[Zurück]

M. Gillinger, M. Schneider, A. Bittner, P. Nicolay, U. Schmid:
"Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films";
Journal of Applied Physics, 117 (2015).

Aluminium nitride (AlN) is a promising material for challenging sensor applications such as
process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric
properties, its high temperature stability and good thermal match to silicon. Basically, the
operational temperature of piezoelectric materials is limited by the increase of the leakage current
as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses
on the characterization of aluminum nitride thin films after post deposition annealings up to
temperatures of 1000 C in harsh environments. For this purpose, thin film samples were
temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with
respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that
AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up
to 900 C. At 1000 C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable
up to 1000 C. The activation energy of the samples was determined from leakage current
measurements at different sample temperatures, in the range between 25 and 300 C. Up to an
annealing temperature of 700 C, the leakage current in the thin film is dominated by Poole-Frenkel
behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms
is observed.

Aluminium nitride (AlN) is a promising material for challenging sensor applications such as
process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric
properties, its high temperature stability and good thermal match to silicon. Basically, the
operational temperature of piezoelectric materials is limited by the increase of the leakage current
as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses
on the characterization of aluminum nitride thin films after post deposition annealings up to
temperatures of 1000 C in harsh environments. For this purpose, thin film samples were
temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with
respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that
AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up
to 900 C. At 1000 C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable
up to 1000 C. The activation energy of the samples was determined from leakage current
measurements at different sample temperatures, in the range between 25 and 300 C. Up to an
annealing temperature of 700 C, the leakage current in the thin film is dominated by Poole-Frenkel
behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms
is observed.

http://dx.doi.org/10.1063/1.4907208