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The characteristics of the switching oxide defects in the HfOx based resistive random access memory (RRAM) device are studied. The forming step is performed to bring the low leakage fresh device to a higher current level (low resistance state) by introducing the oxygen vacancy filament, awaking the switching capability. A subsequent reset sweeping is able to convert the device from low resistance state to high resistance state. Experimental results show that on the TiN/HfO2/TiN device sample, the high resistance state current triggered by the reset sweeping is several orders higher than the fresh device leakage, indicating that majority of the forming generated oxide defects in the conductive filament are un-switchable and resulting in a marginal memory window. Whereas on the TiN/HfO2/Pt sample, the high resistance current can be brought back to pre-forming leakage level though reset sweeping, implying that almost all the defects in the CF are switchable and achieving a huge memory window. Our corresponding simulation work gives evidence that a proper configuration of the oxide defects generated during the forming step that is the necessity to ensure the switching capability of the oxide defects, and under the Pt-mediated condition, the generation of the switching oxide defects is facilitated by a more controllable forming process.

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