Zr-oxide film was deposited by remote plasma-enhanced atomic layer deposition (PEALD) and showed relatively low impurity contamination. In the Zr-oxide film deposition process, the plasma diagnostics were performed to investigate the effects and characteristics of O-2 remote plasma. The carbon contents in Zr-oxide film were decreased with increasing rf power. The electron density and optical emission of species were measured using cutoff and optical emission spectroscopy during the deposition. The electron density in O-2 remote plasma was about 7.8 x 10(9) to 2.1 x 10(10) cm(-3). The dominant emission species of O-2 remote plasma was the excited atomic and molecular oxygen. (C) 2005 The Electrochemical Society.