integrated with the sample holder 1. 5 is an outer shield provided on the outside of the cryogen tank 4, 6 is a yoke, and 7 is an aperture.

In the above configuration, a sample is mounted on the sample holder 1, and a cryogen such as liquid helium is injected into the cryogen tank 4 from the cryogen inlet pipe 8 to cool the sample mounted on the sample holder 1 by heat conduction. The gas evaporated in the cryogen tank 4 enters the outer shield 5 from the connecting pipe 9, cools the outside, and passes through the cryogen outlet pipe 10.
is discharged from the system. In this state, the sample is irradiated with an electron beam along the optical axis Z to obtain a transmission image of the sample.

[Problem that the invention seeks to solve]

However, in such conventional sample cooling devices, the sample holder 1 and the cryogen tank 4 have an integral structure, so the sample also moves at the same time due to vibrations generated by the flow and evaporation of the cryogen in the cryogen tank 4. Therefore, there was a problem that high resolution could not be obtained.

This invention is intended to solve the above-mentioned problems. By separating the cooling system from the sample holder, vibrations caused by the flow and evaporation of the cryogen are not transmitted to the sample, and high resolution can be obtained. The purpose is to provide a separate sample cooling device.

[Means for Solving the Problems] The present invention includes a sample holder supported by a moving stage so as to hold a sample in a sample chamber, and a sample holder that is thermally connected to a cooling source and vibration-free. This is a cryogen separation type sample cooling device that is equipped with a heat transfer member that is installed to shut off the heat.

The sample holding section holds a sample cylinder loaded with a sample between the pole pieces, and is preferably supported by a moving stage via a heat insulating material. A cryogen tank can be used as the cooling source, and a metal plate or the like can be used as the heat transfer member, which has a structure that can absorb vibrations and has excellent thermal conductivity at low temperatures.

[For production]

A sample loaded in a sample tube or the like is held in a sample holding section supported by a moving stage. When the cooling source is cooled with a cryogen or the like, the sample is cooled via the heat transfer member. At this time, vibrations caused by the flow and evaporation of the cryogen in the cooling source are blocked by the heat transfer member and are not transmitted to the sample.

In this state, the sample is irradiated with an electron beam or the like and Il! During observation, the sample is cooled while vibrations are isolated, resulting in high resolution.

〔Example〕

Hereinafter, the present invention will be explained with reference to embodiments of the drawings.

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.
The same reference numerals as in FIG. 2 indicate the same or corresponding parts.

The sample holder 1 has a structure close to a funnel shape, and has a holding space 12 therein for holding a sample tube 11 having a structure close to a cannonball shape.
A sample cylinder 11 loaded with a sample is placed in the sample chamber 3 so as to be held between the pole pieces 2. The sample holding section 1 is connected to a donut plate-shaped moving stage 14 via a heat insulating material 13.
is supported in the center of the The heat insulator 13 is made of a corrugated donut-like material made of a material with poor thermal conductivity such as plastic, but may be made of other materials and structures as long as it can support the sample holder 1 in a heat-insulated state. But that's fine.

The moving stage 14 has screws 15 arranged at equal intervals on the circumference for adjusting the height, and are placed on bosses 16 provided on the yoke 6.

The moving stage 14 also includes a bin 17 protruding from the yoke 6.
It is movable in the horizontal direction relative to the yoke 6 while being pressed downward by a spring 18 supported by the yoke 6, and a plurality of adjustable screws 19 protruding inward from the yoke 6 are attached to the periphery of the yoke. contact, and positioning in the horizontal direction is performed.

A cryogen tank 4 serving as a cooling source is provided in the sample chamber 3 in a donut shape, and a cooling cryogen inlet pipe 21 and an outlet pipe 22 communicate with each other across a partition plate 20 provided at one location in the transverse direction. are doing. The inner circumferential edge 23 of the cryogen tank 4 is thermally connected to the sample holder 1 through a plurality of heat transfer members 24 in a vibration-blocking manner. As the heat transfer member 24, a metal plate having excellent thermal conductivity at low temperatures, such as gold or copper, is preferably bent into a corrugated structure to absorb vibrations, but it may also have a net-like structure.

A doughnut-shaped outer shield 5 with a crank-shaped cross section is provided on the outside of the cryogen tank 4. The outer periphery of the outer shield 5 is supported by a yoke 6 by a support 25, and the inner periphery is supported by a support 25.
6 supports the cryogen tank 4. An annular cooling pipe 27 is joined to the side wall of the outer shield 5, and its both ends are connected to a shielding cryogen inlet pipe 28 and an outlet pipe 29.

A shield plate 30 is provided on the upper part of the outer shield 5 so as to cover the cryogen tank 4. Also, the moving stage 14
A shield plate 31 is provided at the bottom of the sample holder 1 and the heat insulating material 13 so as to cover the lower side thereof.

In the above configuration, the sample tube 11 loaded with a sample is held in the holding space 12 of the sample holding section 1, and horizontally positioned using the screw 19. Then, the cooling agent is injected from the cooling agent inlet pipe 21, goes around the cryogen tank 4, and is discharged from the outlet pipe 22, and the shielding agent inlet pipe 2
A shielding cryogen is injected from 8, circulates around the cooling pipe 27, and is discharged from the outlet pipe 29 to perform cooling.

The sample cylinder 11 is cooled by heat conduction from the sample holding part 1 to the cryogen tank 4 via the heat transfer member 24. At this time, vibrations caused by the flow and evaporation of the cooling agent in the cryogen tank 4 are absorbed by the heat transfer member 24 and blocked, and are not transmitted to the sample holding section 1. The outer shield 5 is cooled by the shielding cryogen 5 in the cooling pipe 27, thereby providing heat shielding. Since the outer shield 5 is isolated from the sample holder 1, vibrations are not transmitted thereto.

In this state, if the sample in the sample tube 11 is irradiated with an electron beam along the optical axis Z and observed, a high-resolution sample image can be obtained because the sample is cooled with vibrations blocked. .

The sample is replaced by introducing a chuck (not shown) through the opening 32 of the shield plate 3o and chucking the sample tube 11.

Although the embodiments described above relate to transmission electron microscopes, the present invention can also be applied to sample cooling devices for scanning electron microscopes and other devices that irradiate a sample with charged particles.

〔Effect of the invention〕

According to this invention, since the cooling system is separated from the sample holding section, vibrations caused by the flow and evaporation of the cryogen are not transmitted to the sample, and therefore high resolution can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG. 2 is a vertical sectional view showing a conventional sample cooling device. In each figure, the same reference numerals indicate the same or equivalent parts; 1 is a sample holding part, 2 is a pole piece, and 3 is a sample chamber. 4 is a cryogen tank, 5 is an outer shield, 6 is a yoke, 11
13 is a sample tube, 13 is a heat insulating material, 14 is a moving stage, 24 is a heat transfer member, and 27 is a cooling tube.

Claims (5)

[Claims] (1) A sample holder supported by a moving stage to hold the sample in the sample chamber, and a heat transfer member provided to thermally connect the sample holder to a cooling source and isolate vibrations. Cryogen separation type sample cooling device equipped with (2) The cryogen separation type sample cooling device according to claim 1, wherein the sample holding section holds a sample cylinder loaded with a sample between the pole pieces. (3) A cryogen separation type sample cooling device according to claim 1 or 2, wherein the sample holding section is supported by a moving stage via a heat insulating material. (4) A cryogen separation type sample cooling device according to any one of claims 1 to 3, wherein the cooling source is a cryogen tank. (5) The cryogen separation type sample cooling device according to any one of claims 1 to 4, wherein the heat transfer member is a metal plate having excellent thermal conductivity at low temperatures.