Resistive switching characteristics of Si₃N₄-based resistive-switching random-access memory cell with tunnel barrier for high density integration and low-power applications

In this letter, a bipolar resistive-switching random-access memory (RRAM) in Ni/Si₃N₄/SiO₂/p⁺-Si structure and its fabrication process are demonstrated. The proposed device with double-layer dielectrics consisting of Si₃N₄ layer (5 nm) as a resistive switching and SiO₂ (2.5 nm) layer for the tunnel barrier is investigated in comparison with that having a single layer of Si₃N₄. Double-layer cell shows ultra-low power operation under a compliance current (I_COMP) of 500 nA, which ensures the reset current (I_RESET) of sub-1 μA much lower than that of the single-layer cell. Also, large on/off ratio (∼10⁵) has been obtained since the SiO₂ layer efficiently suppresses the current in the high-resistance state. Moreover, maximum selectivity in double-layer cell is 122 when 1/2 read bias scheme is applied to the crossbar array. Highly nonlinear I-V characteristics of the double-layer Si₃N₄-based RRAM cell warrant the realization of selector-free RRAM cell in the crossbar array pursuing higher integration density.