Reduction of dry etching damage to PZT films etched with a Cl-based plasma and the recovery behavior

Abstract

In this work, on the reduction of plasma etching damage with additive gas and the recovery of the plasma etching damage by using O-2 annealing after PZT thin-film etching have been investigated. To reduce the etching damage, we etched the PZT thin films with Ar or O-2 added into a Cl-2/CF4 gas mixture with a mixing ratio of 8/2. The maximum etch rates of the PZT thin films were 1450 Angstrom/min for 30% Ar added the Cl-2/CF4 gas mixture with a mixing ratio of 8/2 and 1100 Angstrom/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 600 degreesC in an O-2 atmosphere. From the hysteresis curves and switching polarization, the reduction of the etching damage and the recovery due to the annealing is effective when O-2 is added to Cl-2/CF4 rather than Ar. From X-ray diffraction (XRD), the structural damage when O-2 is added to Cl-2/CF4 is reduced, and the improvement in the ferroelectric behavior of the annealed samples is consistent with the increased intensities of the (100) and the (200) PZT peaks. From X-ray photoelectron spectroscopy (XPS), the intensities of the Pb-O, the Zr-O, and the Ti-O peaks are changed and the chemical residue peaks are reduced due to O-2 annealing. The atomic force microscopy (AFM) images show that the surface roughnesses of annealed samples are improved after etching.