JPS5991648A - Preventive device for sample pollution - Google Patents

Abstract

PURPOSE:To exchange a sample and tilt and observe the big sample by providing a cooling member for preventing sample pollution that can be extruded and withdrawn through the opening of a sample chamber such as a scanning electron microscope and then a valve that blocks up the connecting path between the opening of the sample chamber and a cooling device when the cooling member is withdrawn. CONSTITUTION:A sample chamber 2 that loads a sample 14 at the lower part of the mirror body 1 of a scanning electron microscope is provided. A cooling device 7 with a cooling member 4 for preventing sample pollution made of good heat conductive material that can be extruded and withdrawn through the opening 3 of a sample chamber 2 is provided. The member 4 is mounted on the wall section of a cooling tank 6 containing coolant 5 and an electron beam passing hole 4a is formed on the tip of the member 4. The bellows 8 covering the member 4 are airtightly connected to a ring type metal cap member 10 with the opening 3 through a packing 12. In addition, the other end of the bellows 8 is airtightly connected to a case 9 that covers the tank 6. An air lock valve 11 is provided on the end face at the sample chamber side of the member 10 through a packing 13 and a path that connects the opening 3 and device 7 is airtightly blocked up by the valve 11. As a result, the sample can be exchanged and the big sample can be tilted and observed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sample contamination prevention device for use in scanning electron microscopes and similar devices.

Generally, in an electron microscope or the like, stains are generated on a sample by irradiating the sample with an electron beam.5 This stain causes a decrease in secondary electron generation efficiency and resolution.

Therefore, a cooling member cooled by a refrigerant such as liquid nitrogen is fixedly disposed within the sample chamber to prevent this contamination.

However, as is well known, it is not possible to expose the cooling member fixed in the sample chamber to the atmosphere. It was necessary to install it adjacent to the sample chamber.

Naturally, exchanging large samples such as IC wafers requires a large sample exchange room, which not only adds bulk to the entire space, but also makes it particularly difficult to move, rotate, or tilt the sample. 2. Description of the Related Art Scanning electron microscopes and the like for observing samples have a problem in that their operation is complicated and requires skill.

Furthermore, since the cooling member is fixed in a fixed position, if a large sample is used and the sample is tilted significantly, there is a risk that the sample will hit the cooling member.

The present invention aims to solve these problems, and by providing a cooling member that can be freely extended and retracted into the sample chamber, it is possible to create an atmosphere inside the sample chamber and to make it possible to exchange samples. An object of the present invention is to provide a sample contamination prevention device that can be viewed at a large angle.

For this reason, the sample contamination prevention device of the present invention is provided with a cooling device to prevent contamination of the sample in the sample chamber in a scanning electron microscope and similar devices.
The sample chamber is provided with a cooling device for preventing sample contamination that can be protruded from and retracted into the sample chamber through an opening formed in the sample chamber, and the cooling member is retracted into the cooling device.
In order to maintain the cooling member in a vacuum state when the cooling member is in a vacuum state, the passage connecting the opening of the sample chamber and the cooling device is provided with a hanging valve that airtightly closes the passage. .

Hereinafter, a sample contamination prevention device as an embodiment of the present invention will be explained with reference to the drawings.
FIG. 2 is a configuration diagram showing the main parts of the modified example.

As shown in FIG. 1, a sample chamber 2 in which a sample 14 is placed near the objective lens is provided at the bottom of the mirror body 1 of the scanning electron microscope S or EM. opening 3
is formed.

A cooling device 7 for preventing sample contamination is provided which has a cooling member 4 for preventing sample contamination made of a good heat conductive material that can be protruded from and retracted into the sample chamber 2 through this opening 3.

The base end of the cooling member 4 is attached to the wall of a cooling tank 6 containing a refrigerant 5 such as liquid nitrogen.

Furthermore, an electron beam passage hole 4a is formed at the tip of the cooling member 4.

By the way, the bellows 8 that covers the cooling member 4 has one end attached to the annular cap part 10 with the opening 3 of the sample chamber 2.
2 and are airtightly connected.

1, the other end of the bellows 8 is airtightly connected to a rigid cooling tank case 9 that covers the cooling tank 6.

Further, the bellows 8 is contracted and expanded by a mechanical mechanism such as a screw (not shown).

This activates the bellows contraction/extension mechanism,
When the bellows 8 is contracted σ, the cooling member 4 can be protruded into the sample chamber 2 as shown by the chain line in FIG. 1, and when the bellows 8 is expanded using the same mechanism, the solid line is shown in FIG. As shown, the cooling member 4 is transferred from the sample chamber 2 into the cooling device 7.
can be drawn in.

In addition, in the protruding state of the cooling part side 4, the electron beam passage hole 4a is at a position coaxial with the objective lens optical axis O.

In addition, a gasket 1 is attached to the end surface of the cap member lO on the sample chamber side.
An air lock valve 11 is provided through the sample chamber opening 3 and the cooling device 7, and the air lock valve 11 can airtightly close the passage connecting the sample chamber opening 3 and the cooling device 7.

With the above-described configuration, during sample observation, the cooling member 4 is normally used by protruding into the sample chamber 2, as shown by the chain line in FIG. This sufficiently prevents contamination caused by irradiation of the sample 14 with the electron beam.

By the way, if you want to exchange the sample and observe another sample,
First, while keeping the inside of the sample chamber 2 in a vacuum state, the cooling member 4 is drawn into the cooling device 7 as shown by the solid line in FIG. 1, and then the air lock valve 11 is closed.

Next, the inside of the sample chamber 2 is brought to an atmospheric condition, and the sample is exchanged within this sample chamber 2.

At this time, since the inside of the cooling device 7 is maintained in a vacuum state, the cooling member 4 is not exposed to the atmosphere even if the inside of the sample chamber 2 is brought into an atmospheric state.

Roughly speaking, at this time, the bellows 8 is maintained in an extended state by the bellows contraction/extension mechanism, so the bellows 8 does not contract due to the differential pressure inside and outside the cooling device.

After the sample is replaced, the inside of the sample chamber 2 is again brought into a vacuum state, and then the air lock valve 1 is opened to allow the cooling member 4 to protrude into the sample chamber 2 to prevent sample contamination.

Note that when the sample 14 is large or when the sample 14 is tilted significantly, the cooling member 4 is drawn into the cooling device 7. This can prevent the sample 14 from hitting the cooling part @4 and damaging the sample 14. In this case, the air lock valve [■] may remain open.

By the way, as shown in FIG. 2, the cooling device 7' is equipped with a casing made of a rigid body that covers the cooling member 4 and the cooling tank 6 and is airtightly connected to the edge of the sample chamber opening 3 via a gasket 12'. In this case, the cooling member 4 is connected to the cooling tank 6 via a mesh copper wire 15, and a heat insulating member 6 is connected to the base end of the cooling member 4. Attachment of the operating member 17 with the knob 17a takes place.

Therefore, if the cooling member 4 is to protrude as shown by the chain line in FIG. 2, it is sufficient to push the knob 17a in the direction of the arrow; conversely, as shown by the solid line in FIG. To pull the knob 17a in the opposite direction of the arrow.

Note that during sample exchange with the airlock valve 11 closed, there is a risk that the knob 17a may be pulled in due to the differential pressure inside and outside the cooling device, so in this case as well, a mechanical mechanism is used to close the knob 17a.
K is arranged so that pushing in and pulling out of a is performed.

In addition, the reference numeral 18 in FIG. 2 indicates the operation unit 17 and the cooling device 7.
2, the same reference numerals as in FIG. 1 indicate almost the same parts.

By the way, in order to evacuate the inside of the cooling device 7, 7' at all times or when the inside of the cooling device 7, 7/ is airtightly closed by the air lock valve 11, the cooling device 7, 7' is closed.
The evacuation system can be set up in multiple stages, and in this way, even if the sample chamber 2 is kept in an atmospheric state for a long time and samples are exchanged, there will be no problem.

r,1 The present device can also be used in scanning electron microscopes and similar devices.

As described in detail above, according to the sample contamination prevention device of the present invention, a scanning electron microscope and similar devices are equipped with a cooling device for preventing contamination of a sample in a sample chamber, and the cooling device can be used as described above. The cooling member is provided with a cooling member for preventing sample contamination that can be protruded from and retracted into the sample chamber through an opening formed in the sample chamber, and when the cooling member is pulled into the cooling device, the cooling member is In order to maintain the vacuum state, the sample chamber can be exchanged in a simple manner by providing a valve in a passage connecting the opening of the sample chamber and the cooling device to airtightly close the passage. This method also has the advantage that even if a large sample is tilted significantly, it can be observed without damaging the sample.

[Brief explanation of the drawing]

The figure shows a sample contamination prevention device as an embodiment of the present invention, and FIG. 1 is an overall configuration diagram thereof. FIG. 2 is a configuration diagram showing the main parts of the modified example. 1. Mirror body, 2. Sample chamber, 3. Opening, 4. Cooling member for preventing sample contamination, 4a. Electron beam passage hole, 5. Coolant, 6. Cooling tank, 7° 7'・・Cooling device for preventing sample contamination, 8・・Bellows, 9・・Cooling tank case, 10
...Base member, 11...Air lock valve, 12.12'
. 13...Packing, 14Φ-sample, 15...Mesh copper wire, 1
6. Heat insulation member, 17. Operation part shrine, 17ae-knob, 1B--packet, SEM@-scanning electron microscope. Agent Patent Attorney Yoshihiko Iinuma

Claims (1)

[Claims] In scanning electron microscopes and similar equipment, a cooling device is provided to prevent contamination of the sample in the sample chamber.
The cooling device is configured to include a cooling member for preventing sample contamination that can be protruded from and retracted from the sample chamber through an opening formed in the sample chamber, and the cooling member is drawn into the cooling device. In order to maintain the cooling member in a vacuum state, the passageway communicating the opening of the sample chamber and the cooling device is provided with a valve capable of airtightly closing the passageway. Sample contamination prevention device.