JPH0439657Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a cathodoluminescence device that detects cathodoluminescence light generated by irradiating a sample with an electron beam.

[Prior art] In general, in a scanning electron microscope, cathodoluminescence light is generated when an electron beam is irradiated onto a sample such as a living organism, mineral, or semiconductor. There is a cathode luminescence device that allows observation as a luminescence image. Recently, such devices have been developed that do not simply detect cathodoluminescence light, but instead split the cathodoluminescence light using a spectrometer to detect only those of a specific wavelength. .

[Problems to be solved by the invention] In a device that spectrally detects cathodoluminescence light as described above, the cathodoluminescence light incident on the spectrometer is wavelength-dispersed, so its intensity is is detected by the detector after being attenuated by 1/100 to 1/1000, so the detection signal is extremely weak. As a result, the cathodoluminescence image displayed on the display device has only a poor signal-to-noise ratio. This means that it is not suitable for roughly specifying the luminescent region of a sample when analyzing the sample, and that it is extremely difficult to find the field of view of the sample. However, if the cathodoluminescence light is detected directly with a detector without spectroscopy,
Since the detector detects cathodoluminescence light over the entire effective wavelength range of the detector, the detection signal is sufficiently large and a clear cathodoluminescence image can be obtained. Therefore, the field of view of the sample can be easily searched. Therefore, in order to be able to find the field of view of the sample using a device that does not disperse cathodoluminescence light, and then observe it in detail using a device that spectrally disperses cathodoluminescence light, two steps were taken: Comparative observation of cathodoluminescence images of the two types is required.

On the other hand, for samples such as diamond or GaAs compound semiconductors that have two peaks in the spectrum of cathodoluminescence light, the cathodoluminescence image obtained by spectroscopy of cathodoluminescence light and the cathodoluminescence image obtained by spectroscopy of cathodoluminescence light A completely different image is observed from a cathodoluminescence image obtained without separating the light. Therefore, even in such cases, it is required to observe the cathodoluminescence image while comparing the cathodoluminescence image in which the cathodoluminescence light is split into each wavelength peak and the cathodoluminescence image in which the cathodoluminescence light is not split. .

The object of the present invention is to provide a device that can satisfy the above-mentioned requirements.

[Means for Solving the Problems] In order to achieve the above object, the cathodoluminescence device of the present invention includes a means for generating cathodoluminescence light from a sample by irradiating an electron beam, and the means. a condensing means for condensing the cathodoluminescence light generated by the condensing means; a spectroscopy means for spectrally dispersing the cathodoluminescence light condensed by the condensing means; a first detection means for detecting the cathodoluminescence light collected by the light collecting means; a second detection means for directly detecting the cathodoluminescence light collected by the light collecting means without spectroscopy; means for simultaneously or selectively guiding the cathodoluminescence light focused by the light focusing means to the first and second detection means; The present invention is characterized in that it includes means for simultaneously or selectively displaying the sample images based on the signals from the two detection means side by side.

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

[Embodiment] The attached drawing is a schematic diagram showing an embodiment of the present invention, and numeral 1 indicates a mirror body of a scanning electron microscope or the like. Reference numeral 2 denotes an electron gun placed above this mirror body, and the generated electron beam EB is focused by a focusing lens 3 and irradiated onto a sample 4. Reference numeral 5 denotes a deflection coil for scanning the electron beam irradiated onto the sample 4 within a certain area, to which a scanning signal is supplied from a scanning signal generating circuit 6 via an amplifier 7.

Reference numeral 8 denotes a parabolic mirror placed above the sample 4, which captures cathodoluminescence light L generated when the sample 4 is irradiated with the electron beam EB.
It serves to reflect the light toward a light extraction window 9 made of vacuum-resistant glass formed on the side wall of the mirror body 1. Further, a hole 8a is formed in this mirror 8 to allow the electron beam EB to pass therethrough. The cathode luminescence light transmitted through the light extraction window 9 is passed through the incident slit 11 of the spectroscope 11 by the condenser lens 10.
After being focused at a position a and subjected to wavelength dispersion by a spectroscope 11, only those of a specific wavelength are detected by the first detector 12. A semi-transparent mirror 13 is placed between the condenser lens 10 and the spectroscope 11, and a part of the cathodoluminescence light condensed by the condenser lens 10 goes directly to the spectroscope 11. The light is incident on a second detector 14 placed in the direction. Further, the condenser lens 10 and the semi-transparent mirror 13 are supported within a guide tube 15 that is shielded from external light.

Detection signals from the first and second detectors 12, 14 are supplied to intensity modulation grids of first and second cathode ray tubes 18, 19 via amplifiers 16, 17, respectively. Deflection coil 20 of each cathode ray tube,
21 is supplied with a scanning signal synchronized with the scanning signal to the deflection coil 5 from the scanning signal generating circuit 6 via the amplifier 22, so that a cathode luminescence image is displayed on each cathode ray tube. It turns out.

In such an apparatus, when the electron beam EB is scanned over the sample 4 by the deflection coil 5, cathodoluminescence light is generated from the sample. The generated cathodoluminescence light is reflected by the mirror 8 toward the light extraction window 9, passes through the light extraction window, and is focused by the condenser lens 10. At this time, since a semi-transparent mirror 13 is installed behind the condensing lens 10,
The cathodoluminescence light transmitted through the condenser lens 10 is separated by a semi-transparent mirror 13 into a spectroscope 11 and a second detector 14 . Here the second
Since the cathode luminescence light generated from the sample 4 enters the second detector 14 as it is, this detector outputs a signal corresponding to the intensity of the cathode luminescence light. A cathodoluminescence image without spectroscopy is displayed. On the other hand, the cathodoluminescence light incident on the spectrometer 11 is separated by wavelength scanning of the spectrometer.
As the spectral wavelength approaches the peak wavelength of the cathodoluminescence light, the output signal from the first detector 12 gradually increases, and an image begins to appear on the first cathode ray tube 18. When the spectral wavelength and the peak wavelength match, the image becomes the brightest and a spectral cathodoluminescence image is obtained.

Therefore, first, determine the luminescent area of the sample to be observed while observing the image of the second cathode ray tube 19, which displays a non-spectral cathodoluminescence image. Observation can be made while looking at the screen of the cathode ray tube 18 of No. 1 while adjusting the spectral wavelength of the spectrometer 11 to match the peak wavelength of the cathodoluminescence light.

Next, a case will be described in which a sample whose cathodoluminescence light spectrum has two peaks is observed.

For example, in the case of diamond, the main peak of the spectrum of cathodoluminescence light is seen at 430 nm, and the sub-peak is seen around 520 nm. It is displayed as a cathodoluminescence image, and the first cathode ray tube 18 can display a cathodoluminescence image with a matched spectral wavelength, for example, around 430 nm.
Therefore, it is possible to clearly identify to which part of the non-spectral cathodoluminescence image the cathodoluminescence image with a wavelength of 430 nm corresponds, or to which part of the cathodoluminescence image with a wavelength of 520 nm corresponds.

Incidentally, a semi-transparent mirror with a separation ratio of 1:1 for cathodoluminescence light may be used, but the intensity of cathodoluminescence light usually decreases from 1/100 to 1/100 while passing through the spectrometer 11. Since the attenuation is 1/1000, we want to increase the amount of cathodoluminescence light that enters the spectrometer as much as possible. Therefore,
It is better to set the separation ratio of the semi-transparent mirror to, for example, 1:9 so that more cathodoluminescence light is sent to the spectroscope. If the 10% loss of cathodoluminescence light becomes a problem, the semi-transparent mirror can be made movable and removed from the optical path as necessary.

In the above explanation, the non-spectral cathodoluminescence image and the spectroscopic cathodoluminescence image were displayed side by side by displaying them on dedicated cathode ray tubes, but the detection signals from each detector can be time-divided. Alternatively, the light may be supplied to one cathode ray tube, the screen may be divided into two, and the two cathode luminescence images may be displayed side by side. In addition, although we have described the case where a semi-transparent mirror is used to simultaneously obtain a non-spectral cathodoluminescence image and a spectrally-spectral cathodoluminescence image, the present invention is not limited to this. It is also possible to configure the device so that it can be inserted into and removed from the camera, so that two types of cathodoluminescence images can be selectively obtained. Furthermore, two detectors are equipped with a photomultiplier tube and a photomultiplier tube depending on the spectral wavelength range of the cathodoluminescence light.
The detector may be appropriately selected from Si detectors, Ge detectors, PbS detectors, etc. and used. Furthermore, a cathode ray tube for displaying a cathode luminescence image may be a cathode ray tube for displaying a secondary electron image or a backscattered electron image in a scanning electron microscope.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to compare and observe a non-spectral cathodoluminescence image and a spectroscopic cathodoluminescence image, and it is very easy to find a field of view.

[Brief explanation of the drawing]

The accompanying drawings are schematic diagrams showing an embodiment of the present invention. 1... Mirror body, 2... Electron gun, 3... Focusing lens, 4... Sample, 5, 20, 21... Deflection coil, 6... Scanning signal generation circuit, 7, 16, 17,
22...Amplifier, 8...Mirror, 9...Light extraction window, 10...Condenser lens, 11...Spectroscope, 1
2, 14...first and second detectors, 13...semi-transparent mirror, 15...guide tube, 18, 19...first and second cathode ray tubes.

Claims (1)

[Claims for Utility Model Registration] (1) A means for generating cathodoluminescence light from a sample by irradiating it with an electron beam, and a condensing means for condensing the cathodoluminescence light generated by the means. a spectroscopic means for spectrally dispersing the cathodoluminescence light condensed by the condensing means; and a first detection means for detecting the cathodoluminescence light spectrally spectrally separated by the spectroscopic means. a second detection means for directly detecting the cathodoluminescence light collected by the light collection means without separating it; and a second detection means for directly detecting the cathodoluminescence light collected by the light collection means, 1 and a second detection means simultaneously or selectively, and a sample image based on a signal from the first detection means and a sample image based on a signal from the second detection means in parallel. A cathodoluminescence device comprising means for simultaneous or selective display. (2) The means for simultaneously or selectively guiding the cathodoluminescence light focused by the light focusing means to the first and second detection means is a semi-transparent mirror;
The cathodoluminescence device according to claim 1, characterized in that the semi-transparent mirror guides the cathodoluminescence light to the first and second detection means simultaneously. (3) The means for simultaneously or selectively guiding the cathodoluminescence light collected by the light collecting means to the first and second detection means is a reflecting mirror;
A utility model characterized in that the cathodoluminescence light is selectively guided to the first and second detection means by inserting and removing the reflecting mirror on the optical path of the cathodoluminescence light. A cathodoluminescence device according to claim 1.