Thin oxide degradation after high-energy ion irradiation

We have investigated the degradation induced by I- and Si-ions on 10- and 3-nm-thick oxide MOS capacitors. Ten-nanometer oxides were biased at low electric field (/spl les/3.3 MV/cm) during irradiation up to 100 Mrad(Si). DC radiation induced leakage current (RILC) has been observed after irradiation, and the differences of RILC characteristics between 10-nm and thinner oxides are discussed. In 10-nm oxides, RILC is attributed to multitrap assisted tunneling, which is reduced by subsequent Fowler-Nordheim electron injection. The density of the radiation-induced positive charged defect, the positive charge recombination by Fowler-Nordheim electron injection, and the negative charge trapping in radiation-induced neutral electron traps have been also addressed. On the other side, radiation-induced soft breakdown (RSB) is triggered by I-ions in 3-nm oxides at low doses (<1 krad(Si)) for moderate applied electric fields (4.4 MV/cm). Silicon ion irradiation is unable to produce RSB and RILC in 10-nm oxides, but it can generate a peculiar RILC in 3-nm oxides.