Ultra compact electrochemical metallization cells offering reproducible atomic scale memristive switching

Abstract

Here we show electrochemical metallization cells with compact dimensions, excellent electrical performance, and reproducible characteristics. An advanced technology platform has been developed to obtain Ag/SiO 2 /Pt devices with ultra-scaled footprints (15 × 15 nm 2), inter-electrode distances down to 1 nm, and a transition from the OFF to ON resistance state relying on the relocation of only few atoms. This technology permits a well-controlled metallic filament formation in a highly confined field at the apex of an atomic scale tip. As a consequence of this miniaturization process, we achieve set voltages around 100 mV, ultrafast switching times of 7.5 ns, and write energies of 18 fJ. Furthermore, we demonstrate very good cell-to-cell uniformity and a resistance extinction ratio as high as 6 • 10 5. Combined abinitio quantum transport simulations and experiments suggest that the manufactured structures exhibit reduced self-heating effects due to their lower dimensions, making them very promising candidates as next-generation (non-)volatile memory components.

Nanosecond resistive switching in Ag/AgI/PtIr nanojunctions

“…They were directly followed by the onset of stable hysteretic traces without the need of any further dedicated electroforming procedure. We argue, that the indention of the tip to the surface layer reduces the effective thickness of the dielectric layer resulting in the down-scaling of the electroforming voltage to the range of the set voltage in agreement with the tendency commonly observed in nanoscale resistive switching systems [8,9,22]. Resistive switching was characterized by the analysis of hysteretic I(V) traces that were acquired by using the setup shown in the upper inset of Figure 1a.…”

“…(ii) The Fermi wavelength in these filaments falls in the regime of the interatomic distances granting metallic conductance also in this ultimate scaling limit. (iii) The device conductance is largely determined by the rearrangement of only a few atoms in this narrowest cross section, which can take place at a very large bandwidth and unprecedentedly low energy cost [5][6][7][8][9]. Furthermore, since such rearrangements are subject to activated processes, the induced conductance changes are typically non-volatile at sub-threshold electric fields.…”

Thermal scanning probe lithography—a review

“…b Molding of various soft transparent polymers directly from the patterned resist, as well as galvanic plating of metals, is possible 31,60 . c Direct use of the patterned resist as an etch mask allows etch transfer (wet or dry etch) of 2D and 3D features into various materials 54,61,[63][64][65] . d A second layer under the temperature-sensitive resist can be used to amplify the final etch depth as well as for 3D features 67,66 .…”

“…4d). The resulting memristive device forms an atomistic metal filament between the electrodes allowing reliable switching at low voltages of 100 mV with operation speeds in the nanosecond range 65 . Such sharp 3D top contacts are increasingly relevant for many nanoelectronic devices.…”

“…d Atomic scale memristor devices fabricated by etching a cone-shaped t-SPL indent from PPA into SiO 2 . Adapted under CC BY 4.0 License from ref 65 ,. Copyright 2019 Springer Nature.…”