1 - Erich Schmid Institute

D.3 Results
Figure D.5: SEM picture of the loading of cantilever 3 by means of the in-situ microindenter (front
view). The bright hump 10µm left of the indenter tip is the FIB-deposited tungsten mark
necessary for the exact positioning of the indenter in the mirror plane of the cantilever.
D.3 Results
The as-recorded as well as the corrected load-deflection-curves show perfect linear behaviour
until fracture for all cantilevers tested as depicted in Fig.D.6 for cantilever
1 (without pre-crack), for example. Owing to the substrate thickness of 8.7µm, this
cantilever is relatively stiff, which leads to a significant penetration of the indenter tip
and therefore to a remarkable difference between the two curves. The corrected loaddeflection-curves
of all eight cantilevers tested are depicted in Fig.D.7.
Figure D.6: As-recorded and corrected load-deflection-curve for cantilever 1. The corrected curve describes
solely the force necessary to deflect the cantilever, whereas the as-recorded curve
considers additionally the contribution of the penetration of the indenter tip into the thin
film. This contribution can be neglected in case of cantilevers with thin substrates, where
only small forces are necessary to produce a certain amount of bending, which leads to
shallow indents.
The deflection resulting from loading, the load at fracture and the corresponding deflection
as well as the loading distance between the indenter tip and the cantilever origin
are listed in Table D.3.
The investigation of the fractured cantilevers shows that the notched cantilevers fractured
exactly at the FIB-fabricated pre-crack, whereas the cantilevers without pre-crack
fail in vicinity of the cantilever origin as depictured in Fig.D.8.
The fracture stress of the TiN film is determined from the cantilevers without notch by
D–7
D