A resistive
switching device with controlled formation and evolution
of conductive filament possesses great capability of being miniaturized
to atomic scale for the construction of high-density memory arrays
and even in-memory computing architectures. Although the switching
mechanism based on ion migration and electrochemistry has been clarified,
precise control of the evolution dynamics is still a challenge that
hinders the direct application of the memory devices. In this contribution,
we propose an effective scanning probe microscope tip-assisted approach
for the performance modulation of oxide-based resistive switching
devices. The directional migration of oxygen anions inside the hafnium
oxide nanofilm is regulated by using the voltage-biased scanning probe
microscope (SPM) tip as a microelectrode, so that a single filament
would be formed deliberately inside the switching matrix to greatly
improve the stability and reliability of the memory device. The variations
of the switching parameters, e.g. programming voltages and ON/OFF
resistances, have been reduced by at least 33%. More importantly,
the elaborate tuning of the filament dimension also gives rise to
single atomic point contact in the resistive switching device, producing
at least 16 half-integer multiples of quantized conductance states
that can be used for multilevel data storage and high-order neuromorphic
computing paradigm.