Polarity-dependent dielectric breakdown-induced epitaxy (DBIE) in Si MOSFETs

The physical evidence describing the structural deformation at the failure site of soft breakdowns (SBDs) in the 33-Angstrom and 25-Angstrom ultrathin gate oxide of narrow MOSFETs is reported. A hillock type epitaxial Si spot with size ranging from 2 to 100 nm associated with the gate-oxide breakdown failure is always found in the vicinity of the gate oxide and its formation depends strongly on the stress polarity. This epitaxial spot is believed to be induced by the breakdown event and this phenomenon can be named as polarity-dependent dielectric breakdown-induced epitaxy (DBIE).