1063-7397/04/3305- © 2004 MAIK “Nauka /Interperiodica”
Russian Microelectronics, Vol. 33, No. 5, 2004, pp. 263–270. Translated from Mikroelektronika, Vol. 33, No. 5, 2004, pp. 325–333.
Original Russian Text Copyright © 2004 by Serov, Margolin, Potsar, Soltovskaya, Tupik, Fantikov.
With circuit feature sizes approaching the nanome-
ter region, there is a growing need for batch methods of
making a desired pattern over the whole wafer surface
or a major part of it. However, atomic- and even molec-
ular-scale resolution in wafer-by-wafer processing can-
not be achieved by a combination of electron-beam
[1, 2] and x-ray lithography . The issue might be
resolved by using self-organization. Presumably, this
strategy will make it possible to produce nanoscale
ﬁlms with desired surface patterns in the same run .
In this paper, an experimental study is reported of
the growth of nanoscale metal ﬁlms with fractal topog-
raphy. The ﬁlms were produced by magnetron sputter-
ing or vacuum evaporation, and fractal topography was
induced with Aires shapers.
The materials selected for the experiment were cop-
per, titanium, nickel, and titanium nitride. They were
deposited by vacuum evaporation or direct-current
magnetron sputtering. The latter method received the
most attention, because it provides an incident ﬂux of
higher energy, so that the nanoscale ﬁlm closely
assumes the surface pattern of the substrate. The sub-
strates were K-8 polished glass photolithographic tem-
plates and Si(100) and Si(111) wafers .
In deposition, self-organization was induced by
third- and fourth-generation Aires fractal shapers .
These were synthesized holograms in the form of a
complex diffraction grating consisting of intersecting
closed contours as ﬁne as about 1
m . The shapers
were clamped to the back side of the substrate, being
totally isolated from the deposition ﬂux.
The ﬁlms were examined by optical microscopy;
scanning electron microscopy (SEM) using S-3500N
(Hitachi) and JSM-35; atomic-force microscopy
(AFM) using AutoProbe M5, Solver P47, and Solver
P47H; electron-spin-resonance (ESR) spectroscopy
using EPR 10 MINI; and x-ray diffraction (XRD) using
Without shapers, the structure of a ﬁlm is similar to
that of the substrate. Films produced with the assistance
of shapers assumed different surface patterns: smooth
domes; indented domes (Fig. 1a); rings (Fig. 1b); and
truncated triangular, quadrangular, and hexagonal pyr-
amids, with or without a central pit. These protuber-
ances varied in size over a ﬁlm. The ﬁlms also exhibited
fractal-like spiral protuberances. It was also noticed
that the complexity and density of features rise toward
the center of the substrate; furthermore, they increase
with the number of deposition runs, indicating a mem-
ory effect . As ﬁlm topography becomes increas-
ingly close to a fractal, competition arises between dif-
ferent types of surface feature (Fig. 1c), which also
change shape signiﬁcantly (Fig. 1d), with the result that
the entire ﬁlm surface becomes covered with protuber-
ances (Fig. 1d). Furthermore, a protuberance develops
smaller ones that show greater complexity, so that we
observe a hierarchy of features differing in fractal
degree. The arrangement of surface features was found
to depend on the number, complexity, and relative ori-
entations of the shapers (Figs. 1e, 1f). However, it is not
yet possible to control the self-organized growth of
fractal surface patterns, and their character can be pre-
dicted only in broad terms.
Similar results were obtained with silicon substrates
and ﬁlms of titanium, nickel, and titanium nitride. Spe-
cial features of these ﬁlms will be discussed in a forth-
ESR and XRD examinations showed that the
nanometer ﬁlms had the same composition as submi-
crometer ones produced by conventional methods.
Deposition of Nanoscale Films with Fractal Topography
I. N. Serov*, V. I. Margolin*, N. A. Potsar**, I. A. Soltovskaya*,
V. A. Tupik**, and V. S. Fantikov**
* Aires Foundation for the Advancement of Medical Technology, St. Petersburg, Russia
** LETI State University of Electrical Engineering, St. Petersburg, Russia
Received July 28, 2003
—An experimental study is reported of the growth of nanoscale metal ﬁlms with fractal topography.
The ﬁlms are produced by magnetron sputtering or vacuum evaporation, and fractal topography is induced with
Aires shapers. The ﬁlms are examined by optical microscopy, SEM, and AFM. A discussion of the results is