Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2001-03-12
2003-12-23
Le, Que T. (Department: 2874)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S306000
Reexamination Certificate
active
06667467
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microprobe used for observing a very small area (on a nanometer order) of a surface of a sample and a scanning type probe apparatus using the microprobe.
2. Description of the Prior Art
Currently, there is known a Scanning Probe Microscope (SPM) as one of the microscopes (scanning type probe apparatus) used for observing a very small area on a nanometer order at a surface of a sample. One type of scanning type probe microscope, an Atomic Force Microscope (AFM), uses a cantilever provided with a stylus at its front end portion as a microprobe, the stylus of the cantilever is scanned along a surface of a sample, and interactive action (an attractive force or repulsive force, or the like) between the surface of the sample and the stylus is detected as an amount of bending of the cantilever to thereby enable one to measure a shape of the surface of the sample.
The bending amount of the cantilever is detected by irradiating a front surface of the cantilever with an irradiation beam such as a laser beam and measuring a reflection angle of a beam reflected from the front surface of the sample. Actually, the reflection angle is provided by using an optical detector of a photodiode or the like divided in two and from an intensity distribution of the beam received at respective detecting portions.
In observing the sample by AFM, generally, there is selected a cantilever having sharp stylus which differs in sharpness in accordance with observation accuracy and observation range and the cantilever is used by being mounted to an apparatus. For example, when a wide area of micrometer order is intended to be measured at a high speed, a cantilever having a stylus with a low sharpness degree is used although the resolution is low (hereinafter, referred to as a cantilever for low resolution), further, when a narrow area of nanometer order is intended to measure with high resolution, there is used a cantilever having a stylus with a high sharpness degree (hereinafter, referred to as a cantilever for high resolution).
In this way, there causes a need of interchanging a cantilever in accordance with an object of observation and the interchange operation becomes a troublesome operation of finely adjusting an irradiation angle of the above-described irradiation beam or a receive angle of an optical detector or the like. Further, before and after the interchanging operation, a position of observation is frequently shifted considerably and it is difficult to carry out accurate sample observation.
Hence, there is proposed a microprobe of a double lever type having both of the cantilever for low resolution and the cantilever for high resolution by making common a support portion thereof. Particularly, according to the double lever type microprobe, in accordance with the object of observation, by switching operation utilizing thermal expansion of a heater, switching of the two kinds of cantilevers is made possible.
FIG. 12
is a perspective view showing a microprobe
1
of the double lever type and a constitution of essential portions of a scanning type prove apparatus using the microprobe
1
. Further,
FIG. 13
is a side view for explaining operation of the double lever type microprobe
1
.
In
FIG. 12
, the microprobe
1
is arranged above a sample
4
and is fabricated with silicon as a base material and a support portion
1
a
is formed with a cantilever portion
1
b
for low resolution and a cantilever portion
1
d
for high resolution. As shown by
FIG. 12
, the low resolution cantilever portion
1
b
and the high resolution cantilever portion
1
d
are supported by the support portion
1
a
to project in minus y-axis direction designated in the drawing from an end edge of the support potion
1
a
and to be spaced apart from each other by an interval
1
f.
Further, in actual use, the support portion
1
a
is fixed to a fixing member, not illustrated.
Further, the sample
4
is moved in xy plane and in z-axis direction shown in the drawing by actuators, not illustrated, thereby, scanning over the surface of the sample of the microprobe
1
and proximity control between the microprobe
1
and the surface of the sample are achieved.
Further, the low resolution cantilever portion
1
b
and the high resolution cantilever portion
1
d
are formed to bend in z-axis direction shown in the drawing with portions thereof bonded to the support portion
1
a
as bending portions. Further, a front end portion of the low resolution cantilever portion
1
b
is formed with a sharpened stylus
1
c
for low resolution to project in minus z-axis direction.
The low resolution stylus
1
c
is proximate to a sample surface
4
a
of the sample
4
, a sharpness degree thereof is lower than a sharpness degree of a stylus
1
e
for high resolution, mentioned later, and a length thereof in z-axis direction is longer than a length of the high resolution stylus
1
e.
That is, the low resolution stylus
1
c
(low resolution cantilever portion
1
b
) is used in measuring a wide area with low resolution.
Meanwhile, a front end portion of the high resolution cantilever portion
1
d
is formed with the sharpened stylus
1
e
for high resolution to project in minus z-axis direction. According to the high resolution stylus
1
e,
the sharpness degree is made higher than the sharpness degree of the low resolution stylus
1
c
and the length in z-axis direction is made shorter than the length of the low resolution stylus
1
c.
That is, the high resolution stylus
1
e
(high resolution cantilever portion
1
d
) is used in measuring a narrow area with high resolution.
As described above, detection of bending of the low resolution cantilever portion
1
b
and the high resolution cantilever portion
1
d
is carried out by measuring reflection beam reflected at surfaces of the cantilevers. Detection of bending of the low resolution cantilever portion
1
b
is carried out such that irradiation beam La
1
irradiated from a light emitting element
5
1
is reflected and reflection beam Lb
1
is received by a light receiving element
6
1
. Further, similarly, detection of bending of the high resolution cantilever portion
1
d
is carried out such that irradiation beam La
2
irradiated from a light emitting element
5
2
is reflected and reflection beam Lb
2
is received by a light receiving element
6
2
.
Further, according to the low resolution cantilever portion
1
b,
as shown by
FIG. 13
, there is formed a heater
3
for the above-described switching operation on a surface of a side of the low resolution stylus
1
c.
Particularly, the heater
3
is formed at a bond portion (bending portion) for bonding the low resolution cantilever portion
1
b
and the support portion
1
a,
and is heated by conducting electricity thereto via a wiring, not illustrated, and the low resolution cantilever portion
1
b
can be bent in z-axis plus direction at the heater
3
portion by thermal expansion of the heater
3
per se or by a difference in thermal expansion of a side of the low resolution cantilever portion
1
b
formed with the heater
3
and a side thereof opposed thereto.
Here, temperature of the heater
3
before bending the low resolution cantilever portion
1
b
is designated by notation T
0
and temperature of the heater
3
for bending the low resolution cantilever portion
1
b
(operational temperature) is designated by notation T(>T
0
).
Therefore, according to a scanning type probe apparatus using the microprobe
1
, an initial state, that is, a state in which temperature of the heater
3
is T
0
, is set to a state in which the low resolution stylus
1
c
having a height higher than that of the high resolution stylus
1
e
can be used as a state in which the low resolution stylus
1
c
is more proximate to the sample surface
4
a
than the high resolution stylus
1
e
and under the state, observation of a wide area with low resolution can be carried out.
Further, when the low resolution cantilever portion
1
b
is bent in z-axis plus direction b
Binnig Gerd K.
Brugger Jurgen P.
Häberle Walter
Shimizu Nobuhiro
Shirakawabe Yoshiharu
Adams & Wilks
Le Que T.
Seiko Instruments Inc.
Spears Eric J
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