Evidence for compliance controlled oxygen vacancy and metal filament based resistive switching mechanisms in RRAM

We present electrical evidence on asymmetric metal–insulator–semiconductor (MIS) based test structures in support of the presence of two different independent switching mechanisms in a resistive random access memory (RRAM) device. The valid mechanism for switching depends on the compliance capping (Igl) for forming/SET transition. Our results convincingly show that low compliance based switching only involves reversible oxygen ion drift to and from oxygen gettering gate electrodes, while high compliance switching involves formation and rupture of conductive metallic nanofilaments, as verified further by our physical analysis investigations. We have observed this unique dual mode switching mechanism only in NiSi-based gate electrodes, which have a moderate oxygen solubility as well as relatively low melting point.

Use of an asymmetric M–I–S structure for RRAM to decode the switching mechanisms for low and high compliance capped SET transitions. Both electrical characterization and physical analysis has been performed.Figure optionsDownload as PowerPoint slideHighlights
► Metal–Insulator–Semiconductor (MIS) transistor with NiSi gate used as an RRAM.
► Two switching modes depending on compliance capping for SET transition identified.
► Switching mechanism for low compliance SET governed by oxygen ions and vacancies.
► High compliance SET is governed by metal nano-filament nucleation and rupture.
► Same RRAM can be used in dual switching modes with prolonged operational lifetime.