Imaging of current paths and defects in Al and TiSi interconnects on very-large-scale integrated-circuit chips using near-field optical-probe stimulation and resulting resistance change

The optical-beam-induced resistance-change-detection (OBIRCH) method has been improved by using a near-field optical probe as the heat source instead of a laser beam. The near-field OBIRCH method has two advantages over the conventional one: (1) its spatial resolution is higher (50 vs 400 nm) and (2) the optical-probe-induced resistance change caused by heating can be observed using a metallized probe without interference from a photocurrent created by electron-hole-pair generation. In the conventional-OBIRCH method, the laser beam creates not only a resistance change, but also a photocurrent that can mask the resistance change signals.