Role of CMOS Back-End Metals as Active Electrodes for Resistive Switching in ReRAM Cells

Abstract

With the goal to render the ReRAM memory integrable with CMOS backend and compatible with current BEOL metal choices (Cu, Ta, Ti, W), we have chosen the well-behaved and well-characterized Cu/TaO x /Pt ReRAM cell as a benchmark device and have replaced the active (Cu) and inert (Pt) electrodes with Ta and Ti electrodes. Five derivative devices were manufactured including: Pt/TaO x /Pt, Cu/TaO x /Ti, Cu/TaO x /Ta, Ta/TaO x /Pt, and Ti/TaO x /Pt. Out of these five devices, only the Ti/TaO x /Pt produced reliable set and reset switching characteristics. Nevertheless, the switching behavior of the other derivative devices provides a great deal of insight into the formation, shape and rupture of conductive filaments in ReRAM devices which would be difficult to gain otherwise from only one type of a device. The present findings are compared with results on the same and similar devices reported elsewhere in the literature.

High-precision and linear weight updates by subnanosecond pulses in ferroelectric tunnel junction for neuro-inspired computing

“…In addition, the utilization of metal electrode with low work function, such as Ag ~4.26 eV, is also beneficial to reduce the operation voltage. To investigate the effect of electrode on the FTJ performance, FTJ devices with other electrodes including Cu (CMOS-compatible 49 ) and Pt were studied, as shown in Supplementary Fig. S4 and Table S2 .…”

Performance Degradation of Nanofilament Switching Due to Joule Heat Dissipation

“…The thickness of TaO x was 25 nm. The thickness of the TaO x on the sloped sidewalls of the Pt line was 98% of the planar thickness as confirmed by Ta 2 O 5 atomic layer cells manufactured with Ta 2 O 5 deposition by atomic layer deposition (ALD) [16]. The oxygen-deficient TaO x (x ≈ 1.9) was also deposited in the PVD-250 chamber by evaporating Ta 2 O 5 pellets without O 2 injection into the evaporation chamber.…”

“…The oxygen-deficient TaO x (x ≈ 1.9) was also deposited in the PVD-250 chamber by evaporating Ta 2 O 5 pellets without O 2 injection into the evaporation chamber. The details of the sample manufacturing process were given in Reference [16], where the role of the parameter x in TaO x (as opposed to the stoichiometric Ta 2 O 5 ) on resistive switching properties was discussed in detail. The width of metal lines varies between 5 µm and 35 µm resulting in rectangular device areas of the device in the range of (5 to 5) × (35 to 35) µm 2 .…”

Electric conductivity of remotely heated Cu nanofilaments in Cu/TaOx/Pt ReRAM cells

“…The Cu/TaO x /Pt/Ti resistive RAM cell arrays [Fig. 1(a)] have been fabricated in a crossbar array on a thermally oxidized Si wafer 16 with a SiO 2 layer 650 nm thick. Cu (150 nm), Pt (50 nm), and Ti (25 nm) have been deposited by e-beam PVD.…”