A study of charge neutralization method during high current ion implantation for ultra thin gate dielectrics

Ultra thin gate oxide breakdown due to excess electrons supplied by charge neutralization system such as plasma flood system (PFS) is discussed. For the ultra thin gate oxide below 5 nm, the oxide breakdown due to not only positive charge build-up by ions but also negative charge build-up by PFS becomes noticeable. The maximum energy of electrons from PFS dominates the oxide breakdown instead of total electron flux. For the 3.5 nm gate oxide, maximum electron energy should not exceed 9 eV to suppress the breakdown. For the ultra thin gate dielectrics, the energy control of electron is most important to suppress the oxide breakdown by excess electrons from PFS.