Failures in ultrathin oxides: Stored energy or carrier energy driven?

Oxide failure manifestation is reported to be even softer as the oxide thic kness scales downwards the SiO2 limits. In this context, this paper gives a useful clarification between quasi-breakdown and breakdown phenomena occur ring in ultrathin oxides. It is demonstrated that two failure modes, charac terized by noise occurrence and current increase take place: one called qua si-breakdown, which failure site may be aged up to a stable stage, generati ng a leakage current significantly smaller than the classical hard breakdow n and a second, the breakdown, which becomes more progressive with the oxid e thickness reduction. Moreover, physical reasons explaining these softer b ehaviors are discussed and it is shown that the energy stored in the capaci tor only impact the progressiveness of the failure site aging. On the contr ary, the carrier energy at the anode drives the failure and can conduct to one or the other failure mode. (C) 2001 Elsevier Science Ltd. All rights re served.