High total dose tolerance of prototype silicon nanocrystal non-volatile memory cells

Abstract

Abstract-We report the first results pertinent to the high total dose tolerance of Si nanocrystal nonvolatile memory cells. The studied prototype nc-Si field effect transistors made by ion implantation retained virtually unchanged write/erase characteristics, typical for the two-state devices, to cumulative doses exceeding 15 Mrad(Si).Index Terms-Field effect transistors (FETs), nonvolatile memory (NVM).

Radiation Hardness of Flash and Nanoparticle Memories

“…All the programmed NC MOS capacitors undergo a bit flip 1→0 following irradiation, (Fig. 21b), in agreement with Petkov (Petkov et al, 2004) . If the oxide trapped charge is not removed from the oxide a permanent shift of the memory window would result, causing serious problems in reading the memory state.…”

“…The initial, dose dependent, radiation induced shift disappears gradually by increasing the voltage sweep. Therefore, the memory window of irradiated devices approaches the memory window of the unirradiated devices, as also reported by Petkov (Petkov et al, 2004). In particular it was found that the radiation induced oxide charge can be removed with 1 write or erase pulse as shown in Fig.…”

“…While some works already investigated the effect of ionizing radiation on FG Flash memories, until now, few works have investigated this issue in NC NVMs and will be briefly reviewed in the next. Petkov (Petkov et al, 2004) report the first results pertinent to the high total dose (TID) tolerance of Si nanocrystal NVM cells studying prototype NC-Si field effect transistors made by ion implantation. Si ions were implanted at 5 keV to a fluence of 1.3 10 16 cm -2 into a bare 15 nm-thick SiO 2 layer, grown on top of p-type doped Si wafer.…”

Nanocomposite SiO2(Si) films as a medium for non-volatile memory

“…Several techniques of nanocrystal formation have recently been developed based on chemical vapor deposition (CVD) of Si nanocrystals onto an oxidized Si substrate, ion implantation of Si or Ge into SiO 2 , annealing of a silicon-rich oxide, aerosol deposition, etc. [4].…”

Radiation-Induced Modifications of the Electrical Characteristics of Nanocrystal Memory Cells and Arrays

“…While some works already investigated the effect of ionizing radiation on FG Flash memories [14]- [17], until now, few works have investigated this issue in NCMs [18], [19]. Oldham, et al, [18] reported better resistance of NCMs under heavy-ion irradiation compared to Flash memories, without any degradation of the NCM cell retention characteristic.…”