Journal of Alloys and Compounds 976 (2024) 173273

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Journal of Alloys and Compounds

journal homepage: www.elsevier.com/locate/jalcom

Research article

Synthesis and characterization of c-TiAlN/h-Cr2N multilayer films

deposited by magnetron sputtering on Si (100) substrates
Hairui Ma a, b, Qiang Miao a, c, *, Wenping Liang a, Per Eklund b, Arnaud le Febvrier b, **
a
College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
b
Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83 Linköping, Sweden
c
Wuxi Research Institute, Nanjing University of Aeronautics and Astronautics, China

A R T I C L E I N F O A B S T R A C T

Keywords: A series of c-TiAlN/ h-Cr2N multilayer films with modulation periods Λ of 10, 20 and 30 nm and thickness ratios
Multilayer film (Cr2N thickness /Λ) of 25%, 50% and 75% were prepared by dc magnetron sputtering on the Si substrate. The
Cubic-TiAlN microstructures were characterized by scanning electron microscopy, x-ray diffraction, and the mechanical
Cr2N
properties were measured by curvature measurement method and nanoindentation. With the Cr2N ratio
Mechanical properties
increasing from 25% to 75%, the orientation of Cr2N layers changed from a randomly orientation to a 0001
Residual stress
preferential orientation, while inversely, the c-TiAlN layer changed from a 001 preferential orientation to a 111
preferential orientation or a randomly orientation. In the meantime, and regardless of the modulation period, the
lattice parameter of c-TiAlN decreased from 4.16 Å to 4.12 Å and was explained by an increase of tensile stress
between + 0.2 and + 1.3 GPa when the increase of Cr2N% in the modulation. With the increase of Cr2N ratio, the
morphology of the film changed and led to surface with apparent porosity and large grain sizes of 100 × 300 nm.
The film with 25% Cr2N ratio and modulation period of 20 nm exhibited the highest hardness reaching 22 ± 1.3
GPa and reduced Young’s modulus of 253 ± 6 GPa.

1. Introduction phenomena take place, including defect introduction or annihilation,

grain growth, and recrystallization [22]. The island mechanism for film
Multilayer films are important in mechanical engineering [1,2], fuel growth often leads to the generation of tensile stress due to the
cell technology [3,4], electronics [5–7], solar energy [8,9], biomedical impingement and coalescence of islands, namely the formation of the
devices [10,11]. In particular, TiAl-based nitride films are widely used in boundaries is the origin of the tensile stress [23]. This phenomenon is
industries like cutting tool manufacturing, mold making, and mechani­ typically observed at the coalescence stage of film deposition on silicon
cal component fabrication. These films possess good thermal, chemical when the film thickness and grain width are on the order of several
stability, wear resistance, high hardness, and great corrosion resistance, dozen nanometers [24,25]. After the formation of the boundaries, the
making them highly desirable materials [2,14,15]. Among the tech­ insertion of atoms into the grain boundaries will generate compressive
niques employed for fabricating films, chemical vapor deposition (CVD) stress during the film growth [26,27].
and physical vapor deposition (PVD) stand out. Notably, PVD is the Another factor that influences the residual stress is the difference in
prevailing choice due to its widespread utilization and effectiveness. coefficient of thermal expansion (CTE) between the component of the
Thin films prepared by PVD usually exhibit compressive-tensile- films and the substrate. Studies indicate that CTE of hard coating
compressive (CTC) behaviors as the film thickness increases [12–20]. strongly depends on film thickness [28], grain size [29] and chemical
This behavior can be attributed to the common island growth mode in composition [30]. The high residual stress will lead to buckling, brittle
polycrystalline films, where the films initially grow by the nucleation of fracture, delamination, and early failure of the coatings [31,32]. For
island of different crystallographic orientation, then coalescence to the example, Kattamis et al. [33] have demonstrated that the amplification
complete coverage of the substrate, followed by coarsening as the film of tensile stress in SiC coatings resulted in an increment of the wear rate.
grows thicker [21]. Throughout this dynamic process, various The residual stress can be manipulated in various ways in monolithic

* Corresponding author at: College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.
** Corresponding author.
E-mail addresses: miaoqiang@nuaa.edu.cn (Q. Miao), arnaud.le.febvrier@liu.se (A. le Febvrier).

https://doi.org/10.1016/j.jallcom.2023.173273
Received 15 August 2023; Received in revised form 29 November 2023; Accepted 20 December 2023
Available online 26 December 2023
0925-8388/© 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

film, such as annealing with different temperature [34], adjusting was operated at 45 kV and 40 mA in a Bragg-Brentano configuration.
deposition parameters like deposition rate, pressure, and substrate The scanning angle was set to range from 15◦ to 90◦ , with a step size of
temperature [35–37]. Besides these parameters, another method to 0.02◦ . The sample was constantly rotated during the measurement.
control stress is the design of the film structure. Leveraging the Wafer curvature measurements were utilized to determine the re­
distinctive characteristics of each monolithic film, it becomes feasible to sidual stress, which is quantified through XRD ω-scans of Si (001). Then,
govern stress distribution within the film through meticulous design of a the in-plane residual stress were calculated based on the Stoney formula
multilayer structure. In multilayer films, each individual layer may have [46,47]:
a different CTE, leading to inherent stress within the film. Research
Ms × ts 2
clearly shows that optimizing nanoscale strain by varying composition, σf =
6Rs × tf
bilayer periods, and layer thickness ratios is an effective way to over­
come the stress problem [38]. Researchers optimize the overall stress in
Where, Ms is the biaxial modulus of Si (100), which is 1.803 GPa [47],
multilayers by changing the modulation periods and modulation ratios
Rs is the curvature of the substrate, tf is the thickness of the film and ts is
[39–41].
the thickness of substrate (500 µm). Stress measurements were con­
In our previous study [42], we focused on heteroepitaxial multilayer
ducted using the Phillips X′Pert MRD system with a point focus config­
films of h-Cr2N/c-TiAlN, which were grown on Al2O3 (0001). Our
uration, employing cross slit and parallel plate setups within the
findings indicated that the epitaxial quality of the multilayer film
receiving module.
improved with the Cr2N thickness increases yielding an increase of
Nanoindentation experiments were performed using a Hysitron Tri­
hardness up to a maximum reach for a multilayer with a maximum of 10
boindenter 950 equipped with a Berkovich diamond tip. To mitigate the
nm Cr2N layer thickness. The statement remained unexplored whether
substrate effects, indentation depth was limited to below one-tenth of
these observed trends hold true when applied to random oriented films.
the thickness of the film. The measurements were conducted using a
In this paper, we deposit c-TiAlN/h-Cr2N multilayer films on Si
displacement-controlled mode with a displacement of 40 nm. The
substrates. This study focuses on investigating the influence of process
hardness (H) and reduced elastic modulus (Er) were determined utilizing
parameters, such as modulation period, thickness ratio on the mechan­
the Oliver and Pharr method [48] based on the load-displacement curve
ical properties of c-TiAlN/h-Cr2N multilayer films. Characterization
of the indenter. To obtain a statistically significant distribution, each
techniques such as X-ray diffraction and scanning electron microscopy
sample was measured using two groups of 4 × 4 arrays, resulting in 32
were employed to analyze the structural, morphological, and residual
measurement points for each sample.
stress of the films. Overall, this research contributes to the under­
standing of the random oriented c-TiAlN/h-Cr2N multilayer film grown
3. Results and discussion
on Si and provides valuable insights into the optimization of its prop­
erties for enhanced mechanical performance in various engineering
The composition of the multilayered film was determined by
applications.
analyzing a monolithic c-TiAlN reference film deposited on Si, which
was considered equivalent in the multilayer. The composition of the
2. Experimental details
monolithic TiAlN film was determined using Time-of-Flight Elastic
Recoil Detection Analysis (ToF-ERDA) measurements combined with
c-TiAlN/h-Cr2N multilayered films were grown on Si (100) sub­
EDS. As shown in Fig. 1, the Ti, Al, N concentrations were 29.8 ± 0.5,
strates in an ultrahigh vacuum dc magnetron sputtering system
18.1 ± 0.5, and 50.1 ± 0.5 at%, respectively. The oxygen content in the
described elsewhere [43]. Most of the deposition conditions were
film was 2 ± 0.5 at%. Therefore, the Ti/Al ratio is 40/60, with a nitro­
similar to our previous work [42]. In brief, the Ti, Al, and Cr targets with
gen content of 50%, which includes 2 at% of oxygen post-deposition
a diameter 2 in., were sputtered alternatively to form multilayers by
contamination due to columnar growth.
applying constant power of 121 W, 79 W and 50 W for Ti, Al, and Cr, in
θ-2θ XRD patterns of c-TiAlN/h-Cr2N multilayered films are shown in
an N2/(Ar+N2) % flow ratio of 30% with a constant pressure of 0.32 Pa.
Fig. 2. The XRD patterns of the multilayers have reflections identified as
The composition condition was optimized to obtain crystalline layers of
TiAlN 111, 200 and 220 at 2θ around 37.8◦ , 44.0◦ , and 64.0◦ , and Cr2N
cubic Ti0.4Al0.4N (c-TiAlN) and hexagonal Cr2N (h-Cr2N) at 680 ◦ C. Note
0002, 1121 and 1122 at 2θ around 40.3◦ , 42.5◦ and 56.2◦ . No peaks
that the conditions of depositions were optimized for depositing the
from other phases such as wurtzite TiAlN or NaCl-B1 CrN were observed.
cubic Ti0.4Al0.4N and the hexagonal Cr2N at this temperature [42,44].
The phase formation by magnetron sputtering in the Cr-N material
The different multilayers with different modulation periods and ratios
system is sensitive to the mixture N2/Ar temperature where at a high
were controlled by varying the time of deposition for each layer using
automated shutter for each target. Before deposition, the Si (100) wafer
substrates were ultrasonic cleaned by acetone and ethanol for 10 min
each and blow dried by nitrogen gas. The samples are named as S
(Modulation period) - (% of Cr2N in the bilayer) e.g., S10–25 refers to
the modulation period Λ of 10 nm and the Cr2N thickness ratio of 25%
within the bilayer. Note that all multilayers started and are terminated
by a TiAlN layer.
Surface and cross-sectional morphology analysis of the films were
conducted using Scanning Electron Microscope (SEM, Sigma 300, Zeiss).
The SEM was equipped with an in-lens secondary electron detector and
operated with an acceleration voltage of 2–3 kV. Chemical compositions
of monolithic films were determined using an Energy-Dispersive X-ray
Spectrometer (EDS, Oxford Instruments X-Max) operated at an acceler­
ation voltage of 20 kV and time-of-flight elastic recoil detection analysis
(ToF-ERDA) measurement performed at Uppsala University [45]. The
obtained spectra were evaluated using the Potku software package.
A PANalytical X′Pert diffractometer system was used to conduct X-
ray diffraction (XRD) analysis. The system was equipped with a copper
Kα radiation source with a wavelength of 1.54 Å. The radiation source Fig. 1. ToF-ERDA elemental depth profile of the monolithic TiAlN film.

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H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

Fig. 3. Lattice parameters of TiAlN and Cr2N versus Cr2N % ratio in the
modulation period estimated from the 111 (c-TiAlN) and 0002
(Cr2N) reflections.

Fig. 4 shows the surface morphology of multilayer films which

correspond to the top TiAlN layer. The top surface multilayers
morphology can be categorized into two distinct groups based on their
features, as delimitated by the red solid line and dashed line in Fig. 4 and
named in this paper as group A and group B. The top TiAlN layer of the
films in group A exhibit a dense structure with equiaxed grains with an
apparent grain size ranging from 40 to 80 nm. Notably, the morphology
of S10–25 shows the classic characteristic of “pyramid” shape [52,53] of
TiAlN growing along the direction of (111) nominal to the surface with a
size below 80 nm. Conversely, the top TiAlN layer of group B exhibits a
Fig. 2. XRD θ-2θ pattern of TiAlN/ Cr2N multilayer films on Si. certain apparent porous structure on the surface and is characterized by
elongated grains with a size ranged from 50 × 200 nm to
100 × 300 nm. When the Cr2N thickness ratio in the multilayer was set
temperature of 680 ◦ C, only Cr2N formed [44].
at 75%, the size of agglomerates of top TiAlN layer was increased with
In the case of the 30 nm modulation period, the Cr2N has: i) a
the modulation from 10 nm to 20 nm. Comparing specific samples,
random orientation for a multilayer containing 25% Cr2N; ii) a mixture
S30–50 displayed a similar TiAlN grain size to S20–75, with both being
of (0002) preferentially oriented grains and randomly oriented grains
around 70 × 150 nm.
when containing 50% Cr2N; iii) finally (0002) preferential orientation
As reported in the literature, grain size evolution of monolithic film is
when containing 75% Cr2N. On the other hand, TiAlN has: i) (200)
correlated with film thickness by a power law, whose exponent depends
preferentially oriented grains when containing 25% Cr2N (75% TiAlN),
on the temperature of the specific material [54]. However, in the case of
ii) randomly oriented grains at 50% Cr2N ratio, iii) and (111) prefer­
our multilayer film, the situation appears to be more complex and does
entially oriented grains or randomly oriented grains when containing
not conform to this established trend. Upon analyzing the film with a
75% Cr2N (25% TiAlN). In general, with the Cr2N ratio increasing from
25% Cr2N thickness ratio, we observed that when the TiAlN layer pre­
25% to 75%, the orientation of Cr2N changed from randomly oriented
dominates in the bilayer with a smaller modulation period, the grain size
grains to (0002) preferential orientation, while the TiAlN changed from
is also relatively small. Conversely, when the Cr2N layer predominates in
(002) preferential orientation to random orientation. These trends were
the bilayer with a larger modulation period (75% Cr2N), the grain size
similar for the 20 nm modulation period. At lower modulation period,
increases significantly. From this observation, we can deduce that the
orientation trend for the Cr2N layer is similar, while the TiAlN changes
Cr2N ratio contributes to the promotion of grain size growth in the film.
from the randomly orientation to (200) orientation with the Cr2N ratio
Fig. 5 displays the fracture cross-section morphology of the multi­
increasing from 25% to 75%.
layered films. All multilayers exhibit a clear layered structure except
Fig. 3 displays the evolution of the lattice parameters of each layer
S10–25 and S10–75. However, these two samples have different mor­
versus the Cr2N thickness ratio. The cell parameters were determined
phologies. The sample S10–75 shows a more pronounced columnar
from the position of the peak 111 TiAlN and 0002 Cr2N (c lattice). Due to
structure in the top half of the film, where porosity is evident between
overlapping, and low intensity observed for the Cr2N layer, the Cr2N
each column and no clear layered structure for the S10–25 has been
lattice constant from the multilayer with the thinnest layer of Cr2N could
observed in this magnification. This porosity is further supported and
not be determined. The lattice constant of TiAlN and c lattice constant of
confirmed by the surface morphology described above (Fig. 4). For
Cr2N fall within the range of 4.12 Å to 4.16 Å and 4.46 Å to 4.50 Å,
S20–75, although it exhibits a layered structure, a similar porous
respectively. The lattice parameters of TiAlN are consistent with the
structure is observed in the top one-third part, resembling that seen in
values reported in literature with c lattice constant of 4.16 Å [49]. The
S10–75.
lattice parameters of Cr2N are slightly higher than the value reported in
The surface morphology of the top TiAlN layer in the epitaxial c-
the literatures with c lattice constant of 4.41 Å [50,51]. Specifically, an
TiAlN/h-Cr2N multilayer films deposited on sapphire occupies less than
overarching pattern emerges wherein films containing 25% Cr2N exhibit
10% of the total surface area [42], contrasting with the morphology
the highest cell parameters, succeeded by those with 50% Cr2N, while
described in this paper, where it covers the entire surface (100%). This
the films with a 75% Cr2N ratio display the lowest cell parameters.
discrepancy could potentially be attributed to the fact that the actual
Notably, for TiAlN films with modulation periods of both 20 nm and
temperature on the sapphire substrate is approximately 30 ◦ C lower
30 nm, comparable values are evident across each Cr2N ratio, with the
than the temperature on Si substrate, when the heater temperature was
30 nm period showcasing a slight reduced value.
maintained at 680 ◦ C. The variation in grain shape can be attributed to

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H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

Fig. 4. The surface morphology of c-TiAlN/h-Cr2N multilayer films of different modulation ratio and Cr2N thickness ratio. The surface morphology corresponds to
the Top c-TiAlN layer.

Fig. 5. The cross-section morphology of TiAlN/Cr2N multilayer films with different modulation period and different thickness ratios.

the distinct orientations of the films. of 30 nm and 20 nm, with Cr2N thickness ration of 50% and 75%,
Fig. 6 shows the cross-sectional HAADF images and corresponding respectively. The EDS mapping of c-TiAlN/h-Cr2N multilayer films
EDS mapping of S30–50 and S20–75 deposited on sapphire. HRTEM demonstrates a good correspondence between the dark and bright layers
images in Fig. 6a and b exhibit a characteristic multilayer structure and the TiAlN and Cr2N layers. The distribution of Ti, Al, and Cr is ho­
consisting of alternating bright and dark layers with modulation periods mogenous, and interfaces are relative sharp. Notably, the TiAlN layer

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H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

Fig. 6. HAADF-STEM and corresponding EDS mapping of (a) S30–50, and (b) S20–75.

exhibits a higher N content compared to the Cr2N layer, which can be ratio increases from 25% to 75% regardless of the modulation periods.
attributed to the higher affinity of N with Ti rather than Cr. Regarding the evolution of the residual stress with the Cr2N thickness,
Fig. 7 shows the evolution of residual stress with the thickness ratios an overall increasing trend can be observed (Fig. 7b).
and Cr2N thickness in each multilayer. The monolithic TiAlN coating The assessment of film stress serves as a crucial parameter in com­
exhibits a compressive residual stress estimated at − 0.604 GPa. The prehending its mechanical characteristics. Whether in a monolithic or
Cr2N reference coating suffered high diffusion between the substrate and multilayered structure, the existence of stress significantly influences
the film leading to the formation of silicide and was excluded in the grain orientation and size, thereby inherently shaping the ultimate
present work as reference. Note that in the present case with the mechanical properties of the film. Schalk et al. reported that when
multilayer starting with TiAlN, the diffusion of Si in the film was Ti0.37Al0.63N was deposited on Si (100) substrates, it forms a poly­
prevented. crystalline structure and exhibited a tensile stress under bias voltages of
All multilayers have a tensile residual stress between + 1.2 and − 40 V and − 50 V. However, at higher bias voltages, the material ex­
+ 1.3 GPa. It is noteworthy that the residual stress increases as the Cr2N hibits compressive stress [55]. Tillmann et al. [56] have reported that

Fig. 7. Residual stress of the multilayers versus the Cr2N% in the bilayer and versus the Cr2N thickness in the bilayer. The residual stress is determined by the wafer
curvature method using XRD.

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H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

with TiAlN/TiAlCN multilayered films deposited on hot-worked tool

steel using DC deposition method, the films exhibited a tensile stress
while the monolithic film exhibited compressive stress. They attributed
this variation of stress from compressive to tensile due to a competitive
between stress generation and relaxation mechanism [12].
In the present study the samples with high stress seem also to have
large grain size as shown in Fig. 4. As most of the films grown in poly­
crystalline are grown in an island mechanism. The island mechanism for
film growth often leads to the shrinkage of film volume and the gener­
ation of tensile stress due to the impingement and coalescence of islands
[22]. This phenomenon is typically observed during the initial stages of
film deposition on silicon when the film thickness and grain width are on
the order of several dozen nanometers [24,25]. For the multilayer films
with 75% ratio of Cr2N shows in Fig. 5, the fine grains and compact
structure at the bottom part of the film, while with coarser and porous
structure crowded at the top. Consistent with prior scholarly works, it is
Fig. 9. The hardness versus the tensile residual stress.
established that the process of grain coarsening invariably leads to a
reduction in compressive stress or a concurrent elevation in tensile
stress, as expounded upon in reference [57]. As the film adopted a tensile residual stress increases. The presence of higher tensile residual
higher degree of tensile stress, the lattice parameters of TiAlN (111) stress can facilitate the movement of dislocations, leading to a higher
exhibited a reduction (Fig. 3). degree of plastic deformation and subsequent dislocation annihilation.
Fig. 8 shows the hardness and reduced elastic modulus of the c- In our previous work [42] on heteroepitaxial c-TiAlN/h-Cr2N
TiAlN/h-Cr2N multilayers films as a function of Cr2N ratio. The hardness multilayer films deposited on Al2O3 (0001) substrates, the S20–50
of TiAlN reference sample deposited on Si was 18.5 ± 0.8 GPa. Single- exhibited the highest hardness of 27.1 ± 0.7 GPa. We observed that the
phase epitaxial Cr2N film deposited on sapphire has been reported in multilayer film with a modulation period of 20 nm displayed superior
earlier work and literature with a hardness around 19 GPa and an hardness compared to the variant with a 10 nm modulation period.
reduced elastic modulus of 260 GPa [42]. Notably, the sample with the highest recorded hardness also showcased
A general trend is difficult to extract when observed versus the Cr2N a remarkably smooth and well-defined interface between the individual
% ratio in the multilayer independently of the modulation period. For layers, indicating enhanced epitaxial quality. The Cr2N layer has a high
the 10 nm modulation period, the hardness initially increased as the degree of geometric regularity and homogeneity, significantly impacting
Cr2N ratio increased from 25% to 75%, followed by a decrease from 50% the mechanical properties (hardness and reduced Young’s modulus).
to 75%. This multilayer film exhibiting the highest mechanical proper­ These properties were found to be intricately linked to the thickness of
ties also exhibited the lowest tensile stress in the series of samples the Cr2N layer, thus exerting a substantial influence on the overall
(Fig. 7) and a denser morphology along with smaller grain size (Figs. 4 epitaxial quality of the multilayer films.
and 5). This observation follows the usual observation on the influence In this paper, we investigated c-TiAlN/h-Cr2N multilayer films
of the stress on the mechanical properties where increasing compressive deposited onto Si (100) substrates, S20–25 variant exhibited the highest
stress enhances hardness, while a decreases in hardness and formation of measured hardness at 22.03 ± 1.27 GPa. Interestingly, the incorpora­
thermal cracks can be observed when tensile stress increases [58]. In tion of a high thickness Cr2N layer within the TiAlN layer seemed to
contrast, for the 75% Cr2N ratio, the hardness demonstrated a positive have a detrimental impact on the resulting polycrystalline multilayer
correlation with the modulation period. This can be attributed to the films and an increase of tensile stress. A notable observation is that the
increase in structural density from S10–75 to S30–75. Notably, the role 75% Cr2N ratio has a (0002) oriented Cr2N layer and a larger grain size,
of grain size appears to be less significant when the structure exhibits contributing to heightened residual stress and concurrently reduced
porosity. For the 50% ratio, the hardness, grain size, and porosity lie in hardness. Evidently, the mechanical properties of the random oriented
an intermediate range. c-TiAlN/h-Cr2N multilayer films were intricately linked to the residual
Fig. 9 presents the evolution between hardness and tensile residual stress and to a minor extend the grain size.
stress where the hardness reduces from 22 GPa to 10 GPa when the

Fig. 8. Hardness and reduced Young’s modulus of all multilayers versus their Cr2N% ratio.

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H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

4. Conclusion [3] S. Pugal Mani, M. Kalaiarasan, K. Ravichandran, N. Rajendran, Y. Meng, Corrosion

resistant and conductive TiN/TiAlN multilayer coating on 316L SS: a promising
metallic bipolar plate for proton exchange membrane fuel cell, J. Mater. Sci. 56
In this study, c-TiAlN/h-Cr2N multilayer films with different modu­ (2021) 10575–10596, https://doi.org/10.1007/s10853-020-05682-4.
lation periods and thickness ratios were prepared by dc magnetron [4] P. Yi, L. Peng, T. Zhou, H. Wu, X. Lai, Cr-N-C multilayer film on 316L stainless steel
sputtering on Si substrate. When the Cr2N ratio in the bilayer increased as bipolar plates for proton exchange membrane fuel cells using closed field
unbalanced magnetron sputter ion plating, Int. J. Hydrog. Energy 38 (2013)
the Cr2N layers orientation varied from randomly oriented to 0002 1535–1543, https://doi.org/10.1016/j.ijhydene.2012.11.030.
oriented grains while inversely the TiAlN layer varied from randomly [5] R. Grover, R. Srivastava, M.N. Kamalasanan, D.S. Mehta, Multilayer thin film
orientated layer to 001 orientated grains. encapsulation for organic light emitting diodes, RSC Adv. 4 (2014) 10808–10814,
https://doi.org/10.1039/c3ra46077k.
The tensile residual stress of multilayer films increased as the Cr2N [6] M. Asadirad, Y. Gao, P. Dutta, S. Shervin, S. Sun, S. Ravipati, S.H. Kim, Y. Yao, K.
ratio increased and was attributed mainly due to different thermal H. Lee, A.P. Litvinchuk, V. Selvamanickam, J.H. Ryou, High-performance flexible
expansion between the layer and the substrate. The evolution of tensile thin-film transistors based on single-crystal-like germanium on glass, Adv.
Electron. Mater. 2 (2016) 1–7, https://doi.org/10.1002/aelm.201600041.
stress in the multilayers dependent on the Cr2N% and modulation period [7] Y.S. Ghim, H.G. Rhee, A. Davies, Simultaneous measurements of top surface and its
had important impacts on morphology and mechanical properties: i) underlying film surfaces in multilayer film structure, Sci. Rep. 7 (1) (2017) 11,
The grain size of the multilayer films increased with the incorporation of https://doi.org/10.1038/s41598-017-11825-6.
[8] H. Wang, Z. Zheng, C. Ji, L. Jay Guo, Automated multi-layer optical design via deep
Cr2N thickness ratio and been porous at the same time ii) the mechanical reinforcement learning, Mach. Learn. Sci. Technol. 2 (2021), 025013, https://doi.
properties also decreased with the Cr2N thickness ratio from 25% to org/10.1088/2632-2153/abc327.
75%. The highest hardness (22 ± 1.3 GPa) and reduced Young’s [9] Y. Lin, Y. Fang, J. Zhao, Y. Shao, S.J. Stuard, M.M. Nahid, H. Ade, Q. Wang, J.
E. Shield, N. Zhou, A.M. Moran, J. Huang, Unveiling the operation mechanism of
modulus (253 ± 6 GPa) was measured on S20–25 which exhibited the
layered perovskite solar cells, Nat. Commun. 10 (1) (2019) 11, https://doi.org/
lowest tensile stress, lower lattice parameter, and a denser morphology 10.1038/s41467-019-08958-9.
with smaller grain size. [10] B.L. Wang, K.F. Ren, H. Chang, J.L. Wang, J. Ji, Construction of degradable
multilayer films for enhanced antibacterial properties, ACS Appl. Mater. Interfaces
5 (2013) 4136–4143, https://doi.org/10.1021/am4000547.
CRediT authorship contribution statement [11] J. Tanum, H. Jeong, J. Heo, M. Choi, K. Park, J. Hong, Assembly of graphene oxide
multilayer film for stable and sustained release of nitric oxide gas, Appl. Surf. Sci.
486 (2019) 452–459, https://doi.org/10.1016/j.apsusc.2019.04.260.
Eklund Per: Conceptualization, Funding acquisition, Project
[12] G. Abadias, E. Chason, J. Keckes, M. Sebastiani, G.B. Thompson, E. Barthel, G.
administration, Supervision, Writing – review & editing. le Febvrier L. Doll, C.E. Murray, C.H. Stoessel, L. Martinu, Review Article: Stress in thin films
Arnaud: Conceptualization, Formal analysis, Investigation, Supervi­ and coatings: current status, challenges, and prospects, J. Vac. Sci. Technol. A Vac.,
sion, Writing – review & editing. Ma Hairui: Conceptualization, Data Surf., Film. 36 (2018) 10–11, https://doi.org/10.1116/1.5011790.
[13] N. Ahmed, Z. S. Khan, A. Ali, Microstructure and residual stress dependence of
curation, Formal analysis, Investigation, Writing – original draft. Miao molybdenum films on DC magnetron sputtering conditions, Appl. Phys. A Mater.
Qiang: Funding acquisition, Supervision, Writing – review & editing. Sci. Process. 128 (2022) 1–13, https://doi.org/10.1007/s00339-022-06097-5.
Liang Wenping: Formal analysis, Investigation. [14] A. Al-Masha’al, A. Bunting, R. Cheung, Evaluation of residual stress in sputtered
tantalum thin-film, Appl. Surf. Sci. 371 (2016) 571–575, https://doi.org/10.1016/
j.apsusc.2016.02.236.
[15] H. Li, D. Gao, S. Xie, J. Zou, Effect of magnetron sputtering parameters and stress
Declaration of Competing Interest state of W film precursors on WSe 2 layer texture by rapid selenization, Sci. Rep. 6
(1) (2016) 9, https://doi.org/10.1038/srep36451.
The authors declare that they have no known competing financial [16] D.L. Ma, P.P. Jing, Y.L. Gong, B.H. Wu, Q.Y. Deng, Y.T. Li, C.Z. Chen, Y.X. Leng,
N. Huang, Structure and stress of Cu films prepared by high power pulsed
interests or personal relationships that could have appeared to influence
magnetron sputtering, Vacuum 160 (2019) 226–232, https://doi.org/10.1016/j.
the work reported in this paper. vacuum.2018.11.039.
[17] I.G. McDonald, W.M. Moehlenkamp, D. Arola, J. Wang, Residual stresses in Cu/Ni
Data Availability Multilayer Thin Films Measured Using the Sin2ψ Method, Exp. Mech. 59 (2019)
111–120, https://doi.org/10.1007/s11340-018-00447-2.
[18] R.E. Ogilvie, J. Nicolich, Stress analysis in tungsten and Si3N4 coated silicon
Data will be made available on request. The data that support these wafers, Spectrochim. Acta - Part B . Spectrosc. 64 (2009) 788–790, https://doi.org/
findings are available from the corresponding author on request. 10.1016/j.sab.2009.05.014.
[19] P. Panda, R. Ramaseshan, N. Ravi, G. Mangamma, F. Jose, S. Dash, K. Suzuki,
H. Suematsu, Reduction of residual stress in AlN thin films synthesized by
Acknowledgments magnetron sputtering technique, Mater. Chem. Phys. 200 (2017) 78–84, https://
doi.org/10.1016/j.matchemphys.2017.07.072.
[20] T.J. Vink, J.B.A.D. van Zon, Stress in sputtered Mo thin films: the effect of the
This work was supported financially by the Swedish Government discharge voltage, J. Vac. Sci. Technol. A Vac., Surf., Film. 9 (1991) 124–127,
Strategic Research Area in Materials Science on Functional Materials at https://doi.org/10.1116/1.577111.
Linköping University (Faculty Grant SFO-Mat-LiU No. 2009 00971), the [21] N. Kaiser, Review of the fundamentals of thin-film growth, Appl. Opt. 41 (2002).
[22] J.A. Floro, E. Chason, R.C. Cammarata, D.J. Srolovitz, Physical origins of intrinsic
Knut and Alice Wallenberg foundation through the Wallenberg Acad­ stresses in Volmer-Weber thin films, MRS Bull. 27 (2002) 19–25, https://doi.org/
emy Fellows program (KAW-2020.0196), the Swedish Research Council 10.1557/mrs2002.15.
(VR) under Project No. 2021-03826, and the Swedish Energy Agency [23] R.W. Hoffman, Stresses in thin films: the relevance of grain boundaries and
impurities, Thin Solid Films 34 (1976) 185–190, https://doi.org/10.1016/0040-
under project 52740-1. H.M. also acknowledges the financial support 6090(76)90453-3.
from the National Natural Science Foundation of China (Grant No. [24] A.L. Shull, F. Spaepen, Measurements of stress during vapor deposition of copper
52272065), the National Major Science and Technology Projects of and silver thin films and multilayers, J. Appl. Phys. 80 (1996) 6243–6256, https://
doi.org/10.1063/1.363701.
China (Y2022-III-0004-0013), the National Major Science and Tech­ [25] S.C. Seel, C.V. Thompson, S.J. Hearne, J.A. Floro, Tensile stress evolution during
nology Projects of China (NWK20220113), the Fundamental Research deposition of Volmer-Weber thin films, J. Appl. Phys. 88 (2000) 7079–7088,
Fund for the Central Universities (No. NP2022424) and the China https://doi.org/10.1063/1.1325379.
[26] E. Chason, A.M. Engwall, Relating residual stress to thin film growth processes via
Scholarship Council (CSC, 202106830068).
a kinetic model and real-time experiments, Thin Solid Films 596 (2015) 2–7,
https://doi.org/10.1016/j.tsf.2015.06.061.
References [27] G. Thurner, R. Abermann, Internal stress and structure of ultrahigh vacuum
evaporated chromium and iron films and their dependence on substrate
temperature and oxygen partial pressure during deposition, Thin Solid Films 192
[1] X. Sui, G. Li, C. Jiang, K. Wang, Y. Zhang, J. Hao, Q. Wang, Improved toughness of
(1990) 277–285, https://doi.org/10.1016/0040-6090(90)90072-L.
layered architecture TiAlN/CrN coatings for titanium high speed cutting, Ceram.
[28] R. Daniel, K.J. Martinschitz, J. Keckes, C. Mitterer, The origin of stresses in
Int. 44 (2018) 5629–5635, https://doi.org/10.1016/j.ceramint.2017.12.210.
magnetron-sputtered thin films with zone T structures, Acta Mater. 58 (2010)
[2] B. Liu, B. Deng, Y. Tao, Influence of niobium ion implantation on the
2621–2633, https://doi.org/10.1016/j.actamat.2009.12.048.
microstructure, mechanical and tribological properties of TiAlN/CrN nano-
[29] R. Daniel, D. Holec, M. Bartosik, J. Keckes, C. Mitterer, Size effect of thermal
multilayer coatings, Surf. Coat. Technol. 240 (2014) 405–412, https://doi.org/
expansion and thermal/intrinsic stresses in nanostructured thin films: experiment
10.1016/j.surfcoat.2013.12.065.

7
H. Ma et al. Journal of Alloys and Compounds 976 (2024) 173273

and model, Acta Mater. 59 (2011) 6631–6645, https://doi.org/10.1016/j. [44] N.K. Singh, V. Hjort, D. Gambino, A. Febvrier, Effect of W alloying on the electronic
actamat.2011.07.018. structure, phase stability, and thermoelectric properties of epitaxial CrN films,
[30] M. Bartosik, R. Daniel, Z. Zhang, M. Deluca, W. Ecker, M. Stefenelli, M. Klaus, (〈https://doi.org/10.48550/arXiv.2311.02453〉).
C. Genzel, C. Mitterer, J. Keckes, Lateral gradients of phases, residual stress and [45] M. Mayer, S. Möller, M. Rubel, A. Widdowson, S. Charisopoulos, T. Ahlgren,
hardness in a laser heated Ti 0.52Al 0.48N coating on hard metal, Surf. Coat. E. Alves, G. Apostolopoulos, N.P. Barradas, S. Donnelly, S. Fazinić, K. Heinola,
Technol. 206 (2012) 4502–4510, https://doi.org/10.1016/j.surfcoat.2012.02.035. O. Kakuee, H. Khodja, A. Kimura, A. Lagoyannis, M. Li, S. Markelj, M. Mudrinic,
[31] T. Guo, L. Qiao, X. Pang, A.A. Volinsky, Brittle film-induced cracking of ductile P. Petersson, I. Portnykh, D. Primetzhofer, P. Reichart, D. Ridikas, T. Silva, S.
substrates, Acta Mater. 99 (2015) 273–280, https://doi.org/10.1016/j. M. Gonzalez De Vicente, Y.Q. Wang, Ion beam analysis of fusion plasma-facing
actamat.2015.07.059. materials and components: Facilities and research challenges, Nucl. Fusion. 60
[32] J. Buchinger, L. Löfler, J. Ast, A. Wagner, Z. Chen, J. Michler, Z.L. Zhang, P. (2020), https://doi.org/10.1088/1741-4326/ab5817.
H. Mayrhofer, D. Holec, M. Bartosik, Fracture properties of thin film TiN at [46] P.A. Flinn, Measurement and interpretation of stress in copper films as a function of
elevated temperatures, Mater. Des. 194 (2020) 1–10, https://doi.org/10.1016/j. thermal history, J. Mater. Res. 6 (1991) 1498–1501, https://doi.org/10.1557/
matdes.2020.108885. JMR.1991.1498.
[33] T.Z. Kattamis, M. Chen, S. Skolianos, B.V. Chambers, Effect of residual stresses on [47] G.C.A.M. Janssen, M.M. Abdalla, F. van Keulen, B.R. Pujada, B. van Venrooy,
the strength, adhesion and wear resistance of SiC coatings obtained by plasma- Celebrating the 100th anniversary of the Stoney equation for film stress:
enhanced chemical vapor deposition on low alloy steel, Surf. Coat. Technol. 70 Developments from polycrystalline steel strips to single crystal silicon wafers, Thin
(1994) 43–48, https://doi.org/10.1016/0257-8972(94)90073-6. Solid Films 517 (2009) 1858–1867, https://doi.org/10.1016/j.tsf.2008.07.014.
[34] E. Mastropaolo, R. Latif, E. Grady, R. Cheung, Control of stress in tantalum thin [48] W.C. Oliver, G.M. Pharr, An improved technique for determining hardness and
films for the fabrication of 3D MEMS structures, J. Vac. Sci. Technol. B, elastic modulus using load and displacement sensing indentation experiments,
Nanotechnol. Microelectron. Mater. Process. Meas. Phenom. 31 (2013) 06FD02, J. Mater. Res. 7 (1992) 1564–1583, https://doi.org/10.1557/jmr.1992.1564.
https://doi.org/10.1116/1.4824697. [49] D. Holec, R. Rachbauer, L. Chen, L. Wang, D. Luef, P.H. Mayrhofer, Phase stability
[35] J. Lin, J.J. Moore, W.D. Sproul, S.L. Lee, J. Wang, Effect of negative substrate bias and alloy-related trends in Ti-Al-N, Zr-Al-N and Hf-Al-N systems from first
on the structure and properties of Ta coatings deposited using modulated pulse principles, Surf. Coat. Technol. 206 (2011) 1698–1704, https://doi.org/10.1016/j.
power magnetron sputtering, IEEE Trans. Plasma Sci. 38 (2010) 3071–3078, surfcoat.2011.09.019.
https://doi.org/10.1109/TPS.2010.2068316. [50] H. Era, Y. Ide, A. Nino, K. Kishitake, TEM study on chromium nitride coatings
[36] L.A. Clevenger, A. Mutscheller, J.M.E. Harper, C. Cabral, K. Barmak, The deposited by reactive sputter method, Surf. Coat. Technol. 194 (2005) 265–270,
relationship between deposition conditions, the beta to alpha phase https://doi.org/10.1016/j.surfcoat.2004.05.022.
transformation, and stress relaxation in tantalum thin films, J. Appl. Phys. 72 [51] M.F. Yan, H.T. Chen, Structural, elastic and electronic properties of Cr2N: a first-
(1992) 4918–4924, https://doi.org/10.1063/1.352059. principles study, Comput. Mater. Sci. 88 (2014) 81–85, https://doi.org/10.1016/j.
[37] E. Chason, P.R. Guduru, Tutorial: understanding residual stress in polycrystalline commatsci.2014.02.035.
thin films through real-time measurements and physical models, J. Appl. Phys. 119 [52] M. Ben Hassine, H.O. Andrén, A.H.S. Iyer, A. Lotsari, O. Bäcke, D. Stiens,
(2016), https://doi.org/10.1063/1.4949263. W. Janssen, T. Manns, J. Kümmel, M. Halvarsson, Growth model for high-Al
[38] D.J. Li, M. Cao, X.Y. Deng, X. Sun, W.H. Chang, W.M. Lau, Multilayered coatings containing CVD TiAlN coatings on cemented carbides using intermediate layers of
with alternate ZrN and TiAlN superlattices, Appl. Phys. Lett. 91 (2007), https:// TiN, Surf. Coat. Technol. 421 (2021), https://doi.org/10.1016/j.
doi.org/10.1063/1.2826284. surfcoat.2021.127361.
[39] G.B. Thompson, L. Wan, X. xiang Yu, F. Vogel, Influence of phase stability on the in [53] R. Qiu, O. Bäcke, D. Stiens, W. Janssen, J. Kümmel, T. Manns, H.O. Andrén,
situ growth stresses in Cu/Nb multilayered films, Acta Mater. 132 (2017) 149–161, M. Halvarsson, CVD TiAlN coatings with tunable nanolamella architectures, Surf.
https://doi.org/10.1016/j.actamat.2017.04.036. Coat. Technol. 413 (2021), https://doi.org/10.1016/j.surfcoat.2021.127076.
[40] M. Renzelli, M.Z. Mughal, M. Sebastiani, E. Bemporad, Design, fabrication and [54] A. Dulmaa, F.G. Cougnon, R. Dedoncker, D. Depla, On the grain size-thickness
characterization of multilayer Cr-CrN thin coatings with tailored residual stress correlation for thin films, Acta Mater. 212 (2021), 116896, https://doi.org/
profiles, Mater. Des. 112 (2016) 162–171, https://doi.org/10.1016/j. 10.1016/j.actamat.2021.116896.
matdes.2016.09.058. [55] N. Schalk, C. Mitterer, J. Keckes, M. Penoy, C. Michotte, Influence of residual
[41] L. Yu, G. Pan, Z. Cao, Y. Ma, S. Tang, X. Meng, Tailorable stress window of stress- stresses and grain size on the spinodal decomposition of metastable Ti1-xAlxN
induced martensitic transition in NiTi/W nanostructured multilayer films, coatings, Surf. Coat. Technol. 209 (2012) 190–196, https://doi.org/10.1016/j.
Intermetallics 128 (2021), 106996, https://doi.org/10.1016/j. surfcoat.2012.08.052.
intermet.2020.106996. [56] W. Tillmann, D. Grisales, D. Stangier, C.A. Thomann, J. Debus, A. Nienhaus,
[42] H. Ma, Q. Miao, W. Liang, P.O.Å. Persson, J. Palisaitis, X. Gao, Y. Song, P. Eklund, D. Apel, Residual stresses and tribomechanical behaviour of TiAlN and TiAlCN
A. le Febvrier, Effect of modulation period and thickness ratio on the growth and monolayer and multilayer coatings by DCMS and HiPIMS, Surf. Coat. Technol. 406
mechanical properties of heteroepitaxial c-Ti0.4Al0.6N/h-Cr2N multilayer films, (2021), https://doi.org/10.1016/j.surfcoat.2020.126664.
Surf. Coat. Technol. 472 (2023), 129921, https://doi.org/10.1016/J. [57] D. Fan, H. Lei, C.Q. Guo, D.L. Qi, J. Gong, C. Sun, Stress study on crn thin films
SURFCOAT.2023.129921. with different thicknesses on stainless steel, Acta Metall. Sin. (Engl. Lett. 31 (2018)
[43] A. le Febvrier, L. Landälv, T. Liersch, D. Sandmark, P. Sandström, P. Eklund, An 329–336, https://doi.org/10.1007/s40195-017-0620-5.
upgraded ultra-high vacuum magnetron-sputtering system for high-versatility and [58] P. Schlund, P. Kindermann, R. Schulte, H.G. Sockel, U. Schleinkofer, K. Görting,
software-controlled deposition, Vacuum 187 (2021), https://doi.org/10.1016/j. W. Heinrich, Mechanical behaviour of PVD/CVD-coated hard metals under cyclic
vacuum.2021.110137. loads, Int. J. Refract. Met. Hard Mater. 17 (1999) 179–185, https://doi.org/
10.1016/S0263-4368(99)00009-8.