Dynamic Imaging of Current Conduction in Dielectric Films by Emission Microscopy

Real time images of the dielectric breakdown were shown in a movie produced by Emission Microscopy. We show that a faint light is emitted during current conduction through dielectric films. Current flows through a large area in an undamaged oxide. Upon breakdown the current flow immediately constricts into a tiny point. Current flow at asperities dances around between multiple asperities. This behavior can be understood as a result of electron trapping and detrapping in the vicinity of poly asperities. Emission Microscopy is the only known technique for viewing current localization at asperities. It is also the most sensitive and the fastest technique for locating oxide defects in VLSI products.