Experimental and theoretical investigations of delamination at free edge of interface between piezoelectric thin films on a substrate

The interface strength of Pb(Zr,Ti)O3 (PZT) thin films on a silicon substrate is studied experimentally and theoretically in this work. The focus is put on crack initiation from the free edge of the interface. A novel method of sandwiched cantilever specimen is utilized to perform the delamination tests. Theoretical analyses are performed on the singular behavior of the stress in the vicinity of the free edge along the interface between Cr layer and PZT layer, and on the distribution of normal stress at the delamination loads. Based on these results, a delamination criterion involving stress intensity parameter is adopted to estimate the interface toughness for crack initiation at the free edge along the interface Cr/PZT.