JPS59201356A - Scanning type electron microscope - Google Patents

Abstract

PURPOSE:To detect secondary electrons even from any direction around a sample by providing a detctor around the sample so as to rotate or arranging a number of detectors around the sample on the circumference and selecting the detector that extracts electron detection signals. CONSTITUTION:An annular detector holder 4 is idly fit on the external surface of a sample holder 3 so as to rotate for the objective lens 1 of a scanning type electron microscope. A semiconductor electron detector 5 is mounted on the inner surface of a section 41 that is protruded at the upper part of one place of the detector holder 4. A gear 42 is cut on the external surface of the detector holder 4 and the detector holder 4 can be rotated around the sample holder 3 by turning a worm 6 mounted on the main unit of the scanning type electron microscope from the outside of an engagement main unit. When the detector holder 4 is rotated, the detector 5 moves around a sample 2. The sample holder 3 is mounted on the sample fine movement unit within the scanning type electron microscope main unit so as to freely be attached and deattached. This mounting is performed by sliding a protrusion section 31 on the lower surface of the sample holder 3 in a groove on the sample stand 7 of the sample fine movement unit.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a scanning electron microscope.

(b) In conventional scanning electron microscopes, the direction of the electron beam that irradiates the sample corresponds to the line of sight from which the sample is viewed, and the detector that detects secondary electrons 7 reflected electrons etc. emitted from the sample is the light source that illuminates the sample. corresponds to For example, consider a sample having one convex portion P as shown in Figure A.

The reference plane of the sample is 8. When the electron beam is irradiating the sample from the direction A, the apex P of the convex portion is detected when the electron beam is scanning point a on the reference surface S of the sample,
When the electron beam is irradiated from direction B, the apex P of the convex portion is detected while scanning point b. That is, parallax occurs in the image of the convex portion depending on the irradiation direction of the electron beam. This means that the irradiation direction of the electron beam corresponds to the line-of-sight direction. On the other hand, when the detector is in the position shown in the figure, when comparing the right slope and the left slope of the convex portion P, secondary electrons etc. emitted from the right slope are easier to detect than those from the left slope. Therefore, in the image, the slope on the side where the detector is located is brighter.

That is, the detector forms a contrast image of the sample surface in response to the illumination.

However, in conventional scanning electron microscopes, the position of the detector is fixed, which means that the direction in which the sample is illuminated is fixed. However, for samples with uneven surfaces, the contrast varies depending on the illumination direction, as shown in Figure 1B.
If the detector is placed at position D with respect to a sample surface like be recognized as something. On the other hand, if the detector is placed at position D', the area C will have a low detection efficiency for secondary electrons, etc., and will appear shaded, and the unevenness of the surface will become clear. As described above, depending on the state of the sample surface, the interpretation of the state of the sample surface from the image varies depending on the direction of illumination, that is, the position of the detector. Compared to optical microscopes, electron microscopes have a much deeper depth of focus and are suitable for observing the three-dimensional structure of the sample surface, but as mentioned above, there are significant differences in contrast depending on the position of the detector. Therefore, it cannot be said that conventional scanning electron microscopes, in which the position of the detector is fixed, make full use of the characteristics suitable for three-dimensional observation.

(c) Purpose The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a scanning electron microscope capable of detecting secondary electrons, etc. from any direction around a sample.

(d) Configuration In the scanning electron microscope of the present invention, a detector is rotatably provided around the sample, or a plurality of detectors are arranged circumferentially around the sample, and a detector for extracting an electronic detection signal is selected. It is characterized by electrically achieving the same result as rotating the detector around the sample.

Embodiment FIGS. 2 and 3 show an embodiment of the present invention. 1 in Figure 2
2 is an objective lens of a scanning electron microscope, 2 is a sample, and 3 is a sample holder. An annular detector holder 4 is rotatably fitted around the outer periphery of the sample holder 3. This detector holder 4 has a portion 41 that protrudes upward at one location, and a semiconductor electronic detector 5 is attached to the inner surface of this portion. A gear 42 is cut on the outer periphery of the detector holder 4 and is adapted to mesh with a worm 6 attached to the main body of the scanning electron microscope. This worm can be turned from outside the main body, thereby allowing the detector holder 4 to rotate around the sample holder 3. By rotating the detector holder 4, the detector 5 moves around the sample 2.

The sample holder 3 is detachably attached to a sample fine movement device within the main body of the scanning electron microscope. This installation is done on sample holder 3.
This is done by sliding the protrusion 3 on the lower surface of the sample slider into the groove on the sample stage 7 of the sample fine movement device to an appropriate size. In this operation, a sample holder inserted into a preliminary evacuation chamber provided on the side surface of the scanning electron microscope body is moved into the scanning electron microscope body from outside the vacuum and set on the sample stage 7. The detector holder 4 is fitted onto the sample holder 3 in advance, and by sliding the sample holder 3 onto the sample stage 7 in the direction of the arrow, the gear 42 on the outer periphery and the worm 6 automatically mesh. Since the protrusion 31 on the lower surface of the sample holder 3 engages with the groove on the sample stage 7, the sample holder 3 will not rotate even if the detector holder 4 is rotated.

FIG. 4 shows another embodiment of the invention. In this embodiment, the electron detector 5 is fixedly arranged in a circumferential manner around the sample holder 3, and the electron detector 5 is divided into eight pieces.
This allows the sum of the outputs of any two adjacent electron detectors to be calculated.

(F) Effects The scanning electron microscope of the present invention has the above-mentioned configuration, has a simple structure, can view images of the sample surface by changing the illumination direction arbitrarily, and can provide abundant data on the three-dimensional shape of the sample surface. can be obtained.

[Brief explanation of drawings]

1A and 1B are diagrams showing the relationship between the sample surface and the irradiated electron beam, FIG.
This figure is a plan view of the main part of the same embodiment, and FIG. 4 is a plan view of the main part of another embodiment of the present invention. 2... Sample, G... Sample holder, 4... Detector holder, 5... Electronic detector, 6... Worm, 7...
Sample stand. Agent: Patent Attorney Hiroshi Agata (I5)

Claims (1)

[Claims] One electron detector can be rotatably provided around the sample, or a plurality of fixed electron detectors can be provided circumferentially around the sample, and any one of them can be selected. A scanning electron microscope characterized in that an electron detector can be placed in any direction around a sample.