Residual stress of (Pb_0.92La_0.08)(Zr _0.52Ti_0.48)O₃ films grown by a sol-gel process

We deposited ferroelectric (Pb0.92La0.08)(Zr0.52Ti0.48)O3 films of ≈0.35 to ≈3.1 μm in thickness on platinized silicon substrates by chemical solution deposition. A dielectric constant of ≈1350 and dielectric loss of ≈0.04 were measured at room temperature. Hysteresis loop tests revealed that the remanent polarization increases while the coercive field decreases with PLZT film thickness. The residual stress in the PLZT films, as determined by the x-ray diffraction sin²ψ method, decreased from ≈380 to ≈200 MPa when the film thickness increased from 0.35 to 3.1 μm. The dependence of the residual stress (σ) on the PLZT film thickness (t) can be described by an empirical equation, σ = A0exp(-t²/λ²), with A0 ≈ 390 MPa and λ ≈ 3.8 μm.