Abstract
Our results show that the physical origin of the digital telegraph noise observed in the early stage of the progressive breakdown is originated from the defective oxide with low oxygen concentrations. The outer shells of the percolation path contribute significantly to the random switching of current levels as a result of the ON/OFF state of percolation path. The formation of a nanosize conductive Si path in the inner shell of the percolation path pushes the oxide to a high leakage state and suppresses the visibility of the digital noise.