Radiant energy – Inspection of solids or liquids by charged particles
Reexamination Certificate
2002-06-12
2004-05-11
Lee, John H. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
C250S433000
Reexamination Certificate
active
06734426
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a probe scanning device such as a scanning probe microscope, and particularly relates to a probe scanning device capable of measurement with little temperature drift and low noise.
2. Description of the Related Art
The applicant has previously invented a probe scanning device having a zooming function shown in FIG.
10
and applied for a patent (Japanese Patent Publication No. Hei. 10-221348). The structure and function of this probe scanning device will be briefly described below.
A case
1
has a scanning tube
20
having a thin tube
14
projecting to a sample chamber and a thick tube
15
connected thereto as main components. An inner tube
13
is supported inside the thick tube
15
through the viscous material
17
. The thick tube
15
, the inner tube
13
, and the thin tube
14
are made with the same quality and heat conductivity and the thermal expansion coefficients thereof are substantially equal. A lower melting-point metal holder
74
is fixed to an outer side face of the thick tube
15
. The low melting-point metal holder
74
consists of an insulating material such as ceramic or a super-engineered plastic and a low melting-point metal
75
such as u alloy is insulatively housed in a groove formed on a top face thereof.
A first voice coil motor (VCM) is fitted to the top of the case
1
.
This first voice coil motor comprises a magnet
2
having a shaft
3
, a needle
4
a
surrounded by a wound on coil
5
, a needle component
4
b
fixed to the needle
4
a
, a membrane
6
a
, and a fixing component
6
b
fixing an outer circumference of the membrane
6
a
. A spindle
8
extending in a z direction is fixed to the needle component
4
b
. A detector
9
for detecting a displacement of a tip
10
is installed in a bottom side end of this spindle
8
.
The spindle
8
is supported elastically by first and a second springs
11
and
12
held by the inner tube
13
. A heating coil
16
is wound around at a position outside the thick tube
15
and opposite to the viscous material
17
. The heating coil
16
is electrified for softening the viscous material
17
in coarse adjustment of the tip
10
in the z direction.
A second voice coil motor, which comprises a magnet
21
having a shaft
22
, a needle
23
a
surrounded by a wound on coil
24
, a needle component
23
b
fixed to the needle
23
a
, a membrane
25
, and a fixing component
25
a
fixing the outer circumference of the membrane
25
, is mounted on a side of the case
1
.
A thin annular plate spring
23
c
is fitted to a lateral side of the case
1
for preventing the needle
23
a
from making contact with the shaft
22
or the magnet
21
, when the thick tube of the scanning tube
20
tilts in an XY direction. At the thin annular plate spring
23
c
, the outer circumference thereof is pushed by the case
1
and the membrane fixing component
25
a
and an inner circumference thereof is pushed by the needle component
23
b
and an annular spring component
23
d
. A spindle
27
extending in an x direction is fitted to the needle component
23
b
and the annular spring component
23
d
. An open end of the spindle
27
is fixed to a projecting portion
15
a
of the thick tube
15
.
A third voice coil motor (not shown) is installed in a direction differing by 90° from the second voice coil motor. The third voice coil motor is constituted as being identical or equal to the second voice coil motor. A y direction (a direction at right angles to the paper) spindle connects a movable component fixed to the needle of the third voice coil motor to the thick tube
15
. Driving the second and third voice coil motors allows the tip
10
to scan in the xy direction. A sample table (not shown) is mounted at a position opposite the tip
10
and a sample is mounted on the sample table.
An outer tube
71
, of which one end is fixed to the case
1
, extends to the outside of the thin tube
14
in the direction coaxial with the thin tube
14
and so as to project to the sample chamber. At the outer circumference of a front end of the outer tube
71
, a heat conductive cylinder
73
is installed through the insulative member
72
formed from ceramic material. A heating coil
76
is wound around the outer circumference of the heat conductive cylinder
73
. The bottom end of the heat conductive cylinder
73
is embedded in the low melting-point metal
75
of the low melting-point metal holder
74
.
According to such a structure, controlling electrification of the heating coil
76
for melting or solidifying the low melting-point metal
75
allows switching spring rigidity of the scanning tube
20
to any one of spring rigidity of the thin tube
14
only or spring rigidity created by adding the thin tube
14
to the outer tube
71
. As a result, even if the driving current supplied to the voice coil motors is equal, a movable range of the scanning tube
20
in the XY direction can be made to be different to express the zooming function.
When measuring the sample, first, the heating coil
16
of the thick tube is electrified to raise the temperature of the viscous material
17
so as to finally decrease the viscosity of the viscous material
17
. Next, the voice coil motor is electrified in a z direction to carry out coarse adjustment of the spindle
8
in the z direction. When the tip
10
makes contact with the sample surface and then an extent of bending reaches a predetermined value, electrification of the voice coil motor is suppressed and moving down of the tip
10
is stopped. At this time, coarse adjustment is completed.
Subsequently, electrification of the heating coil
16
is suppressed to drop the temperature of the viscous material
17
to a preheated temperature. As a result, viscosity of the viscous material
17
increases resulting in the thick tube
15
with the inner tube
13
becoming substantially integral due to the viscosity of the viscous material
17
and the sample therefore becomes measurable.
In the probe scanning device according to the structure as described above, a surface shape of the sample can be accurately measured preferably by lowering a scanning speed of the tip
10
in the xy direction. A resonance frequency of a z axis is a function of a resultant force of a first
11
and a second
12
spring and a mass of the movable portion on the z axis, and thus, if frequency components, when a change of the z axis is subjected to frequency resolution making the scanning speed of the x axis and the y axis to a time axis, contains the resonance frequency of the z axis, increased amplitude is observed in this component. Such resonance can be prevented by lowering the scanning speed in the xy direction.
However, when the scanning speed is decreased, time for measurement necessarily increases.
The viscous material
17
has a small viscosity at preheating temperatures and the inner tube
13
moves down or up slightly against the thick tube
15
. Therefore, when measurement time becomes longer, a distance of the inner tube
13
which is moved down or up increases which causes data related to the z direction to contain an error corresponding to the distance made by moving down or up.
When electrification of the heating coil
16
during measurement is limited, the temperature of individual parts containing the thick tube
15
and the inner tube
13
decreases gradually causing thermal shrinkage and data relating to the z direction therefore contains an error corresponding to thermal shrinkage.
SUMMARY OF THE INVENTION
The advantage of the present invention is to provide a probe scanning device capable of measurement of high precision and low noise even when measuring at slow scanning speeds.
The present invention is characterized by a probe scanning device having a thick tube extended in a z direction and an end thereof supported by a case, an inner tube passing through the inside of the thick tube, a tip mounted on the front end of the inner tube, a viscous material filled in a space between the thick tube and the inner tube, first
Honma Akihiko
Matsuzaki Ryuichi
Sato Yukihiro
Adams & Wilks
Lee John H.
SII NanoTechnology Inc.
Smith II Johnnie L
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