JPS5856952B2 - Sample processing equipment for scanning electron microscopes and similar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frozen sample observation device for a charged particle beam device,
In particular, the present invention relates to a sample processing device suitable for use in a scanning electron microscope.

Observation of frozen samples is considered to be extremely important, especially in the field of biological sample research for scanning electron microscopy, as it is thought that it can be observed in the same state as when it was alive.

However, when preparing frozen samples, it is necessary to pay sufficient attention to sample deformation due to temperature changes and frost buildup.

For this reason, in the conventional technology, a part of the sample chamber of a scanning electron microscope is provided with a preliminary chamber that communicates with the vacuum. ,
A method has been considered in which a cooling knife or the like is provided to expose a fresh sample surface free of frost, and the frozen sample is immediately introduced into the sample chamber for observation after preparation.

However, in order to observe frozen samples satisfactorily, it is often important for such a preliminary chamber to have not only the above-mentioned cooling means but also a device for applying conductive treatment to the sample by metal vapor deposition or ion sputtering coating. becomes.

However, if we tried to provide such a function in each preparatory chamber, it would inevitably become complicated, the moving rod for moving the sample between the sample chamber and the preparatory chamber would become long, and the entire preparatory chamber would become larger and heavier. This has the disadvantage of making it more difficult to operate.

The present invention has been made in view of the above-mentioned shortcomings of the prior art, and is designed to prevent frost from forming during handling of frozen samples, and
The purpose is to provide a sample processing device that is easy to operate.

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

As shown in the figure, a sample processing chamber 2 provided adjacent to a sample chamber 1 is in vacuum communication with an air lock means consisting of an O-ring 3 for vacuum sealing, an air lock valve 4, etc.
It is now possible to block it.

The sample processing chamber 2 is provided with a sample stage 7 on which a sample 5 and a sample table 6 for holding a sample are placed.

One end of the sample stage is immersed outside a vacuum in a refrigerant 9 such as liquid nitrogen contained in a refrigerant container 8 such as a dewar bottle, so that the sample 5 can be maintained in a frozen state even during sample processing. .

Test 5: If the biological sample is in a frozen state, it is possible to observe secondary electron images in the same state as when it was alive, even without conductive treatment.

However, in general, when the observation magnification increases to several thousand times or more, it becomes difficult to obtain secondary electron signals, making it difficult to observe the morphology of the sample surface well.

In such cases, if the sample surface is subjected to conductive treatment, the secondary electron signal from the sample will increase, making it possible to perform high-magnification, high-resolution observation.

Therefore, in this embodiment, between the sample processing chamber 2 and the sample processing chamber 2,
O-rings 10 and 11 for vacuum sealing and air lock valve 12
, an air lock shaft 13, etc. A preliminary chamber 14 that is communicated with or shut off by vacuum means
The preparatory chamber is provided with a gas introduction valve 15 capable of introducing dry gas, an exhaust valve 16 capable of preliminary evacuation with a rotary pump or the like (not shown), and means for performing conductive treatment on the sample 5. ing.

FIG. 1 shows an example in which an ion coating device using ion sputtering is provided as the conductive treatment means.

The ion coating device includes an electrode 17 made of a coating material such as gold, an electrode support rod 18 for the electrode, an insulating material (for example, acrylic material) 19 that electrically insulates and supports these, and an O for vacuum sealing. It is composed of a ring 20, 21 and an ion sputtering power supply device 22 for producing ion sputtering, and for the preliminary chamber 14,
It can be installed removably.

The power supply device 22 can switch the polarity of the electrode 17 to either ■, e, or AC high voltage, and can be used not only for conductive treatment but also for
Sample processing such as ion etching and hydrophilic treatment can also be performed.

The sample 5 that has been subjected to the conductive treatment by the ion coating device is moved between a sample moving rod 23 provided in the separation processing chamber 2 and a support made of a material that supports the sample movement rod and allows the inside of the separation processing chamber to be seen through. The sample is transferred into the sample chamber 1 by a sample exchange means consisting of a shaft 24 and O-rings 25 and 26 for vacuum sealing, and placed on a sampling stage 28 attached below the objective lens 27 in the same chamber.

The sample-receiving part of the sorting stage 28 is cooled by cooling means (not shown) provided in another part of the sorting chamber, and the sample is maintained in a frozen state 11 below the objective lens 27. A focused electron beam (not shown) is scanned to perform secondary electron image observation such as biological identification.

Since the sample processing chamber 2 and the preparatory chamber 14 can be vacuum isolated by an air lock means, after the conductive treatment described above is completed, the sample processing chamber 2 and the preliminary chamber 14 can be isolated from each other without being exposed to the atmosphere. Sample processing means can be replaced and installed in the preliminary chamber 14.

FIG. 2 is a schematic diagram of an embodiment of the present invention in which a cooling knife device is installed in the preliminary chamber 14 as another sample processing means.

In the following description, the same members as those in FIG. 1 are indicated by the same reference numerals.

In the preliminary chamber 14, a cooling knife 29 which has been pre-cooled by being immersed in a refrigerant in the atmosphere, a cooling knife moving rod 30 and its support 31, and a cooling knife device which is connected to O-rings 20 and 21 can be detachably attached. It is provided.

After preliminary evacuation of the preliminary chamber through the exhaust valve 16, the air lock valve 12 is opened, the moving rod 30 is pushed in, the cooling knife 29 is inserted into the separation processing chamber 2, and the knife 29 is rotated to perform the separation. By cutting the surface, a fresh, frost-free sample surface can be exposed.

In the prior art, a method was considered in which the cooling knife means was fixedly provided in the sample processing chamber, but in this embodiment,
It is extremely easy to handle because it is installed in the preliminary chamber and used immediately after being cooled in the atmosphere, and has the advantage that it does not require a large space in the sample processing chamber.

FIG. 3 is a schematic configuration diagram showing another embodiment of the present invention.

In this embodiment, the preliminary chamber 14 includes, for example, a basket-shaped tungsten filament 32 and its supporting electrodes 33, 33.
', an insulator 34 for electrically insulating these,
The O-ring 21 for vacuum sealing, the evaporation power source 35, and the evaporation material (not shown) attached to the filament 32 are
This figure shows a state in which a vapor deposition device including a shield plate 36 for preventing vapor deposition on other surfaces is detachably provided.

Although the air lock shaft 13 that moves the air lock valve in the preliminary chamber is not shown, it is provided in a direction perpendicular to the plane of the drawing and is configured to be able to open and close freely.

Furthermore, in this embodiment, the sample mounting table 7 is installed upright on a cooling device that can freely move the sample mounting table between the sample chamber 1 and the sample processing chamber 2.

The cooling device includes a cooling body 37 connected to a sample mounting table 7 on which a sample 5 and a sampling table 6 are erected, a refrigerant 9 cooling the other end, and a heat insulating material 38 thermally insulating the refrigerant. and an outer cover 39 having a movable shaft structure so that the entire cooling device can be moved, a holding table 40 for holding these, and O-rings 41 and 42 for vacuum sealing.

In this embodiment, after sample processing such as electrical conductivity treatment for sampling using the evaporation device, the sample can be immediately moved to the sampling chamber together with the cooling device and frozen sample observation can be performed. This eliminates the need to provide a special separation stage or cooling means, which not only simplifies the size of the sample chamber, but also has the advantage of providing high cooling efficiency since there is no need to transfer samples each time.

In addition, since the vapor deposition device is detachable from the preparatory chamber 14, the filament 32 can be easily replaced without exposing the sample processing chamber to the atmosphere, and a slight amount of frost on the sample surface during the sampling process can be removed. It can also be used to sublimate using radiant heat from a filament and to control the temperature of the sample surface.

FIG. 4 is a schematic configuration diagram showing another embodiment of the present invention.

This embodiment shows a state in which a sample manipulator device for gouging or scratching the sample to expose the inner surface of the sample is attached to the preliminary chamber 14.

The manipulator device includes a manipulator needle 43 that has been cooled by immersing it in a refrigerant in the atmosphere, a manipulator moving shaft 44, a support 45 for these, and O-rings 20 and 21 for vacuum sealing.

The cooling device for cooling the sample is of a movable type similar to the embodiment shown in FIG. 3, but has a vertically elongated metal cooling tank 46.

Further, the outer cover 39' is also vertically elongated and is welded to the inner cooling tank 46, so that it can be heat-insulated and vacuum-sealed.

By making it vertically long, there is an advantage that the distance between the cooling device and the sorting chamber can be shortened.

As described above, according to the present invention, it is possible to provide a sample processing device that is resistant to frost buildup during handling of frozen samples and is compact and easy to operate.

Furthermore, the content of the present invention can be applied not only to a scanning electron microscope, but also to a transmission electron microscope and a scanning image observation device as an auxiliary device therefor, as well as a freezing sample analysis device for an ion microanalyzer. be effective.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG.
FIGS. 3 and 4 are longitudinal cross-sectional views showing other embodiments, respectively. DESCRIPTION OF SYMBOLS 1... Trial chamber, 2... Sample processing chamber, 4... Air lock valve, 5... Sample, 9... Refrigerant, 12... Air lock valve, 13... Air lock shaft , 14...
Preparation chamber, 17... Electrode, 18... Electrode support rod, 19
... Insulating material, 22 ... Power supply device for ion sputtering, 29 ... Cooling knife, 32 ... Tungsten filament, 35 ... Power supply for vapor deposition, 37 ... Cooling body, 43 ... Manipulator Needle, 44... Manipulator movement axis, 46... Cooling tank.

Claims (1)

[Scope of Claims] 1. A sample processing chamber that is in vacuum communication with the sample chamber via an air lock means and is capable of processing the sample, including an apparatus for introducing a frozen sample into a sample chamber for observation. and a vine preparatory chamber which is in vacuum communication with the sample processing chamber via another air lock means, and means for processing the sample within the sample processing chamber is provided in the preparatory chamber. A sample processing device for a scanning electron microscope and similar devices. 2. Claim 1, wherein the sample processing means is configured to perform conductive treatment on the sample.
A sample processing device for a scanning electron microscope and similar devices described in Section 1. 3. A sample processing device for a scanning electron microscope or similar device as claimed in claim 1, wherein the sample processing means includes a cooling knife for cutting the sample. 4. A sample processing device for a scanning electron microscope or similar device as claimed in claim 1, wherein the sample processing means includes a sample manipulator for picking up or gouging out the sample.