Annealing behavior study on floating gate errors induced by γ followed by heavy ion irradiation

[Background] Flash memories have been widely used in many space systems because of their high density and non-volatility. The single event effect (SEE) and total ionizing dose (TID) of Flash memories are attracting more and more attentions. [Purpose] This study aims at the impact of total ionizing dose on annealing of floating gate errors induced by heavy ion irradiation. [Methods] The commercial single level cell (SLC) 25 nm NAND flash devices manufactured by Micron technology Inc. were selected for experimental study. TID irradiations were performed with ⁶⁰Co γ-rays at Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. Then heavy ion irradiations were conducted at the heavy ion research facility in Lanzhou (HIRFL) using three ion sources. [Results] The percentage of annealing error of samples previously irradiated with TID is very different from that of unirradiated samples. [Conclusions] The charge loss of floating gate (FG) and charge trapping in the tunnel oxide induced by γ-rays have great influence on the percentage of annealing error of FG cells. (authors)