Structure and conductance of the breakdown spot during the early stages of progressive breakdown

It has been shown that under accelerated stress at relatively low voltage thin gate oxides are subjected to the phenomenon of progressive breakdown (BD), which consists in a progressive growth of the BD spot. In this work, we investigate the conduction mechanisms of the BD spot through the measurement of the I-V characteristics using carrier separation coupled with modelling based on the concept of either co-tunneling or tunnelling through a thinned oxide region. These models are compared to direct TEM observations.