(Pb,La)(Zr,Ti)O-3 thin films prepared by electron cyclotron resonance plasma enhanced chemical vapor deposition for the charge storage capacitor of a gigabit-scale dynamic random access memory

Abstract

Perovskite single phase (Pb,La)(Zr,Ti)O-3 (PLZT) (0-22/60/40) thin films with a stoichiometric composition were successfully fabricated on Pt/Ti/SiO2/Si substrates at 490 degrees C by the electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR PECVD). The characteristics of PLZT films for various La concentrations were investigated for the application to the charge storage capacitor of a gigabit-scale dynamic random access memory (DRAM). The La doped films showed paraelectric-like slim loop P-V hysteresis curves and almost no frequency dependence of permittivity. The doping of La caused the film surface to be very smooth. After rapid thermal annealing at 650 degrees C for 1 min, the capacitance as well as the leakage current characteristics of the films were greatly improved. The 50-nm-thick PLZT(5.5/56/44) film had an effective capacitance of 133 fF/mu m(2) and an SiO2 equivalent thickness of 0.26 nm.