REACTIVE ION ETCHING OF LEAD-ZIRCONATE-TITANATE (PZT) THIN-FILM CAPACITORS

One of the key processing concerns in the integration of PbZrxTi1-xO3 (PZT) thin film capacitors in to the existing VLSI for ferroelectric or dynamic random access memory a plications is the patterning of these films and the electrodes. In this work, we have identified a suitable etch gas (CCl2F2) for dry etching of PZT thin films on RuO2 electrodes. The etch rate and anisotropy have been studied as a function of etching conditions. The trends in the effect on the etch rate of the gas pressure, RF power and O2 additions to the etch gas have been determined and an etching mechanism has been proposed. It was found that ion bombardment effects are primarily responsible for the etching of both PZT and RuO2 thin films. Etch rates of the order of 20-30 nm/min were obtained for PZT thin films under low gas pressure and high RF power conditions. The etch residues and the relative etch rates of the components of the PZT solid solution were determined using XPS. The results show that the etching of PbO is the limiting factor in the etch process.