JPH1140094A - Exhaust system and exhaust method of vacuum device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of pumps for the low vacuum chamber side while a high vacuum state of the main vacuum chamber is maintained, to simplify the device constitution at a low cost, and to improve a degree of a vacuum, by connecting an exhaust pipe of the high vacuum pump for a main vacuum chamber side with the suction side of a reserve vacuum chamber, consequently connecting two high vacuum pumps in two stages. SOLUTION: A sample observation chamber 101 and a reserve exhaust chamber 108 are exhausted respectively by a turbo molecular pump 105, and a turbo molecular pump 106, an oil-less pump 107. In this device, a rear exhaust pipe of the turbo molecular pump 105 of the sample observation chamber 101 is connected with the suction side of the turbo molecular pump 106 of the reserve exhaust chamber 108, and the sample observation chamber 101 is exhausted by the turbo molecular pump 105, the turbo molecular pump 106 and the oil-less pump 107. By this structure, it become possible to deal with a normal pump, and reduce the cost of the equipment, then save the space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for observing a sample or processing a work in a high vacuum, and a main vacuum chamber for performing an observation or processing and a preliminary exhaust chamber for taking a sample or a work into and out of the chamber. The present invention relates to a method for connecting a vacuum pump to a device provided with a vacuum pump, and more particularly to a high-resolution electron microscope in which a high vacuum is required in a main vacuum chamber, and a vacuum evacuation of a main vacuum chamber of a molecular beam epitaxial apparatus.

[0002]

2. Description of the Related Art In the prior art, the exhaust of a vacuum apparatus having a main vacuum chamber for performing observation and processing and a preliminary exhaust chamber for taking samples and works in and out of the main vacuum chamber is performed in each of the main vacuum chamber and the preliminary exhaust chamber. If high vacuum pumps are provided and these high vacuum pumps are discharge type pumps such as oil diffusion pumps and turbo molecular pumps, and further low vacuum pumps are required on the exhaust side, each high vacuum pump One pump for low vacuum was provided for each pump for pumping.
5-47645).

There is also a proposal for a system in which the exhaust of two high vacuum pumps is exhausted by one low vacuum pump (Japanese Patent Application No. 6-146630). In order to increase the degree of vacuum in the main vacuum chamber, a large high vacuum pump is generally used. There is also a type in which high vacuum pumps are arranged in two stages in series to obtain a high vacuum.

[0004]

In an apparatus requiring a high vacuum, such as a high-resolution electron microscope for observing a sample in a high vacuum or a molecular beam epitaxial apparatus (MBE apparatus) for processing a work, a high Various efforts are made to achieve a vacuum. For example, in the case of the MBE apparatus, special processing is performed on the inner wall of the main vacuum chamber, or a large turbo molecular pump is attached.

In these apparatuses, a preliminary evacuation chamber is provided adjacent to the main vacuum chamber in order to put the sample into the main vacuum chamber. Then, the partition between the main vacuum chamber is opened and the sample is guided to the main vacuum chamber.

[0006] Some devices seem to share a dry pump or an oil rotary pump attached to the exhaust side of the high vacuum pump in the main vacuum chamber and the preliminary exhaust chamber, but in order to maintain a high vacuum in the main vacuum chamber, Those provided independently were common. For this reason, a single device must be provided with a plurality of pumps, and there are difficulties in terms of cost, arrangement, piping, and the like. However, it has been regarded as unavoidable in terms of the device configuration.

In an electron microscope, a decrease in the degree of vacuum in the sample chamber may worsen the contamination of the sample by electron beam irradiation. In this respect, it is desirable to make the vacuum as high as possible.

On the other hand, there is a countermeasure such as attaching a low-temperature trap plate near the sample. However, in order to lower the temperature of the trap plate, it is necessary to supply liquid nitrogen or the like. Met.

[0009] Furthermore, a high-resolution electron microscope includes:
A field emission electron gun is used, but a high vacuum is required to handle it. If the degree of vacuum in the sample chamber is insufficient, the degree of vacuum of the electron gun is affected, and the stability and life of the electron gun may be adversely affected.

In order to increase the degree of vacuum in the vacuum chamber, a large high vacuum pump is generally used. However, there are several obstacles to this. For example: large pumps are expensive.

[0011] Large pumps take up space.

[0012] A large pump has large noise and vibration.

And so on. Problems such as noise and vibration are inevitable for a high-resolution electron microscope or the like, and may impair the original performance of the apparatus.

When two high-vacuum pumps are connected in series, there is a problem that they are expensive and take up space as described above.

An object of the present invention is to reduce the number of pumps on the low vacuum side while maintaining a high vacuum in the main vacuum chamber, to simplify the device configuration at low cost, and to further reduce the vacuum in these devices requiring a high vacuum. It is intended to provide a method and system for evacuation that can be improved even more.

[0016]

In order to achieve the object of the present invention, the exhaust pipe of the high vacuum pump on the main vacuum chamber side is connected to the suction side of the high vacuum pump in the auxiliary vacuum chamber. As a result, the exhaust of the main vacuum chamber is connected as a high vacuum pump of the main vacuum chamber, a high vacuum pump of the preliminary exhaust chamber, a low vacuum pump of the preliminary exhaust chamber, and the high vacuum pump is connected in two stages. In other words, the evacuation capacity (attained vacuum degree) of the main vacuum chamber is greatly improved. Furthermore, the low vacuum side pump for the main vacuum chamber is
It is unnecessary because it is shared with the low vacuum side pump of the preliminary exhaust chamber.

Normally, when a workpiece is being processed, the main vacuum chamber is evacuated by a two-stage high vacuum pump as described above, and is evacuated with high evacuation capability.

When the work is taken out, first, the work is moved to the preliminary exhaust chamber to be isolated from the main vacuum chamber. Then, only the preliminary exhaust chamber breaks the vacuum. At this time, the high vacuum pump in the preliminary exhaust chamber is operating, but is isolated from the preliminary exhaust chamber by the valve, and only exhausts the high vacuum pump in the main vacuum chamber.

When the pre-evacuation chamber is at atmospheric pressure, the gate is opened, and the work is replaced, the gate is closed again and the evacuation of the pre-evacuation chamber is started. First, the valve between the high vacuum pump and the low vacuum pump in the preliminary exhaust chamber is closed, the valve between the low vacuum pump and the preliminary exhaust chamber is opened, and rough exhaust of the preliminary exhaust chamber is started. At this time, the two high vacuum pumps continue to operate. Although the exhaust at the back of the high vacuum pump in the preliminary exhaust chamber stops, the exhaust side of the high vacuum pump in the main vacuum chamber is exhausted by the high vacuum pump in the preliminary exhaust chamber.
In a short time, there is almost no effect. Also, if the rough evacuation time is long enough to affect, a reservoir tank should be provided on the back of the high vacuum pump in the preliminary exhaust chamber, so that the pressure on the back of the high vacuum pump in the preliminary exhaust chamber does not easily rise. I just need.

Next, when the degree of vacuum in the preliminary exhaust chamber approaches the ultimate vacuum of the low vacuum pump, the valve between the low vacuum pump and the preliminary exhaust chamber is closed, and the high vacuum pump in the preliminary exhaust chamber and the preliminary exhaust chamber are closed. Is opened, and the pre-evacuation chamber is evacuated to high vacuum. At this time, the pressure on the back side of the high vacuum side pump in the main vacuum chamber temporarily rises, but since this pressure is close to the ultimate vacuum degree of the conventional low vacuum pump, at least the exhaust performance over the conventional one is , Can be maintained. At this time, a valve is provided between the back side of the high vacuum pump in the main vacuum chamber and the suction side of the high vacuum pump in the preliminary exhaust chamber. Can be prevented from rising.

Further, when the evacuation time is long enough to affect the evacuation of the main vacuum chamber, a reservoir tank is provided on the back of the high vacuum pump of the main vacuum chamber, and the back of the high vacuum pump of the main vacuum chamber is provided. Care should be taken so that the pressure is hardly increased.

[0022]

FIG. 1 shows an embodiment of a charged particle beam apparatus according to the present invention. In particular, FIG. 1 shows an example in which the present invention is applied to a scanning electron microscope for a large sample such as a semiconductor.

The sample observation room 101 has a stage 103 on which a sample 102 is placed and moved. The sample observation chamber 101 is evacuated by a turbo molecular pump 105. Above the sample observation room 101, there is a mirror 104 of an electron microscope.
Further, a preliminary exhaust chamber 108 for exchanging a sample is provided in a part of the sample observation chamber 101. The preliminary exhaust chamber 108 is also exhausted by the turbo molecular pump 106 and the dry pump 107. Here, the turbo molecular pump 10 in the sample observation chamber 101
5 is connected to the suction side of the turbo-molecular pump 106 of the preliminary exhaust chamber 108, and is connected to the sample observation chamber 101.
Is exhausted by the turbo molecular pump 105 in the sample observation chamber 101, the turbo molecular pump 106 in the preliminary exhaust chamber 108, and the dry pump 107.

When exchanging the sample 102, the stage 1
The sample 102 on 03 is moved to the preliminary exhaust chamber 108, the gate valve 110 is closed, and the preliminary exhaust chamber 108 is isolated from the sample observation chamber 101 in a vacuum. Then, the purge valve 111 is opened, and a gas such as air is discharged only to the preliminary exhaust chamber 108 to make the pressure equal to the atmospheric pressure. At this time, the preliminary exhaust chamber 10
8 on the intake side of the turbo molecular pump 106
Is closed, the exhaust system of the sample observation chamber 101, the turbo molecular pump 105 → the turbo molecular pump 106 → the dry pump 107 of the preliminary exhaust chamber 108 are not affected.

When the atmospheric pressure is reached, the sample is replaced. When the exchange of the sample is completed, the inside of the preliminary exhaust chamber 108 is evacuated. First, the valve 113 between the turbo molecular pump 106 and the dry pump 107 is closed. Next, the valve 11 between the preliminary exhaust chamber 108 and the dry pump 107
4 is opened, and rough evacuation of the preliminary evacuation chamber 108 is started. At this time, the evacuation of the back surface of the turbo-molecular pump 106 in the preliminary evacuation chamber 108 stops, but the evacuation side of the turbo-molecular pump 105 in the sample observation chamber 101 is evacuated by the turbo-molecular pump 106 in the pre-evacuation chamber 108, so If it is time, it will not be affected.

When the rough evacuation time is so long as to affect, a reservoir tank 105 is provided on the back of the turbo-molecular pump 106 of the preliminary evacuation chamber 108 as shown in FIG. Care should be taken so that the pressure on the back of the turbo molecular pump 106 does not easily rise. The degree of vacuum in the preliminary exhaust chamber 108
7, the valve 114 between the preliminary exhaust chamber 108 and the dry pump 107 is closed, and the turbo molecular pump 106 and the dry pump 10 in the preliminary exhaust chamber 108 are closed.
7 is opened.

Next, the valve 112 on the intake side of the turbo molecular pump 106 in the preliminary exhaust chamber 108 is opened, and the preliminary exhaust chamber 1 is opened.
08 High vacuum evacuation is started. At this time, the sample observation room
Although the pressure on the back side of the turbo molecular pump 105 of 101 rises, since this pressure is close to the ultimate vacuum degree of the conventional low vacuum pump, at least the exhaust performance higher than the conventional one can be maintained. Further, a valve 106 is provided between the back surface of the turbo-molecular pump 105 in the sample observation chamber 101 and the suction side of the turbo-molecular pump 106 in the preliminary exhaust chamber 108, and if this valve 106 is closed temporarily, the turbo in the sample observation chamber 101 The pressure on the back of the molecular pump 105 can be prevented from rising.

Further, when the evacuation time is long enough to affect the evacuation of the sample observation chamber 101, as shown in FIG.
A reservoir tank 117 may be provided on the back of the 105, and care should be taken so that the pressure on the back of the turbo-molecular pump 105 in the sample observation chamber 101 is unlikely to rise.

When the degree of vacuum in the preliminary exhaust chamber 108 reaches the level of the sample observation chamber 101, the gate valve 110 is opened, and the sample 102 is brought to the observation position below the mirror 104 of the electron microscope. When the movement of the sample 102 is completed, the gate valve 110 is closed, the valve 116 on the back of the turbo molecular pump 105 in the sample observation chamber 101 is opened, and the sample observation chamber 101 is evacuated. This is a series of operations for sample observation and replacement.

FIG. 4 shows the configuration of a conventional exhaust system.

The turbo molecular pump 10 in the sample observation chamber 101
An independent roughing pump 107 'is provided on the back of the pump 5, so that the back pressure of the turbo-molecular pump 105 is not affected even when the exhaust sequence is running. However, it is necessary to prepare two roughing pumps for this purpose.

In the embodiments, an electron microscope for semiconductors has been mainly described as an example, but the effects of the present invention are also effective for electron microscopes other than those for semiconductors.

In this embodiment, an electron microscope is taken as an example. However, the effect of the present invention is that a vacuum having a vacuum chamber such as a preliminary exhaust chamber such as an apparatus other than the electron microscope, for example, an electron beam lithography apparatus or a FIB apparatus is used. The device is equally effective.

[0034]

According to the present invention, conventionally one roughing pump is required for each high vacuum pump, but this can be processed by one roughing pump.

As a result, the cost of the apparatus can be reduced, and the space and maintenance can be improved.

Further, since the two-stage high vacuum pumps are connected in series, it is possible to improve the ultimate vacuum of the sample observation chamber. As a result, for example, in a high-resolution electron microscope, contamination of the sample due to residual gas is reduced, and stability and life of the electron gun are improved.

[Brief description of the drawings]

FIG. 1 is an exhaust system diagram of a scanning electron microscope in one embodiment of a charged particle beam apparatus according to the present invention.

FIG. 2 is an exhaust system diagram of a scanning electron microscope, showing a development of a charged particle beam apparatus according to an embodiment of the present invention.

FIG. 3 is an exhaust system diagram of a scanning electron microscope, showing a further development of a charged particle beam apparatus according to an embodiment of the present invention.

FIG. 4 is an exhaust system diagram of a conventional scanning electron microscope.

[Explanation of symbols]

101: sample observation room, 102: sample, 103: stage, 104: mirror body of electron microscope, 105: turbo molecular pump for exhausting the sample observation room, 106: turbo molecular pump for exhausting the preliminary exhaust room, 107: exhaust of the preliminary exhaust room Dry pump, 108: preliminary exhaust chamber, 110: gate valve between the sample observation chamber and the preliminary exhaust chamber, 111: preliminary exhaust chamber purge valve, 112: preliminary exhaust chamber main exhaust valve, 113: preliminary exhaust chamber, back of turbo molecular pump Valve: 114: preliminary exhaust chamber roughing exhaust valve; 115: preliminary exhaust chamber: reservoir tank for turbo-molecular pump; 116: rear valve of sample observation chamber turbo-molecular pump; 117: reservoir tank for sample observation chamber turbo-molecular pump.

Claims (3)

[Claims] An apparatus for observing a sample or processing a workpiece in a high vacuum, wherein a preliminary exhaust chamber is provided adjacent to the main vacuum chamber for moving the sample and the workpiece into and out of the vacuum. Therefore, a discharge pump such as a turbo molecular pump or an oil diffusion pump is used for high vacuum evacuation of these rooms, and when the sample or the work is put into the main vacuum chamber of the apparatus, the preliminary evacuation is first performed. The chamber is opened to atmospheric pressure, the sample and the work are inserted therein, the pre-evacuation chamber is evacuated to a high vacuum, and then the sample and the work are inserted into the main vacuum chamber. When the work is taken out, the sample and the work are moved from the main vacuum chamber to the preliminary exhaust chamber, and after the main vacuum chamber is sealed, the vacuum in the preliminary exhaust chamber is broken to atmospheric pressure, and the preliminary Opening the atmosphere side door of the exhaust chamber to remove the sample or workpiece In the apparatus, an exhaust system of the exhaust pipe of the high vacuum pump of the main vacuum chamber vacuum system, characterized in that connected to the intake side of the high vacuum pump of the pre-evacuation chamber. 2. An apparatus for observing a sample or processing a work in a high vacuum, wherein a preliminary exhaust chamber is provided adjacent to the main vacuum chamber for moving the sample and the work into and out of the vacuum. Therefore, a discharge pump such as a turbo molecular pump or an oil diffusion pump is used for high vacuum evacuation of these rooms, and when the sample or the work is put into the main vacuum chamber of the apparatus, the preliminary evacuation is first performed. The chamber is opened to atmospheric pressure, the sample and the work are inserted therein, the pre-evacuation chamber is evacuated to a high vacuum, and then the sample and the work are inserted into the main vacuum chamber. When the work is taken out, the sample and the work are moved from the main vacuum chamber to the preliminary exhaust chamber, and after the main vacuum chamber is sealed, the vacuum in the preliminary exhaust chamber is broken to atmospheric pressure, and the preliminary Opening the atmosphere side door of the exhaust chamber to remove the sample or workpiece In the apparatus, when the main vacuum chamber is evacuated, the suction side of the high vacuum pump of the preliminary vacuum chamber is connected to the exhaust side of the high vacuum pump, and two high vacuum pumps are connected in tandem. A method of evacuating a vacuum apparatus, wherein the evacuating is performed. 3. The vacuum apparatus according to claim 3, wherein a reservoir tank is provided on the exhaust side of the high-vacuum pump in the preliminary exhaust chamber, the main vacuum chamber, or both. How to exhaust the device.