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

•Direct observation of breakdown spots generation in metal-insulator-metal structures is demonstrated.•Recorded information (time-to-breakdown, location of spot) can be used for spatio-temporal statistical analysis.•The obtained results confirm spatio-temporal uncorrelation of the breakdown events in MIM devices. 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(30nm)/Pt structures based on image subtraction and thresholding is reported.