Improved Switching Voltage Variation of Cu Atom Switch for Nonvolatile Programmable Logic

Switching voltage variation of a Cu atom switch (AS) is improved to δ = 9.5 % by adjusting the buffer oxidation state and electrode surface roughness. The complementary AS (CAS) connects two Cu lines at each edge and is composed of a dual-layered electrolyte of oxidized Ti buffer metal/polymer solid electrolyte. A sufficiently oxidized Ti buffer layer prevents both Cu oxidation and Ti diffusion during the fabrication processes, reducing the OFF-state leakage current and making the ON/OFF current ratio high. A dry cleaning process reduces the Cu electrode surface roughness, tightening the set voltage distribution and enabling the use of a low programming voltage, 1.8 V. A large-scale crossbar switch block consisting of CASs has been operated by the improved switches.