Fabrication and characterization of monocrystalline-based composite Pb(Zr, Ti)O3 thin film patterned with polycrystalline crack stopper structure

This paper presents a novel form of Pb(Zr,Ti)O3 (PZT) thin film with a structure in which monocrystalline (Mono) PZT is sectioned with narrow mesh-like polycrystalline (Poly) PZT. The motivation is to overcome the inherent brittleness of piezoelectric Mono thin films. The design assumes that the Poly pattern will stop crack propagation within the Mono area. As a proof of concept, a Mono-Poly PZT composite thin film with a 20-µm-pitch and 2-µm-wide Poly pattern was sputter-deposited on a patterned underlayer on a Si substrate. Its piezoelectric properties were close to those of pure Mono PZT thin films, while its dielectric constant was significantly lower than those of pure Poly PZT thin films. Indentation tests confirmed the Poly patterns effectively stops crack propagation, which is likely to improve the mechanical durability of the overall film.