Ak. Chu et al., Deposition of polycrystalline AlN thin films by coherent magnetron sputtering at temperatures < 80 degrees C, J ELEC MAT, 30(1), 2001, pp. 1-5
AlN thin films were reactively deposited onto Al layers on negatively biase
d glass and Si substrates at temperatures < 80<degrees>C by coherent magnet
ron sputtering. The low temperature deposition of the films without substra
te heating was achieved by increasing the target-to-substrate distance, and
therefore the heating effect of the plasma is relieved. The microstructure
and morphology of the films deposited at, different bias voltage and targe
t-to-substrate distance were investigated. The films are amorphous when the
target is far from the substrate for a bias voltage up to -320 V. When the
target-to-substrate distance is decreased to 17 cm a preferred (002) orien
tation of AlN films is observed at a bias voltage of -240 V. Additionally,
the deposited films have specular reflectance and no voids can be observed.
This low temperature technique can be used for applications in acoustic wa
ve devices due to the improved homogeneity of the films and step coverage.