In this study, we investigate the oxygen plasma-immersion-ion-implantation (PIII) treatment on the characteristics of tungsten nanocrystal (W-NC) nonvolatile memories. The oxygen PIII has multi-species plasma of O+, O++ and O-2(+), and the simulation can successfully fit the oxygen secondary ion mass spectrometry (SIMS) profile. It is observed that the oxygen PHI treatment can effectively improve the disturbance effect and endurance characteristics for over 1.5 V memory window under 10(4) program/erase cycling. The discrete W-NCs are clearly observed from the high-resolution transmission electron microscopy (HRTEM) image and confirmed by the energy-dispersive X-ray (EDX) analysis. Nevertheless, some damage of O-2 PIII on tunneling oxide and silicon surface may lead to the inadequate retention characteristics. By fine-tuning the plasma ions, the PIII technique can be applied into future nonvolatile memory manufacturing. (c) 2012 Elsevier Ltd. All rights reserved.