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The existence of insoluble residues as intermediate products produced during the wet etching process is the main quality-reducing and structure-patterning issue for lead zirconate titanate (PZT) thin films. A one-step wet etching process using the solutions of buffered HF (BHF) and HNO 3 acid was developed for patterning PZT thin films for microelectomechanical system (MEMS) applications. PZT thin films with 1 μm thickness were prepared on the Pt/Ti/SiO 2 /Si substrate by the sol-gel process for compatibility with Si micromachining. Various compositions of the etchant were investigated and the patterns were examined to optimize the etching process. The optimal result is demonstrated by a high etch rate (3.3 μm min −1 ) and low undercutting (1.1: 1). The patterned PZT thin film exhibits a remnant polarization of 24 μC cm −2 , a coercive field of 53 kV cm −1 , a leakage current density of 4.7 × 10 −8 A cm −2 at 320 kV cm −1 and a dielectric constant of 1100 at 1 KHz.

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Polycrystalline lead zirconate titanate (PZT) thin films were synthesized on titanium substrates at a processing temperature of 160°C for 16 hours by using a hydrothernal method. The effects of KOH concentration on the phase evolution and morphology of the films were investigated. The as-synthesized PZT thin films using KOH concentration of 4 mol/1 have a dielectric constant and loss of 515 and 0.35 at 103 Hz respectively. The dielectric loss, tan6 and leakage current of hydrothermal PZT thin films were reduced by additional annealing at 100-400°C in air. Moreover, the annealed hydrothermal PZT thin films exhibit typical ferroelectric hysteresis loops at room temperature.