Cu Atom Switch With Steep Time-to-ON-State Versus Switching Voltage Using Cu Ionization Control

Abstract

To break the tradeoff relationship between fast and low-voltage programming of a Cu atom switch, the effect of the composition in the AlTi oxide buffer layer placed on a Cu electrode is investigated. To improve the voltage dependence of time-to-ON-state, namely, switching slope (SS), the Cu ionization rate is increased by changing the composition ratio of the AlTi oxide buffer. An Al 0.5 Ti 0.5 O y buffer leads to an extremely steep SS of 56 mV/decade by eliminating metallic Al residue on the Cu electrode. This buffer enables fast (10 ns) and lowvoltage (∼2 V) programming, as demonstrated in a 1-Mbit array. Cycle endurance (>10 3 cycles) with a high ON/ OFF resistance ratio (>10 4 ) was also confirmed. The steep SS technology is indispensable for conducting bridges used in a low-power nonvolatile field-programmable gate array.Index Terms-Atom switch, electrochemical reaction, fieldprogrammable gate array (FPGA), nonvolatile memory, polymer, reconfigurable logic, solid electrolyte.

Three-fold improved set-voltage variability of a Cu atom switch with a split electrode for very-large-scale integration

“…The buffer metal prevents the oxidation of Cu and changes to a metal oxide, playing the role of a solid electrolyte. 26,27) The PSE and a Ru alloy are deposited on the buffer. The PSE 5,6) contributes to the formfree programming.…”