The results of an experimental study of the modification of probes for critical-dimension atomicforce
microscopy (CD-AFM) by the deposition of carbon nanotubes (CNTs) to improve the accuracy with
which the surface roughness of vertical walls is determined in submicrometer structures are presented. Methods
of the deposition of an individual CNT onto the tip of an AFM probe via mechanical and electrostatic
interaction between the probe and an array of vertically aligned carbon nanotubes (VACNTs) are studied. It
is shown that, when the distance between the AFM tip and a VACNT array is 1 nm and the applied voltage is
within the range 20–30 V, an individual carbon nanotube is deposited onto the tip. On the basis of the results
obtained in the study, a probe with a carbon nanotube on its tip (CNT probe) with a radius of 7 nm and an
aspect ratio of 1:15 is formed. Analysis of the CNT probe demonstrates that its use improves the resolution
and accuracy of AFM measurements, compared with the commercial probe, and also makes it possible to
determine the roughness of the vertical walls of high-aspect structures by CD-AFM. The results obtained can
be used to develop technological processes for the fabrication and reconditioning of special AFM probes,
including those for CD-AFM, and procedures for the interoperational express monitoring of technological
process parameters in the manufacturing of elements for micro- and nanoelectronics and micro- and nanosystem
engineering.

INTRODUCTION
Increasing the degree of very-large-scale integrated
circuit (VLSIC) integration results in topological standards
of less than 90 nm, with the influence exerted on
the parameters and working capacity of VLSICs by the
deviation of element sizes from given values dramatically
increasing. In particular, the roughness of the
vertical wall of the gate greatly affects the threshold
voltage of metal–oxide–semiconductor (MOS) transistors
in VLSICs [1]. Here, an important task is the
development of procedures and technical means for
determining the geometric parameters and the roughness
of vertical walls in high-aspect nanostructures.
Critical-dimension atomic-force microscopy
(CD-AFM) is a promising method that can effectively
solve problems associated with the inter-op express
monitoring of the technological process during the
manufacturing of VLSICs by examining the morphology
and local surface properties of high-aspect structures
with a high spatial resolution [1].

The resolvability of an AFM microscope is determined
by the radius of curvature and aspect ratio of
the probe-tip sides [2–6]. Therefore, the development
of methods for the fabrication of probes with parameters
that make it possible to minimize distortions of the
surface morphology of the sample surface in an AFM
investigation is a topical issue. There exist several technological
methods for the fabrication of AFM probes.
Commercially available probes are fabricated from silicon
by microelectronic methods, with the result that
a pyramidal tip with a radius of 10–100 nm is formed
on the cantilever [2]. Surfaces containing high-aspect
structures are studied by the AFM technique with cantilevers
which have probes whose tip is modified by the
method of focused ion beams (FIB), with a probe-tip
radius of about 9 nm [6–8]. A small radius of curvature
and high aspect ratio between sides of the probe
tip are obtained by modification with local electronbeam
and ion-stimulated deposition methods [2, 9].

deposition of CNTs onto the tip of probes of this kind
enables their reconditioning for further use in the precision
surface studies of materials and also in determining
the parameters of high-aspect structures.
The goal of our study is to examine methods for the
modification and reconditioning of AFM probes via
the deposition of a carbon nanotube onto a probe tip
under the action of mechanical and electrostatic interactions
between the AFM probe and an array of vertically
aligned carbon nanotubes (VACNTs) to form
CNT probes. Also, the characteristics of AFM probes
in analyzing high-aspect structures via the CD-AFM
method are examined.