Study of sputtered hafnium oxide films for sensor applications

Results of the deposition and annealing of Hf oxide thin films are reported. Due to the sensor application in mind, thicknesses between 30 and 150 nm were deposited by r.f. sputtering of a high purity oxide target. Annealing has an important influence on the layer structure, stress and application correlated properties. A detailed understanding of the layer prepn. is necessary to adjust deposition and annealing. After deposition the layers are predominately amorphous, annealing leads to textured layers with monocline or orthorhombic phases. Besides gas sensor applications optimized layers may serve as protective coating or combined with a 2nd material to multi layer stacks as high reflective dielec. mirror.