JP2854466B2 - Charged particle beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a charged particle beam apparatus for observing a sample using a focused charged particle beam (electron beam or ion beam) such as an electron microscope and an ion microscope. A charged particle beam using the above convergent charged particle beam for the purpose of inspecting and observing the fine structure and processed shape of a sample during or after (or after observation or processing) in an observation device or a processing device. The present invention relates to an improved structure for facilitating mounting of the apparatus on the above-mentioned other observation apparatus, processing apparatus, and sample transport path attached to the apparatus.

[0002]

2. Description of the Related Art Conventionally, observation and inspection of a sample using a charged particle beam have been performed using independent observation / inspection devices, respectively. For example, a scanning electron microscope (SE
The observation and inspection of the sample by M) are performed by an independent dedicated SEM
This has been done using equipment. For this reason, when observing or inspecting a sample being observed or processed (or after processing) in another observation device or processing device by the SEM device, the sample is taken out from the other observation or processing device. hand,
The troublesome task of having to reload the SEM device has been required.

However, very recently, an SEM device in which the entire lens barrel is formed in an ultra-small structure by forming the converging lens optical system entirely with an electrostatic lens has been developed. By attaching to the processing and processing equipment to form a composite, the sample being observed and processed (or after observation and processing) by other observation and processing means in the composite equipment can be taken out of the equipment without being taken out. , As it is,
Observation can be performed by the microminiature SEM device (for example, see Japanese Patent Application Laid-Open Nos. 04-4548 and 04-51439). However, when mounting the ultra-small SEM device on the other observation and processing device to form a composite, it was necessary to once expose the inside of the ultra-small SEM device to atmospheric pressure. However, it is extremely important to keep the inside of the device at a high degree of vacuum at all times in terms of its performance and operability when using devices that use extremely finely focused charged particle beams, such as SEM devices. It is.

[0004]

SUMMARY OF THE INVENTION The above-mentioned ultra-small SEM
As in the apparatus, by configuring all the converging optical systems of the charged particle beam apparatus with electrostatic lenses, the structure of the lens barrel portion including the charged particle source and the converging optical system can be made very small and lightweight. It became easy to attach the lens barrel to other observation and processing devices, etc., to form a composite device. However, exposing the interior of the lens barrel to the atmosphere each time it is attached or detached makes it difficult to maintain a good performance state of the charged particle source, or the interior of the lens barrel is evacuated again. It is not preferable because it requires troublesome work and time for pulling.

An object of the present invention is to keep the inside of a lens barrel housing a charged particle source at a high vacuum at all times.
An object of the present invention is to provide an improved charged particle beam device structure that can be attached (and detached) to other observation and processing devices and the like. Another object of the present invention is to observe the relative position relationship between the lens optical system of the charged particle beam device and the sample to be inspected after the charged particle beam device is mounted on another observation, processing device, or the like. It is an object of the present invention to provide an improved charged particle beam device structure suitable for optimal optimization.

[0006]

To achieve the above object, the present invention provides a charged particle source for generating at least charged particles and a charged particle convergence for converging charged particles from the charged particle source. In a charged particle beam device having a lens barrel that houses an optical system, below the last lens unit in the charged particle focusing optical system, the lens barrel is used as a partner device to which the charged particle beam device is to be combined. By providing a vacuum flange portion for vacuum-tight mounting on the other hand, and providing a vacuum shut-off valve for maintaining a vacuum in the internal space of the lens barrel portion in the vacuum flange portion, the charged particle beam device can When attached to and detached from the partner device to be combined, the vacuum shut-off valve is closed to maintain a vacuum in the internal space of the lens barrel. It is characterized by a door. Further, in the present invention, an opening through which a distal end portion (final lens portion) of the barrel portion can pass through a vacuum flange portion for mounting the barrel portion of the charged particle beam device to a partner device to be combined. A vacuum gate valve is provided, and the lens barrel is movably connected to the vacuum flange via a vacuum bellows, so that the tip of the lens barrel (final lens part) is connected to the vacuum gate. It is characterized in that it can be put in and out of the partner device to be combined through the opening of the valve. This makes it possible to bring the final lens portion in the compounding device sufficiently close to the sample surface, and to perform high-resolution observation with a short working distance. Still further, in the present invention, a means for tilting and moving the lens barrel with the focal position of charged particle convergence by the final lens part of the lens barrel being fixed is added,
Thereby, it is characterized in that the incident direction of the charged particle beam can be set arbitrarily while the observation position (charged particle beam irradiation position) on the sample surface is fixed.

[0007]

According to the above-mentioned characteristic structure of the present invention, when the lens-barrel is attached to and detached from the partner device to be combined, there is no possibility that the inside of the lens-barrel is exposed to the atmosphere as in the conventional device. In addition, it is possible to prevent the charged particle source housed in the lens barrel and the charged particle focusing optical system from being destabilized due to exposure to the atmosphere. further,
When mounting and dismounting the lens barrel, it is not necessary to perform troublesome operations such as re-evacuating the lens barrel and heating and baking out, and it is also possible to prevent waste of time.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following examples, the case where the present invention is applied to a scanning electron microscope using a convergent electron beam will be described. However, the application range of the present invention is not limited thereto, and generally, the convergent electron beam and the convergent electron beam are used. The present invention can be applied to all charged particle beam devices using ion beams. FIG. 1 is a vertical sectional view of a charged particle beam apparatus using a micro scanning electron microscope according to one embodiment of the present invention. In FIG. 1, a part of an electron beam 2 field-emitted from the electron source 1 is extracted through a central opening of the extraction electrode 3 by an extraction electric field formed between the field emission type electron source 1 and the extraction electrode 3. You. The extracted electron beam 2 is converged by an electric field formed between the extraction electrode 3 and the second lens electrode 4, the first lens electrode 5, and the final electrode 6 constituting the converging lens system, It is narrowly focused and focused on the sample surface 7. The focused electron beam 2 is deflected by the deflection coil 8 and is two-dimensionally scanned on the sample 7. Secondary electrons 11 generated from the sample 7 by irradiation of the electron beam 2 are detected by a secondary electron detector 12. Using this detection signal as a video signal, a surface image of the sample 7 can be displayed on a display screen of an appropriate display device.

Since the above-mentioned electron source 1 is a field emission type electron source, in order to obtain a stable field emission electron flow therefrom, an ultra-high vacuum having a degree of vacuum around the electron source 1 of about 10 to ⁸ Pa is required. It is necessary to be. Therefore, in this embodiment, an ion pump is used as the ultrahigh vacuum exhaust pump 14 for evacuating the internal space of the electron source 1 and the lens barrel 13. Electron source 1, extraction electrode 3, lens electrodes 4, 5, 6
The lens barrel 13 including the converging lens system and the ion pump 14 is air-tightly fixed to an upper flange 17, and the upper flange 17 is air-tightly mounted to a lower flange 16 incorporating the gate valve 9 via a bellows 15. I have. FIG. 1 shows a state in which the scanning electron microscope according to the present invention is attached to another observation and processing device or the like. The lower flange 16 is attached to a vacuum chamber wall 18 of another observation or processing device or the like. It shows a state in which the lens barrel 13 is pressed down below the lower flange 16 by being airtightly mounted via an O-ring 19 and the like. FIG. 2 shows a state in which the scanning electron microscope according to the present invention is separated from other observation and processing devices and the like, and the gate valve 9 is closed.

In the scanning electron microscope of the present invention, the internal space of the lens barrel 13 is constantly evacuated to a high vacuum by the ion pump 14. While maintaining this high vacuum evacuation state, first, the lower flange 16 of the present apparatus is hermetically attached to the vacuum chamber wall 18 of another apparatus to which the present apparatus is to be mounted, and then the vacuum chamber of the other apparatus is evacuated. After the exhaust, the gate valve 9 is opened, the lens barrel 13 is pushed down,
The position adjustment screw 20 adjusts the relative positional relationship to the sample surface.
By adjusting after adjusting, the connection to another device to be combined can be completed without exposing the internal space of the lens barrel 13 to the atmosphere and maintaining a high vacuum state. This makes it easy to combine the present apparatus with another apparatus, and immediately after the completion of the combining, an electron beam is extracted from the electron source 1 and a scanning image of the sample surface can be observed. Once the inside of a field emission type electron source is exposed to the atmosphere, the desired field emission performance cannot be exhibited until the gas molecules adsorbed on the inner surface of the electron source are completely desorbed. For re-evacuation after exposure, a so-called bake-out evacuation operation is generally required to perform long-time evacuation while heating the electron source. According to the present invention, such bake-out evacuation operation is not required. As a result, operability from a practical viewpoint is significantly improved.

According to the construction of the above embodiment, the gate valve 9 is opened and the upper flange 17 is
By pushing down and fixing the lens barrel 13 until it comes into contact with the upper part, the tip of the lens barrel (final electrode 6) can be pushed down and fixed below the sample opening (position on the sample side) through the valve opening 10. The distance (working distance) between the final electrode 6 and the sample 7 necessary for obtaining high resolution with a microscope can be set sufficiently small. Also,
By forming the contact surfaces of the flanges 16 and 17 into a spherical shape with the focal position of the electron beam 2 as the center of curvature, the inclination direction and the inclination angle of the lens barrel 13 with respect to the surface of the sample 7 can be arbitrarily adjusted. Can be. This not only increases the degree of freedom in selecting the observation direction with respect to the sample surface, but also changes the emission conditions of the secondary electrons 11 depending on the position and shape of the sample 7.
By adjusting the tilt direction and the tilt angle described above, it is possible to always set the conditions under the optimum detection condition.

Although the embodiments of the present invention have been described above, the present invention is not limited to the specific structures shown in these embodiments, and various modifications can be made. For example, in the above embodiment, the case where the present invention is applied to a scanning electron microscope has been described. However, the present invention is also applicable to other electron beam application devices such as an electron beam measuring device, and an ion beam using a focused ion beam. It can be applied to an applied device as it is.

[0013]

According to the present invention, it is easy to attach a lens barrel for generating convergent charged particle beams to another device to form a composite device, and to re-start the vacuum after the compounding. A stable use state can be obtained immediately without the need for complicated and long-time work such as baking out.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic configuration of a scanning electron microscope according to an embodiment of the present invention, showing a state in which a lens barrel is attached to a counterpart device to be combined.

FIG. 2 is a schematic cross-sectional view showing a basic configuration of a scanning electron microscope according to one embodiment of the present invention, in which a lens barrel is cut off from a partner device to be combined and a gate valve is closed. It shows the state where it is.

[Explanation of symbols]

1: electron source, 2: electron beam,
3: extraction electrode, 4: second lens electrode, 5: first lens electrode, 6: final electrode, 7: sample,
8: deflection coil, 9: gate valve, 10:
Valve opening, 11: secondary electron, 12: secondary electron detector, 13: lens barrel, 14: ion pump, 15: bellows, 16: lower flange,
17: Upper flange, 18: Vacuum wall of the partner device,
19: O-ring, 20: Position adjustment screw.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 37/16 H01J 37/18 H01J 37/28

Claims (2)

(57) [Claims] 1. A charged particle source for generating charged particles.
Charged particles for converging charged particles from the charged particle source
A lens barrel containing the converging optical system and the lens barrel
Vacuum flange for vacuum-tight mounting to other equipment
And the inside of the lens barrel provided on the vacuum flange
A vacuum-tight partition between the space and the internal space of the other devices
And a vacuum valve for the
Both ends of the charged particle emission side
Inserted into the internal space of the other device through the opening
Vacuum-tight connection to the above vacuum flange as possible
A charged particle beam device characterized by being performed. 2. The focal position of converged charged particles from the lens barrel.
With the lens fixed, move the lens barrel to the focus position
A means for tilting and moving in the center has been added
The charged particle beam device according to claim 1, wherein
Place.