Radiant energy – Inspection of solids or liquids by charged particles – Analyte supports
Reexamination Certificate
2001-04-05
2003-06-10
Lee, John R. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Analyte supports
C250S311000
Reexamination Certificate
active
06576910
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sample holder for holding a sample to be observed in an electron microscope such as a transmission electron microscope, a sample mount on which the sample is affixed, and a sample mount jig for grasping and holding the sample mount.
2. Description of the Background Art
Structural evaluation using an electron microscope has been conventionally employed as one of methods for examining and evaluating semiconductor devices. The electron microscopes mainly include the scanning electron microscopes (SEM) and the transmission electron microscopes (TEM). In the SEM, a beam of electrons is applied to a cleavage plane or an FIB (Focused Ion Beam) processed plane of the sample being observed (observed sample) and secondary electrons etc. obtained from there form an image for observation. In the TEM, a beam of electrons is transmitted through a very thin, 1 &mgr;m thick or less, observed sample and transmitted electrons and scattered electrons (elastically scattered electrons) form an image for observation of the internal structure of the sample.
FIGS. 19A and 19B
are diagrams showing a generally used conventional TEM sample holder.
FIG. 19A
is a plane view of the conventional TEM sample holder and
FIG. 19B
is a front view showing the structure. A sample
105
to be observed, e.g. a semiconductor device, is set on a sample mount
101
provided at an end of the sample holder
100
. The observed sample
105
is shaped like a plate having a film thickness of 0.5 &mgr;m or less in the direction of incidence of the electron beam (Z direction). The part where the observed sample
105
is set on the sample mount
101
is a pole piece element, which is opened above and below the observed sample
105
(in the Z direction) to allow passage of the electron beam.
The TEM sample holder
100
shown in
FIGS. 19A and 19B
is a so-called two-axis inclined sample holder which has been conventionally used, where the observed sample
105
can be turned and inclined about axes in the X direction and the Y direction.
FIG. 20
shows the observed sample
105
turned and inclined on the axis extending along the X direction (hereinafter referred to as X-axis inclination). In the drawing, the arrow AR
20
shows the direction of incidence of the electron beam, i.e. the direction of observation. The X-axis inclination is achieved by a goniometer attached to the body of the TEM; the entirety of the TEM sample holder
100
turns on the axis in the X direction. As the TEM sample holder
100
turns, the sample mount
101
and the observed sample
105
set on it turn and incline, too. In the conventional TEM sample holder
100
, the X-axis inclination is possible within a maximum inclination angle of ±30°.
FIG. 21
is a diagram showing the observed sample
105
turned and inclined on the axis extending in the Y direction (hereinafter referred to as Y-axis inclination). The arrow AR
21
in the diagram shows the direction of incidence of the electron beam, i.e. the direction of observation. In the Y-axis inclination, a motor provided in the TEM sample holder
100
turns the sample mount
101
. As the sample mount
101
turns relative to the TEM sample holder
100
on the axis in the Y direction, the observed sample
105
set on it, too, turns and inclines accordingly. In the conventional sample mount
101
, the Y-axis inclination is possible within a maximum inclination angle of ±30°.
Thus, with the conventional two-axis inclined sample holder, the observed sample
105
can be observed from desired directions, e.g. from a particular orientation of the crystal structure, through the X-axis inclination and the Y-axis inclination of the observed sample
105
.
The recent remarkable advances in manufacture of the semiconductor devices are achieving finer and more complicated structures and therefore more detailed structural evaluations are needed. It is hence desirable to observe the semiconductor device from a greater number of directions.
However, the conventional X-axis inclination and Y-axis inclination can be made within the limited ranges (e.g. ±30°) and therefore the semiconductor device can be observed only in the limited ranges. It has been hence extremely difficult to observe the semiconductor device in many directions.
The processing by FIB is now attracting particular interests as a technique for forming the thin-film sample
105
from a semiconductor device. The FIB usually uses Ga liquid metal etc. as the ion source; an ion beam focused to several micrometers or less scans the object to sputter-etch a particular area, whereby the area to be observed can be precisely obtained as a thin film. The observed sample
105
formed by the FIB processing is so small that its handling is complicated and difficult. Therefor it will be convenient if the FIB process can be applied to a sample being mounted on a TEM sample holder.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a sample holder for holding a sample to be observed in an electron microscope comprises: a sample mount on which the sample is affixed; and a rotation driving mechanism for rotating the sample mount about a predetermined axis in the range of 0 to 360°.
Preferably, according to a second aspect, in the sample holder, the rotation driving mechanism rotates the sample mount in the range of 0 to 360° about an axis extending along a direction other than the direction of electron beam incidence in the electron microscope.
Preferably, according to a third aspect, the sample holder further comprises a cartridge portion coupled to the sample mount and a fixed portion coupled to the main body of the sample holder, wherein the cartridge portion can be attached to and removed from the fixed portion.
A fourth aspect is directed to a sample mount jig for grasping and holding a sample mount provided in a sample holder for holding a sample to be observed in an electron microscope. According to the fourth aspect, the sample mount jig comprises: a protecting portion for covering the sample affixed on the sample mount when the sample mount jig is grasping the sample mount; and a grip portion fixed to the protecting portion.
A fifth aspect is directed to a sample mount on which a sample to be observed is affixed and which is provided in a sample holder for holding the sample in an electron microscope. According to the fifth aspect, the sample mount comprises: a mount plate having a gap whose width is narrower than the length of the sample, for supporting the sample affixed thereon, wherein the sample is laid over opposite portions of the gap of the mount plate.
Preferably, according to a sixth aspect, the sample mount is composed of the mount plate and a support plate for supporting the mount plate, the mount plate and the support plate being combined in the shape of L in section.
Preferably, according to a seventh aspect, in the sample mount, the mount plate is in the form of a flat plate.
An eighth aspect is directed to a sample holder for holding a sample to be observed in an electron microscope. According to the eighth aspect, the sample holder comprises: a sample mount composed of a mount plate on which the sample is affixed and supported and a support plate for supporting the mount plate, the mount plate and the support plate being combined in the shape of L in section; and a holding portion for holding the support plate of the sample mount; wherein the mount plate has a gap whose width is narrower than the length of the sample and the sample is laid over opposite portions of the gap of the mount plate.
Preferably, according to a ninth aspect, in the sample holder, the holding portion holds the sample mount in such a manner that the part of the mount plate where the sample is affixed protrudes from the sample holder.
Preferably, according to a tenth aspect, in the sample holder, the holding portion comprises a first holding portion for holding the support plate in such a manner that the normal direction of the mount plate ex
Fukumoto Koji
Hashikawa Naoto
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