scholarly journals Effects of Residual Stress Distribution on Interfacial Adhesion of Magnetron Sputtered AlN and AlN/Al Nanostructured Coatings on a (100) Silicon Substrate

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 896 ◽  
Author(s):  
Rashid Ali ◽  
Marco Renzelli ◽  
M. Khan ◽  
Marco Sebastiani ◽  
Edoardo Bemporad

The present study investigated the influence of nanoscale residual stress depth gradients on the nano-mechanical behavior and adhesion energy of aluminium nitride (AlN) and Al/AlN sputtered thin films on a (100) silicon substrate. By using a focused ion beam (FIB) incremental ring-core method, the residual stress depth gradient was assessed in the films in comparison with standard curvature residual stress measurements. The adhesion energy was then quantified by using a nanoindentation-based model. Results showed that the addition of an aluminum layer gave rise to additional tensile stress at the coating/substrate interface, which can be explained in terms of the differences of thermal expansion coefficients with the silicon substrate. Therefore, the coatings without the Al layer showed better adhesion because of a more homogeneous compressive residual stress in comparison with the coating having the Al layer, even though both groups of coatings were produced under the same bias voltage. Results are discussed, and some general suggestions are made on the correlation between coating/substrate property combinations and the adhesion energy of multilayer stacks. The results suggested that the Al bond layer and inhomogeneous residual stresses negatively affected the adhesion of AlN to a substrate such as silicon.

Author(s):  
Rashid Ali ◽  
Marco Renzelli ◽  
Muhammad Imran Khan ◽  
Marco Sebastiani ◽  
Edoardo Bemporad

Compressive residual stresses in thin films can inhibit crack propagation under normal or sliding contact loading, with associated enhancement of the coating apparent toughness, load bearing capacity and wear resistance. This study investigates the influence of residual stress distributions on the thin film/substrate adhesion using a nanoindenter coupled with scanning electron microscope (SEM) investigations of indentation induced failure modes. Reactive and un-reactive magnetron sputtering with ion plating was used to coat a (100) silicon substrate with aluminum nitride (AlN) with and without an aluminum (Al) adhesion layer. The presence of an Al bond layer gives additional interfacial tensile stress because of the difference in thermal expansion coefficient. Additionally, a different magnitude of residual stresses in the AlN coating was achieved by changing the applied bias voltage onto the substrate. Wafer curvature method and incremental focused ion beam (FIB) milling, combined with high-resolution in situ scanning electron microscopy (SEM) imaging and full field strain analysis by digital image correlation (DIC), were used to measure the average and in-depth stress residual stress distribution in the produced coatings. The adhesion energy was then quantified by using a nanoindentation based model. Results demonstrate that the additional tensile residual stress in the aluminum adhesion layer decrease significantly the coating adhesion, even in presence of a higher compressive stress state in the AlN top-layer. Therefore, the coatings without Al-layer showed better adhesion because of a more homogeneous compressive residual stress in comparison with the coating having Al layer, even though both groups of coatings are produced under same bias voltage. Results are discussed, and some general suggestions are made on the correlation between coating/substrate property combination and the adhesion energy of multilayer stacks. The results suggested that Al bond-layer and inhomogeneous residual stresses affected the adhesion of AlN negatively to a substrate like silicon.


2006 ◽  
Vol 983 ◽  
Author(s):  
Kim M. Archuleta ◽  
David P. Adams ◽  
Michael J. Vasile ◽  
Julia E. Fulghum

AbstractMedium energy (30 keV) focused gallium ion beam exposure of silicon results in a compressive in-plane stress with a magnitude as large as 0.4 GPa. Experiments involve uniform irradiation of thin polysilicon microcantilevers (200 micron length) over a range of dose from 1 x 1016 to 2 x 1018 ions/cm2. The radii of curvature of microcantilevers are measured using white light interferometry before and after each exposure. The residual stress is determined from these radii and other measured properties using Stoney's equation. The large residual stress is attributed to ion beam damage, microstructural changes and implantation.


MRS Advances ◽  
2017 ◽  
Vol 2 (18) ◽  
pp. 981-986 ◽  
Author(s):  
Swagata Samanta ◽  
Pallab Banerji ◽  
Pranabendu Ganguly

ABSTRACTThis work deals with SU-8 waveguides and waveguide structures fabricated on an oxidized silicon substrate using ‘Focused ion beam (FIB) lithography’. From our experimentation it seems that FIB method is practically not suitable for fabricating long SU-8 waveguide structures, rather it is more suitable for nanoscale modification of already fabricated waveguides, such as, to fabricate photonic crystal structures.


2005 ◽  
Vol 20 (5) ◽  
pp. 1356-1368 ◽  
Author(s):  
A. Cavaleiro ◽  
A.P. Marques ◽  
J.V. Fernandes ◽  
N.J.M. Carvalho ◽  
J.Th. De Hosson

W–Si–N films were deposited by reactive sputtering in a Ar + N2 atmosphere from a W target encrusted with different number of Si pieces and followed by a thermal annealing at increasing temperatures up to 900 °C. Three iron-based substrates with different thermal expansion coefficients, in the range of 1.5 × 10−6 to 18 × 10−6 K−1 were used. The chemical composition, structure, residual stress, hardness (H), and Young’s modulus (E) were evaluated after all the annealing steps. The as-deposited film with low N and Si contents was crystalline whereas the one with higher contents was amorphous. After thermal annealing at 900 °C the amorphous film crystallized as body-centered cubic α–W. The crystalline as-deposited film presented the same phase even after annealing. There were no significant changes in the properties of both films up to 800 °C annealing. However, at 900 °C, a strong decrease and increase in the hardness were observed for the crystalline and amorphous films, respectively. It was possible to find a good correlation between the residual stress and the hardness of the films. In several cases, particularly for the amorphous coating, H/E higher than 0.1 was reached, which envisages good tribological behavior. The two methods (curvature and x-ray diffraction) used for calculation of the residual stress of the coatings showed fairly good agreement in the results.


2012 ◽  
Vol 520 (6) ◽  
pp. 2073-2076 ◽  
Author(s):  
Xu Song ◽  
Kong Boon Yeap ◽  
Jing Zhu ◽  
Jonathan Belnoue ◽  
Marco Sebastiani ◽  
...  

2014 ◽  
Vol 251 ◽  
pp. 151-161 ◽  
Author(s):  
M. Sebastiani ◽  
C. Eberl ◽  
E. Bemporad ◽  
A.M. Korsunsky ◽  
W.D. Nix ◽  
...  

1999 ◽  
Vol 587 ◽  
Author(s):  
Fabian Radulescu ◽  
John M. McCarthy

AbstractThe residual stress and the microstructure associated with it were studied in connection with the Pd-Ge ohmic contact formation on GaAs. Evaporated Pd (20 nm) / Ge (150 nm) / Pd (50 nm) thin film stacks on GaAs were annealed at various temperatures and the resulting microstructures were investigated by transmission electron microscopy (TEM). Micro-cantilever beam structures were fabricated with a focused ion beam (FIB) workstation and the residual stress present was calculated from the deflection magnitude. It was found that Ge solid phase epitaxial (SPE) growth on GaAs is associated with a stress relaxation of the thin film system. A new model that suggests the tensile stress induced by the intermediate layer may play an important role in the SPE growth mechanism is proposed. Other cases of solid phase heteroepitaxial growth with an intermediate medium, such as Ge/Au/Si, Co/Ti/Si (the TIME method) and Co/SiOx/Si (the OME method) are discussed in light of this newly proposed model. Also, the possibility of using controlled stress to engineer new methods for growing SPE based heterostructures will be presented.


1987 ◽  
Vol 31 ◽  
pp. 255-260
Author(s):  
M. Bagby ◽  
SJ Marshall ◽  
GW Marshall

Residual stresses in dental castings are widely held to be the cause of distortion and change of fit in ceramic bonded to metal dental restorations. Residual stresses are thought to result from the casting process and from ceramic/metal mismatch of thermal expansion coefficients. Such stresses have not been confirmed experimentally. The purpose of this study was to measure residual stress with x-ray diffraction at the various porcelain application steps for two noble dental alloys with two dental opaque porcelains.


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