Investigations on the passivation of thin film flow sensors on flexible substrates

Characterization of aluminium nitride and aluminium oxide thin films sputter-deposited on organic substrates

“…12a, the surface characteristics of the aged polyimide/AlN/Al 2 O 3 assembly is shown. In contrast to investigations on pure Al 2 O 3 thin films (Schmid et al 2007) no failure of the passivation layer is observed demonstrating the good adhesion to the organic substrate due to the absence of any voids at the interface (see Fig. 12b).…”

“…During deposition, the oxygen content in the plasma was measured and controlled in a closed-loop, thus enhancing the reproducibility of targeted film properties using a so called plasma emission monitor. This optical add-on component works in the wavelength range of 185 to 650 nm and has a low reaction time below 20 ms (Schmid et al 2007 and reference cited herein). The back pressure in the deposition chamber was set to 2 · 10 -3 mbar and the argon flux to 60 sccm.…”

“…This finding suggests that the substrate nature has little impact on the film properties of the passivation layer. A sputtering power below 500 W is not recommended as the process time increases substantially to achieve a relevant film thickness of 500 nm or higher (Schmid et al 2007). In Fig.…”

“…To investigate the origin of void formation, pure aluminium thin films were sputter deposited on polyimide foils (Schmid et al 2007). Applying the FIB technique to study the interface quality, a sharp transition on the nanometer-range is displayed giving no indication that the presence of the pure argon-based plasma needed for the sputtering process generates the defects observed.…”