Radiant energy – Inspection of solids or liquids by charged particles – Analyte supports
Reexamination Certificate
1999-07-14
2002-10-01
Nguyen, Kiet T. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Analyte supports
C310S328000, C369S126000
Reexamination Certificate
active
06459088
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a drive stage and also to a scanning probe microscope and an information recording/reproducing apparatus using such an drive stage.
2. Related Background Art
The recent invention of the scanning tunneling microscope (hereinafter referred to as STM) made it possible to visually observe an image of the surface of an electrocoductive substance with a degree of resolution of the nanometer level or lower (U.S. Pat. No. 4,343,993) so that now the arrangement of atoms of the surface of metal or semiconductor and the orientation of organic molecules are equally observable. Furthermore, the atomic force microscope (hereinafter referred to as AFM) adapted to observe the surface of an insulating substance with the degree of resolution of the STM has been developed as an extension of the STM technology (U.S. Pat. No. 4,724,318). The scanning near-field optical microscope (hereinafter referred to as SNOM) has also been developed from the STM. It can be used to examine the surface of a specimen by utilizing evanescent light seeping out from the micro-aperture arranged at the micro-tip of the sharp probe of the microscope [During et al., J. Appl. Phys. 59, 3318 (1986)]. Currently, these and other similar microscopes are globally referred to as the scanning probe microscope (hereinafter abbreviated as SPM) and used to measure the tunneling current, the electronic state density, the interatomic force, the intermolecular force, the frictional force, the elastic force, the evanescent light, the magnetic force and other various physical values of the surface of a specimen.
The above described SPM technology is being applied to memories. For example, Japanese Patent Application Laid-Open Nos. 63-161552 and 63-161553 describe a method of recording/reproducing information by means of an STM and a recording medium of a material capable of storing information on the volt-ampere switching characteristic of the recording medium, which may typically be realized in the form of a thin film layer of a &pgr;-electron type organic compound or a chalcogen compound. With the proposed method, a change in the characteristic is made to occur and recorded in a minute region of the recording medium located right below the probe of the STM by applying a voltage higher than a certain threshold level, utilizing the phenomenon that the tunneling current flowing between the probe and the recording medium changes depending on the recording section and the non-recording section of the recording medium. With the proposed method, an information processing apparatus having a recording density of 10
12
bits/cm
2
can be realized, provided that a bit size of 10 nm in diameter is selected for the recording.
It is also known that a recording medium in the form of a thin film of a metal such as Au or Pt that becomes locally molten or evaporated to produce a projection or a recess on the surface when a voltage exceeding a certain threshold level is applied thereto can be used for recording/reproducing information concurrently.
With any of the above described SPMs, the probe is driven to move relative to the surface of a specimen or a recording medium by a drive stage and the physical interaction between the probe and the specimen is detected in order to obtain an image or record/reproduce information.
FIGS. 1 through 3
of the accompanying drawings schematically illustrate known drive stages.
The drive stage shown in
FIG. 1
comprises a cylindrical piezoelectric element
1000
and four electrodes
1001
through
1004
arranged on the outer periphery of the cylindrical piezoelectric element in four respective equally divided sectors thereof (although the electrode
1004
is not visible in FIG.
1
). A mechanical stage
1005
is connected to the top of the piezoelectric element (although it is separated from the piezoelectric element in FIG.
1
). The cylindrical piezoelectric element
1000
can be made to bend by controlling voltages applied to a pair of oppositely disposed electrodes (
1001
and
1003
or
1002
and
1004
) so as to cause one to expand and the other to contract. The piezoelectric element
1000
can be made to axially extend or contract by applying a same and identical voltage to all the four electrodes. Thus, the piezoelectric element
1000
can be made to extend or contract three-dimensionally by controlling the voltages applied to the four electrodes
1001
through
1004
. Then, the mechanical stage
1005
bonded to the top of the piezoelectric element can be driven to move three-dimensionally.
FIG. 2
illustrates a uniaxial drive stage. It comprises a support body
2001
and a mechanical stage
2002
linked to the support body
2001
by means of parallel hinge springs
2003
. These components may be integrally manufactured or assembled to produce the drive stage. Additionally, a piezoelectric actuator
2004
is linked to the mechanical stage
2002
and the support body
2001
respectively at the opposite ends thereof. With the illustrated drive stage, the mechanical stage
2002
can be driven to move leftwardly or rightwardly in
FIG. 2
relative to the support body
2001
by applying a voltage to the piezoelectric actuator
2004
to make it expand or contract.
FIG. 3
illustrates a drive mechanism disclosed in Japanese Patent Publication No. 6-46246. Referring to
FIG. 3
, a mechanical stage
3003
is supported by two pairs of parallel hinge springs
3010
,
3011
and
3012
,
3013
at an end of each of them. The pair of parallel hinge springs
3010
,
3011
are connected at the other end of each of them to a Y-axis drive piezoelectric actuator
3005
by way of an auxiliary support body
3001
, while the pair of parallel hinge springs
3012
,
3013
are connected at the other end of each of them to an X-axis drive piezoelectric actuator
3006
by way of another auxiliary support body
3002
.
The auxiliary support body
3001
is supported by the parallel hinge springs
3010
,
3011
and also by parallel hinge springs
3014
,
3015
arranged perpendicularly relative to the hinge springs
3010
,
3011
at an end of each of them, whereas the auxiliary support body
3002
is supported by the parallel hinge springs
3012
,
3013
and also by parallel hinge springs
3016
,
3017
arranged perpendicularly relative to the hinge springs
3012
,
3013
at an end of each of them. All the parallel hinge springs
3014
,
3015
, the parallel hinge springs
3016
,
3017
, the Y-axis drive piezoelectric actuator
3005
and the X-axis drive piezoelectric actuator
3006
are connected at the other end of each of them to a substrate
3000
.
With the above described arrangement, both the mechanical stage
3003
and the auxiliary support body
3001
are driven to move along the Y-axis as they are supported respectively by the parallel hinge springs
3012
,
3013
and the parallel hinge springs
3014
,
3015
when the Y-axis drive piezoelectric actuator
3005
is expanded or contracted. On the other hand, the parallel hinge springs
3010
,
3011
are highly rigid along the Y-axis and hence move together in that direction. Similarly, both the mechanical stage
3003
and the auxiliary support body
3002
move together along the X-axis when the X-axis drive piezoelectric actuator is expanded or contracted.
Thus, the mechanical stage
3003
follows the motion of the Y-axis drive piezoelectric actuator
3005
and that of the X-axis drive piezoelectric actuator
3006
with complete fidelity so that the two motions do not interfere with each other on the mechanical stage
3003
.
Then, the mechanical stage
3003
can be driven to move both in the X-axis and in the Y-axis in any desired fashion by means of the X-axis drive piezoelectric actuator
3006
and the Y-axis drive piezoelectric actuator
3005
.
However, with any of the known drive stages of
FIGS. 1 through 3
, the inertial force generated in the mechanical stage increases as the drive stage is driven to move faster so that the support members will eventually vibrate due to the inertial forc
Seki Jun-ichi
Shido Shunichi
Yasuda Susumu
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