Subcritical crack growth in SiNx thin-film barriers studied by electro-mechanical two-point bending

Abstract

Mechanical failure resulting from subcritical crack growth in the SiNx inorganic barrier layer applied on a flexible multilayer structure was studied by an electro-mechanical two-point bending method. A 10 nm conducting tin-doped indium oxide layer was sputtered as an electrical probe to monitor the subcritical crack growth in the 150 nm dielectric SiNx layer carried by a polyethylene naphthalate substrate. In the electro-mechanical two-point bending test, dynamic and static loads were applied to investigate the crack propagation in the barrier layer. As consequence of using two loading modes, the characteristic failure strain and failure time could be determined. The failure probability distribution of strain and lifetime under each loading condition was described by Weibull statistics. In this study, results from the tests in dynamic and static loading modes were linked by a power law description to determine the critical failure over a range of conditions. The fatigue parameter n from the power law reduces greatly from 70 to 31 upon correcting for internal strain. The testing method and analysis tool as described in the paper can be used to understand the limit of thin-film barriers in terms of their mechanical properties.

Environmentally Assisted Cracking in Silicon Nitride Barrier Films on Poly(ethylene terephthalate) Substrates

“…As the strain rate is increased above 0.01%·s –1 , ε c becomes independent of the environment. The effect of strain rate on ε c is consistent with the study by Guan et al., and the effect of humidity on time-dependent crack growth is consistent with the study by Vellinga et al Both studies demonstrated environmentally assisted cracking of the SiN x coatings on PEN polymers. Here, the crack growth rates and behavior were further characterized as a function of applied strains (from 0.6% to 0.85%)/driving forces (see numerical model in Figure c for corresponding G ss ), in different environments (laboratory air, dry nitrogen, dry air).…”

“…They argued that this environmental effect was unlikely due to the hygroscopic expansion of the polymer, and instead concluded that SiN x barriers undergo environmentally assisted cracking. Guan et al also performed electromechanical two-point bending tests in dynamic and static loading modes to determine the subcritical crack growth exponent n in SiN x coatings on PEN substrates. Their results suggest that SiN x thin films behaves differently from bulk Si 3 N 4 ceramics that are essentially immune to environmentally assisted cracking. , However, these studies neither directly measured the crack growth rates as a function of driving force for channel cracking nor considered the aforementioned potential effects of polymer relaxation.…”

Bending effect on the resistive switching behavior of a NiO/TiO2 p–n heterojunction

“…32 Guan et al have indicated that cracks may form in oxides at relatively low mechanical strains due to their brittle nature. 33 For the case of crack formation in the function layer, the resistance may increase upto a specic level and then lead to the initiation of the nal failure. 33,34 Chung et al have shown that the resistive switching of the Al/GeO 2 : S/Au device can withstand a tensile or compressive strain of up to 1.2%.…”

“…33 For the case of crack formation in the function layer, the resistance may increase upto a specic level and then lead to the initiation of the nal failure. 33,34 Chung et al have shown that the resistive switching of the Al/GeO 2 : S/Au device can withstand a tensile or compressive strain of up to 1.2%. 35 Shang et al have reported that cracks appear in the ITO/HfO x /ITO lm coated on the PET substrate when the mechanical tensile stress is up to 1.59%.…”

Mechanical failure of brittle thin films on polymers during bending by two-point rotation

“…In recent years, a great deal of research has been dedicated to the study of the mechanical failure of brittle thin films on a polymer substrate [4][5][6][7][8][9][10][11][12][13][14][15][16]. Three main techniques have been widely used to analyze the mechanical properties of thin brittle, hard films on soft substrates, namely nanoindentation and the related scratch test [17,18], the tensile fragmentation test [16,11], and the electro-mechanical two-point bending test (which, more properly would be addressed as the two-plate bending test (2PB), as we will do in the current paper) [6,16]. Among these methods the fragmentation test, which enables a direct observation of the failure process and thus an accurate determination of failure mechanism in brittle thin films, is the most commonly used one.…”