Structure and mechanical properties of ZrO 2 films deposited by gas flow sputtering

Abstract

ZrO 2 films were deposited by reactive gas flow sputtering (GFS) where voltage is applied to a cyindrical hollow-cathode target from a DC source, the discharge being produced at relatively high sputtering pressure. In this system, secondary electrons form a major component of the total current flow and lead to heating of the substrate which in turn has an effect on the properties of deposited films. The present experiments were carried out under the following conditions: Ar gas flow rate of 200 sccm, O 2 flow rate F O 2 in the range between 0.003 and 1 sccm, and sputtering power ( P S) in the range of 50–800 W. The reults showed that the crystal structure of the films deposited for P S below 200 W was monoclinic but for P S above 400 W, the films included tetragonal cystals of stable structure formed at high temperature by the electron bombardment. The films were formed with grains of 20–100 nm in diameter in a porous structure. The mechanical properties of the films were determined by a nanoindentation technique. Martens hardness ( H M) of the porous films was found to be in the range between 220 and 330 MPa which is substantially less than that of films typically deposited by rf magnetron sputtering.