JP2001076660A - Charged-particle beam apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibrations of a lens barrel. SOLUTION: A dynamic vibration absorber 20 is formed to have a characteristic, frequency substantially equal to the characteristic frequency of supports 10A, 10B, 10C mounted with an exhaust system 3 thereon and mounted on a flange 11. Vibrations arize from a floor 12, via a vibration resistant table and a pedestal 8, into the supports and the dynamic vibration absorber 20. The dynamic vibration absorber 20 produces resonance due to a vibration with a frequency equal to or substantially equal to that of the supports among the incoming vibrations, thus absorbing vibration of such a frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a charged particle beam apparatus provided with a mechanism for preventing vibration from entering a lens barrel.

[0002]

2. Description of the Related Art FIG. 1 shows a schematic example of an electron microscope.

In FIG. 1, reference numeral 1 denotes a lens barrel, which includes an electron gun, a focusing lens,
An electron optical system such as a deflection system lens, a correction system lens for astigmatism correction, etc., a sample holder for holding a sample to be observed, and the like are provided. Reference numeral 2 denotes an image observation room, which is provided with a fluorescent plate so that a sample image based on the electron beam transmitted through the sample is formed on the fluorescent plate.

[0004] Reference numeral 3 denotes an exhaust device for exhausting the inside of the lens barrel 1. The exhaust device 3 includes, for example, an ion pump 4, a bacher pipe 5, and an exhaust pipe 6 connecting the ion pump 4 and the inside of the lens barrel 1.
Reference numeral 7 denotes a magnet forming a part of the ion pump, which is attached to a part of the outer surface of the ion pump 4.

A microscope main body comprising the lens barrel 1 and the image observation room 2 and the exhaust device 3 are installed on a base plate 9 on a gantry 8. However, the exhaust device 3 is installed as follows.

On a base plate 9, three columns 10 A, 10 B, 1 of the same length, perpendicular to the upper surface of the base plate 9.
0C is attached at an appropriate interval (for example, an interval connecting points of the same length of each pillar to form a regular triangle), and a flange 11 is attached to the tip of each pillar. An ion pump 4 is attached to the lower surface of the flange between the three pillars through the bacher tube 5. Accordingly, the lower surface of the flange 11 has the appearance that the buffer tube 5 and the ion pump 4 with the magnet 7 hang.

The gantry 8 is installed on the floor 12 via a vibration isolator (not shown).

[0008]

The flange 1
Since the exhaust device 3 hanging at 1 has a considerable weight, the supporting columns 10A, 10B, 10C supporting these exhaust devices 3
Will have a low vibration frequency.

In some cases, vibrations may enter the column from the floor 12 via a vibration isolator (not shown) and the gantry 8. Then, the column vibrates in the horizontal direction (the left-right direction on the paper surface of FIG. 1), and the vibration causes the exhaust device 3 to swing. The shaking is transmitted to the microscope main body, and in particular, the lens barrel 1 shakes more.
As a result, the influence of the fluctuation appears on the observation image of the electron microscope. That is, the image under observation shakes and hinders the observation,
The captured image is blurred.

Further, since the exhaust device 3 is provided with the ion pump having the magnet 7, the magnetic field fluctuates due to the swing of the magnet 7, which adversely affects the operation of the electron optical system of the electron microscope. In addition, there is a case where the frequency of the vibration entering the support is the same or almost the same as the natural frequency of the support, and there is a certain difference, and in the former case, the support vibrates relatively large, and the above-described problem occurs. It becomes a big thing that cannot be ignored. However, in the latter case, the vibration of the strut is relatively small, and the above problem is considered to be acceptable.

Therefore, in order to reduce the influence as described above, the rigidity of each of the columns is increased (for example, the system of the columns is made extremely thick so that the weight of the columns becomes extremely large).
Although there is a method of increasing the natural frequency of the support, not only the support but also the flange 11 and the base plate 9 need to be increased. As a result, the overall size is increased and the cost is significantly increased.

The present invention solves such a problem, and provides a novel charged particle beam device.

[0013]

Means for Solving the Problems A charged particle beam apparatus according to the present invention includes a lens barrel, an exhaust device for exhausting the inside of the lens barrel, and a plurality of columns on a base plate on which the lens barrel is mounted. In a charged particle beam apparatus in which the exhaust device is mounted on a table supported by the column, a dynamic vibration absorber having a natural frequency substantially equal to the natural frequency of the column is mounted on the table. I have.

The charged particle beam device according to the present invention is characterized in that the exhaust device has a magnet.

The charged particle beam apparatus according to the present invention is characterized in that the dynamic vibration absorber comprises an elastic body and a weight.
Further, in the charged particle beam device according to the present invention, the elastic body of the dynamic vibration absorber is formed of a plurality of columnar elastic bodies having one end mounted on the table and the other end mounted on a weight. .

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows a schematic example of an electron microscope as an example of the charged particle beam apparatus of the present invention. In the figure, the same reference numerals as those used in FIG. It is. In the figure, reference numeral 20 denotes the columns 10A, 10B, 1
This is a dynamic vibration absorber for absorbing the vibration that has entered OC, and is mounted on the flange 11.

FIG. 3 shows an example of the configuration of such a dynamic vibration absorber 20. In the figure, 21A, 21B, 21C are rubber pads, 22 is a weight, and flanges 23A1, 23A2, 23B1, 23B2, 2 are provided at both ends of each rubber pad, respectively.
3C1 and 213C2 are attached, and one of the flanges 23A1, 23B1 and 23C1 is
The other flanges 23A2, 23B2, 213C2 are fixed to the flange 11 by screws or the like.

Now, the columns 10A, 10B, 1 in a state in which the exhaust device 3 composed of the ion pump 4 with the Bacher tube 5 and the magnet 7 is attached to the flange 11 in advance.
The natural frequency of 1C is measured by, for example, modal analysis or the like. The dynamic vibration absorber 20 is formed so as to have a natural frequency substantially equal to the natural frequency of the column determined by this measurement. That is, for example, the weight of the weight body 22 is changed by using a weight body 22 having a different thickness or a weight body of a different material so that the natural frequency is substantially the same as the natural frequency of the column. Alternatively, the natural frequency of the dynamic vibration absorber 20 is adjusted by increasing or decreasing the number of rubber pads.

In this manner, the dynamic vibration absorber 20 having a natural frequency substantially equal to the natural frequency of the column in a state where the exhaust system 3 is mounted is formed and mounted on the flange 11.

Thus, the vibration isolating table (not shown) is separated from the floor 12.
When vibration is applied to the column via the gantry 8, the vibration also enters the dynamic vibration absorber 20. At this time, of the incoming vibrations, the vibration having the same or almost the same frequency as that of the support column causes the dynamic vibration absorber 20 to resonate and absorb the vibration of such a frequency.

Due to such absorption, the column hardly vibrates in the horizontal direction (the left-right direction on the paper surface of FIG. 1). Therefore, the exhaust device 3 hardly shakes, and therefore, the microscope main body and, in particular, the lens barrel 1 do not shake. As a result, the observation image of the electron microscope shows that the support 10A, 1
There is no effect due to the vibration entering 0B and 10C.
Also, since the magnet 7 of the ion pump 4 hardly fluctuates, the magnetic field does not fluctuate and does not affect the operation of the electron optical system of the electron microscope. The dynamic vibration absorber 20 as described above is used.
Are extremely small and inexpensive. In the above example, the dynamic vibration absorber is substantially composed of the rubber pad and the weight,
Another elastic body, for example, a spring may be used instead of the rubber pad.

In the above embodiment, the flange is supported on the plurality of columns, but the flange may be supported on the middle of each column.

In the above example, an electron microscope supporting the exhaust device with three columns has been described as an example. However, the present invention is also applicable to an electron microscope supporting the exhaust device with another plurality of columns. Needless to say. Further, in the above-described example, an example in which an ion pump is provided as an exhaust device has been described.
Needless to say, the present invention can be applied to other pumps having no magnet, such as an oil diffusion pump and an oil rotary pump, and an electron microscope using an exhaust device provided with another pump having a magnet.

In the above example, an electron microscope is taken as an example. However, the present invention has a structure in which at least a mirror body and an exhaust device for exhausting the interior of the mirror body are provided, and the exhaust device is supported by columns. Scanning electron microscope, electron beam writer,
It goes without saying that the present invention can be applied to a charged particle beam apparatus such as an ion beam processing apparatus.

[Brief description of the drawings]

FIG. 1 shows a schematic example of an electron microscope.

FIG. 2 shows a schematic example of an electron microscope as an example of the charged particle beam device of the present invention.

FIG. 3 shows a structural example of a dynamic vibration absorber used in the electron microscope of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Barrel 2 ... Image observation room 3 ... Exhaust device 4 ... Ion pump 5 ... Bacher tube 6 ... Exhaust tube 7 ... Magnet 8 ... Stand 9 ... Base plate 10A, 10B, 10C ... Column 11 ... Flange 12 ... Floor 20 ... Moving Vibration absorbers 21A, 21B, 21C rubber pad 22 weights 23A1, 23A2, 23B1, 23B2, 23C1,
213C2 ... Flange

Claims (5)

[Claims] An evacuation device for evacuating the interior of the lens barrel, a plurality of columns being erected on a base plate on which the lens barrel is mounted, and the exhaust supported by a column supported by the column. A charged particle beam device, comprising: a dynamic vibration absorber having a natural frequency substantially equal to a natural frequency of the column is mounted on the table. 2. The charged particle beam device according to claim 1, wherein the exhaust device includes a magnet. 3. The charged particle beam apparatus according to claim 1, wherein said dynamic vibration absorber comprises an elastic body and a weight body. 4. The charged particle beam apparatus according to claim 3, wherein the elastic body of the dynamic vibration absorber comprises a plurality of columnar elastic bodies having one end mounted on the base and the other end mounted on a weight. 5. The charged particle beam device according to claim 1, wherein the elastic body of the dynamic vibration absorber comprises a rubber pad.