[Zurück]

M. Schneider, A. Bittner, A. Klein, U. Schmid:
"Impact of film thickness and temperature on the dielectric breakdown behavior of sputtered aluminum nitride thin films";
Microelectronic Engineering, 140 (2015), S. 47 - 51.

In micromachined devices, piezoelectric aluminum nitride (AlN) thin films are commonly used as functional material
for sensing and actuating purposes. Additionally, AlNfeatures a high chemical and thermal stability,making
it also a good choice for passivation purposes for microelectronic devices.With those aspects and current trends
towardsminimization inmind, the dielectric reliability of ultra-thin AlN films is of utmost importance for the realization
of advanced device concepts.
In this study, we present a systematic analysis of the transversal dielectric strength of sputtered AlN thin films of
varying film thickness (i.e. 70 nm to 400 nm) up to 300 °C. Using a time-zero approach, the dielectric strength is
measured by applying a voltage rampto stress the film up to the point of breakdown. The results are subsequently
analyzed using the Weibull approach.
For temperatures T N 180 °C, the characteristic breakdown field Eb,0 follows the relationship Eb, 0 ∼ T2,while showing
aweak temperature dependence below, thus indicating a transitory regime between thermally induced breakdown
at higher T and electrically induced breakdown at lower T. It is shown, that the characteristic breakdown field increases
at lower film thickness which is in good correlation with a corresponding decrease in leakage current.

In micromachined devices, piezoelectric aluminum nitride (AlN) thin films are commonly used as functional material
for sensing and actuating purposes. Additionally, AlNfeatures a high chemical and thermal stability,making
it also a good choice for passivation purposes for microelectronic devices.With those aspects and current trends
towardsminimization inmind, the dielectric reliability of ultra-thin AlN films is of utmost importance for the realization
of advanced device concepts.
In this study, we present a systematic analysis of the transversal dielectric strength of sputtered AlN thin films of
varying film thickness (i.e. 70 nm to 400 nm) up to 300 °C. Using a time-zero approach, the dielectric strength is
measured by applying a voltage rampto stress the film up to the point of breakdown. The results are subsequently
analyzed using the Weibull approach.
For temperatures T N 180 °C, the characteristic breakdown field Eb,0 follows the relationship Eb, 0 ∼ T2,while showing
aweak temperature dependence below, thus indicating a transitory regime between thermally induced breakdown
at higher T and electrically induced breakdown at lower T. It is shown, that the characteristic breakdown field increases
at lower film thickness which is in good correlation with a corresponding decrease in leakage current.

Aluminum nitride; Thin film; Dielectric breakdown; Time-zero approach; Weibull distribution

http://dx.doi.org/10.1016/j.mee.2015.06.001