Interfacial Delamination of PZT Thin Films
The interface strength of Pb(Zr,Ti)O3(PZT) thin films on a silicon substrate is studied experimentally and numerically in this work. First, a sandwiched cantilever specimen is proposed to perform the delamination tests. The experimental results show that the multilayered Cr/PZT/PLT/Pt/Ti thin films deposited on single-crystal silicon substrates are delaminated along the interface between Cr and PZT layers in a brittle manner. Second, based on cohesive zone models (CZMs), numerical simulations are carried out to extract the fracture toughness of the interface Cr/PZT. Three types, exponential, bilinear and trapezoidal, of CZMs are adopted. Characteristic CZM parameters are obtained through comparisons with experimental results. The simulation results indicate that (i) cohesive strength and work of separation are the dominating parameters in the CZMs; (ii) the bilinear CZM is more suitable in describing this brittle interfacial delamination; and (iii) compared with typical film/coating materials of several millimetre thicknesses, the fracture energy of this weak interface Cr/PZT is quite low. Our study demonstrates a methodology of how to measure and determine the interface bonding strength parameter of PZT thin films, which will be useful for assessing the structural integrity and reliability of PZT devices.
KeywordsCohesive Strength Cohesive Zone Model Weak Interface Multilayered Thin Film Delamination Crack
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