Characterization of Porous BEOL Dielectrics for Resistive Switching

Porous back-end dielectric materials with porosity ranging from 8% to 25% have been characterized in terms of their resistive switching behavior. The porous dielectric is sandwiched between Cu and W or Pt electrodes. Some metal-insulator-metal structures have a 2 nm SiCN diffusion barrier at either electrode or at both electrodes. 90% of samples are intrinsically conductive due to strong Cu doping of the dielectric. About 10% of the samples display resistive switching behavior, of which devices with two SiCN barriers can be switched repeatedly, demonstrating that resistive switching in porous dielectrics is feasible. The forming voltage of the filaments increases with increasing porosity of the dielectric. Depending on the voltage polarity, Cu and oxygen vacancy conductive filaments can be formed. The properties of resistive switching established in this work provide a solid basis for further improvement of ReRAM devices based on porous dielectrics compatible with CMOS backend.