Universal Non-Polar Switching in Carbon-doped Transition Metal Oxides (TMOs) and Post TMOs

TL;DR

This paper demonstrates universal, non-volatile resistive switching in carbon-doped TMOs and PTMOs, with a new electronic switching model enabling high-temperature operation and integration into scalable, CMOS-compatible memory arrays.

Contribution

It introduces a spectroscopic understanding of carbon impurity states, a temperature-independent electronic switching mechanism, and demonstrates scalable integration into 1T1R arrays for advanced memory applications.

Findings

Switching is not thermally dependent, enabling high-temperature operation.

Achieved 1T1R arrays up to 1 kbit on 300 mm wafers.

Devices operate with 2 ns write pulses and retain states up to 200°C for 24 hours.

Abstract

Transition metal oxides (TMOs) and post-TMOs (PTMOs), when doped with Carbon, show non-volatile current-voltage (I-V) characteristics, which are both universal and repeatable. We have shown spectroscopic evidence of the introduction of carbon-based impurity states inside the existing larger bandgap effectively creating a smaller bandgap which we suggest could enable Mott-like correlation effect. Our findings indicate new insights for yet to be understood unipolar and nonpolar resistive switching in the TMOs and PTMOs. We have shown that device switching is not thermal-energy dependent and have developed an electronic-dominated switching model that allows for the extreme temperature operation (from 1.5 K to 423 K) and state retention up to 673 K for a 1-hour bake. Importantly, we have optimized the technology in an industrial process and demonstrated integrated 1-transistor/1-resistor (1T1R) arrays up to 1 kbit with 47 nm devices on 300 mm wafers for advanced node CMOS-compatible correlated electron RAM (CeRAM). These devices are shown to operate with 2 ns write pulses and retain the memory states up to 200 C for 24 hours. The collection of attributes shown, including scalability to state-of-the-art dimensions, non-volatile operation to extreme low and high temperatures, fast write, and reduced stochasticity as compared to filamentary memories such as ReRAMs show the potential for a highly capable two-terminal back-end-of-line non-volatile memory.