JPH06123685A - Manufacture of sample for transmission type electron microscope - Google Patents

Abstract

PURPOSE:To manufacture a sample for observing a specific part with a transmission type electron microscope easily. CONSTITUTION:The film thickness at the center is mechanically ground to 30mum. Then, a glass 8 is adhered to the surface of a sample 1 with a wax, and a mark 9 for specifying an observation part 2 is put on the surface of the glass 8 with laser beams 6. Then, a metal film 10 is deposited on the glass 8. Then, the metal film 10 near the mark 9 is eliminated with the laser beams 6, thus providing an opening 11. If the sample is etched with an ion milling device, the completion of the etching is detected with an end detector using the laser beams 6 and a semiconductor detector 7 when a hole 4 in the sample 1 is opened near the observation part 2. Then, the glass 8 is finally peeled off as an observation sample.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a sample for a transmission electron microscope.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of elements, transmission electron microscopes have been used to observe the inside. Generally, a transmission electron microscope is used at an accelerating voltage of several 100 kV. Therefore, the film thickness of the sample observed with the transmission electron microscope needs to be 0.1 μm or less. Therefore, it is difficult to prepare a thin film sample for observation, and various methods have been devised.

A conventional sample preparation method for observing a semiconductor device in a plane, particularly a sample preparation method for observing a specific portion such as an electrically defective portion with a transmission electron microscope will be described with reference to the drawings.

11 to 14 are sectional views for explaining a conventional method for preparing a sample for observation. In the figure, 1 is an observation sample, 2 is a specific portion to be observed in the sample 1, 3 is an ion beam for thinning the sample,
4 is a hole made in the sample 1 by the ion beam, 5,
Is a laser light source for detecting that a minute hole 4 is opened in the center of the sample 1 by etching using the ion beam 3, 6 is a laser beam, and 7 is a semiconductor detector.

A sample preparation method for observing the specific portion 2 in the sample 1 shown in FIG. 11 will be described. First, the thickness of the central portion of the sample is set to about 30 μm by mechanical polishing (FIG. 1).
2). Next, as shown in FIG. 13, a minute hole 4 is formed at the center of the sample by etching using the ion beam 3. An apparatus for etching using such an ion beam is an ion milling apparatus, which is often used for preparing a sample for a transmission electron microscope.

A method for detecting the opening of the hole 4 will be described with reference to FIGS. In the ion milling apparatus, the laser beam 6 emitted mainly from the laser light source 5 and the semiconductor detector 7 detect that a hole has been formed. That is, in the state of FIG. 15 in which no hole is formed, the laser beam 6 is reflected by the sample 1 and does not reach the semiconductor detector 7. When the etching further progresses and a minute hole 4 opens in the center of the sample as shown in FIG. 16, the laser beam 6 is detected by the semiconductor detector 7. When it is detected that a minute hole is opened, the etching using the ion beam 4 is completed. A device that detects the completion of such etching is called an end point detector.

In the case of observing not the specific portion 2 but an arbitrary place, a sample having a minute hole 4 as shown in FIG. 13 is observed with a transmission electron microscope at a thin film portion around the hole 4.

However, in the case of observing the specific portion 2, the etching using the ion beam 3 is further performed, as shown in FIG.
As described above, it is necessary to widen the hole 4 to the extreme periphery of the observation part 2, usually to a position within 2 μm, and thin the sample film thickness of the specific part 2. When the hole is expanded to the peripheral part of the observation part 2 by the etching using the ion beam 3, in order to prevent the observation part 2 from being etched, the hole 4 is expanded by repeating the etching and the optical microscope observation little by little. .

[0009]

However, in the above-mentioned conventional sample preparation method for the transmission electron microscope, the end point detector using the laser beam 6 and the semiconductor detector 7 detects that a hole is formed in the center of the sample. After that, the etching sample is repeatedly manufactured by performing the etching and the optical microscope observation little by little, so that there is a problem that a large amount of time and labor are required for manufacturing the sample.

[0010]

In order to solve this problem, the sample preparation method of the present invention is such that a glass is adhered to a sample surface having a predetermined sample film thickness, and a mark for identifying an observation position is formed on the glass surface. After providing, a metal film is vapor-deposited on the glass surface, the metal film around the observation part is removed using the laser beam based on the mark, and the glass is removed after etching by ion milling. .

[0011]

In the sample preparation method of the present invention, the metal film is vapor-deposited on the glass adhered to the surface of the sample, and the metal film around the observation portion is removed by the laser beam to observe the etching of the sample by the ion beam. A sample for observing the specific portion with a transmission electron microscope can be prepared by detecting the end point by an etching end point detection method using a laser beam and a semiconductor detector at the time of reaching the periphery of the specific portion. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 to 7 show a method of preparing a sample for a transmission electron microscope in one embodiment of the present invention. In FIG. 1, 1 is an observation sample, 2 is a specific portion in the observation sample 1 to be observed, 3 is an ion beam for thinning the sample, 4 is a hole made in the sample 1 by the ion beam, and 5 is A laser light source for detecting that a minute hole is formed in the center of the sample 1 by etching using the ion beam 3, 6 is a laser beam, and 7 is a semiconductor detector, which have the same configuration as the conventional example. Reference numeral 8 is glass, 9 is a mark provided on the glass 8, 10 is a metal film deposited on the glass 8, and 11 is an opening of the metal film 10 provided in the peripheral portion of the observation portion 2.

The method for preparing the sample will be described below.
First, similarly to the conventional example, the sample whose cross-sectional view is shown in FIG. 1 is mechanically polished to a film thickness of 30 μm in the central portion (FIG. 2).
Next, the glass 8 having a film thickness of 300 μm is adhered to the surface of the sample 1 by using wax, and the laser beam 6 is used on the surface of the glass 8 to provide the mark 9 for identifying the observation portion 2 (FIG. 3). Next, the metal film 10 is vapor-deposited on the glass 8 (FIG. 4). In this example, an aluminum film having a thickness of about 1 μm was deposited by vacuum deposition. Next, the metal film 1 near the mark 9
0 is removed by the laser beam 6 to provide the opening 11 (FIG. 5). The size of the opening is about 5 μm × 5 μm.
As shown in FIG. 5, the opening is provided in the direction in which the hole 4 is first opened by the ion beam 3 with the observation section 2 as one end. When such a sample is etched by an ion milling device as in the conventional example, the end point detector using the laser beam 6 and the semiconductor detector 7 is reached when the hole 4 opened in the sample 1 is opened to the vicinity of the observation part 2. The end of etching is detected by (FIG. 6).
Finally, the glass 8 is peeled off to obtain an observation sample (FIG. 7).

The process of etching by ion milling will be described in more detail with reference to FIGS.

FIG. 8 is a sectional view at the time when etching is started. At this time, the laser beam 6 is reflected by the sample 1 and does not reach the semiconductor detector 7. Even if the etching further progresses and a minute hole 4 is opened in the center of the sample 1, the laser beam 6 does not reach the semiconductor detector 7 because it is reflected by the metal film 10 deposited on the glass 8 (FIG. 9). In the conventional sample preparation method, the laser beam 6 reaches the semiconductor detector 7 at this point and the end of etching is detected. In the present sample preparation method, when the etching further progresses and the hole 4 of the sample 1 expands and reaches the opening 11 of the metal film 10, the laser beam 6 passes through the opening 11 and reaches the semiconductor detector 7 (FIG. 10). ). This is recognized as the end of etching. Although the laser beam 6 is shown by a straight line in FIGS. 8 to 10, the actual diameter of the laser beam is larger than that of the sample.

The observation sample produced by this method is the specific section 2
Since the hole 4 extends to the vicinity, the transmission electron microscope observation of the specific portion 2 is possible without further etching.

Although the aluminum film is vapor-deposited on the glass in this embodiment, another vapor-deposited thin film such as gold may be used instead of the aluminum film.

[0019]

According to the sample preparation method of the present invention, an aluminum film is vapor-deposited on the glass adhered to the surface of the sample, and the aluminum film around the observation portion is removed by a laser beam to observe the etching of the sample by the ion beam. When it reaches the periphery of the specified part, the end point is detected by the etching end point detection method using a laser beam and a semiconductor detector, making it easy to prepare a sample for observing the specific part with a transmission electron microscope. Can be

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 2 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 3 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 4 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 5 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 6 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 7 is a schematic sectional view showing a sample manufacturing method of the present invention.

FIG. 8 is a diagram explaining the detection of the etching end point in the sample preparation method of the present invention.

FIG. 9 is a diagram illustrating the detection of the etching end point in the sample preparation method of the present invention.

FIG. 10 is a diagram for explaining the detection of the etching end point in the sample preparation method of the present invention.

FIG. 11 is a schematic sectional view showing a conventional sample manufacturing method.

FIG. 12 is a schematic sectional view showing a conventional sample manufacturing method.

FIG. 13 is a schematic sectional view showing a conventional sample preparation method.

FIG. 14 is a schematic sectional view showing a conventional sample manufacturing method.

FIG. 15 is a diagram illustrating a method for detecting an etching end point in an ion milling device.

FIG. 16 is a diagram illustrating an etching end point detection method in an ion milling device.

[Explanation of symbols]

 1 Sample 2 Specific Part 3 Ion Beam 4 Hole 5 Laser Light Source 6 Laser Beam 7 Semiconductor Detector 8 Glass 9 Mark 10 Metal Film 11 Opening

Claims (1)

[Claims] 1. A glass is adhered to a sample surface having a predetermined sample thickness, a mark for identifying an observation position is provided on the glass surface, and then a metal film is vapor-deposited on the glass surface. A method for producing a transmission electron microscope sample, which comprises removing the metal film around the observation portion using the laser beam, etching by ion milling, and then removing the glass.