Sol-gel doped-PZT thin films for integrated tunable capacitors

Abstract

Integrated metal-insulator-metal (MIM) capacitors using sol-gel PZT doped with lanthanum (La, PLZT), manganese (Mn, PMZT) and niobium (Nb, PNZT) were successfully processed and characterized for tunable applications. Dielectric properties of doped-PZT were investigated and compared to those of pure PZT. Wafer-level measurements were conducted with a particular attention on tunability evaluation under DC bias voltage. Tunability, leakage current density and breakdown voltage of pure PZT thin films were 77.6% (i.e. 4.5:1) at 10kHz/10V, 4.8.10−5 A/cm2 at 870kV and 37.5V (i.e. 1.63 MV/cm) respectively. The breakdown voltage increased by 25% with La doping and by 50% with Nb and Mn. The lowest leakage current were achieved by PNZT (7.0.10−7 A/cm2 at 870kV) while PMZT films exhibited an outstanding tunability reaching 88.8% (i.e. 8.9:1) at 100 kHz and 20V. Enhanced performances of the developed doped-PZT were compared to the state of the art. Results indicate that electrical properties of sol-gel doped-PZT achieved those of conventionally deposited materials. It is noteworthy that obtained PMZT tunability is among the highest ones reported in the literature for PZT-derived thin films but also for other piezoelectric materials.