VARIOUS PROPERTIES OF SPUTTER-DEPOSITED HFB2 FILMS

This paper discusses several structural, stress, electrical, and oxidation characteristics of planar dc-sputtered HfB2 films. Films deposited near room temperature are virtually amorphous while those made on substrates heated to ∼300°C have a very fine grain size (<200Å) and the hexagonal crystal structure characteristic of the bulk diboride. Limited but well-controlled grain growth occurs when films are heat-treated in the 400°–1200°C range and the electrical resistivity decreases inversely with increasing grain size. Film stress increases rapidly from small tensile values to roughly 6 × 1010 dynes/cm2 as the substrate bias during deposition is increased from 0 to −100 V. The modulus of elasticity was estimated from the stress (determined by substrate bowing) vs. strain (from lattice parameter) data and found to agree moderately well with the bulk value. The oxidation behavior of HfB2 films was established using electrical resistance, AES, and XPS measurements to analyze films oxidized in O2 at temperatures in the 300°–800°C range. The diboride films exhibited parabolic oxidation behavior and oxide growth rates in good agreement with extrapolated values obtained on bulk material at much higher temperatures. © 1990, The Electrochemical Society, Inc. All rights reserved.