JPH01159948A - Vacuum exhaust system for scanning electron microscope - Google Patents

Abstract

PURPOSE:To prevent image obstacle because of coolant by furnishing a tank using an elastic member on a coolant path, thereby absorbing the kinetic energy of a turbulent flow generated with pulsation of water, and by providing standing flow condition at all times. CONSTITUTION:Through a baffle 2 an oil diffusion pump 3 is installed at the suction port of a specimen chamber 1, wherein a coolant suction hose 5 using a tank 7 is arranged at the baffle 2 while a coolant exhaust hose 6 at the oil diffusion pump 3, and further a coolant hose 4 is fitted between the baffle 2 and oil diffusion pump 3. At the tank 7 an elastic rubber tank 8 pressed by a spring 9 is coupled with coolant hose by a metal fitting 10, and when the stream in the coolant suction hose 5 becomes pulsated stream, the rubber tank 8 expands/contracts in the transverse direction in accordance with the pulsation because the longitudinal direction of the tank 8 is restrained by the metal fitting 10, wherein the expansion and contraction is so controlled by the spring 9 that the rate of flow out of the tank 7 will be constant. Accordingly the pulsated stream in the coolant suction hose 5 becomes standing flow because of passage through tank 7.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a vacuum evacuation system for a scanning electron microscope,
In particular, the present invention relates to a vacuum pumping system equipped with a tank suitable for damping vibrations generated by cooling water such as an oil diffusion pump.

[Conventional technology]

Conventional cooling waterways simply use vinyl tubes to connect water directly to cooling waterways such as oil diffusion pumps through water valves. In this case, every time the water pressure of the water conveying water changes, minute vibrations occur in the cooling channel, which interferes with images taken with a scanning electron microscope.

As another conventional example, a method has been proposed in which a coiled pipe is provided in the cooling waterway and water is run through it to remove vibrations.
There is also a drawback that vibrations cannot be removed when large pulsating flows occur. Incidentally, related systems of this type include, for example, rQ&A Vacuum 50 Space (Rikkyo Publishing Co., Ltd., published December 25, 1980) P42. There is a "Figure 1".

[Problem that the invention seeks to solve]

The above conventional technology does not take into account the flow rate of the cooling water, and when the cooling water is in a pulsating state, it becomes a turbulent flow and the resulting vibrations cause image disturbances such as the edges of the scanning electron microscope image being shaken. There was a problem that occurred.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vacuum evacuation system for a scanning electron microscope that can reduce image disturbances caused by the cooling water by keeping the flow rate of the cooling water constant.

[Means for solving problems]

The second objective was achieved by providing a tank using an elastic body in the cooling channel, and by absorbing the kinetic energy of the turbulent flow generated from the pulsating water flow with the elastic body, and making the flow always laminar. Ru.

[Effect]

When the cooling water is in a pulsating flow state, the elastic tank provided in the cooling water channel expands and contracts in response to the pulsating flow.

As a result, the kinetic energy of the pulsating water flow is absorbed by the elastic body, resulting in a constant flow state. Therefore, the cooling water does not interfere with the image of the scanning electron microscope.

〔Example〕

An embodiment of the present invention will be explained below.

FIG. 1 is a cross-sectional view of a cooling water tank that is a good example of the features of the present invention, and FIG. 2 is a diagram showing an exhaust system for a scanning electron microscope using the tank.

In FIG. 2, an oil diffusion pump 3 is attached to an inlet of a sample chamber 1 of a scanning electron microscope through a panfur 2. A cooling water intake hose 5 using a tank 7 is connected to the baffle 2, and a cooling water discharge hose 6 is connected to the oil diffusion pump 3.
A cooling water hose 4 is connected between the panflu 2 and the oil diffusion pump 3. In FIG. 1, the tank 7 has a structure in which a rubber tank 8, which is an elastic body pressed by a spring 9, is connected to a cooling water hose by a piping fitting 10.

In FIG. 1, when a pulsating flow occurs in the cooling water suction hose 5, the rubber tank 8 expands and contracts in the lateral direction because it is held down by the piping fitting 10 in the vertical direction in response to the pulsating flow. Its expansion and contraction are also controlled by the spring 9 so that the flow rate flowing out from the tank 7 is constant. Therefore, the pulsating flow of the cooling water suction hose 5 becomes a steady flow by passing through the tank 7.

According to this embodiment, even if the cooling water flowing into the cooling water suction hose 5 becomes a pulsating flow, the tank 7 always maintains a steady flow.
The cooling water flowing into the exhaust system is always a steady flow. Therefore, this embodiment has the effect of reducing image disturbances caused by vibrations, such as vibrations caused when the cooling water becomes a pulsating flow that shakes the edges of an image observed by a scanning electron microscope.

In the above embodiment, the tank 7 is used only for the cooling water intake hose 5, but as shown in FIG. It may be something that exists. In this embodiment, the pulsating flow of cooling water flowing into the exhaust system and the pulsating flow generated by the cooling water passing through the baffle 2 and oil diffusion pump 3 in the exhaust system are also connected to the tank used for each hose. 7 is always a steady flow, and the cooling water in a steady flow state flows in all the cooling channels of the exhaust system, which has the effect of reducing image disturbance due to vibration.

〔Effect of the invention〕

According to the present invention, even if there is a pulsating flow of cooling water, the tank made of an elastic body absorbs the kinetic energy and the flow can always be maintained as a steady flow. It can prevent vibration and has the effect of reducing image disturbances in scanning electron microscopes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cooling water tank according to an embodiment of the present invention;
FIG. 2 is a diagram showing an exhaust system for a scanning electron microscope using a tank, and FIG. 3 is a diagram showing an exhaust system for a scanning electron microscope using a tank in another embodiment. 1. Sample chamber, 2. Baffle, 3. Oil diffusion pump, 4
...Cooling water hose, 5...Cooling water suction hose, 6...
・Cooling water discharge hose, 7. Tank, 8. Rubber tank,
Figure 1 Figure 2 Figure 3 "-11 7

Claims (1)

[Claims] 1. In a vacuum pumping system for a scanning electron microscope using a vacuum pump such as an oil diffusion pump that requires a water cooling passage, a tank using an elastic body is provided in the water channel for cooling the vacuum pump. A vacuum evacuation system for a scanning electron microscope, characterized by the following: 2. Claim 1 states that in a vacuum exhaust system in which the vacuum pump and the baffle are directly connected, a tank made of an elastic body is provided in the water channel connecting the vacuum pump and the baffle. Features a vacuum evacuation system for scanning electron microscopes.