Impact of conductivity and size of the breakdown spot on the progressive-breakdown of thin SiO_2 gate oxides

摘要

In this work, for the first time, a conductive atomic force microscope has been used to electrically characterize the progressiveness of the breakdown phenomenon of stressed thin (2.9 and 4.2 nm) SiO_2 films at a nanometer scale. The extremely high lateral resolution of the technique allows to analyse independently the role of the oxide conductivity and the area of the breakdown (BD) spot. In particular, the results show that the gradual increase of the overall current that flows through the broken down oxide area is the consequence of the progressive growth of both parameters: the oxide conductivity at the location where BD was initially triggered and the size of the BD spot.