JPH06203782A - Incidental device for electron microscope - Google Patents

Abstract

PURPOSE:To smoothly perform switching even when synchronously performed switching a vacuum exhaust pump and opening an air lock valve by providing a check valve by a specific mode in a partitioning plate for closing a fluid passage of the air lock valve in an incidental device. CONSTITUTION:When an incidental device 2, in a high vacuum degree condition, is separated from an electron microscope main unit 1 and left alone in the atmosphere, a partitioning plate 20 of an air lock valve 3 is closed. In a check valve 21 of the partitioning plate 20 of the air lock valve 3, by a pressure difference between a vacuum and the atmosphere and by pressing force of a spring 25, a ball unit 23 is pressed by a valve seat sealed with a vacuum, to provide an always closed condition, and a vacuum in the inside of the incidental device 2 can be held. After connecting the incidental device 2 to the main unit 1, when a vacuum degree of the main unit 1 is increased in a condition of closing the partitioning plate 20 of the air lock valve 3 in the incidental device 2, the vacuum degree, when it leads to a fixed value, is detected by a vacuum degree sensor, and a vacuum pump is switched from a rotary pump to a diffusion pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting portion with an electron microscope main body so that a vacuum can be efficiently held when it is attached to an electron microscope main body and various analyzes using an electron beam are performed. The present invention relates to an auxiliary device for an electron microscope provided with an improved airlock valve in the vicinity.

[0002]

2. Description of the Related Art In recent years, in addition to the purpose of observing an enlarged image of a sample in an electron microscope, a vacuum container in which a sample to be analyzed is arranged is attached as an accessory device, and the electron beam of the electron microscope is irradiated onto the vacuum container. Then, it is used as an analyzer. However, as shown in FIG. 2, the accessory device has a limit in its function only by attaching one accessory device 2 to the electron microscope 1. Therefore, a plurality of accessory devices 2a, 2b, etc. are prepared. Every time, it is necessary to replace it with an accessory device suitable for the purpose of the analysis.

Therefore, the accessory device 2 or the like is replaced and other accessory devices 2a, 2b or the like are attached. However, when the accessory device 2 is replaced, the inside of the electron microscope main body 1 becomes atmospheric pressure. Since it is unavoidable, it is convenient to maintain the vacuum of the accessory device 2 or the like in order to make the vacuum again later, and in other various points. When the air lock valve 3 is provided at a portion close to, and is separated from the electron microscope main body 1, the air lock valve 3 is closed so that the vacuum in the accessory device 2 is maintained even if the air lock valve 3 is separated.

FIG. 3 shows a vacuum pump for evacuating the electron microscope main body 1 and the auxiliary device 2, a valve forming an air passage thereof and a control device thereof, which are vacuum from atmospheric pressure to a constant pressure. Rotary pump 5 for roughing, diffusion pump 6 for further high vacuum, rotary pump suction side valve V1 between main body 1 and rotary pump 5, atmospheric leak valve V2, main body 1 and diffusion pump 6 And a diffusion pump suction side valve V3, a diffusion pump discharge side valve V4 between the diffusion pump 6 and the rotary pump 5, a vacuum sensor 7 provided in the main body 1, and a control device for controlling these pumps and valves. Made of eight.

FIG. 4 shows a cross section of the airlock valve 3 and the auxiliary device 2 in the vicinity thereof. The airlock valve 3 is provided between the mounting flange 11 of the main body 1 and the mounting flange 12 of the auxiliary device 2 itself. 3 has a valve body 13 in which a hollow portion 14 is formed, and a partition plate 15 is slidable in the hollow portion 14 so that the partition plate 15 is driven. 16 is connected to this. A vacuum seal 16 is provided between the opening / closing shaft 16 and the valve body 13.
It is sealed by a.

A vacuum seal 17 is interposed between the upper surface of the partition plate 15 and the hollow portion 14 so as to maintain airtightness, and the cylindrical protrusions 1 are provided on both sides of the partition plate 15.
8 protrudes and is engaged with a slope-shaped push-up fitting 19 fixed to the valve body 13. When the partition plate 15 is pushed by the opening / closing shaft 16 to close the passage 13a of the valve body 13, the cylindrical protrusion 18 and the push-up fitting 19 are pushed up by the push-up fitting 19. The upper surface of the partition plate 15 is pressed against the lower surface of the upper wall of the hollow portion 14 of the valve body 13, and the vacuum seal 1
It adheres by 7 and maintains airtightness.

When performing the measurement, first, the pump and the valve shown in FIG. 3 must be controlled to make the main body 1 and the auxiliary device 2 a vacuum. First, the auxiliary device 2 which is also placed in the atmosphere at the beginning is attached at the connecting portion 4, the air lock valve 3 of the auxiliary device 2 is opened, the valve V1 is opened, and the valves V2, V
With 3, 3 and V4 closed, the rotary pump 5 is fully rotated to roughly pull the air in the main body 1 and the auxiliary device 2 to a low vacuum.

When the degree of vacuum inside the main body 1 and the accessory device 2 rises and the vacuum degree sensor 7 detects that the degree of vacuum is below a certain value, the valve V2 stays at that state and the rotary pump 5 also. Although it is still rotating, the valve V1 is closed and the valves V3 and V4 are opened to operate the diffusion pump 6. Then, the inside of the main body 1 and the accessory device 2 is permanently pulled to a high vacuum, and in that state, various measurements and the like are performed by the accessory device 2.

Next, in order to separate the accessory device 2 and replace it with other accessory devices 2a, 2b, etc. for measurement, etc., the air lock valve 3 of the accessory device 2 is closed and the inside of the accessory device 2 is closed. It is kept in vacuum, separated from the main body at the connecting portion 4, and replaced with the accessory devices 2a, 2b and the like. However, if these accessory devices 2a, 2b etc. have previously been measured once, these airlock valves 3 should be closed and the vacuum should be maintained.

Therefore, after connecting the new accessory devices 2a, 2b, etc. to the main body 1, the degree of vacuum of the main body 1 and the accessory devices 2a, 2b, etc. must be increased.
Since b and the like are already in a vacuum, the air lock valve 3 is closed while the rotary pump 5 is roughing, and the vacuum degree sensor 7 keeps the vacuum degree in the main body 1 below a certain value. The air lock valve 3 is opened in synchronism with the fact that the failure is detected.

In this way, the vacuum held by the accessory devices 2a, 2b, etc. is usually slightly lowered due to a small leak, and the degree of vacuum after the rough drawing of the main body 1 is usually low. Since it is considered that the value is close to, the switching from the rotary pump 5 to the diffusion pump 6 by the vacuum sensor 7 and the opening of the air lock valve 3 are synchronized, so that the switching can be performed at an appropriate time. become.

Further, if the vacuum held by the accessory devices 2a, 2b, etc. is maintained at a value higher than the vacuum degree after the main body 1 is subjected to roughing, the vacuum degree sensor 7 shows a constant value. Thus, when the airlock valve 3 is opened in synchronization with the switching from the rotary pump 5 to the diffusion pump 6, at that time, when viewed from the side of the accessory devices 2a, 2b, etc., the degree of vacuum of the main body 1 is still its own. The degree of vacuum is not reached, and the auxiliary devices 2a, 2
Although air will once flow into b, etc., it is pulled by the diffusion pump 6 from the side of the main body 1 and made into a high vacuum again.

[0013]

By the way, the above-mentioned switching from the rotary pump 5 to the diffusion pump 6 is performed by the vacuum degree sensor 7, and the air lock valve 3 is opened in synchronism therewith. In the device, when the air lock valve 3 is scratched or dust is attached to cause a leak and the pressure in the accessory device is low vacuum or atmospheric pressure, the switching as described above is performed. Does not work.

That is, at the time of switching, the main body 1 side is already in a considerable vacuum, and the diffusion pump 6 is already about to start operating. Therefore, if the airlock valve 3 is opened there, a considerable vacuum is reached. Low vacuum air or atmospheric pressure flows into the main body 1 and enters the main body 1 or into the diffusion pump 6 all at once, destroying the diffusion pump 6 and, if worse, causing an explosion to cause damage to the main body of the electron microscope. There was a problem that the function was paralyzed.

The present invention has been made in view of such a conventional problem. Even when the auxiliary device is in a low vacuum or at atmospheric pressure, the rotary pump is switched to the diffusion pump and the air lock valve is used. It is an object of the present invention to provide an accessory device for an electron microscope in which the opening of the electron microscope is performed in synchronization, the switching is smoothly performed, and the degree of vacuum can be effectively increased.

[0016]

As a means for solving the above-mentioned problems, the present invention has the structure of an electron microscope in which a vacuum container is attached to an electron microscope main body and an air lock valve is provided in the vacuum container. In the accessory device, the partition plate that closes the fluid passage of the airlock valve always closes the flow passage on the backflow side, and operates only when the air pressure on both sides of the flow passage on the operating side exceeds a certain pressure difference. It was decided to install a check valve that does this.

[0017]

Next, the operation of the present invention will be described. When the accessory device is evacuated and left in the atmosphere,
The check valve is always closed. Then, after connecting the accessory device to the main unit, with the partition plate of the air lock valve of the accessory device closed, increasing the vacuum level on the main unit side detects when the vacuum level reaches a certain value with the vacuum level sensor. Then, the vacuum pump is switched to the diffusion pump.

The vacuum held in the accessory device is
If the vacuum level is the same as that after the roughing of the main body, the check valve provided on the partition plate is closed, and the vacuum level sensor indicates a constant value, so the rotary pump changes to the diffusion pump. When the air lock valve is opened in synchronism with the switching of the above, the pressures on the main body side and the auxiliary device side are the same and there is no flow between them, and both are made into a high vacuum by the diffusion pump.

Further, the vacuum held in the accessory device is
When the vacuum is maintained at a value higher than that after the roughing of the body, the check valve provided on the partition plate remains closed, and the vacuum sensor shows a constant value. When the airlock valve is opened in synchronism with the changeover from the diffusion pump to the diffusion pump, air will flow from the low vacuum main unit side to the accessory device as in the conventional case, but the diffusion pump will re-enable the high vacuum. It

On the other hand, when the degree of vacuum of the accessory device is lower than the constant value indicated by the vacuum degree sensor, the degree of vacuum on the main body side gradually increases, and before the vacuum degree sensor shows the constant value, the incident degree is increased. Although it reaches a level higher than the vacuum level of the device, in this state, the check valve provided on the partition plate operates, and the vacuum inside the accessory device is pulled by the vacuum on the main body side, and at the same time as the main body side, it is vacuumed. Since the degree of vacuum increases, when the vacuum sensor shows a constant value and the exhaust from the rotary pump is switched to the diffusion pump, the air lock valve is opened to smoothly perform the switching.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
The electron microscope main body 1, the accessory device 2, and the air lock valve 3 thereof according to the present invention are the same as those shown in FIGS. 3 and 4 of the related art in that the air lock valve 3 is provided with a partition plate. The same members are designated by the same reference numerals.

FIG. 1 shows the construction of the present invention and is an enlarged sectional view in which a check valve 21 is mounted in a partition plate 20 of the airlock valve 3. The structure of the check valve 21 is the partition plate 2
A through hole 22 is formed in the center of 0, and a sphere 23 is placed in contact with a valve seat 24 which is a vacuum seal. Then, press the sphere 23 downward so that the spring 2
5 is mounted via a spring retainer 26, and the spring retainer 26 is attached to the partition plate 20 by a screw 27 between the spring retainer 26 and the inner surface of the through hole 22.

When the auxiliary device 2 has a high degree of vacuum and is separated from the electron microscope body 1 and left in the atmosphere, the partition plate 20 of the airlock valve 3 is closed and the airlock valve 3 is closed. Check valve 21 of partition plate 20
Is due to the pressure difference between the vacuum and the atmosphere and the pressing force of the spring 25,
The spherical body 23 is pressed by the valve seat 24, which is a vacuum seal, and is always closed, so that the vacuum in the accessory device 2 can be maintained.

After connecting the accessory device 2 to the main body 1,
When the vacuum degree of the main body 1 is increased with the partition plate 20 of the air lock valve 3 of the accessory device 2 closed, the vacuum degree sensor 7 detects when the vacuum degree reaches a certain value, and the vacuum pump rotates the rotary pump. Pump 5 to diffusion pump 6
Switch to.

When the vacuum held by the accessory device 2 is the same as the vacuum detected by the vacuum sensor 7 after the main body 1 is roughly drawn, the vacuum is provided on the partition plate 20. The check valve 21 is closed by the force of the spring 25, and since the vacuum sensor 7 shows a constant value, the check valve 21 is synchronized with the switching from the rotary pump 5 to the diffusion pump 6 and the air lock valve 3 operates. When the partition plate 20 is opened, the pressures on the main body 1 side and the auxiliary device 2 side are the same and there is no flow between them.
It is made high vacuum.

Further, when the vacuum held in the accessory device 2 is maintained at a value higher than the vacuum detected by the vacuum sensor 7 after roughing the main body 1, the partition plate 20 is used.
The non-return valve 21 provided in the is kept closed, and since the vacuum sensor 7 shows a constant value, in synchronization with the switching from the rotary pump 5 to the diffusion pump 6,
When the partition plate 20 of the airlock valve 3 is opened, air temporarily flows from the low-vacuum main body 1 side toward the high-vacuum auxiliary device 2, but the air flowing into the auxiliary device 2 is , The diffusion pump 6 makes a high vacuum again. In this way, the degree of vacuum of the accessory device 2 is determined by the degree of vacuum sensor 7
If the degree of vacuum is higher than or equal to the degree of vacuum detected in, the check valve 21 is the same as the conventional one.

However, when the air lock valve 3 is damaged or dust adheres to cause a leak and the pressure in the accessory device 2 is low vacuum or atmospheric pressure, the rotary pump 5 is used. As a result of the rough drawing, the degree of vacuum on the main body 1 side gradually rises and reaches a state higher than the degree of vacuum of the accessory device 2 before the vacuum degree sensor 7 shows a constant value. Then, the check valve 2 provided on the partition plate 20
1 is because the pressure of the auxiliary device in the lower part of the figure is higher,
The spherical body 23 rises against the force of the spring 25, and an air passage from below to above the check valve 21 is completed.

Then, the low vacuum or the atmosphere in the accessory device 2 is
The degree of vacuum rises at the same time as the body 1 side is pulled by the vacuum of the body 1 side and reaches a certain value detected by the vacuum degree sensor 7. However, since both are the same and are the same, the rotary pump 5 is used. Even if the exhaust gas is switched to the diffusion pump 6 and the air lock valve 3 is opened in synchronization with it, the switching is smoothly performed as in the conventional case.

In the above embodiment, the valve body 13
As a partition plate 20 to be inserted into the
Check valve 2 using sphere 23, valve seat 24 and spring 25 for this
1 has been described, the partition plate is not limited to a flat plate, and any type may be used as long as it closes the fluid passage of the airlock valve, and the check valve is also a spherical body as in the present embodiment. The form of the spring is not limited.

[0030]

As described above, according to the present invention, since the check valve is provided in the partition plate that closes the fluid passage of the air lock valve of the accessory device, the accessory device is removed from the electron microscope main body. In this case, the vacuum can be maintained, and when the vacuum in the accessory device leaks to a low vacuum or atmospheric pressure, this accessory device is directly connected to the main body of the electron microscope to separate the accessory device from the main body. Evacuate at the same time, and even if the airlock valve is opened in synchronization with the switching from the rotary pump to the diffusion pump,
It has an effect that exhaust can be performed without causing trouble, and measurement by an electron microscope and an auxiliary device can be efficiently performed.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a partition plate of an airlock valve showing the configuration of the present invention.

FIG. 2 is an explanatory diagram for attaching a plurality of accessory devices to an electron microscope, which is a premise of the present invention.

FIG. 3 is a system diagram in the case where the electron microscope and the auxiliary device are evacuated.

FIG. 4 is a partially cutaway sectional view showing an air lock valve of a conventional accessory device and a connecting portion between the accessory device and a main body.

[Explanation of symbols]

 1 Electron Microscope Main Body 2 Attached Device 3 Airlock Valve 20 Partition Plate 21 Check Valve

Claims (1)

[Claims] 1. An electron microscope incidental device comprising a vacuum container attached to an electron microscope main body and an air lock valve provided in the vacuum container, wherein a partition plate for closing a fluid passage of the air lock valve is provided with a flow path on the backflow side. The auxiliary device of the electron microscope, which is provided with a check valve that is always closed and that is activated only when the air pressure on both sides of the flow passage on the operating side exceeds a certain pressure difference.