1063-7397/05/3405- © 2005 MAIK “Nauka /Interperiodica”
Russian Microelectronics, Vol. 34, No. 5, 2005, pp. 309–315. Translated from Mikroelektronika, Vol. 34, No. 5, 2005, pp. 367–374.
Original Russian Text Copyright © 2005 by Chuklanov, Bukharaev, Borodin.
Recent years have seen increasing use of the shear-
force microscope for studying the surface of micro- and
nanostructures . A newly invented form of the scan-
ning-probe microscope (SPM), it gave a powerful
impetus for the development of near-ﬁeld optical
microscopy, providing investigators with both a reﬂec-
tion or transmission optical micrograph and a topo-
graphic image of a surface area.
In the shear-force microscope, the probe is made to
vibrate parallel to the surface being examined. If the
tip–surface spacing is sufﬁciently small (<10 nm), the
vibration is damped due to friction and other forms of
dissipation, resulting in changes in vibration amplitude
Using the shearing force allows one to maintain a
constant tip–surface spacing to a high accuracy for a
wide variety of materials being examined. Another
advantage of the shear-force microscope is that unlike
the atomic-force microscope (AFM) it does not require
a laser beam to detect tip vibrations and so is suitable
for specimens susceptible to laser radiation.
The lateral resolution of the microscope (in either
mode of operation) is directly related to the shape of the
probe tip, improving with decreasing tip radius and
angle. Knowledge of the tip shape can therefore be use-
ful for interpreting topographic images and estimating
the optical resolution.
Control over tip shape is also important in making
ferromagnetic nanocontacts to obtain giant magnetore-
sistance [2–4]. Recent studies have shown that a mag-
netoresistance of several thousand percent can be
achieved by means of a metal probe with a tip of radius
100 nm on which nickel or other metal has been
deposited electrochemically [5, 6].
EXPERIMENTS ON TIP-SHAPE
Electron microscopy, though generally useful for
checking the shape of micrometer- and nanometer-
sized objects, is inadequate for this study because it
necessitates breaking the tip off the probe. Tip shape
was therefore reconstructed by an approach (known to
be very useful with AFMs) involving imaging a spe-
cially designed test structure of known shape and
dimensions . The reconstruction procedure employs
deconvolution to extract an actual tip shape from an
image dependent on the shapes of both the test structure
and the tip [8, 9].
Two types of test structure were used. One of them,
NT-MDT’s TGT01, is a staggered array of conical sili-
con spikes about 300 nm high with a tip angle of
and a tip radius of about 10 nm . The other structure
consists of single latex spheres of diameter 200 nm with
10-nm gold coating, placed on a silicon surface.
With the probe executing lateral vibration, recon-
struction yields a reversed, vibration-broadened image
of the probe, the magnitude of broadening depending
on the vibration amplitude
To assess the effect of lateral vibration on topo-
graphic images, we conducted experiments in which
the probe was scanned over a test structure of ﬁrst type
at different amplitudes of probe driving voltage, the
vibration amplitude being proportional to the voltage
amplitude. The probe was made from 80-
wire and pointed by a technique employed in scanning
tunneling microscopy . Imaging was performed
with an NT-MDT’s Solver SNOM microscope, which
can be operated in shear-force and near-ﬁeld modes.
The results are presented in Fig. 2.
Figure 2 gives averaged data from four experiments
with tungsten probes. It displays observed probe diam-
eter against driving voltage, the former referring to a
Tip-Shape Reconstruction for a Laterally Vibrating SPM Probe
A. P. Chuklanov, A. A. Bukharaev, and P. A. Borodin
Zavoisky Physical-Technical Institute, Kazan Scientiﬁc Center, Russian Academy of Sciences, Kazan, Tatarstan, Russia
Received December 20, 2004
—This study is concerned with the tip-shape reconstruction for the shear-force scanning probe micro-
scope and the near-ﬁeld scanning optical microscope, in which the probe executes lateral vibrations. The spatial
resolution of the microscopes is directly dependent on the tip radius. A reconstruction method is proposed that
employs specially designed test structures and is based on deconvolution. The method is used to generate
images of tungsten and nickel wire probes, fabricated by electrochemical etching, and near-ﬁeld optical-ﬁber
probes. The results are veriﬁed by TEM imaging of the probes. By the same approach, correlation is revealed
between reconstructed probe aperture and resolution for the near-ﬁeld optical microscope.
MATERIALS AND MICROSTRUCTURE