Plasma-induced damage in PZT thin films etched by inductively coupled plasma

Abstract

We investigated the etching damage induced by Ar/(Cl 2+CF 4) plasma and improvement in etching damage by O 2 annealing. PZT thin films were etched for 1 min in an ICP using a gas mixture of Cl 2 80%/CF 4 20% with 20% Ar addition. The etching conditions were fixed at a substrate temperature of 30 °C, RF power of 700 W, DC bias voltage of −200 V and a chamber pressure of 15 mTorr. To improve the ferroelectric properties of PZT thin films after etching, the samples were annealed for 10 min at 600 °C in O 2 atmosphere. After O 2 annealing, the remanent polarization-on-fatigue property was recovered to the characteristics of the as-deposited film. According to X-ray diffraction (XRD) analysis, an increase in (100) and (200) phases showed the improvement in structure of the PZT thin films after the O 2 annealing process. In addition, transmission electron microscope (TEM) images showed that the etched PZT surface is damaged by the bombardment of energetic particles, but that the damaged surface can be recovered by O 2 annealing. The results of electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) showed that O 2 annealing supports the substitution of oxygen vacancies on the PZT surface by O atoms. This decrease in oxygen vacancies improves the fatigue characteristics of PZT thin films.