JP3076681B2 - Method for preparing sample for transmission electron microscope observation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion milling apparatus for preparing a sample for observation with a transmission electron microscope.

[0002]

2. Description of the Related Art Generally, it is desirable that the thickness of a sample to be observed with a transmission electron microscope be 100 nm or less. For this reason, various techniques have been developed to produce this sample. The most common method is to mechanically polish the sample and then perform sputter etching using an ion beam such as argon (Ar) to etch the sample to a predetermined thickness. Is realized by an ion milling device. An ion milling device is useful for thinning a sample. However, when observing the interface of a sample having a multilayer structure formed of different materials, a problem arises in sample preparation. Therefore, conventional problems and techniques used to solve the problems will be described.

FIG. 5 shows a relationship between a sample and an ion beam in a conventional ion milling apparatus. In FIG. 5, 1 is a sample, 2 is a rotatable sample stage, and 3 is an ion beam for sputter etching the sample 1. FIG. 5A is a side view, and FIG. 5B is a plan view.

A sample 1 is set on a sample table 2 and
Sputter etching is performed by the ion beam 3 while rotating. The rotation of the sample 1 is for uniform etching. The rate of sputter etching by ions differs depending on the elements constituting the sample.

Therefore, as shown in FIG. 6, when a sample composed of materials 4 and 5 having different rates of sputter etching by ions is sputter-etched by a conventional method, a step occurs at the interface 6 of the material.

Such a step is caused by the ion beams 3a, 3a of the ion beam 3, which are mainly incident in a direction parallel to the sample interface.
3c. On the other hand, even if the ion beams 3b and 3d are incident and a step is generated, as shown in FIG. 7, the incident ion beam is not necessarily only in a direction perpendicular to the sample surface. For this reason, the ion beam 3 that is obliquely incident on the sample is not irradiated on a portion that is a shadow of the step. For this reason, the etching amount at the interface 6 is small, and finally the step is reduced. However, the steps of the ion beams 3a and 3c are completely eliminated and cannot be made flat. Thus, if a step is formed at the interface in the sample manufactured by the above-described method, observation using a transmission electron microscope becomes difficult.

A conventional method used to solve the problem will be described with reference to FIG. FIG.
In the figure, 1 is a sample, 2 is a sample stage, 3 is an ion beam, these are the same as those in FIG. 5, and 7 is a blocking plate for blocking the ion beam. In FIG. 8, (a)
Is a side view and (b) a plan view.

The blocking plate 7 blocks an incident ion beam from a direction parallel to the sample interface, which is a main cause of a step at the sample interface. As a result, it is possible to prevent a step from occurring at the interface, and it is possible to produce a sample suitable for transmission electron microscope observation.

[0009]

However, in the above-mentioned conventional structure, there is a problem that the ion beam hits the shielding plate, the shielding plate is etched, and the ion beam adheres to the sample and contaminates the sample.

[0010]

In order to solve this problem, an ion milling apparatus of the present invention rotates a sample stage holding a sample at a constant rotation speed, and rotates one end of the sample stage by rotating the sample stage. The sample is irradiated with an ion beam while moving up and down in synchronization with the ion beam.

[0011]

With this configuration, the etching rate of the sample is reduced by the ion beam from the specific direction with respect to the sample. For this reason, the interface between samples made of materials having different ion etching rates can be favorably observed. Further, a sample for observation with a transmission electron microscope can be produced without contamination.

[0012]

An embodiment of the present invention will be described below with reference to the drawings.

The present invention utilizes the fact that the sputter etching rate decreases as the angle of incidence of the ion beam incident on the sample decreases.

FIGS. 1 and 2 show a sectional structure of a sample holder of an ion milling apparatus for realizing the present invention.

1 and 2, reference numeral 1 denotes a sample, 2 denotes a rotatable sample table, 3 denotes an ion beam, which are the same as in the prior art, 8 denotes a motor for rotating the sample table 2, 9 denotes a motor. Is a gear for rotating the sample table 2, 10 is a cam for moving one end of the sample table 2 up and down by rotation of the motor 8, and 11 is a column of the sample table 2.

The sample 1 is set on the sample stage 2, and the sample stage 2 is rotated by the motor 8 and the gears 9a and 9b. The ion beam 3 is incident on the sample 1 in the direction of the arrow,
The sample 1 is sputter-etched. At this time, the column 1 of the sample stage 2 is
By moving the sample 1 up and down, the incident angle of the ion beam 3 with respect to the sample stage 2 on which the sample 1 is set is changed.

FIG. 1 shows a state in which the column 11 is lifted most by the cam 10, and the angle of incidence of the ion beam 3 on the sample table 2 is 0 °. In this state, the sample 1 is set so that the incident direction of the ion beam 3 is parallel to the interface of the sample. The state in which the cam 10 is rotated by 180 ° from FIG. 1 is shown in FIG. 2, and the incidence direction of the ion beam 3 is also parallel to the interface of the sample 1 at this time.
In this case, the incident angle of the ion beam 3 with respect to the sample stage 2 is 0 ° with the support 11 at the lowest position.

FIG. 3 shows a plan structure of the cam 10 for realizing such a vertical movement of the column 11. The radius of the cam 10 is R
At this time (position B in FIG. 3), the sample stage 2 becomes horizontal, and the incident angle of the ion beam 3 becomes maximum. The state in FIG. 1 is when the column is supported at point A in FIG. 3, and the state in FIG. 2 is when the column is supported at point C in FIG. When the column 11 is moved up and down using the cam 10, the incident angle θ of the ion beam changes as shown in FIG.
FIG. 4 (b) shows the sample 1 for explaining the rotation angle φ of the sample.
FIG. 4 is a diagram when the relationship between the ion beam 3 and the ion beam 3 is viewed in a plane.

By raising and lowering the column of the sample stage as described above, the incident angle of the ion beam from a direction parallel to the interface is set to 0 °. A sample suitable for transmission electron microscopy observation can be produced because the occurrence of a step can be prevented even at the interface between them.

[0020]

The present invention realizes an ion milling apparatus which can prepare a sample suitable for observation with a transmission electron microscope without contamination of the sample by setting the incident angle of the ion beam to the sample from a specific direction to 0 °. Things.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one state of an ion milling apparatus of the present invention.

FIG. 2 is a configuration diagram showing another state of the ion milling apparatus of the present invention.

FIG. 3 is a plan view of a cam used in the present invention.

FIG. 4A is a diagram illustrating a relationship between a rotation angle of a sample and an ion beam incident angle. FIG. 4B is a diagram illustrating an ion beam incident angle with respect to the sample.

FIG. 5 is a configuration diagram of a conventional ion milling apparatus.

FIG. 6 is a diagram showing a positional relationship between a conventional ion beam and a sample.

FIG. 7 is a cross-sectional view of a sample for observation by a transmission electron microscope on which conventional ion milling has been performed.

FIG. 8 is a configuration diagram of a conventional ion milling device using a blocking plate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sample 2 sample stage 3 ion beam 8 motor 9 gear 10 cam 11 support

Claims (2)

(57) [Claims] 1. A rotating the sample stage for holding a sample at a constant rotational speed, the Rukoto up and down the sample stage at one end in synchronism with the rotation of the sample table, the sample table horizontal state
Between the horizontal state and the state inclined at the maximum angle
To rotate while continuously changing the inclination angle
And the sample stage makes a maximum angle with the horizontal state.
When tilted, the angle of incidence of the ion beam on the sample is
Irradiating the sample with the ion beam to a minimum
A method for observing a sample for transmission electron microscopy, characterized by etching the sample by a method. (2) Made of materials with different etching rates
When placing a sample having a multilayer structure on the sample stage,
Is inclined at a maximum angle with the horizontal state,
The interface of the structure sample is parallel to the ion beam irradiation direction
As described above, the sample is set on the sample stage.
2. The production of the sample for transmission electron microscope observation according to claim 1.
Manufacturing method.