[Zurück]

P Schmid, F. Triendl, C Zarfl, S. Schwarz, W. Artner, M. Schneider, U. Schmid:
"Influence of the AlN/Pt-ratio on the electro-mechanical properties ofmultilayered AlN/Pt thin film strain gauges at high temperatures";
Sensors and Actuators A: Physical, 302 (2020), S. 1 - 7.

tIn this work, the impact of the AlN/Pt ratio on the strain-sensitive properties of multilayered AlN/Ptthin films is investigated. These thin film systems consisting of 10 bi-layers of AlN and Pt each witha thickness of 3 nm AlN and 7 nm Pt or 5 nm AlN and 5 nm Pt are fabricated, evaluated and comparedto those realized with a sequence of 7 nm AlN and 3 nm Pt thin bi-layers. The thin film systems aresputter-deposited on oxidized silicon wafers or sapphire substrates. The influence of different annealingsteps at 900◦C up to 24 h in Argon (Ar) atmosphere on the electrical film resistivity and the temperaturecoefficient of the electrical resistance (TCR) is investigated for these different multilayers using Van-der-Pauw measurements up to 330◦C in air. Furthermore, the impact of the AlN/Pt-ratio on the gauge factorof the thermally stabilized multilayers is determined using a purpose-built measurement setup up to500◦C in air. Transmission electron microscopy and X-ray diffraction analyses are utilized to examine themicrostructure and the crystallographic phase composition of the multilayers before and after thermalloading. Annealing the different multilayers at 900◦C leads to diffusion effects between the AlN andPt thin films and recrystallizations processes in the Pt sublayers depending on the individual sublayerthickness values. After thermal pre-conditioning at 900◦C for 1 h in Ar the samples were stable even inair up to 500◦C. Finally, it is shown that the TCR as well as the gauge factor of an AlN/Pt multilayer can betuned through the AlN/Pt-ratio. The highest gauge factor with a value of 4.7 (±0.3) at room temperature isachieved with a multilayer consisting of 5 nm AlN and 5 nm Pt (pure Pt thin film on Cr adhesion promotor:3.2), while the lowest linear TCR with a value of = 7.4 · 10−4K-1is measured for multilayers with 7 nmAlN and 3 nm Pt sublayers (pure Pt thin film on Cr adhesion promotor: 3.66 · 10-3K-1).

http://dx.doi.org/10.1016/j.sna.2019.111805