RRAMs are considered as the most promising devices for NVM and storage class memory applications at technology nodes below 20nm. In addition, due to their memristive properties pave the way for the realization of neuromorphic prototype circuits. The majority of these devices are two-terminal MIM structures and use as insulator (active material) metal oxides in combination with proper metals. The present models assuming the oxide and metal physical and chemical properties seem that can explain the observed resistive phenomena. Nevertheless, the effect of humidity seems to play a crucial role in the reliability of RRAMs.

In this context, nitride based insulators are of special importance because of their immunity in humidity and oxygen related parasitic effects. The present contribution reports on the preliminary results related to our research on MIM devices where LPCVD Si₃N₄ is used as insulating material, sputtered Cu as active (top) electrode and heavily doped Si (<0.003 Ω.cm) bottom electrode (BE). Both conductivity types of Si n and p have been tested (Figure). The devices have been characterized in terms of static I-V, resistance variability, impedance spectroscopy (IS) and retention measurements. Room temperature I-V measurements suggest that a space charge limited conduction (SCLC) is dominating through the nitride layer. According to our results the MIM diodes with p⁺ Si as BE present higher variability in V_SET and V_RESET compare to those diodes with n⁺ Si BE. IS measurements are in progress to investigate the mechanism for resistance switching. Upon the current results, his mechanism may be attributed to the presence of diffusion process. Temperature variable measurements are currently contacted in order to identify the electronic or ionic nature of the diffusion mechanism. The fabricated devices exhibit attractive multi-state operation under different current compliance values. In addition, retention measurements at room temperature indicated that the LRS is retained for 10 yrs.