JPH11160210A - Observation sample for transmission electron microscope and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily analyze composition in a specific position of a sample which is prepared by using a focused ion beam, by a method wherein an Si substrate on the opposite side of the incident direction of an electron beam is removed largely while a thin-film piece is used as the center. SOLUTION: First, by using a dicing saw, a sample piece 2 in a length of 2.5 mm and a width of 200 μm is cut off from an Si substrate while an observation position 1 is used as the center. At the same time, while the observation position 1 is used as the center, the surface of the Si substrate is shaved down to a depth of 100 μm while its length of 2.5 mm and its width of about 20 μm are left. Then, a part 5 in a width of about 50 μm and a depth of about 50 μm on the surface part of the Si substrate on the opposite side of the incident direction of an electron beam in an observation operation is removed by a laser beam. Lastly, the surface of the Si substrate in both side parts of the observation position 1 is removed in parts 3 by a width of 10 μm, by a depth of 3 μm on the incident side of the electron beam and by a depth of 6 μm on the opposite side. A thin-film piece 4 in a width of 10 μm and a thickness of 0.1 μm is left while the observation opposition 1 is used as the center. As a result, it is possible to largely reduce the generation of X-rays when the electron beam or the like which is scattered in the thin-film piece 4 hits the Si substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an observation sample for a transmission electron microscope manufactured using a focused ion beam and a method for manufacturing the same.

[0002]

2. Description of the Related Art Acceleration voltage is 100 keV to 400 keV.
In a general-purpose transmission electron microscope, the thickness of a sample in which a fine shape can be observed is about 0.2 μm or less, and preparation of such a thin film sample is very important in observation with a transmission electron microscope. Therefore, various sample manufacturing methods have been used. As a sample manufacturing method for observing a cross section of a specific position such as an electrically defective portion of a semiconductor device, there is a manufacturing method using a focused ion beam.

FIGS. 4 and 5 are views for explaining a conventional method for preparing a sample for observing a cross section of a semiconductor device at a specific position using a focused ion beam with a transmission electron microscope.

4 and 5, reference numeral 1 denotes a cross-sectional observation position by a transmission electron microscope, 2 denotes a sample piece having an observation position 1 cut out from a silicon (hereinafter, referred to as Si) substrate, and 3 denotes a focused ion beam. The portion 4 from which the Si substrate has been removed is a thin film piece having an observation position 1 left after being processed by the focused ion beam.

First, a 2.5 mm length and a 2 width centered on an observation position 1 where a cross section is observed with a transmission electron microscope from a Si substrate.
A sample piece 2 of 00 μm is cut out with a dicing saw. At this time, the length around the observation position 1 is 2.5 mm and the width is 20 mm.
The surface of the Si substrate having a thickness of μm is left, and the surface of the Si substrate other than the portion is cut off to a depth of about 100 μm (FIG. 4). Next, using a focused ion beam, a width of about 10 μm and a depth of about 3 μm centering on the observation position 1 on the surface of the Si substrate which has not been removed by the processing of the dicing saw on both sides of the observation position 1
Part 3 is removed, and the width is 10 μ around the observation position 1.
An observation sample for a transmission electron microscope is formed as a thin film piece 4 having a thickness of about 0.1 μm and a thickness of about 0.1 μm (FIG. 5).

[0006]

The observation sample prepared by the above-mentioned conventional focused ion beam is applied to an X-ray attached to a transmission electron microscope.
When a composition analysis is performed by a X-ray analyzer, X-rays generated in areas other than the thinned analysis part are detected with extremely high intensity due to scattered electrons of electrons incident on the observation position in the thinned part. There was a problem that analysis of the analysis data became difficult.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an observation sample for a transmission electron microscope in which a Si substrate on a side opposite to a direction of incidence of an electron beam around a thin film piece is largely removed. This is a manufacturing method. According to the present invention, generation of X-rays due to electron beams or the like scattered in a thin film piece hitting a Si substrate is greatly reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows an embodiment of an observation sample for a transmission electron microscope according to the present invention, and FIGS. 1 to 3, reference numeral 1 denotes an observation position in a transmission electron microscope, 2 denotes a sample piece having an observation position 1 cut out from a Si substrate, 3 denotes a portion where the Si substrate is removed by a focused ion beam, and 4 denotes a focused ion beam. These structures are the same as those of the conventional example in the thin film piece having the observation position 1 which has been processed and left. Reference numeral 5 denotes a portion from which the Si substrate has been removed by the laser beam.

First, a sample piece 2 having a length of 2.5 mm and a width of 200 μm centering on the observation position 1 is cut out from a Si wafer by machining using a dicing saw in the same manner as in the conventional sample preparation method. At this time, the surface of the Si substrate is shaved at a depth of about 100 μm using a dicing saw while leaving a length of about 2.5 mm and a width of about 20 μm centered on the observation position 1 (FIG. 1). Next, a portion 5 having a width of about 50 μm and a depth of about 50 μm of the surface portion of the Si substrate remaining by the dicing saw on the side opposite to the electron beam incident direction at the time of observation is removed with a laser beam (FIG. 2). ). It is sufficient to remove the portion as close as possible to the observation position 1 with a laser, but from the processing accuracy with the laser beam, the portion is removed to about 2 μm at the observation position 1. In this embodiment, processing is performed using a KrF excimer laser.

Finally, the surface of the Si substrate remaining by the dicing saw and the laser beam processing on both sides of the observation position 1 with the focused ion beam is 10 μm wide as in the conventional example.
m, the electron beam incident side has a depth of 3 μm, and the opposite side has a depth of 6 μm.
μm portion 3 is removed and width 1 around observation position 1
A thin film piece 4 having a thickness of 0 μm and a thickness of 0.1 μm is left (FIG. 3).

In the observation sample for the transmission electron microscope according to the present invention, since the Si substrate surface on the side opposite to the electron beam incident direction with respect to the thin film piece finally processed by the focused ion beam is largely removed, The generation of X-rays due to the electron beam or the like scattered in the piece hitting the Si substrate is greatly reduced.

[0012]

According to the observation sample for the transmission electron microscope of the present invention and the method for manufacturing the same, the composition analysis of a specific position in the sample manufactured using the focused ion beam can be facilitated.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of a method for manufacturing an observation sample for a transmission electron microscope of the present invention.

FIG. 2 is a diagram illustrating an embodiment of a method for manufacturing an observation sample for a transmission electron microscope of the present invention.

FIG. 3 is a diagram illustrating an embodiment of an observation sample for a transmission electron microscope of the present invention and a method for manufacturing the same.

FIG. 4 is a diagram illustrating a conventional method for manufacturing an observation sample for a transmission electron microscope.

FIG. 5 is a diagram illustrating a conventional method for producing an observation sample for a transmission electron microscope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Observation position 2 Sample piece 3 Portion where Si substrate was removed by focused ion beam 4 Thin film piece 5 Portion where Si substrate was removed by laser beam

Claims (2)

[Claims] At the same time, a sample piece is cut out from a silicon substrate at a position where a cross section is observed by a transmission electron microscope, and at the same time, the sample piece is left while leaving the silicon substrate surface centered at the observation position. And then on the side opposite to the direction of incidence of the electron beam in transmission electron microscopy observation,
A portion of the silicon substrate surface that has not been scraped away from the observation position is removed by a laser beam, and then, on both sides of the observation position, the unremoved silicon substrate surface is focused ions leaving the periphery of the observation position. An observation sample for a transmission electron microscope, which has been removed with a beam and left a thin film piece. 2. A sample piece is cut out from a silicon substrate at a position where a cross section is observed by a transmission electron microscope, and at the same time, the sample piece is left while leaving the silicon substrate surface centered at the observation position. A first step of shaving off
A second step of removing, with a laser beam, a portion of the silicon substrate surface that has not been scraped off in the first step and away from the observation position, on a side opposite to the electron beam incident direction in transmission electron microscope observation; A third step in which, on both sides of the position, the silicon substrate surface not removed in the first and second steps is removed with a focused ion beam leaving the periphery of the observation position, leaving a thin film piece. A method for preparing an observation sample for an electron microscope.