JP2815658B2 - Secondary electron image display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) In a semiconductor industry field and a material science field, a measurement function is improved in an apparatus for analyzing an electronic device and a functional thin film using a high energy ion beam. The present invention relates to a secondary electronic image display device.

(Prior Art) When an enormous amount of information is processed by a computer, it is required to increase the storage capacity and increase the processing speed.
For this reason, the integration of ICs is changing from LSI to VLSI,
Development to C is underway. Along with this, individual elements and their wirings are miniaturized / multi-layered, and a region extremely shallow from the surface is being used as an active layer. Recently, attention has been paid to a film formation technique at an atomic layer level such as molecular beam epitaxy. In the development and process research of such ICs, it is extremely important to observe the structure in the depth direction at the surface and subcutaneous surface and evaluate the composition. For that purpose, Rutherford backscattering (RBS) using a high energy (MeV) ion beam is required. ) And the particle excitation X-ray method (PIXE) are very effective.

In order to carry out the above-described analysis method of irradiating a high-energy ion beam as a focused spot, in order to instruct a specific spot area to be focused on the sample surface, first, on the sample surface including the spot area to be specified, In this way, it is necessary to obtain some kind of image for a wide area, and then to be able to specify a spot area to be analyzed.

Conventionally, generation of a two-dimensional image using such a charged particle beam has been performed using an electron probe. FIG. 3 shows an example of an electron probe device of a normal electron microscope, and FIG.
The figure shows an example of an electron probe micro-analysis device used in combination with this (see “Micro-beam analysis” edited by Japan Society for the Promotion of Science, Asakura Shoten).

As shown in FIG. 3, the electron beam (c) from the housing (a) and the electron gun (b) passes through the focusing lens (d), and then enters the sample chamber (e).
After focusing and irradiating on the surface of the sample (h) fixed to the sample stage (g) integrated with the sample fine movement mechanism (f), the deflection coil (i) of the objective lens section of the housing (a) Alternatively, the light is deflected by the deflection electrode so that an arbitrary point on the surface of the sample (h) can be observed. When performing elemental analysis on the sample surface, as shown in FIG. 4, an X-ray signal (j) excited by an electron beam (c) is converted into an electric signal by a detector (k) and analyzed. Other excited X-rays (m) also enter the detector (k). When displaying the element distribution on the sample surface as a two-dimensional image, the electron beam (c) is scanned by a deflection coil (i) or the like,
It is output to a display device such as a cathode ray tube.

In the case of observation using an electron beam, since the mass of electrons is small, the electric field and magnetic field required to deflect the beam may be relatively small, high-speed scanning is possible, and one
It is possible to always make a point and one point on the display device correspond one-to-one in time. In addition, long-term observation is possible because the electron beam causes little damage to the sample.

(Problems to be Solved by the Invention) When an ion beam is used as a measurement probe, observation that cannot be performed with an electron beam can be performed by an RBS method or the like. In this case, to create an image of a wide area including the measurement spot area, it is necessary to scan the ion beam with two-dimensional deflection like a television image.

However, in order to deflect a high-energy (MeV) ion beam, a strong deflection electric field or magnetic field that is about 1000 times or more that of an ordinary electron microscope is required. This is mainly because the mass of ions is about 2000 times larger than that of electrons. To obtain such a high electric or magnetic field, a high-voltage deflection power supply is used. It is extremely difficult to control this at high speed, and in the case of an ion beam apparatus, scanning must be performed at low speed. In addition, since the mass of the ions is large, the scanning speed of the ion beam is much lower than that of the electrons. For this reason, when the state is to be displayed as a two-dimensional image on the surface of the sample, if the display device of the after-image type sensitive surface used in the conventional electron microscope is used, the luminance on the sensitive surface is attenuated. In addition, image unevenness and errors increase. In the case of a signal having a poor signal-to-noise ratio, a scanned image with good contrast cannot be obtained.

Also, with conventional electron microscopes, for these measures,
Some have an image memory, but when using an ion beam, the scanning speed for writing to the memory is extremely slower than the scanning speed for display, so competition between writing and reading occurs and the screen flickers. , Normal display cannot be performed.

In addition, since the damage to the sample to be measured by the ion beam is not small, there is a problem that long-time observation cannot be performed.

(Means for Solving the Problems) The present invention has been made to solve the above problems of the prior art, and a secondary electron image display device of the present invention focuses a high energy ion beam on a sample. A plurality of memories for storing information on the scanning position of the ion beam irradiated with the information of the secondary electron signal excited from the sample are provided, and the storage of the information of the secondary electron image and the display of the contents are alternately performed. It is characterized by the following.

Further, in the present invention, the information of the storage device is averaged,
A function part for improving the N ratio can be incorporated. In the present invention, the irradiation position of the ion beam on the displayed secondary electron image is displayed with a cursor, thereby simplifying the beam alignment. Can be added.

(Operation) According to the secondary electron image display device of the present invention, the following operations can be performed.

(A) Since a plurality of memories are provided, and secondary electron information is written while performing beam scanning in one of the memories, while reading and displaying information already written in the other one,
Even if the scanning speed of the display device is faster than the scanning speed of the sample surface, writing and reading can be separated, and there is no competition between the two, so that an image without flicker can be displayed.

(B) An instantaneous secondary electron signal is obtained in synchronization with the scanning position of the ion beam, the position information and the signal intensity information are stored in the storage device, and an image is generated based on the information in the memory. Eliminating image unevenness and error due to attenuation on the sensing surface is eliminated.

(C) When the S / N ratio is poor, the secondary electron signals obtained by scanning a plurality of times can be stored in a memory, averaged, and then output as an image. Good quality images can be obtained.

(D) Since the instantaneous signal is stored in the storage device, the image can be reproduced while reading the information in the memory in a single scan, thereby reducing the number of scans and reducing the destruction of the sample. it can.

(E) In the case where a device for superimposing and displaying a cursor on the display device is provided, the beam spot can be quickly and easily moved to the position of the sample surface to be focused on and used for local analysis.

(Embodiment) Hereinafter, the secondary electron image display device of the present invention will be specifically described with reference to the device configuration of the embodiment shown in FIG. 1 and the flowchart of the storage operation shown in FIG. 2 to clarify its characteristics. .

In Fig. 1, a proton or helium ion beam generated by an accelerator such as a several MeV bandeograph (1)
Is focused on a beam spot by the focusing electromagnet (2), and is then irradiated onto the surface of the sample (4) in the sample chamber (3). The sample (4) is fixed to a sample holder in the sample chamber, mounted on a sample stage integrated with the fine movement mechanism, and is moved upright to match the beam spot.
The ion beam (1) scans an image display area on the sample surface whose trajectory can be changed by the deflection electrode (5). Scanning of ion beam is performed by a scanning position controller (6)
This is performed by the deflection electrode control device (7) applying a deflection voltage to the deflection electrode (5) in response to the signal output from the controller. Secondary electrons excited by the ion beam on the sample surface are converted into electric signals by the secondary electron detector (8), A / D converted by the secondary electron analyzer (9), and encoded into luminance signals. .

This luminance information signal accompanying the scanning of the ion beam is the first
Either the memory (10) or the second memory (11), or the averaging device (12) performs an averaging operation on information obtained by a plurality of scans, and stores the averaged information. It is stored in the third memory (13). The deflection position control device (6) also gives corresponding position information to the first memory (10), the second memory (11) and the third memory (13) at the same time. To store.

Since the actual scanning speed of the ion beam is lower than the reading speed of the display position (14), the first memory (10) and the second memory (11) are used alternately for writing and reading. While writing the secondary electron information being scanned into the first memory (10), the display device (14) displays the information already stored in the second memory (11). As soon as the scanning of the ion beam is completed, the display device (14) is set to the first position.
Switchable to display information in memory (10).
If the S / N ratio of the signal is poor, the averaging device (12)
Through this, it is possible to write information in the third memory (13) by reducing the influence of errors and the like.

The display device (14) can display a cursor line for forming a cross and the like generated by the cursor display device (15) on the already generated image,
Utilizing this, it is possible to enlarge the position of interest or to perform detailed scanning according to the instruction of the measurer.

When a specific measurement region to be noted is determined by displaying the secondary electron image in this way, a detailed analysis is performed by focusing and irradiating the region with an ion beam after adjustment. The X-rays excited by the focused irradiation of the ion beam are converted into electric signals by an excitation X-ray detector (16), and the scattered ions are received by a scattered ion detector (17), and are respectively detected by a wave height analyzer (18) (19). ) To obtain an analysis result.

The secondary electron image display device of the embodiment of the present invention shown in FIG. 1 is operated as shown in the flowchart of FIG. That is, the measurement is started in step I. In step II, measure whether the measurement is in progress. If yes, first and second in step III
A memory for writing and a memory for reading are selected between memories. In step IV, it is determined whether or not to perform the averaging process.
In addition to the contents of 3), if no, the measured value is written to one of the first and second memories selected for writing in step VI.

In step VII, the contents of the memory selected for reading are read / displayed. The result is Step II
Feedback before.

If no in step II, decide whether to display the averaged image in step VIII, and if yes, step IX
Read / display the contents of the third memory (13). If no, the contents of the memory written in step VI in step X are read and displayed. End at step XI.

(Effects of the Invention) As described above, according to the secondary electron image display device of the present invention, when performing analysis using a high energy ion beam, the image information on the sample surface is displayed by the operation of the ion beam with flickering. The display can display images without noise, and can provide a high-quality image without image unevenness due to the attenuation of the display, and can reduce the number of scans to reduce the destruction of the sample. There is a result that the beam spot can be quickly and easily moved to the position of the sample surface to be noticed and local analysis can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing the configuration of a secondary electron image display device according to an embodiment of the present invention, FIG. 2 is a flowchart showing the storage operation, FIG. 3 is a diagram showing an electron probe device of an electron microscope, and FIG. It is a figure showing an electronic probe micro-analysis device. (1) ... ion beam, (2) ... focusing electromagnet,
(3) ... sample chamber, (4) ... sample, (5) ...
... deflection electrode, (6) ... scanning position controller, (7) ...
Deflection electrode control device (8) Secondary electron detector (9)
... secondary electron analyzer, (10) ... first memory, (11)
... Second memory, (12)... Averaging device, (13)... Third memory, (14)... Display device, (15)... Cursor display device, (16)... (17) scattered ion detector (18) (19) wave height analyzer (a) housing (b) electron gun (c) electron beam (d) ) Focusing lens, (e) Sample chamber,
(F) …………………………………………………………………………………………………………………………………………………………………………………………………………………….
... sample, (i) ... deflection coil, (j) ... X-ray signal,
(K) Detector, (m) Excited X-ray.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Inoue 3-3-2 Motoyama Minami-cho, Higashi-Nada-ku, Kobe-shi, Hyogo 4243 Jiklef Motoyama-minami 4303 (72) Inventor Kiyotaka Ishibashi 2-Shinohara Akiminoyama-cho, Nada-ku, Kobe, Hyogo Prefecture 3-1 (72) Inventor Akira Kobayashi 4- 6-23 Fukuda, Tarumi-ku, Kobe City, Hyogo Prefecture JP-A-2-189848 (JP, A) JP-A 1-289058 (JP, A) JP-A-60-117533 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 37 / 22 H01J 37/28 H01J 37/252

Claims (2)

(57) [Claims] A storage device including a plurality of memories for focusing and irradiating a sample with a high-energy ion beam and storing information of a secondary electron signal excited from the sample and information of a scanning position of the irradiation ion beam; The apparatus has a memory in which information of the secondary electron signal accompanying the scanning of the ion beam is written,
A plurality of memories that are used for displaying a secondary electron image based on information of the secondary electron signal that has already been stored, while the information of the secondary electron signal is stored in one of the memories. A secondary electron image is displayed based on the information of the secondary electron signal stored in another of the plurality of memories, and the storage of the information of the secondary electron signal in one of the memories is completed. Then, while displaying the secondary electron image based on one storage of the memory, the secondary electron signal accompanying the scanning of the ion beam is stored in the other memory, and the storage of the secondary electron signal is performed. And display of a secondary electron image are alternately performed between the one memory and another memory, and a function of averaging information of the secondary electron signal in a part of the storage device. Part incorporated An averaging operation is performed on information of a plurality of secondary electron signals obtained by performing the ion beam scanning a plurality of times, and the averaging information obtained by the averaging operation is stored in the memory. The memory is stored in a third memory that is different from the one and the other memories, and the S / N ratio is improved based on the storage in the third memory.
A secondary electron image display device, wherein a secondary electron image is displayed. 2. The secondary electron image display apparatus according to claim 1, wherein the irradiation position of the ion beam is displayed by a cursor on the displayed secondary electron image to simplify the beam scanning position alignment.