The chemistry of gate dielectric breakdown

Using scanning transmission electron microscope with high resolution electron energy loss spectroscopy, the chemical nature of the percolation path formed in ultrathin SiON layers is studied for digital and analog breakdown (BD). Our results show that the diameter of the percolation path dilates from 30 nm to 55 nm as the gate leakage current increases from 2 muA to 40 muA. Oxygen deficiency in the percolation path is radially distributed from the BD path center to its surrounding areas. The chemical composition in the center of percolation path changes from SiO_1.3 to SiO_1.0 as the BD path evolves from digital to analog BD.