High-Capacitance Thin-Film Capacitors on a Polymer Film

Pb(Zr,Ti)O3 (PZT) thin film has been crystallized at below 450°C by means of a sol–gel process that employs a PT-seeding method, and it has been used to fabricate a PZT thin-film capacitor on polyimide film at a high decomposition temperature. The capacitor structure includes a 4-layer bottom electrode: Pt(200 nm)/Ti(50 nm)/Mo(600 nm)/Ti(50 nm). Capacitance density is 12 nF/mm2 in the effective capacitance area. Despite the use of PZT, a high-k material, this thin-film capacitor still offers high insulation resistance (6.2 GΩ at 3 Vdc) and reliability sufficient for use as a decoupling capacitor.