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JPH05297948

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DESCRIPTION JPH05297948
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
stage apparatus capable of positioning in nanometer units.
[0002]
2. Description of the Related Art Conventionally, in a stage apparatus for mounting a sample such
as a scanning probe microscope, as a minute positioning mechanism for finely moving and
positioning a stage, there is a positioning mechanism using a piezoelectric element. This
positioning is performed by using a piezoelectric element which obtains a minute displacement
by controlling an electric field or a current. However, since the piezoelectric element has
hysteresis as shown in FIG. 4, it is necessary to use a control system which feeds back the
amount of movement in order to perform positioning accurately.
[0003]
The above-mentioned conventional micro-positioning mechanism is greatly affected by the
hysteresis of the piezoelectric element and the drift due to the temperature. In order to suppress
these influences, there are some which attach a strain gauge to a piezoelectric element and
perform feedback control, but there was a problem that it was unsuitable for high-speed
operation.
04-05-2019
1
[0004]
The present invention seeks to realize a stage device that has small hysteresis and can be
positioned accurately and at high speed.
[0005]
According to the present invention, there is provided a stage device comprising at least a stage
on which a sample is placed and a drive for finely moving the stage. The electrostrictive element
3 is used, and temperature control means is added to the electrostrictive element 3 to operate
the electrostrictive element in a temperature range where hysteresis is small.
By adopting this configuration, it is possible to obtain a stage device which has small hysteresis
and can be accurately positioned at high speed.
[0006]
In the present invention, in place of the piezoelectric element, an electrostrictive element having
a smaller hysteresis is used for the driving device. The piezoelectric element used in the prior art
generates distortion in proportion to the electric field E. However, the electrostrictive element
used in the present invention is a square of the electric field E, for example, as shown in FIG.
Generates a distortion proportional to and its hysteresis is small.
[0007]
Further, as can be seen from the temperature-hysteresis characteristic diagram of PZT (lead
zirconate titanate) of the piezoelectric element and PMN (lead magnesium niobate) of the
electrostrictive element shown in FIG. 2, PMN has a smaller hysteresis than PZT. And in a certain
temperature range, the hysteresis is further reduced. The present invention adds temperature
control means to the electrostrictive element so as to operate in the temperature range where the
hysteresis is small. Therefore, according to the present invention, highly accurate positioning
with small hysteresis can be performed. Further, high speed operation is possible because
feedback control necessary for the conventional piezoelectric element is not required.
04-05-2019
2
[0008]
FIG. 3 is a view showing an embodiment of the present invention, wherein (a) is a block diagram
and (b) is a perspective view. In this embodiment, as shown in the figure, a base 1, a stage 2
slidably supported on the base in the XX 'direction, one end thereof is fixed to the base 1, and the
other end is a stage 2 And an electrostrictive element 3 such as PMN (lead magnesium niobate)
connected thereto. A heat retaining portion is provided in the electrostrictive element 3 so as to
surround the entire electrostrictive element. The heat retaining portion includes a heating
element 4 such as a nichrome wire for heating the electrostrictive element 3 to a temperature
range where the hysteresis is small, and a temperature measuring element 5 such as a
thermocouple for detecting a temperature. The heating element 4 and the temperature
measuring element 5 are connected to the temperature control unit 6. The electrode 3 a of the
electrostrictive element 3 is connected to the electrostrictive element controller 7.
[0009]
The operation of this embodiment configured in this way will be described next. First, the
electrostrictive element 3 is heated by the heating element 4 and maintained at a temperature
range where the hysteresis of the electrostrictive element 3 is small, for example, 30 to 60 ° C.
in the case of PMN, by the temperature measuring element 5 and the temperature control unit 6 .
Next, to move the stage 2, an electric field is applied to the electrostrictive element 3 by the
electrostrictive element controller 7. At this time, unlike the piezoelectric element, since the
electrostrictive element 3 has no polarity and is displaced as a quadratic function as shown in
FIG. 1, for example, the operating point is offset as shown in FIG. It is necessary to set up and
check the operating voltage with respect to the movement amount.
[0010]
According to the present embodiment, by holding the electrostrictive element 3 in a temperature
range where the hysteresis is small, as shown in FIG. 2, the hysteresis of the conventional
piezoelectric element is about 15%, as in the present embodiment. In the example, it can be
reduced to about 2%. Further, in the present embodiment, since a control system for feeding back
the amount of movement of the stage as in the prior art is not required, high speed operation is
possible. Although this embodiment controls the temperature around the electrostrictive element,
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the method of controlling the temperature of the electrostrictive element is not limited to this
embodiment.
[0011]
According to the present invention, since the hysteresis is small by using the electrostrictive
element instead of the piezoelectric element, accurate positioning can be performed. In addition,
since a mechanism for feedback control of the movement amount is unnecessary, it is possible to
operate at high speed. This is effective for use in a stage apparatus such as a scanning probe
microscope.
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4
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