Angular Distribution of Sputtered Cu
x
Al
y
Alloys:
Simulated Study
K. Bria
1
and M. Ait El Fqih
2
Laboratory of Artificial Intelligence & Complex Systems Engineering (AICSE), ENSAM, Hassan II University of
Casablanca, Morocco
Keywords: Sputtering; Angular distribution; Copper; Aluminum, CuxAly alloys.
Abstract: Angular distribution of Cu and Al from CuxAly alloys are calculated. The simulated sputtered material is
collected from an imaginary cylinder surrounding the fictive targets. The simulation was done with the well-
tested SRIM-code for a large number of incident ions (5 keV Kr+) and let the computer count the number of
Cu and Al toms emitted in the solid angle corresponding to each probe. Furthermore, angular distribution of
differential sputtering yields of both Cu and Al showed cosine and over-cosine tendency.
1 INTRODUCTION
The interaction of an ion beam with a solid target
guide to the phenomenon of sputtering, i.e. The
ejection of atoms and their aggregates according to the
target (Ming, 1991; El Boujlaidi et al., 2012; Jadoual
et al., 2014; Cortona et al., 1999). Sputtering put in
various fields, such as surface analysis, depth
profiling, sputter cleaning, and sputter deposition.
Sputtering has become an essential tool in such
modern technologies as the deposition of high-quality
thin films on almost any substrate, depth
microanalysis, surface cleaning and micromachining
(Dogar and Qayyum, 2006). Experimental and
simulation studies of angular distribution are widely
used in the literature (Behrisch and Wittmaack, 1991).
For example, Chernysh et al. (Chernysh, et al., 2004)
bombarded Si and Ge targets with 3-10 keV Ar+ ions
and determined the angular distributions of sputtered
atoms using Rutherford backscattering analysis. The
collector was made of beryllium foil and had a semi-
cylindrical shape with a radius of 15 cm. In Ref.
(Verdeil et al., 2008), silicon, germanium and indium
phosphide targets were sputtered with a 2-10 keV Cs
ion beam in the range of the incident angles of 30-60°.
Emitted particles were collected on a semi-cylindrical
copper foil. In Ref. (Ait El Fqih, 2010), the angular
distributions of Cu and Be atoms sputtered from
1
https://orcid.org/0000-0002-1647-3238
2
https://orcid.org/0000-0002-7956-5172
Cu
98
Be
2
alloy under 5 keV Kr
+
ion bombardment were
measured at different angles of incidences.
The purpose of this study is to report a new
computational result on angular distribution of
sputtered Cu and Al from a Cu
x
Al
y
alloy targets under
5 keV Kr+ ion bombardment.
2 SIMULATION
The simulation used was the well tested computer
SRIM-code (Ziegler and Biersack, 1985). For a large
number of incident ions, the computer counts the
number of copper atoms emitted in the solid angle
corresponding to each simulated square side (probe).
SRIM software provides information including the
total sputtering yield as well as ion implantation into
the target. One of the main approximations known
in this software consists in the surface of the target
which becomes smooth again after each ion impact.
In SRIM calculation, ZBL potential is used. The
ratios of Cu atoms emitted in the solid angle were
counted. The SRIM software requires the
introduction of several parameters, the simulation
conditions considered are that usually used in various
experiments. Some of them, like energy and
incidence angle of the ions, are obtained
experimentally. The raw data obtained from SRIM
Bria, K. and Ait El Fqih, M.
Angular Distribution of Sputtered CuxAly Alloys: Simulated Study.
DOI: 10.5220/0010736700003101
In Proceedings of the 2nd International Conference on Big Data, Modelling and Machine Learning (BML 2021), pages 471-473
ISBN: 978-989-758-559-3
Copyright
c
 2022 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
471

software are processed by another software, called
Angulaire [11]. Indeed, the SRIM gives information
only on the velocity of ejected particles and not on
their numbers. Hence, an analytical treatment is
undertaken through a mathematical formalism, via
Angulaire, to find the sputtered products.
3 RESULTS AND DISCUSSION
Note that the square side in the cylindrical (Mylar)
foil is called b and the arc delimited by the square in
the z-direction depends on the angle µ. We denote by
z
0
the value of z at the center of the square, and by µ
0
= 0 the value of µ at the center. The variation domain
of the angle µ is then 𝑏  2𝑟; 𝑏  2𝑟 and
for z is: 𝑧
0
 𝑏  2; 𝑧
0
 𝑏  2 . The solid angle
Ω under which we see the square from point O can be
written as [11]:
𝛺𝑧

 𝑑𝑢




𝑑𝑧
𝑟

𝑟

𝑧














Figure 1 shows the angular distributions of relative
sputtering yield of Cu and Al particles from a
sputtered Cu
90
Al
10
, Cu
50
Al
50
and Cu
10
Al
90
target
obtained for 5 keV Ar
+
ions bombardment for a series
of surfaces along, the x-axis as a function of angle .
Dotted lines are the best-fit curves determined using
the cosine fitting function:
Y    cos
n
(  )
where Y is the angular distribution,  is the angle of
emission and n the cosine exponent. The distribution
curves exhibited an under-cosine (n < 1) tendency.
Previous experimental observations and computer
simulations established over-cosine distribution is a
rather general feature in the cascade regime [12 -13].
The origin of the unregister tendency is attributed to
the linear-collision cascade theory.
4 CONCLUSIONS
In summary, angular distributions of sputtered Al
and Cu particles from a sputtered Cu
x
Al
y
target was
studied by computer simulation for the case of 5 keV
Ar
+
ion bombardment at normal incidence. The
angular distribution of the sputtering yield exhibits an
under-cosine tendency for x-axis and attributed to the
linear-collision cascade theory and to a surface-
induced anisotropy in the recoil flux below the
surface, or to an anisotropic surface scattering of an
isotropic recoil flux.
Figure 1: Simulated angular distribution of sputter-
ejected Cu and Al particles from Cu
x
A
ly
alloys target
sputtered with 5 keV Kr+ ions.
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