JPH11273604A - Ultrahigh vacuum charged particle device and method for adjusting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure with an improved function of the ultrahigh vacuum packing of an ultrahigh vacuum charged particle device. SOLUTION: An ultrahigh vacuum charged particle device has a hermetic connection where a metal gasket 3 is used as ultrahigh vacuum packing, and the vacuum packing of an O-ring 7 is added to the outside of the metal gasket. This adjusting method includes adjusting the relative position of the connection by first holding a gap in the hermetic connection under a state in which the O-ring 7 works as the vacuum packing while the metal gasket 3 does not work as vacuum packing, and after the adjustment is finished, reducing the gap in the connection to achieve a state in which the metal gasket 3 works as the vacuum packing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high vacuum sealed structure in an ultra-high vacuum charged particle device.

[0002]

2. Description of the Related Art Auger electron spectroscopy (hereinafter referred to as Auger) as an ultra-high vacuum charged particle device is several keV.
Auger electrons, secondary electrons, reflected electrons, and the like generated by irradiating a sample with an electron beam accelerated to several tens keV from
This is an apparatus that detects important information signals such as X-rays and analyzes the sample surface. For detection of these information signals, each detector is arranged around the sample. On the other hand, the sample stage efficiently detects these information signals,
A mechanism is required that can change the direction and inclination of the sample surface in the direction of each detector, and at the same time, obtain the analysis results in the same micro area without changing the sample analysis position (electron beam irradiation position).

In order to satisfy such conditions, the Auger apparatus is strongly required to have a "eucentric function", and in the adjustment stage of the apparatus, the optical axis of the electron beam coincides with the center of the tilt axis of the sample stage. It is important to make it happen.

Normally, the "eucentric function" of a charged particle device is set such that the tilt axis of the sample stage is on the sample surface and the tilt axis is located at the center of the visual field on the focal plane. . For this reason, even if the sample is tilted from the horizontal state, an image can be observed without any movement or defocusing of the focused portion at the center of the visual field. The position where the tilt axis is at the center of the field of view on the focal plane as described above is called the "eucentric position".

FIG. 2 is a view for explaining an example of the eucentric position alignment using an Auger apparatus. In the figure, 1 is a lens barrel, 2 is a sample chamber, 3 is a metal gasket as a vacuum packing for ultra-high vacuum, 4 is a connection bolt for hermetically fixing the lens barrel 1 and the sample chamber, 5 is a sample stage, 6 Is the tilt axis of the sample stage, and 10 is the optical axis of the electron beam.

In order to obtain the "eucentric function" of this Auger apparatus, mechanical alignment is performed so that the displacement L between the optical axis 10 of the electron beam and the tilt axis 6 of the sample stage 5 coincides with each other. In FIG. 2, this mechanical alignment is performed by moving the position of the lens barrel 1 with respect to the sample chamber 2 and adjusting the lens barrel 1 so that the displacement L becomes zero. Next, such eucentric position alignment will be described.

First, in order to obtain the shift amount L, the Auger device is started up to such an extent that a secondary electron image can be obtained (it is not necessary to use an ultra-high vacuum as the Auger device).
From the secondary electron image, the optical axis 10 of the electron beam (center of the secondary electron image)
And the tilt axis 6 of the sample stage 5 (the point where the image is not moved because the stage is tilted) are obtained.

Next, in order to adjust the eucentric position, the apparatus is stopped, the sample chamber 2 is evacuated, the connection bolt 4 is loosened, and the position of the lens barrel 1 with respect to the sample chamber 2 is shifted by an amount L. Make the move. This series of operations is repeated two or three times to perform eucentric position alignment.

[0009]

However, the following problems occur in a series of operations in the eucentric position alignment as described above.

An Auger apparatus analyzes a sample in a clean state in an ultra-high vacuum. Therefore, the vacuum packing
Usually, as shown in FIG. 2, a metal gasket 3 is used as a sealing member for ultra-high vacuum. The metal gasket 3 is made of oxygen-free copper having a thickness of 2 mm, and in vacuum sealing, the projections 8 of the upper and lower flange grooves cut into the sealing surface of the metal gasket 3 to maintain airtightness. As a result, when the metal gasket 3 is used once, a trace of the projection 8 of the flange groove remains on the sealing surface. The number of times the metal gasket 3 is used is usually about two to three times when the upper and lower flanges are used in a fixed position (the traces are the same) without vacuum baking.

However, in the case of the positioning of the eucentric position, since the position of the lens barrel 1 is moved with respect to the sample chamber 2, the trace of the metal gasket 3 is displaced, and a double trace is formed. Will not be maintained. Therefore, it is necessary to replace the metal gasket 3 each time alignment is performed. To replace the metal gasket 3, the lens barrel 1 is completely separated from the sample chamber 2, and then replaced with a new metal gasket 3. Therefore, the positional relationship between the sample chamber 2 and the lens barrel 1 cannot be maintained, and in order to maintain the positional relationship, it is necessary to measure an accurate positional relationship in advance or use a dedicated jig or the like.

The adjustment time of the alignment is determined by starting the Auger apparatus until a secondary electron image can be obtained, or after activating the sample chamber 2 to the atmosphere and starting again until a secondary electron image can be obtained. It takes a very long time to repeat position confirmation and the like.

Accordingly, the present invention is to solve the above-mentioned conventional problems, and has an ultra-high height capable of aligning the eucentric position without replacing the metal gasket 3 of the vacuum packing of the Auger device. It is an object of the present invention to provide a vacuum charged particle device and a method of adjusting the same.

[0014]

According to the present invention, there is provided an air-tight connection using a metal gasket as an ultra-high vacuum packing, and an O-ring vacuum packing is provided outside the metal gasket. It is characterized by having done.

The method for adjusting an ultra-high vacuum charged particle device according to the present invention has an airtight connection using a metal gasket for an ultra-high vacuum packing, and an O.D.
In an ultra-high vacuum charged particle device provided with a vacuum packing of a ring, the O-ring acts as a vacuum packing first in a gap of an airtight connection, and the metal gasket is set to a state where it does not act as a vacuum packing. Are adjusted, and after the adjustment is completed, the gap between the connecting portions is narrowed so that the metal gasket functions as a vacuum packing.

[0016]

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

FIG. 1 shows an embodiment of the positioning of the eucentric position in the Auger device of the present invention. FIG. 1A shows the sample chamber and the mirror when the positioning of the eucentric position is performed. FIG. 1B is a sectional view showing the vacuum packing surface of the cylinder along the electron optical axis, and FIG. 1B shows a state where airtightness is maintained as an ultra-high vacuum after the completion of the eucentric position alignment. In FIG. 1, the same reference numerals as those in the explanatory view of FIG. 2 denote the same components, but the difference from the conventional example of FIG.
It is a point that is additionally attached to the outside of.

In the configuration shown in FIG. 1, reference numeral 7 denotes an O-ring as a vacuum packing, and reference numeral 9 denotes a gap between a vacuum packing surface of the sample chamber 2 and the lens barrel 1. The operation of positioning the eucentric position in such a configuration will be described below.

In the embodiment shown in FIG.
The connection between the lens barrel 1 and the lens barrel 1 is adjusted by tightening the connection bolts 4 so that the gap 9 is maintained such that the protrusion 8 does not come into contact with the metal socket 3 although the O-ring 7 is slightly crushed. You. As a result, the connection between the sample chamber 2 and the lens barrel 1 is kept air-tight by the O-ring 7, and the metal gasket 3 does not function as a vacuum packing in a state of floating with respect to the upper and lower protrusions 8. .

After the connecting section is set in such a state, in order to obtain the "eucentric function" of the Auger apparatus, the optical axis 10 of the electron beam and the sample stage 5 are formed in the same manner as in the prior art.
Are made to coincide with each other.

First, the optical axis 10 of the electron beam and the sample stage 5
Is determined using a secondary electron image in the same manner as in the prior art. Next, in order to mechanically correct the displacement L, the generation of the electron beam is stopped, the connection bolt 4 fixing the sample chamber 2 and the lens barrel 1 is loosened, and the lens barrel is moved relative to the sample chamber 2. 1
Is moved by the displacement amount L. It is desirable to move the sample chamber 2 to atmospheric pressure as necessary.

During the adjustment of the eucentric position of the present embodiment, only the O-ring 7 is used as the vacuum packing, and the metal gasket 3 is not used as the vacuum packing. No need to do.

As a result, when the displacement amount L of the lens barrel 1 is moved with respect to the sample chamber 2, it is not necessary to separate the lens barrel 1 from the sample chamber 2 as in the related art. The alignment accuracy is improved, and it can be adjusted within the expected range in a single operation. To confirm the alignment of the eucentric position, the apparatus is restarted in the same manner as in the related art, and the amount L of displacement between the optical axis 10 of the electron beam and the tilt axis 6 of the sample stage 5 is confirmed using a secondary electron image.

Next, after it is confirmed that the deviation amount is within the tolerance, the connection bolt 4 is used to tighten the gap 9 between the sample chamber 2 and the lens barrel 1 until the gap 9 disappears. As a result, FIG.
As shown in (B), the upper and lower protrusions 8 bite into the sealing surface of the metal gasket 3 and a sufficient airtightness can be obtained as an ultra-high vacuum.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example,
Although the apparatus has been described as an Auger apparatus, as a general ultra-high vacuum charged particle apparatus, a photoelectron spectroscopy apparatus (commonly called ESCA Esca), an ultra-high vacuum transmission electron microscope, an ultra-high vacuum scanning electron microscope, etc. It can be used for mechanical alignment as well.

Further, in the above-described embodiment, the case where the metal gasket is used as the ultra-high vacuum packing has been described.
Helicox (trade name of CEFILAC of France), metal hollow O-ring,
And so on.

[0027]

As described above, according to the present invention, apart from the metal gasket of the ultra-high vacuum packing, O
A vacuum packing with a ring is also installed. When mechanically moving the connecting part for the eucentric position alignment (electron beam optical axis alignment) of the ultra-high vacuum charged particle device, only the O-ring is used as a vacuum packing, and the ultra-high vacuum is used. Do not use metal gaskets for packing. As a result, the metal gasket for ultra-high vacuum packing is not replaced every time alignment is performed, so there is no need to cut off the ultra-high vacuum packing surface, so that the alignment accuracy is improved and the alignment can be performed only once. became.

[0028]

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of positioning of a eucentric position of an ultra-high vacuum charged particle device of the present invention, showing a cross section perpendicular to an electron beam optical axis.

FIG. 2 is a view showing one embodiment of positioning of a eucentric position of a conventional ultra-high vacuum charged particle device, and showing a cross section perpendicular to an electron beam optical axis.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Barrel, 2 ... Sample chamber, 3 ... Metal gasket, 4 ... Connection bolt, 5 ... Sample stage, 6 ... Tilt axis, 7 ... O-ring, 8 ... Projection, 10 ... Optical axis of electron beam, L ... The amount of deviation,

Claims (2)

[Claims] 1. An ultra-high vacuum charged particle device having an airtight connection using a metal gasket as an ultra-high vacuum packing, and having an O-ring vacuum packing provided outside the metal gasket. 2. An ultra-high vacuum charged particle device comprising an airtight connection using a metal gasket as an ultra-high vacuum packing, and an O-ring vacuum packing provided outside the metal gasket. First, the O-ring acts as a vacuum gasket at the gap between the joints, and the metal gasket adjusts the relative position of the joint so that the metal gasket does not act as the vacuum gasket. A method for adjusting an ultra-high vacuum charged particle device, characterized in that the gap between the connecting portions is narrowed so as to act as a device.