High-Performance In₂O₃-Based 1T1R FET for BEOL Memory Application

In this article, we report high-performance one-transistor-one-resistor (1T1R) FETs for nonvolatile memory application based on nanometer-thick indium oxide (In2O3) as channel material deposited by atomic layer deposition (ALD). ALD grown hafnium oxide (HfO2) and aluminum oxide (Al2O3) are used as gate dielectrics as well as insulator in resistive part. Two nonvolatile states with different threshold voltages are realized. High ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}} > 10^{10}$ at ${V}_{\mathrm {GS}} =0$ V, large memory window (MW) exceeding 10 V, and deep sub-60-mV/dec subthreshold slope (SS) are achieved on ALD In2O3 1T1R FETs. Channel length ( ${L}_{\mathrm {ch}}$ ) and channel thickness ( ${T}_{\mathrm {ch}}$ ) dependence of device properties are systematically investigated. Optimized In2O3 thickness is determined to 1.2 nm, balancing ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ , MW, device variation, and stability. The fabrication process has a low thermal budget below 225 °C. Thus, these 1T1R FETs are back-end-of-line (BEOL) compatible and promising for monolithic 3-D integration to realize near-/in-memory computing.