JPH0228609Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a scanning electron microscope.

There are roughly two types of scanning electron microscopes. The first type of apparatus is as shown in FIG. 1, in which a sample 1 is placed below an objective lens 2;
Secondary electrons SE and the like generated from the sample 1 by irradiation with the electron beam EB are detected by a secondary electron detector 3 disposed between the sample 1 and the objective lens 2. This type of apparatus has the advantage that it has a large degree of freedom in moving and tilting the sample stage, is suitable for observing large samples, and can arrange various attachments around the objective lens. On the other hand, it is not recommended to reduce the distance between the objective lens 2 and the sample 1 too much because the secondary electron collection electric field extending from the detector 3 to the sample 1 side will be obstructed and the secondary electron detection efficiency will decrease. Therefore, there is a drawback that high-resolution scanning images cannot be obtained. In the second type, as shown in Fig. 2, the sample 1 is placed within the lens magnetic field of the objective lens 4, and the secondary electrons SE generated from the sample 1 by irradiation with the electron beam EB are placed in the lens magnetic field. The sample is guided upward along the lens 4 and detected by the detector 5 placed above the lens 4. Such a device reduces the distance between the objective lens and the sample to reduce the spherical aberration coefficient Cs, and achieves high resolution. image can be obtained, but it has the disadvantage that movement, tilting, etc. of the half-plane sample 1 are severely restricted. Therefore, although high resolution is not required, different types of 2
This required additional equipment.

The present invention aims to solve these conventional drawbacks and provide a device that can meet the above two demands.

The present invention consists of an objective lens for focusing and irradiating a sample with an electron beam, and a detector placed between the objective lens and the sample for detecting secondary electrons generated from the sample by irradiation with the electron beam. The apparatus includes an auxiliary lens, and a thin thin plate attached to the upper end surface of the auxiliary lens for detecting secondary electrons from the sample that have flown along the electron beam passage hole of the auxiliary lens. An electron multiplication detector, and a means for moving the integrated structure of the auxiliary lens and the electron amplification detector in a direction substantially perpendicular to the optical axis so as to be detachably attached to the lower end surface of the objective lens. It is characterized by

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 3 showing an embodiment of the present invention, 6 is an objective lens, and 7 is a sample. By being attached to the lower end surface of the objective lens 6, an auxiliary objective lens 8 can be placed between the objective lens 6 and the sample 7. A thin electron multiplier detector 9 is integrally attached to the side of the auxiliary objective lens 8 that faces the objective lens 6. As shown in FIG. 4, the electron multiplier detector 9 has a hole 9b in the center for passing the irradiated electron beam EB, and
It has many small holes 9a for taking in secondary electrons. It also has a collector electrode 9c for collecting the multiplied secondary electrons. A continuous dynode D is formed on the inner surface of the small hole 9a as shown in FIG. The secondary electron incident side of this dynode D is maintained at a positive potential by a power source _E1 shown in FIG. In addition, a power supply is connected to both ends of the continuous dynode D.
Voltage is applied by E ₂ . Therefore, the secondary electron SE generated from the sample 7 and guided into the small hole 9a is
As shown in FIG. 5, the light is multiplied while repeatedly colliding with the dynode D, and is absorbed by the collector electrode 9c, which is kept at a more positive potential than the end of the dynode D by the power source _E3 . The detection signal from the collector electrode 9c is supplied as a luminance signal to a cathode ray tube (not shown). As shown in FIG. 6, an insertion guide 6a is provided on the lower end surface of the objective lens 6 so that an integral structure 8, 9 of an auxiliary objective lens 8 and an electron multiplier detector 9 can be attached thereto. On the other hand, the guide 6a is provided on the upper end surface of the integral structures 8 and 9.
A protrusion T that can be inserted into the guide 6a is fixed thereto, and a leaf spring R is fixed thereon as can be seen from the side view of FIG. The integral structures 8 and 9 are attached to the objective lens 6 without play. The integral structures 8 and 9 are fixed to the tip of a rod-shaped support 10, and the rod-shaped support 10 is removed from the vacuum housing 11.
By moving the other end along arrow K,
The objective lens 6 can be attached to and detached from the lower end surface as desired. In addition, in Fig. 6b, 1
2 is an O-ring, and 13 is a sample stage. Further, a lead wire for applying a detection signal and a high voltage is taken out to the outside of the vacuum through the inside of this rod-shaped support 10.

In such a configuration, when attempting to obtain a high-resolution image, by manipulating the rod-shaped support 10, the integral structures 8 and 9 are attached to the lower end surface of the objective lens 6, and then the sample 7 is Bring it as close to the auxiliary objective lens 8 as possible. In this way, it is possible to reduce the work distance and realize a state where the spherical aberration coefficient Cs is small, and the thin plate-shaped electron multiplier detector 9 is placed facing the sample 7, and the electron beam The secondary electrons generated from the sample 7 by EB irradiation are bound by the magnetic field generated by the auxiliary objective lens 8 and can be effectively guided to the electron multiplier detector 9. high-resolution images can be observed. In addition, when attempting to observe the sample by moving or tilting it greatly, by operating the rod-shaped support 10, the integrated structures 8, 9
from the lower end surface of the objective lens 6, and remove it from the housing 11.
Pull it close to . As a result, a large free space is obtained near the sample 7, so that the sample 7 can be observed by moving or tilting the sample 7 largely. In this case, it goes without saying that the secondary electrons are detected by a detector similar to the secondary electron detector 3 in the apparatus shown in FIG.

FIG. 7 is for showing another embodiment of the present invention. In the apparatus of this embodiment, the electron multiplier detector 9 cannot be directly viewed from the electron beam irradiation point on the sample 7. In addition, the shape of the magnetic pole piece of the auxiliary lens 14 is taken into consideration. Therefore, in the apparatus of this embodiment, among the reflected electrons and secondary electrons generated from the sample 7 due to the incidence of the electron beam EB, the reflected electrons can be cut out and only the secondary electrons can be detected. .

Also, instead of this embodiment, a backscattered electron limiting aperture may be inserted between the auxiliary objective lens and the electron multiplier detector.

FIG. 8 is for showing still another embodiment of the present invention. In this embodiment, the magnetic pole pieces of the auxiliary objective lens 15 are connected to the electron multiplier detector 9 from the sample 7 side.
Care has been taken to ensure that the solid angle from which the sides are viewed is large. Further, the potential on the incident side of the continuous dynode D of the electron multiplier detector 9 is set to 0 volts, so that the incidence of secondary electrons into the electron multiplier detector 9 is prevented. With such a configuration, a sufficient amount of backscattered electrons RE can be taken into the electron multiplier detector 9 to obtain a high-resolution backscattered electron image.

In addition, when attempting to selectively obtain a compositional image and an uneven image of the sample by processing the detection signal of reflected electrons, the collector electrode of the electron multiplier detector 9 is divided in half. It is only necessary to make it possible to extract signals from each electrode independently.

As mentioned above, in the scanning electron microscope based on the present invention, by simple switching operations from the atmospheric side, it is possible to observe a sample while moving or tilting it greatly, and to observe it with high resolution using a single device. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional first type device, Fig. 2 is a diagram showing a conventional second type device, and Fig. 3 is an overall view of an embodiment of the present invention. FIG. 4 is a diagram for explaining the electron multiplier detector, FIG. 5 is a diagram for explaining the small hole 9a, and FIG. 6 is a diagram for explaining the attachment of the integrated structure to the objective lens 6. FIG. 7 is a diagram for explaining the mechanism, FIG. 7 is a diagram for showing another embodiment of the present invention, and FIG. 8 is a diagram for showing still another embodiment of the present invention. 1, 7: sample, 2, 4, 6: objective lens, 3,
5: Secondary electron detector, 8, 14, 15: Auxiliary lens, 8, 9: Integral structure, 9: Electron multiplication detector,
10: Rod-shaped support, 11: Housing, 13: Sample stage.

Claims (1)

[Scope of utility model registration request] An objective lens for focusing and irradiating a sample with an electron beam, and a detector placed between the objective lens and the sample for detecting secondary electrons etc. generated from the sample by irradiation with the electron beam. In a device equipped with
an auxiliary lens; a thin electron multiplier detector attached to the upper end surface of the auxiliary lens for detecting secondary electrons from the sample that have flown along the electron beam passage hole of the auxiliary lens; A scanning electron beam characterized by comprising means for moving the integrated structure of the auxiliary lens and the electron multiplication amplification detector in a direction substantially perpendicular to the optical axis so that the integrated structure of the auxiliary lens and the electron multiplication amplification detector can be attached to and detached from the lower end surface of the objective lens. microscope.