JPS62252055A - Stereoscopic electron microscope - Google Patents

Abstract

PURPOSE:To make it possible to get the three-dimensional data of a cubic sample without moving or rotating the sample itself, by furnishing the first and the second electron beam sources to emit electron beams in time devision and a scanning/deflecting device to deflect the electron beams to convert the incident angles of the electron beams to the sample each other. CONSTITUTION:Electron beams 4A and 4B are radiated from electron guns 1A and 1B time devision respectively, and, the electron beam 4A from the electron gun 1A corresponding to the left eye is focused on a sample through an object lens 11, its incident angle is +7 deg. to the vertical axis, and it is deflected to scan over the sample. The electron beam 4B from the electron gun 1B corresponding to the right eye is also set to be scanned over the same area, and its incident angle is -7 deg. to the vertical axis. By catching the twodimensional images of the cathode-ray tubes 14A and 14B through a stereoscopic mirror or the like with the left and the right eyes respectively, a stereoscopic perception can be acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electron microscope that can be used as a three-dimensional observation device for three-dimensional structures and three-dimensional shapes.

(Prior Art) Three-dimensional structures and shapes of objects to be measured, which have three-dimensionally expanded structures and shapes, are observed using transmission electron microscopes and scanning electron microscopes.

These three-dimensional structures and shapes can be observed using binocular stereoscopic vision (
It is based on the principle of stereo photography.

Using the principle of making the electron gun of a microscope function in a way that corresponds to human eyes, we first take an enlarged photograph (left-eye photograph) of a desired part of the object to be measured, which corresponds to the image seen from the left eye, for example.
to photograph.

Next, an enlarged photograph (right eye photograph) corresponding to the image seen from the right eye is taken, and this is viewed stereoscopically. This pair of left and right photographs is called a 3D pair photograph.

Stereophotographs are created in a conventional manner.

That is, first, after taking a photograph for the left eye with an electron microscope, the object to be measured is tilted at a certain angle (usually 14 to 20 degrees) so that an enlarged photograph corresponding to the image seen from the right eye is obtained. In this state, move the object to be measured so that it has the same field of view and the same magnification as that of the left eye photograph, and take a right eye photograph.

(Problems to be Solved by the Invention) Since electron microscopes are sometimes used at magnifications several thousand times higher, extremely small angle and position adjustment errors become a problem.

In an electron microscope, the moving distance of the object to be measured is also magnified to the same magnification ratio as during observation.

Therefore, after taking a photograph for the left eye, in order to take a photograph for the right eye, it is necessary to tilt and move the measured object so that it has the same field of view and the same magnification as the photograph for the left eye. Adjustments will be required.

In addition to the problem of such spatial deviation, in the case of samples such as living bodies, the time required to take a photograph for the right eye after taking a photograph for the left eye may become a problem.

This is because a shape or qualitative change may occur during that time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stereoscopic electron microscope that can solve the above-mentioned problems and easily obtain three-dimensional observation or three-dimensional data of the three-dimensional structure and shape of a sample.

(Means for Solving the Problems) In order to achieve the above object, a stereoscopic electron microscope according to the present invention scans an electron beam from an electron gun to obtain images of secondary electrons emitted from various parts of a sample. A scanning electron microscope includes first and second electron beam sources that emit electron beams in a time-sharing manner, an electron optical system that focuses the electron beams on a sample, and a pair of electrons from the electron beam sources. scanning deflection means for deflecting the electron beams so that the beams scan the same area on the sample surface and the incident angles of the respective electron beams on the sample are different from each other; and a detector for detecting secondary electrons from the sample. , means for separately extracting and displaying or recording the output of the detector caused by the first electron beam and the output of the detector caused by the second electron beam.

As the detector, a high-sensitivity detector composed of a scintillator and a photomultiplier tube can be used.

The displaying or recording means includes a first cathode ray tube that reproduces a secondary electron image caused by the first electron beam and a cathode ray tube that reproduces a secondary electron image caused by the second electron beam. It is possible to obtain stereoscopic perception by observing this using a stereoscope or the like.

Further, the displaying or recording means is provided for each pair of the electron beams, and is operated in synchronization with a signal that sequentially operates the electron beams so as not to overlap with each other in chronological order. It can be a cathode ray tube that uses alternating scanning lines.

By combining the information obtained by the first and second electron beams, three-dimensional information can be provided.

Each secondary electron image is recorded in a frame memory or the like, and based on this information, it can be used to calculate the distance between two three-dimensional points.

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a block diagram showing an embodiment of a stereoscopic electron microscope according to the present invention.

A pair of electron guns IA and IB corresponding to left and right eyes for stereoscopic vision are provided in the lens barrel 3 of the scanning electron microscope. Electrodes 5a and 5b are focusing and accelerating electrodes.

A condenser coil 7 forming a condenser lens section of the electron optical system and an objective lens coil 11 forming an objective lens section are arranged along the path of the electron beam.

The electron beam is scanned by a scanning coil 9 to which a scanning current is supplied by a scanning signal generator 8, and is deflected by a stereoscopic observation deflection coil 2.

The lens barrel 3 is a vacuum container that can receive the sample 10 and then evacuate it to a vacuum.

Operating power sources are alternately connected to the electron guns IA and IB corresponding to the left and right eyes from a power source 20 via a switch 5.

This switching of the switch 5 is performed by a signal from the control circuit 21.

Therefore, electron beam 4A is generated from electron guns IA and IB.

4B are transmitted in a time-division manner (alternately so as not to overlap).

The electron beam 4A from the electron gun IA corresponding to the left eye is focused and accelerated by electrodes 6a and 6b, further focused by a condenser lens coil 7, and is then focused by a scanning coil 9 driven by a scanning signal generator 8. It is deflected to scan the surface of the sample 10.

This deflected electron beam 4A is transmitted to the objective lens coil 1
The electron beam 4A is focused on the sample surface by the stereoscopic observation deflection coil 2, and the incident angle of the electron beam 4A on the sample surface is +7 degrees with respect to the vertical axis, and the electron beam 4A is deflected so as to scan the sample surface. .

Secondary electrons emitted from the sample 1o by irradiation with the electron beam 4A are detected by an electron detector 12 that is a combination of a scintillator and a photomultiplier tube.

The amount of secondary electrons emitted from this sample is determined by the shape of sample 1o and 2
Determined by the distribution of secondary electron emission rate.

The detected electric signal is amplified by the amplifier 13 and applied to the left-limit cathode ray tube 14A via the switch 15 as a brightness modulation signal of the video signal.

Scanning of the left eye cathode ray tube 14A is performed by a signal from a scanning signal generator 8, and the switch 15 is controlled in synchronization with the switch 5.

Therefore, the left eye cathode ray tube 14A shows an enlarged secondary electron image of the sample 10 as seen by the left eye (by scanning the electron beam from the electron gun IA).

Similarly, the electron beam 4B from the electron gun IB corresponding to the right eye also generates signal electrons through the same process as the electron beam 4A described above.

Note that the electron beam 4B is set to scan the same area of the sample surface that the electron beam 4A described above scans, and the difference is that the deflection coil 2 for stereoscopic observation allows the sample 1 to be scanned.
The angle of incidence on the zero surface is 17 degrees with respect to its vertical axis.

The signal electrons generated by the electron beam 4B are displayed on the right eye cathode ray tube 14B in the same manner as described above to obtain an enlarged secondary electron image of the sample as seen by the right eye.

When the two-dimensional images of the cathode ray tubes 14A and 14B are placed in the left and right eyes using a stereoscope or the like, stereoscopic perception can be obtained.

Although the above embodiment has shown an example in which separate left and right cathode ray tubes 14A and 14B are used, by ordinary television technology, as shown in FIG. By scanning the second scanning line 16B for the right eye, two two-dimensional images can be displayed on the same cathode ray tube.

The information obtained by the first and second electron beams can be combined to provide three-dimensional information.

Therefore, by recording each secondary electron image in the frame memory 22 shown in FIG. 1, it is possible to calculate the distance between two three-dimensional points based on this information.

Furthermore, by performing arithmetic processing on the left and right electronic signals, it is also possible, for example, to facilitate extraction of features of a stereoscopic image.

In order to improve the image quality of the obtained image, the image quality can be improved by slowing down the scanning, storing the signal until one end in a frame memory used in ordinary image processing technology, and then taking it out and reproducing it.

The above explanation was based on the case of a pair of electron guns, but by equipping the lens axis with a pair of electron guns and selecting one of the pairs, stereoscopic data from different angles can be obtained. You can also do that.

(Effects of the Invention) As explained in detail above, the stereoscopic viewing electron a according to the present invention
The m-mirror is a scanning electron microscope that scans the electron beam from the electron gun to obtain images of secondary electrons emitted from each part of the sample.
oi, first and second electron beam sources that emit electron beams in a time-sharing manner; an electron optical system that focuses the electron beams on the sample; and a pair of electron beams from the electron beam sources that emit electron beams onto the sample surface. scanning deflection means for scanning the same area of the sample and deflecting the electron beams so that the incident angles of the respective electron beams on the sample are different from each other; a detector for detecting secondary electrons from the sample; The output of the detector due to the second electron beam and the output of the detector due to the second electron beam are separated and extracted for display or recording.

Therefore, unlike conventional devices, three-dimensional data of a three-dimensional sample can be acquired without moving or rotating the sample itself.

Furthermore, since left eye and right eye data can be obtained simultaneously, it is possible to solve both the spatial and temporal problems at the same time.

Using the apparatus according to the present invention, it is possible to easily observe the three-dimensional shape of a processed semiconductor surface, the shape of a biological sample, and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a stereoscopic electron microscope according to the present invention. FIG. 2 is a schematic diagram for explaining an embodiment in which the output of the stereoscopic electronic mirror according to the present invention is displayed by one cathode ray tube. IA, IB...electronic! (Electron beam source) 2... Deflection coil for stereoscopic observation 3... Microscope lens barrel 4A, 4B... Electron beam 5... Electric switch 6 (6a, 6b)... Electrode 7... Capacitor coil 8... Scanning signal generator 9... Scanning coil 10... Sample 11... Objective lens coil 12... Secondary electron detector 13... Amplifiers 14A, 14B. ...Infrared line tube 15...Electrical switch 16...Scanning line 20...Power source 21...I control circuit 22...Frame memory patent distributor Hamamatsu Photonics Co., Ltd. agent Patent attorney Inoro Jusai 111@

Claims (5)

[Claims] (1) In a scanning electron microscope that scans an electron beam from an electron gun to obtain images of secondary electrons emitted from various parts of a sample, first and second electron beams are emitted in a time-sharing manner. a beam source, an electron optical system that focuses the electron beam on a sample, a pair of electron beams from the electron beam source scans the same area on the sample surface, and the incident angle of each electron beam on the sample is scanning deflection means for deflecting the electron beam differently from each other; a detector for detecting secondary electrons from the sample; and an output of the detector by the first electron beam and the detection by the second electron beam. A stereoscopic electron microscope consisting of means for separating and extracting the output of the instrument for display or recording. (2) The stereoscopic electron microscope according to claim 1, wherein the detector is a highly sensitive detector composed of a scintillator and a photomultiplier tube. (3) The displaying or recording means includes a first cathode ray tube that reproduces a secondary electron image caused by the first electron beam and a cathode ray tube that reproduces a secondary electron image caused by the second electron beam. The stereoscopic electron microscope according to claim 1, which is a tube. (4) The displaying or recording means is provided for each pair of the electron beams, and is operated synchronously by a signal that sequentially operates the electron beams so as not to overlap with each other in chronological order, and the display or recording means is arranged to operate in synchronization with a signal that sequentially operates the electron beams so as not to overlap with each other in chronological order. 2. The stereoscopic electron microscope according to claim 1, wherein the scanning lines are used alternately. (5) The displaying or recording means is a memory that records a secondary electron image caused by the first electron beam and a secondary electron image caused by the second electron beam. Stereoscopic electron microscope described in Section 1.