Reduction of etching damage in lead-zirconate-titanate thin films with inductively coupled plasma

Abstract

In this work, we etched lead-zirconate-titanate (PZT) films with various additive gases (O-2 and Ar) in Cl-2/CF4 plasmas, while mixing ratio was fixed at 8/2. After the etching, the plasma induced damages are characterized in terms of hysteresis curves, leakage current, retention properties, and switching polarization. When the electrical properties of PZT etched in O-2 or Ar added to Cl-2/CF4 were compared, the value of remanent polarization in O-2 added to Cl-2/CF4 plasma is higher than that in Ar added plasma. The maximum etch rate of the PZT thin films was 145 nm/min for 30% Ar added Cl-2/CF4 gas having mixing ratio of 8/2 and 110 nm/min for 10% O-2 added to that same gas mixture. In order to recover the ferroelectic properties of the PZT thin films after etching, we annealed the etched PZT thin films at 550degreesC in an O-2 atmosphere for 10 min. From the hysteresis curves, leakage current, retention property, and switching polarization, the reduction of the etching damage and the recovery via the annealing turned out to be more effective when O-2 was added to Cl-2/CF4 than Ar. X-ray diffraction showed that the structural damage was lower when O-2 was added to Cl-2/CF4 and the improvement in the ferroelectric properties of the annealed samples was consistent with the increased intensities of the (100) and the (200) PZT peaks. (C) 2003 American Vacuum Society.