JPH03738B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron microscope capable of obtaining an energy filter image of a sample.

[Prior art] An energy analyzer is attached to an analytical electron microscope, and only electrons having a specific energy are selectively detected from among the electron beams that have passed through the sample.
Obtaining an energy filter image of a sample is performed.

Among the devices for obtaining such an energy filter image, the first type of device scans the sample surface two-dimensionally with a narrowly focused electron beam,
The electron beam that has passed through the sample during this scanning is guided to an energy analyzer placed after the imaging system, which detects electrons with a specific energy selected by the energy analyzer, and transmits the detection signal to the energy analyzer. It is introduced into a cathode ray tube that is scanned in synchronization with line scanning.

The second type of device is one in which an omega-type analyzer, for example, is provided in the imaging lens system, and an energy loss image is obtained based on electrons of a specific energy in a transmission electron image mode.

[Problems to be Solved by the Invention] In the first type of apparatus described above, since the electron beam probe must be scanned over the sample, the sample is heavily contaminated and a high-quality image cannot be observed. In addition, when trying to obtain an energy loss image at a low magnification, the angle of incidence of the electron beam on the sample increases, so the angle of the electron beam incident on the energy analyzer changes greatly with scanning, and as a result, the exit slit of the energy analyzer Since electron beams with the same energy move above the beam, the energy resolution becomes poor.

Furthermore, in the latter type of device, an energy filter field is inserted into the imaging lens system, which causes distortion in the transmitted image.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional drawbacks and provide an electron microscope that can obtain an energy filter image with high energy resolution and no distortion without contaminating the sample.

[Means for Solving the Problems] In order to achieve such objects, the present invention provides an electron beam irradiation system for irradiating a sample with a focused electron beam, and an electron beam irradiation system for irradiating a sample with a focused electron beam. An imaging lens system for forming an image of the sample; an energy analyzer disposed after the imaging lens system for selecting only electron beams with a specific energy; In an electron microscope equipped with a detector for detecting electrons, a two-stage deflection system provided at an arbitrary position of the imaging lens system, and zero-order diffraction formed by the imaging lens system. means for supplying a scanning signal to the two-stage deflection system for two-dimensionally scanning the sample image by deflecting an electron beam using a point as a deflection fulcrum; The present invention is characterized by comprising means for displaying an energy filter image.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows an example of an apparatus for carrying out the present invention. In the figure, 1 is an electron beam that is focused with good parallelism by a focusing lens system (not shown). is irradiated. The electron beam 1 transmitted through each point of the sample 2 is guided to an objective lens 3, an intermediate lens 4, and a projection lens 5, and an electron microscope image of the sample 2 is projected onto a display screen 6. Reference numerals 7 and 8 denote first and second deflection coils disposed between the projection lens 5 and the display screen 6, and these first and second deflection coils each consist of a deflection coil for X and Y deflection. There is. These deflection coils 7 and 8 receive sawtooth-shaped X and Y direction scanning signals from a scanning signal generating circuit 9 as shown in FIG.
Supplied via. The balance circuit 10 supplies the electron beam to the deflection coils 7 and 8 so that the electron beam is deflected by the deflection coils 7 and 8 using the zero-order electron beam diffraction point O formed below the projection lens as a deflection fulcrum. This is a circuit for adjusting the ratio of scanning signals. 11 and 12 are amplifiers. 13
is an energy analyzer, and 14 and 15 are input and output slits of the energy analyzer 13. 16 is a detector, and the output signal of the detector 16 is sent via an amplifier 17 to a grid 18g of a cathode ray tube 18. A scanning signal from the scanning signal generating circuit 9 is sent to the deflection coil 18d of the cathode ray tube 18 via an amplifier 19.

In such a configuration, each lens 3, 4, 5
When energized, electron microscope images A1 and A2 are formed by the lenses 3, 4, and 5, respectively, and the image A2 is formed as a final image A3 on the screen 7 by the projection lens. Additionally, a diffraction image D is placed on top of each electron microscope image.
1, D2, and D3 are formed. Therefore, by generating sawtooth X and Y scanning signals as shown in FIG.
and 8, the electron microscope image on the display screen 6 is always scanned using the 0th order diffraction point O of the diffraction image D3 as a deflection fulcrum, and along with this scanning, the electron microscope image on the display screen 6 moves two-dimensionally. In the same figure, A3' indicates an electron microscope image corresponding to a deflected electron beam indicated by a chain line. Therefore, the display screen 6 is removed from the optical axis and the transmitted electrons are directed through the incident slit 14.
If it is possible to guide the image A along with the above scanning,
Electrons corresponding to each part of 3 enter the energy analyzer 13. Energy analyzer 13
Since the incident electrons take different trajectories depending on their energy, only electrons having a specific energy pass through the exit slit 15 and are detected by the detector 16. The output signal of the detector 16 is transmitted to the cathode ray tube 12.
The cathode ray tube 12 is sent to the grid 12g.
The energy filter image of the sample is displayed.

The present invention is not limited to the embodiments described above, and can be modified in many ways.

For example, in the above embodiment, a two-stage electron beam deflector is arranged below the projection lens, but for example, a two-stage electron beam deflector is arranged between the intermediate lens and the projection lens, and a two-stage electron beam deflector is arranged directly below the intermediate lens. The electron microscope image may be moved two-dimensionally on the entrance slit by deflecting the electron beam using the zero-order electron beam diffraction point formed in the electron beam as a deflection fulcrum.

[Effects of the Invention] As is clear from the above description, according to the electron microscope based on the present invention, an image without distortion can be obtained because an energy analyzer is not inserted into the imaging lens system. In the present invention, since an energy filter image is obtained without scanning the sample with a focused electron beam, the sample is not contaminated, and the incident angle is always the same as the electron microscope image is scanned. Since electrons can be guided to an energy analyzer, energy resolution can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating one embodiment of the present invention, and FIG. 2 is a diagram illustrating X and Y scanning signals. 1: Electron beam, 2: Sample, 3: Objective lens, 4:
Intermediate lens, 5: Projection lens, 6: Display screen, 7, 8: Deflection coil, 9: Scanning signal generation circuit, 10: Balance circuit, 11, 12, 17, 1
9: Amplifier, 13: Energy analyzer, 1
4: Inlet slit, 15: Output slit, 16:
Detector, 18: Cathode ray tube.

Claims (1)

[Claims] 1. An electron beam irradiation system for irradiating a sample with a focused electron beam, an imaging lens system for forming an image of the sample based on the electron beam transmitted through the sample, and an imaging lens system for forming an image of the sample based on the electron beam transmitted through the sample. In an electron microscope, the imaging lens system is provided with an energy analyzer disposed at a subsequent stage for selecting only electron beams of a specific energy, and a detector for detecting electrons selected by the energy analyzer. The sample image is scanned two-dimensionally by deflecting the electron beam using the zero-order diffraction point formed by the two-stage deflection system installed at an arbitrary position and the imaging lens system as a deflection fulcrum. An electron microscope comprising: means for supplying a scanning signal to the two-stage deflection system; and means for displaying an energy filter image of the sample based on the output signal of the detector.