Direct observation of the generation of breakdown spots in MIM structures under constant voltage stress

Oxide reliability analysis in metal-insulator-metal and metal-insulator-semiconductor structures relies on electrical characterization methods like time-dependent dielectric breakdown (TDDB) tests. It has been demonstrated in previous studies that during a constant voltage TDDB test it is possible to detect the generation of multiple breakdown events in a single device. As we show in this paper, in some occasions, not only the time-to-breakdown but also the spatial location of each failure event over the device area can be recorded. This latest feature adds a new dimension to standard oxide reliability analysis since spatio-temporal statistics can be applied. A simple method for determining the generation rate and location of the breakdown spots in Pt/HfO₂(30 nm)/Pt structures based on image subtraction and thresholding is reported.