JPH05314941A - Fib/eb composite apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a FIB / EB composite device that prevents contamination in the EB column and enables high-resolution image observation. [Structure] A shutter 15 is provided in order to prevent sample particles P entering from the opening of the objective lens 10 of the EB column 4. The shutter 15 is rotated by a rotating shaft 16, and while the sample 1 is being irradiated with FIB to scrape the sample, the rotating shaft is rotated as shown in FIG. Shutter 15
Are placed. As a result, among the particles P sputtered from the sample 1, the particles directed toward the opening 14 are
5 is prevented from entering the opening 14 and contaminating the inside of the EB column 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a FIB / EB composite apparatus in which a sample is shaved with an ion beam and a cross section of the shaved sample is observed by a scanning electron microscope image.

[0002]

2. Description of the Related Art A FIB / EB composite apparatus is used to evaluate the structure of a sample in the depth direction in a semiconductor manufacturing process or the like. In this device, a sample is cut by a focused ion beam (FIB), its cross section is exposed, the cross section is irradiated with an electron beam (EB), and the cross section is scanned with an electron beam. Electrons are detected and this secondary electron image is displayed. The cross-section observation using this apparatus has an advantage that the cross-section can be observed without breaking the sample wafer or the like and destroying the structure other than the observation site. FIG. 1 shows an outline of this type of apparatus, in which a sample 1 is placed in a sample chamber 2. A FIB column 3 and an EB column 4 are attached to the sample chamber 2, and the FIB column 3 has an ion source 5, a focusing lens 6, and an ion source 5.
The objective lens 7 and a deflector (not shown) are included. The EB column 4 has an electron gun 8, a focusing lens 9,
The objective lens 10 and a deflector (not shown) are included. A secondary electron detector 11 is provided close to the sample 1, and a detection signal of the detector 11 is supplied to a cathode ray tube 13 via an amplifier 12.

With the above structure, first, the sample 1 is irradiated with the ion beam IB generated from the ion source 5 after being focused by the focusing lens 6 and the objective lens 7. The irradiation point of the ion beam IB on the sample is deflected by the deflector, and a predetermined position of the sample 1 is cut by the ion beam. FIG. 2A shows a state in which the sample 1 is cut by the focused ion beam FIB. After the arbitrary region and the depth of the sample 1 are cut by the ion beam, the irradiation of the sample 1 with the ion beam is stopped, and the electron beam EB generated from the electron gun 8 is replaced by the focusing lens 9 and the objective lens 10. It is focused and irradiated on the sample 1. The electron beam is scanned on the cross-section portion of the sample 1 which is cut by the ion beam, and the secondary electrons generated based on this scanning are detected by the detector 11. FIG. 2B shows how the cross section of the sample is irradiated with the electron beam EB. This detection signal is supplied to the cathode ray tube 13 synchronized with the scanning of the electron beam, and the cathode ray tube 1
A scan image of the cross section of the sample 1 is displayed on the screen 3.

[0004]

In the configuration of FIG. 1, the FI
The B column 3 and the EB column 4 are arranged so that the centers of the respective beams coincide with each other, and cutting of the sample with the FIB and observation of the sample with the EB can be performed without moving the sample 1. However, the tip of the FIB column 3 and the EB
Since the tip of the column 4 is placed close to the FI, the FI
When the sample 1 is scraped by B, the problem that the constituent particles of the sample sputtered by the ion beam contaminate the EB column occurs. FIG. 3 shows such a state. When the sample 1 is irradiated with the focused ion beam FIB, the sample 1
The particles P sputtered from enter the column through the opening 14 of the objective lens 10 at the tip of the EB column and adhere to the inner wall of the objective lens 10. Due to the contamination due to the adhesion of the particles, the inner wall of the objective lens 10 is charged up at the time of observing the scanning electron microscope image, and as a result, the electron beam is illegally deflected, which causes deterioration of the resolution of the scanning electron microscope image.

The present invention has been made in view of the above points, and an object thereof is to realize a FIB / EB composite apparatus which prevents contamination in the EB column and enables high-resolution image observation. is there.

[0006]

FIB / according to the present invention
The EB compound device is provided with a focused ion beam optical system column and an electron beam optical system column on the sample chamber, cuts the sample with the ion beam, scans the electron beam with the cut sample portion, and obtains based on the scanning. In the FIB / EB composite apparatus which is configured to obtain a scanning image by the signal, a shutter for opening and closing the opening at the tip of the electron beam optical system column is provided.

[0007]

In the FIB / EB combined apparatus according to the present invention, the opening at the tip of the electron beam optical system column is opened and closed by the shutter.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 4 shows an embodiment of the present invention. The same parts as those of the conventional device shown in FIGS. 1 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted. In this example, EB column 4
A shutter 15 is provided in order to prevent the sample particles P entering from the opening of the objective lens 10. The shutter 15 is rotated by the rotating shaft 16 and the sample 1
While the FIB is being irradiated to shave the sample, the rotating shaft is rotated as shown in FIG. 4, and the shutter 15 is arranged in front of the opening 14 of the objective lens 10. as a result,
Of the particles P sputtered from the sample 1, the particles heading toward the opening 14 collide with the shutter 15 and are prevented from entering the opening 14 and contaminating the inside of the EB column 4.
The shutter 15 and the rotating shaft 16 are made of a conductive material, and are kept at the ground potential to prevent charge-up.

When the sample 1 is cut by the focused ion beam FIB and the sample 1 is irradiated with the electron beam EB to observe a scanning electron microscope image, the rotary shaft 16 is rotated 180 ° and the shutter 15 is moved to the objective lens 10. Is removed from the front surface of the opening 14. FIG. 5 shows such a state. ..

FIG. 6 shows another embodiment of the present invention,
In this embodiment, the cross-sectional shape of the shutter 15 is carefully devised. That is, as shown in the figure, the angle of the front surface of the shutter 15 is determined so that the particles P sputtered from the sample 1 are reflected by the front surface of the shutter 15 and the reflected particles are not deposited again on the surface of the sample 1. ing.

In the embodiment shown in FIG. 7, the shutter 17 uses a diaphragm blade system similar to the diaphragm structure of a photographic machine, and a large number of blades 18 are opened and closed by the rotation of a lever 19. ing. In this method, the blade 1
Since 8 is axisymmetric with respect to the electron beam optical axis, the shutter does not necessarily have to be at the ground potential, and a voltage may be applied to the shutter 17 according to the request of the electron beam optical system.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the secondary electron image is obtained in order to observe the cross-sectional shape of the sample, but the backscattered electron image may be observed. Further, the structure and mechanism of the shutter are not limited to those of the above embodiment, and other structures and mechanisms may be used as long as they satisfy the following points.

Completely cover the spread angle (solid angle) of the EB column opening from the FIB irradiation point when the shutter is closed. The secondary particles sputtered from the sample also contain ions, but most of them are neutral particles, and their trajectories are considered to be almost linear. Therefore, when the shutter is closed, the objective lens aperture is opened by the shutter. It doesn't have to be completely closed. However, it is necessary to cover the surrounding wall surface such as the sample surface to such an extent as to prevent the once-introduced reflective particles from entering.

When the shutter is open, the shutter itself does not obstruct the electron beam trajectory. Shutter material should be made of conductive material.

[0015]

As described above, the F according to the present invention
Since the IB / EB composite apparatus is configured to open and close the opening at the tip of the electron beam optical system column by the shutter, it is possible to prevent contamination in the EB column and observe an image with high resolution.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a FIB / EB composite apparatus.

FIG. 2 is a diagram showing how a sample is cut by FIB and a cross section is observed by EB.

FIG. 3 is a diagram showing how EB columns are contaminated by sputtered particles.

FIG. 4 is a diagram showing an embodiment of the present invention.

5 is a diagram showing a state in which a shutter is opened in the embodiment of FIG.

FIG. 6 is a diagram showing another embodiment of the present invention.

FIG. 7 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 sample 2 sample chamber 3 FIB column 4 EB column 10 objective lens 14 objective lens aperture 15 shutter 16 rotation axis

Claims (1)

[Claims] 1. A focused ion beam optical system column and an electron beam optical system column are provided on a sample chamber, a sample is cut with an ion beam, and the cut sample portion is scanned with an electron beam,
A FIB / EB composite apparatus, in which a scanning image is obtained by a signal obtained based on the scanning, is provided with a shutter for opening and closing an opening at a tip of an electron beam optical system column. apparatus.